#include "config.h"#include "system.h"#include "coretypes.h"#include "tm.h"#include "rtl-error.h"#include "tm_p.h"#include "insn-config.h"#include "expr.h"#include "optabs.h"#include "recog.h"#include "df.h"#include "reload.h"#include "regs.h"#include "addresses.h"#include "hard-reg-set.h"#include "flags.h"#include "function.h"#include "params.h"#include "target.h"#include "ira.h"
Data Structures | |
| struct | replacement |
| struct | decomposition |
Macros | |
| #define | REG_OK_STRICT |
| #define | CONST_POOL_OK_P(MODE, X) |
| #define | MATCHES(x, y) |
| #define | MERGABLE_RELOADS(when1, when2, op1, op2) |
| #define | MERGE_TO_OTHER(when1, when2, op1, op2) |
| #define | ADDR_TYPE(type) |
| #define | REG_OK_FOR_CONTEXT(CONTEXT, REGNO, MODE, AS, OUTER, INDEX) |
| #define | reg_inc_found_and_valid_p(regno, endregno, insn) 0 |
Functions | |
| static bool | small_register_class_p () |
| static int | push_secondary_reload (int, rtx, int, int, enum reg_class, enum machine_mode, enum reload_type, enum insn_code *, secondary_reload_info *) |
| static enum reg_class | find_valid_class (enum machine_mode, enum machine_mode, int, unsigned int) |
| static void | push_replacement (rtx *, int, enum machine_mode) |
| static void | dup_replacements (rtx *, rtx *) |
| static void | combine_reloads (void) |
| static int | find_reusable_reload (rtx *, rtx, enum reg_class, enum reload_type, int, int) |
| static rtx | find_dummy_reload (rtx, rtx, rtx *, rtx *, enum machine_mode, enum machine_mode, reg_class_t, int, int) |
| static int | hard_reg_set_here_p (unsigned int, unsigned int, rtx) |
| static struct decomposition | decompose (rtx) |
| static int | immune_p (rtx, rtx, struct decomposition) |
| static bool | alternative_allows_const_pool_ref (rtx, const char *, int) |
| static rtx | find_reloads_toplev (rtx, int, enum reload_type, int, int, rtx, int *) |
| static rtx | make_memloc (rtx, int) |
| static int | maybe_memory_address_addr_space_p (enum machine_mode, rtx, addr_space_t, rtx *) |
| static int | find_reloads_address (enum machine_mode, rtx *, rtx, rtx *, int, enum reload_type, int, rtx) |
| static rtx | subst_reg_equivs (rtx, rtx) |
| static rtx | subst_indexed_address (rtx) |
| static void | update_auto_inc_notes (rtx, int, int) |
| static int | find_reloads_address_1 (enum machine_mode, addr_space_t, rtx, int, enum rtx_code, enum rtx_code, rtx *, int, enum reload_type, int, rtx) |
| static void | find_reloads_address_part (rtx, rtx *, enum reg_class, enum machine_mode, int, enum reload_type, int) |
| static rtx | find_reloads_subreg_address (rtx, int, enum reload_type, int, rtx, int *) |
| static void | copy_replacements_1 (rtx *, rtx *, int) |
| static int | find_inc_amount (rtx, rtx) |
| static int | refers_to_mem_for_reload_p (rtx) |
| static int | refers_to_regno_for_reload_p (unsigned int, unsigned int, rtx, rtx *) |
| static void | push_reg_equiv_alt_mem () |
| reg_class_t | secondary_reload_class (bool in_p, reg_class_t rclass, enum machine_mode mode, rtx x) |
| enum reg_class | scratch_reload_class () |
| static enum reg_class | find_valid_class_1 (enum machine_mode outer, enum machine_mode mode, enum reg_class dest_class) |
| static bool | reload_inner_reg_of_subreg () |
| static int | can_reload_into () |
| int | push_reload (rtx in, rtx out, rtx *inloc, rtx *outloc, enum reg_class rclass, enum machine_mode inmode, enum machine_mode outmode, int strict_low, int optional, int opnum, enum reload_type type) |
| static void | push_replacement () |
| static void | dup_replacements () |
| void | transfer_replacements () |
| int | remove_address_replacements () |
| int | earlyclobber_operand_p () |
| static int | hard_reg_set_here_p () |
| int | strict_memory_address_addr_space_p (enum machine_mode mode, rtx addr, addr_space_t as) |
| int | operands_match_p () |
| static struct decomposition | decompose () |
| static int | immune_p () |
| int | safe_from_earlyclobber () |
| int | find_reloads (rtx insn, int replace, int ind_levels, int live_known, short *reload_reg_p) |
| static rtx | make_memloc () |
| static rtx | subst_reg_equivs () |
| rtx | form_sum () |
| static rtx | subst_indexed_address () |
| void | subst_reloads () |
| void | copy_replacements () |
| static void | copy_replacements_1 () |
| void | move_replacements () |
| rtx | find_replacement () |
| int | reg_overlap_mentioned_for_reload_p () |
| static int | refers_to_mem_for_reload_p () |
| rtx | find_equiv_reg (rtx goal, rtx insn, enum reg_class rclass, int other, short *reload_reg_p, int goalreg, enum machine_mode mode) |
| static int | find_inc_amount () |
| int | regno_clobbered_p (unsigned int regno, rtx insn, enum machine_mode mode, int sets) |
| rtx | reload_adjust_reg_for_mode () |
| DEBUG_FUNCTION void | debug_reload_to_stream () |
| DEBUG_FUNCTION void | debug_reload () |
Variables | |
| int | n_reloads |
| struct reload | rld [MAX_RELOADS] |
| int | n_earlyclobbers |
| rtx | reload_earlyclobbers [MAX_RECOG_OPERANDS] |
| int | reload_n_operands |
| static int | replace_reloads |
| static struct replacement | replacements [MAX_RECOG_OPERANDS *((MAX_REGS_PER_ADDRESS *2)+1)] |
| static int | n_replacements |
| static rtx | this_insn |
| static int | this_insn_is_asm |
| static int | hard_regs_live_known |
| static short * | static_reload_reg_p |
| static int | subst_reg_equivs_changed |
| static int | output_reloadnum |
| static const char *const | reload_when_needed_name [] |
Macro Definition Documentation
| #define ADDR_TYPE | ( | type | ) |
If we are going to reload an address, compute the reload type to use.
| #define CONST_POOL_OK_P | ( | MODE, | |
| X | |||
| ) |
We do not enable this with ENABLE_CHECKING, since it is awfully slow. True if X is a constant that can be forced into the constant pool. MODE is the mode of the operand, or VOIDmode if not known.
| #define MATCHES | ( | x, | |
| y | |||
| ) |
Compare two RTX's.
Referenced by find_valid_class_1().
| #define MERGABLE_RELOADS | ( | when1, | |
| when2, | |||
| op1, | |||
| op2 | |||
| ) |
Indicates if two reloads purposes are for similar enough things that we can merge their reloads.
Referenced by find_valid_class_1().
| #define MERGE_TO_OTHER | ( | when1, | |
| when2, | |||
| op1, | |||
| op2 | |||
| ) |
Nonzero if these two reload purposes produce RELOAD_OTHER when merged.
| #define reg_inc_found_and_valid_p | ( | regno, | |
| endregno, | |||
| insn | |||
| ) | 0 |
Return 1 if registers from REGNO to ENDREGNO are the subjects of a REG_INC note in insn INSN. REGNO must refer to a hard register.
| #define REG_OK_FOR_CONTEXT | ( | CONTEXT, | |
| REGNO, | |||
| MODE, | |||
| AS, | |||
| OUTER, | |||
| INDEX | |||
| ) |
| #define REG_OK_STRICT |
Search an insn for pseudo regs that must be in hard regs and are not. Copyright (C) 1987-2013 Free Software Foundation, Inc.
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3, or (at your option) any later version.
GCC is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with GCC; see the file COPYING3. If not see http://www.gnu.org/licenses/. This file contains subroutines used only from the file reload1.c. It knows how to scan one insn for operands and values that need to be copied into registers to make valid code. It also finds other operands and values which are valid but for which equivalent values in registers exist and ought to be used instead.
Before processing the first insn of the function, call `init_reload'. init_reload actually has to be called earlier anyway.
To scan an insn, call `find_reloads'. This does two things:
- sets up tables describing which values must be reloaded for this insn, and what kind of hard regs they must be reloaded into;
- optionally record the locations where those values appear in the data, so they can be replaced properly later. This is done only if the second arg to `find_reloads' is nonzero.
The third arg to `find_reloads' specifies the number of levels of indirect addressing supported by the machine. If it is zero, indirect addressing is not valid. If it is one, (MEM (REG n)) is valid even if (REG n) did not get a hard register; if it is two, (MEM (MEM (REG n))) is also valid even if (REG n) did not get a hard register, and similarly for higher values.
Then you must choose the hard regs to reload those pseudo regs into, and generate appropriate load insns before this insn and perhaps also store insns after this insn. Set up the array `reload_reg_rtx' to contain the REG rtx's for the registers you used. In some cases `find_reloads' will return a nonzero value in `reload_reg_rtx' for certain reloads. Then that tells you which register to use, so you do not need to allocate one. But you still do need to add extra instructions to copy the value into and out of that register.
Finally you must call `subst_reloads' to substitute the reload reg rtx's into the locations already recorded.
NOTE SIDE EFFECTS:
find_reloads can alter the operands of the instruction it is called on.
- Two operands of any sort may be interchanged, if they are in a commutative instruction. This happens only if find_reloads thinks the instruction will compile better that way.
- Pseudo-registers that are equivalent to constants are replaced with those constants if they are not in hard registers.
1 happens every time find_reloads is called. 2 happens only when REPLACE is 1, which is only when actually doing the reloads, not when just counting them.
Using a reload register for several reloads in one insn:
When an insn has reloads, it is considered as having three parts: the input reloads, the insn itself after reloading, and the output reloads. Reloads of values used in memory addresses are often needed for only one part.
When this is so, reload_when_needed records which part needs the reload. Two reloads for different parts of the insn can share the same reload register.
When a reload is used for addresses in multiple parts, or when it is an ordinary operand, it is classified as RELOAD_OTHER, and cannot share a register with any other reload.
Function Documentation
|
static |
Return true if alternative number ALTNUM in constraint-string CONSTRAINT is guaranteed to accept a reloaded constant-pool reference. MEM gives the reference if it didn't need any reloads, otherwise it is null.
Skip alternatives before the one requested.
Scan the requested alternative for TARGET_MEM_CONSTRAINT or 'o'. If one of them is present, this alternative accepts the result of passing a constant-pool reference through find_reloads_toplev. The same is true of extra memory constraints if the address was reloaded into a register. However, the target may elect to disallow the original constant address, forcing it to be reloaded into a register instead.
|
static |
Return nonzero if IN can be reloaded into REGNO with mode MODE without requiring an extra reload register. The caller has already found that IN contains some reference to REGNO, so check that we can produce the new value in a single step. E.g. if we have (set (reg r13) (plus (reg r13) (const int 1))), and there is an instruction that adds one to a register, this should succeed. However, if we have something like (set (reg r13) (plus (reg r13) (const int 999))), and the constant 999 needs to be loaded into a register first, we need a separate reload register. Such PLUS reloads are generated by find_reload_address_part. The out-of-range PLUS expressions are usually introduced in the instruction patterns by register elimination and substituting pseudos without a home by their function-invariant equivalences.
For matching constraints, we often get notional input reloads where we want to use the original register as the reload register. I.e. technically this is a non-optional input-output reload, but IN is already a valid register, and has been chosen as the reload register. Speed this up, since it trivially works.
To test MEMs properly, we'd have to take into account all the reloads that are already scheduled, which can become quite complicated. And since we've already handled address reloads for this MEM, it should always succeed anyway.
If we can make a simple SET insn that does the job, everything should be fine.
References gcc_assert, GET_CODE, GET_MODE, MEM_P, NULL_RTX, reg_equiv_constant, REG_P, reg_renumber, REGNO, replace_equiv_address_nv(), rtx_equal_p(), and XEXP.
|
static |
If there is only one output reload, and it is not for an earlyclobber operand, try to combine it with a (logically unrelated) input reload to reduce the number of reload registers needed.
This is safe if the input reload does not appear in the value being output-reloaded, because this implies it is not needed any more once the original insn completes.
If that doesn't work, see we can use any of the registers that die in this insn as a reload register. We can if it is of the right class and does not appear in the value being output-reloaded.
Find the output reload; return unless there is exactly one and that one is mandatory.
An input-output reload isn't combinable.
If this reload is for an earlyclobber operand, we can't do anything.
If there is a reload for part of the address of this operand, we would need to change it to RELOAD_FOR_OTHER_ADDRESS. But that would extend its life to the point where doing this combine would not lower the number of spill registers needed.
Check each input reload; can we combine it?
Life span of this reload must not extend past main insn.
Args reversed because the first arg seems to be
the one that we imagine being modified
while the second is the one that might be affected. However, if the input is a register that appears inside
the output, then we also can't share.
Imagine (set (mem (reg 69)) (plus (reg 69) ...)).
If the same reload reg is used for both reg 69 and the
result to be stored in memory, then that result
will clobber the address of the memory ref. We will allow making things slightly worse by combining an
input and an output, but no worse than that. We have found a reload to combine with!
Mark the old output reload as inoperative.
The combined reload is needed for the entire insn.
If the output reload had a secondary reload, copy it.
If required, minimize the register class.
Transfer all replacements from the old reload to the combined.
If this insn has only one operand that is modified or written (assumed to be the first), it must be the one corresponding to this reload. It is safe to use anything that dies in this insn for that output provided that it does not occur in the output (we already know it isn't an earlyclobber. If this is an asm insn, give up.
See if some hard register that dies in this insn and is not used in the output is the right class. Only works if the register we pick up can fully hold our output reload.
Ensure that a secondary or tertiary reload for this output
won't want this register. Check that a former pseudo is valid; see find_dummy_reload.
| void copy_replacements | ( | ) |
Make a copy of any replacements being done into X and move those copies to locations in Y, a copy of X.
Referenced by set_storage_via_setmem().
|
static |
References reg_overlap_mentioned_for_reload_p(), rtx_equal_p(), SET_DEST, SET_SRC, single_set, and true_regnum().
| DEBUG_FUNCTION void debug_reload | ( | void | ) |
| DEBUG_FUNCTION void debug_reload_to_stream | ( | ) |
These functions are used to print the variables set by 'find_reloads'
|
staticread |
Referenced by operands_match_p().
|
staticread |
Describe the range of registers or memory referenced by X. If X is a register, set REG_FLAG and put the first register number into START and the last plus one into END. If X is a memory reference, put a base address into BASE and a range of integer offsets into START and END. If X is pushing on the stack, we can assume it causes no trouble, so we set the SAFE field.
A pseudo with no hard reg.
A hard reg.
This could be more precise, but it's good enough.
A hard reg.
This hasn't been assigned yet, so it can't conflict yet.
|
static |
Duplicate any replacement we have recorded to apply at location ORIG_LOC to also be performed at DUP_LOC. This is used in insn patterns that use match_dup.
| int earlyclobber_operand_p | ( | ) |
This page contains subroutines used mainly for determining whether the IN or an OUT of a reload can serve as the reload register. Return 1 if X is an operand of an insn that is being earlyclobbered.
Referenced by find_valid_class_1(), and reloads_unique_chain_p().
|
static |
Try to find a reload register for an in-out reload (expressions IN and OUT). See if one of IN and OUT is a register that may be used; this is desirable since a spill-register won't be needed. If so, return the register rtx that proves acceptable.
INLOC and OUTLOC are locations where IN and OUT appear in the insn. RCLASS is the register class required for the reload.
If FOR_REAL is >= 0, it is the number of the reload, and in some cases when it can be discovered that OUT doesn't need to be computed, clear out rld[FOR_REAL].out.
If FOR_REAL is -1, this should not be done, because this call is just to see if a register can be found, not to find and install it.
EARLYCLOBBER is nonzero if OUT is an earlyclobber operand. This puts an additional constraint on being able to use IN for OUT since IN must not appear elsewhere in the insn (it is assumed that IN itself is safe from the earlyclobber).
If operands exceed a word, we can't use either of them unless they have the same size.
Note that {in,out}_offset are needed only when 'in' or 'out'
respectively refers to a hard register. Find the inside of any subregs.
Narrow down the reg class, the same way push_reload will; otherwise we might find a dummy now, but push_reload won't.
See if OUT will do.
When we consider whether the insn uses OUT,
ignore references within IN. They don't prevent us
from copying IN into OUT, because those refs would
move into the insn that reloads IN.
However, we only ignore IN in its role as this reload.
If the insn uses IN elsewhere and it contains OUT,
that counts. We can't be sure it's the "same" operand
so it might not go through this reload.
We also need to avoid using OUT if it, or part of it, is a
fixed register. Modifying such registers, even transiently,
may have undefined effects on the machine, such as modifying
the stack pointer. Consider using IN if OUT was not acceptable or if OUT dies in this insn (like the quotient in a divmod insn). We can't use IN unless it is dies in this insn, which means we must know accurately which hard regs are live. Also, the result can't go in IN if IN is used within OUT, or if OUT is an earlyclobber and IN appears elsewhere in the insn.
The only case where out and real_out might
have different modes is where real_out
is a subreg, and in that case, out
has a real mode. However only do this if we can be sure that this input
operand doesn't correspond with an uninitialized pseudo.
global can assign some hardreg to it that is the same as
the one assigned to a different, also live pseudo (as it
can ignore the conflict). We must never introduce writes
to such hardregs, as they would clobber the other live
pseudo. See PR 20973. Similarly, only do this if we can be sure that the death
note is still valid. global can assign some hardreg to
the pseudo referenced in the note and simultaneously a
subword of this hardreg to a different, also live pseudo,
because only another subword of the hardreg is actually
used in the insn. This cannot happen if the pseudo has
been assigned exactly one hardreg. See PR 33732. If we were going to use OUT as the reload reg
and changed our mind, it means OUT is a dummy that
dies here. So don't bother copying value to it.
References gen_rtx_REG(), reg_class_contents, REG_P, and TEST_HARD_REG_BIT.
| rtx find_equiv_reg | ( | rtx | goal, |
| rtx | insn, | ||
| enum reg_class | rclass, | ||
| int | other, | ||
| short * | reload_reg_p, | ||
| int | goalreg, | ||
| enum machine_mode | mode | ||
| ) |
Check the insns before INSN to see if there is a suitable register containing the same value as GOAL. If OTHER is -1, look for a register in class RCLASS. Otherwise, just see if register number OTHER shares GOAL's value.
Return an rtx for the register found, or zero if none is found.
If RELOAD_REG_P is (short *)1, we reject any hard reg that appears in reload_reg_rtx because such a hard reg is also needed coming into this insn.
If RELOAD_REG_P is any other nonzero value, it is a vector indexed by hard reg number and we reject any hard reg whose element in the vector is nonnegative as well as any that appears in reload_reg_rtx.
If GOAL is zero, then GOALREG is a register number; we look for an equivalent for that register.
MODE is the machine mode of the value we want an equivalence for. If GOAL is nonzero and not VOIDmode, then it must have mode MODE.
This function is used by jump.c as well as in the reload pass.
If GOAL is the sum of the stack pointer and a constant, we treat it as if it were a constant except that sp is required to be unchanging.
An address with side effects must be reexecuted.
Scan insns back from INSN, looking for one that copies
a value into or out of GOAL.
Stop and give up if we reach a label.
Don't reuse register contents from before a setjmp-type
function call; on the second return (from the longjmp) it
might have been clobbered by a later reuse. It doesn't
seem worthwhile to actually go and see if it is actually
reused even if that information would be readily available;
just don't reuse it across the setjmp call. If we don't want spill regs ...
... then ignore insns introduced by reload; they aren't
useful and can cause results in reload_as_needed to be
different from what they were when calculating the need for
spills. If we notice an input-reload insn here, we will
reject it below, but it might hide a usable equivalent.
That makes bad code. It may even fail: perhaps no reg was
spilled for this insn because it was assumed we would find
that equivalent. First check for something that sets some reg equal to GOAL.
When looking for stack pointer + const,
make sure we don't use a stack adjust. If we are looking for a constant,
and something equivalent to that constant was copied
into a reg, we can use that reg. We found a previous insn copying GOAL into a suitable other reg VALUE (or copying VALUE into GOAL, if GOAL is also a register). Now verify that VALUE is really valid.
VALUENO is the register number of VALUE; a hard register.
Don't try to re-use something that is killed in this insn. We want to be able to trust REG_UNUSED notes.
If we propose to get the value from the stack pointer or if GOAL is a MEM based on the stack pointer, we need a stable SP.
Reject VALUE if the copy-insn moved the wrong sort of datum.
Reject VALUE if it was loaded from GOAL and is also a register that appears in the address of GOAL.
Reject registers that overlap GOAL.
Reject VALUE if it is one of the regs reserved for reloads. Reload1 knows how to reuse them anyway, and it would get confused if we allocated one without its knowledge. (Now that insns introduced by reload are ignored above, this case shouldn't happen, but I'm not positive.)
Reject VALUE if it is a register being used for an input reload even if it is not one of those reserved.
We must treat frame pointer as varying here, since it can vary–in a nonlocal goto as generated by expand_goto.
Now verify that the values of GOAL and VALUE remain unaltered until INSN is reached.
Don't trust the conversion past a function call
if either of the two is in a call-clobbered register, or memory. Watch out for unspec_volatile, and volatile asms.
If this insn P stores in either GOAL or VALUE, return 0.
If GOAL is a memory ref and this insn writes memory, return 0.
If GOAL is a memory ref and its address is not constant,
and this insn P changes a register used in GOAL, return 0.
|
static |
Find a place where INCED appears in an increment or decrement operator within X, and return the amount INCED is incremented or decremented by. The value is always positive.
| int find_reloads | ( | rtx | insn, |
| int | replace, | ||
| int | ind_levels, | ||
| int | live_known, | ||
| short * | reload_reg_p | ||
| ) |
Main entry point of this file: search the body of INSN for values that need reloading and record them with push_reload. REPLACE nonzero means record also where the values occur so that subst_reloads can be used.
IND_LEVELS says how many levels of indirection are supported by this machine; a value of zero means that a memory reference is not a valid memory address.
LIVE_KNOWN says we have valid information about which hard regs are live at each point in the program; this is true when we are called from global_alloc but false when stupid register allocation has been done.
RELOAD_REG_P if nonzero is a vector indexed by hard reg number which is nonnegative if the reg has been commandeered for reloading into. It is copied into STATIC_RELOAD_REG_P and referenced from there by various subroutines.
Return TRUE if some operands need to be changed, because of swapping commutative operands, reg_equiv_address substitution, or whatever.
These start out as the constraints for the insn and they are chewed up as we consider alternatives.
These are the preferred classes for an operand, or NO_REGS if it isn't a register.
Nonzero for a MEM operand whose entire address needs a reload. May be -1 to indicate the entire address may or may not need a reload.
Nonzero for an address operand that needs to be completely reloaded. May be -1 to indicate the entire operand may or may not need a reload.
Value of enum reload_type to use for operand.
Value of enum reload_type to use within address of operand.
Save the usage of each operand.
JUMP_INSNs and CALL_INSNs are not allowed to have any output reloads; neither are insns that SET cc0. Insns that use CC0 are not allowed to have any input reloads.
Dispose quickly of (set (reg..) (reg..)) if both have hard regs and it is cheap to move between them. If it is not, there may not be an insn to do the copy, so we may need a reload.
Just return "no reloads" if insn has no operands with constraints.
If we will need to know, later, whether some pair of operands are the same, we must compare them now and save the result. Reloading the base and index registers will clobber them and afterward they will fail to match.
Scan this operand's constraint to see if it is an output operand,
an in-out operand, is commutative, or should match another. The last operand should not be marked commutative.
We currently only support one commutative pair of
operands. Some existing asm code currently uses more
than one pair. Previously, that would usually work,
but sometimes it would crash the compiler. We
continue supporting that case as well as we can by
silently ignoring all but the first pair. In the
future we may handle it correctly. Use of ISDIGIT is tempting here, but it may get expensive because
of locale support we don't want. An operand may not match itself.
If C can be commuted with C+1, and C might need to match I,
then C+1 might also need to match I. Note that C is supposed to be less than I.
No need to consider altering both C and I because in
that case we would alter one into the other. Examine each operand that is a memory reference or memory address and reload parts of the addresses into index registers. Also here any references to pseudo regs that didn't get hard regs but are equivalent to constants get replaced in the insn itself with those constants. Nobody will ever see them again. Finally, set up the preferred classes of each operand.
Ignore things like match_operator operands.
If we now have a simple operand where we used to have a
PLUS or MULT, re-recognize and try again. Address operands are reloaded in their existing mode,
no matter what is specified in the machine description. If the address is a single CONST_INT pick address mode
instead otherwise we will later not know in which mode
the reload should be performed. If we made a MEM to load (a part of) the stackslot of a pseudo
that didn't get a hard register, emit a USE with a REG_EQUAL
note in front so that we might inherit a previous, possibly
wider reload. We can get a PLUS as an "operand" as a result of register
elimination. See eliminate_regs and gen_reload. We handle
a unary operator by reloading the operand. This is equivalent to calling find_reloads_toplev.
The code is duplicated for speed.
When we find a pseudo always equivalent to a constant,
we replace it by the constant. We must be sure, however,
that we don't try to replace it in the insn in which it
is being set. Record the existing mode so that the check if constants are
allowed will work when operand_mode isn't specified. We need not give a valid is_set_dest argument since the case
of a constant equivalence was checked above. If the operand is still a register (we didn't replace it with an
equivalent), get the preferred class to reload it into. If this is simply a copy from operand 1 to operand 0, merge the preferred classes for the operands.
Now see what we need for pseudo-regs that didn't get hard regs or got the wrong kind of hard reg. For this, we must consider all the operands together against the register constraints.
The constraints are made of several alternatives. Each operand's constraint looks like foo,bar,... with commas separating the alternatives. The first alternatives for all operands go together, the second alternatives go together, etc. First loop over alternatives.
If insn is commutative (it's safe to exchange a certain pair
of operands) then we need to try each alternative twice, the
second time matching those two operands as if we had
exchanged them. To do this, really exchange them in
operands. Loop over operands for one constraint alternative.
LOSERS counts those that don't fit this alternative
and would require loading. BAD is set to 1 if it some operand can't fit this alternative
even after reloading. REJECT is a count of how undesirable this alternative says it is
if any reloading is required. If the alternative matches exactly
then REJECT is ignored, but otherwise it gets this much
counted against it in addition to the reloading needed. Each
? counts three times here since we want the disparaging caused by
a bad register class to only count 1/3 as much. Swap the duplicates too.
0 => this operand can be reloaded somehow for this alternative.
0 => this operand can be reloaded if the alternative allows regs.
Nonzero means this is a MEM that must be reloaded into a reg
regardless of what the constraint says. Nonzero if a constant forced into memory would be OK for this
operand. If the predicate accepts a unary operator, it means that
we need to reload the operand, but do not do this for
match_operator and friends. If the operand is a SUBREG, extract
the REG or MEM (or maybe even a constant) within.
(Constants can occur as a result of reg_equiv_constant.) Offset only matters when operand is a REG and
it is a hard reg. This is because it is passed
to reg_fits_class_p if it is a REG and all pseudos
return 0 from that function. Force reload if this is a constant or PLUS or if there may
be a problem accessing OPERAND in the outer mode. We must force a reload of paradoxical SUBREGs
of a MEM because the alignment of the inner value
may not be enough to do the outer reference. On
big-endian machines, it may also reference outside
the object.
On machines that extend byte operations and we have a
SUBREG where both the inner and outer modes are no wider
than a word and the inner mode is narrower, is integral,
and gets extended when loaded from memory, combine.c has
made assumptions about the behavior of the machine in such
register access. If the data is, in fact, in memory we
must always load using the size assumed to be in the
register and let the insn do the different-sized
accesses.
This is doubly true if WORD_REGISTER_OPERATIONS. In
this case eliminate_regs has left non-paradoxical
subregs for push_reload to see. Make sure it does
by forcing the reload.
??? When is it right at this stage to have a subreg
of a mem that is _not_ to be handled specially? IMO
those should have been reduced to just a mem. An empty constraint or empty alternative
allows anything which matched the pattern. Scan this alternative's specs for this operand;
set WIN if the operand fits any letter in this alternative.
Otherwise, clear BADOP if this operand could
fit some letter after reloads,
or set WINREG if this operand could fit after reloads
provided the constraint allows some registers. We only support one commutative marker, the first
one. We already set commutative above. Ignore rest of this alternative as far as
reloading is concerned. We are supposed to match a previous operand.
If we do, we win if that one did.
If we do not, count both of the operands as losers.
(This is too conservative, since most of the time
only a single reload insn will be needed to make
the two operands win. As a result, this alternative
may be rejected when it is actually desirable.) If we are matching as if two operands were swapped,
also pretend that operands_match had been computed
with swapped.
But if I is the second of those and C is the first,
don't exchange them, because operands_match is valid
only on one side of its diagonal. If we are matching a non-offsettable address where an
offsettable address was expected, then we must reject
this combination, because we can't reload it. Operands don't match.
Retroactively mark the operand we had to match
as a loser, if it wasn't already. But count the pair only once in the total badness of
this alternative, if the pair can be a dummy reload.
The pointers in operand_loc are not swapped; swap
them by hand if necessary. This can be fixed with reloads if the operand
we are supposed to match can be fixed with reloads. If we have to reload this operand and some previous
operand also had to match the same thing as this
operand, we don't know how to do that. So reject this
alternative. All necessary reloads for an address_operand
were handled in find_reloads_address. Memory operand whose address is not offsettable.
Certain mem addresses will become offsettable
after they themselves are reloaded. This is important;
we don't want our own handling of unoffsettables
to override the handling of reg_equiv_address. Memory operand whose address is offsettable.
If IND_LEVELS, find_reloads_address won't reload a
pseudo that didn't get a hard reg, so we have to
reject that case. A reloaded address is offsettable because it is now
just a simple register indirect. If reg_equiv_address is nonzero, we will be
loading it into a register; hence it will be
offsettable, but we cannot say that reg_equiv_mem
is offsettable without checking. Output operand that is stored before the need for the
input operands (and their index registers) is over. A PLUS is never a valid operand, but reload can make
it from a register when eliminating registers. A SCRATCH is not a valid operand.
Drop through into 'r' case.
If this operand could be handled with a reg,
and some reg is allowed, then this operand can be handled. Record which operands fit this alternative.
Alternative loses if it has no regs for a reg operand.
If this is a constant that is reloaded into the desired
class by copying it to memory first, count that as another
reload. This is consistent with other code and is
required to avoid choosing another alternative when
the constant is moved into memory by this function on
an early reload pass. Note that the test here is
precisely the same as in the code below that calls
force_const_mem. Alternative loses if it requires a type of reload not
permitted for this insn. We can always reload SCRATCH
and objects with a REG_UNUSED note. If we can't reload this value at all, reject this
alternative. Note that we could also lose due to
LIMIT_RELOAD_CLASS, but we don't check that
here. We prefer to reload pseudos over reloading other things,
since such reloads may be able to be eliminated later.
If we are reloading a SCRATCH, we won't be generating any
insns, just using a register, so it is also preferred.
So bump REJECT in other cases. Don't do this in the
case where we are forcing a constant into memory and
it will then win since we don't want to have a different
alternative match then. Input reloads can be inherited more often than output
reloads can be removed, so penalize output reloads. If this operand is a pseudo register that didn't get
a hard reg and this alternative accepts some
register, see if the class that we want is a subset
of the preferred class for this register. If not,
but it intersects that class, use the preferred class
instead. If it does not intersect the preferred
class, show that usage of this alternative should be
discouraged; it will be discouraged more still if the
register is `preferred or nothing'. We do this
because it increases the chance of reusing our spill
register in a later insn and avoiding a pair of
memory stores and loads.
Don't bother with this if this alternative will
accept this operand.
Don't do this for a multiword operand, since it is
only a small win and has the risk of requiring more
spill registers, which could cause a large loss.
Don't do this if the preferred class has only one
register because we might otherwise exhaust the
class. Since we don't have a way of forming the intersection,
we just do something special if the preferred class
is a subset of the class we have; that's the most
common case anyway. Now see if any output operands that are marked "earlyclobber"
in this alternative conflict with any input operands
or any memory addresses. Is this an input operand or a memory ref?
Ignore things like match_operator operands.
Don't count an input operand that is constrained to match
the early clobber operand. Is it altered by storing the earlyclobber operand?
If the output is in a non-empty few-regs class,
it's costly to reload it, so reload the input instead. If an earlyclobber operand conflicts with something,
it must be reloaded, so request this and count the cost. If one alternative accepts all the operands, no reload required,
choose that alternative; don't consider the remaining ones. Unswap these so that they are never swapped at `finish'.
REJECT, set by the ! and ? constraint characters and when a register
would be reloaded into a non-preferred class, discourages the use of
this alternative for a reload goal. REJECT is incremented by six
for each ? and two for each non-preferred class. If this alternative can be made to work by reloading,
and it needs less reloading than the others checked so far,
record it as the chosen goal for reloading. If the commutative operands have been swapped, swap
them back in order to check the next alternative. Unswap the duplicates too.
Unswap the operand related information as well.
The operands don't meet the constraints. goal_alternative describes the alternative that we could reach by reloading the fewest operands. Reload so as to fit it.
No alternative works with reloads??
Avoid further trouble with this insn.
Jump to `finish' from above if all operands are valid already. In that case, goal_alternative_win is all 1.
Right now, for any pair of operands I and J that are required to match, with I < J, goal_alternative_matches[J] is I. Set up goal_alternative_matched as the inverse function: goal_alternative_matched[I] = J.
If the best alternative is with operands 1 and 2 swapped, consider them swapped before reporting the reloads. Update the operand numbers of any reloads already pushed.
If this is an earlyclobber operand, we need to widen the scope.
The reload must remain valid from the start of the insn being
reloaded until after the operand is stored into its destination.
We approximate this with RELOAD_OTHER even though we know that we
do not conflict with RELOAD_FOR_INPUT_ADDRESS reloads.
One special case that is worth checking is when we have an
output that is earlyclobber but isn't used past the insn (typically
a SCRATCH). In this case, we only need have the reload live
through the insn itself, but not for any of our input or output
reloads.
But we must not accidentally narrow the scope of an existing
RELOAD_OTHER reload - leave these alone.
In any case, anything needed to address this operand can remain
however they were previously categorized. Any constants that aren't allowed and can't be reloaded into registers are here changed into memory references.
Reloads of SUBREGs of CONSTANT RTXs are handled later in
push_reload so we have to let them pass here. If we stripped a SUBREG or a PLUS above add it back.
If the alternative accepts constant pool refs directly
there will be no reload needed at all. Record the values of the earlyclobber operands for the caller.
Now record reloads for all the operands that need them.
Operands that match previous ones have already been handled.
Handle an operand with a nonoffsettable address
appearing where an offsettable address will do
by reloading the address into a base register.
??? We can also do this when the operand is a register and
reg_equiv_mem is not offsettable, but this is a bit tricky,
so we don't bother with it. It may not be worth doing. If the address to be reloaded is a VOIDmode constant,
use the default address mode as mode of the reload register,
as would have been done by find_reloads_address. If this operand is an output, we will have made any
reloads for its address as RELOAD_FOR_OUTPUT_ADDRESS, but
now we are treating part of the operand as an input, so
we must change these to RELOAD_FOR_INPUT_ADDRESS. In a matching pair of operands, one must be input only
and the other must be output only.
Pass the input operand as IN and the other as OUT. Avoid further trouble with this insn.
For each non-matching operand that's a MEM or a pseudo-register
that didn't get a hard register, make an optional reload.
This may get done even if the insn needs no reloads otherwise. If this is only for an output, the optional reload would not
actually cause us to use a register now, just note that
something is stored here. An optional output reload might allow to delete INSN later.
We mustn't make in-out reloads on insns that are not permitted
output reloads.
If this is an asm, we can't delete it; we must not even call
push_reload for an optional output reload in this case,
because we can't be sure that the constraint allows a register,
and push_reload verifies the constraints for asms. If a memory reference remains (either as a MEM or a pseudo that
did not get a hard register), yet we can't make an optional
reload, check if this is actually a pseudo register reference;
we then need to emit a USE and/or a CLOBBER so that reload
inheritance will do the right thing. We mark the USE with QImode so that we recognize
it as one that can be safely deleted at the end
of reload. Similarly, make an optional reload for a pair of matching
objects that are in MEM or a pseudo that didn't get a hard reg. Perform whatever substitutions on the operands we are supposed to make due to commutativity or replacement of registers with equivalent constants or memory slots.
We only do this on the last pass through reload, because it is
possible for some data (like reg_equiv_address) to be changed during
later passes. Moreover, we lose the opportunity to get a useful
reload_{in,out}_reg when we do these replacements. If we're replacing an operand with a LABEL_REF, we need to
make sure that there's a REG_LABEL_OPERAND note attached to
this instruction. For a JUMP_P, if it was a branch target it must have
already been recorded as such. If this insn pattern contains any MATCH_DUP's, make sure that they will be substituted if the operands they match are substituted. Also do now any substitutions we already did on the operands. Don't do this if we aren't making replacements because we might be propagating things allocated by frame pointer elimination into places it doesn't expect.
If we detected error and replaced asm instruction by USE, forget about the reloads.
Perhaps an output reload can be combined with another to reduce needs by one.
If we have a pair of reloads for parts of an address, they are reloading the same object, the operands themselves were not reloaded, and they are for two operands that are supposed to match, merge the reloads and change the type of the surviving reload to RELOAD_FOR_OPERAND_ADDRESS.
Scan all the reloads and update their type. If a reload is for the address of an operand and we didn't reload that operand, change the type. Similarly, change the operand number of a reload when two operands match. If a reload is optional, treat it as though the operand isn't reloaded. ??? This latter case is somewhat odd because if we do the optional reload, it means the object is hanging around. Thus we need only do the address reload if the optional reload was NOT done. Change secondary reloads to be the address type of their operand, not the normal type. If an operand's reload is now RELOAD_OTHER, change any RELOAD_FOR_INPUT_ADDRESS reloads of that operand to RELOAD_FOR_OTHER_ADDRESS.
If we have a secondary reload to go along with this reload,
change its type to RELOAD_FOR_OPADDR_ADDR. If there's a tertiary reload we have to change it also.
If there's a tertiary reload we have to change it also.
Scan all the reloads, and check for RELOAD_FOR_OPERAND_ADDRESS reloads. If we have more than one, then convert all RELOAD_FOR_OPADDR_ADDR reloads to RELOAD_FOR_OPERAND_ADDRESS reloads. choose_reload_regs assumes that RELOAD_FOR_OPADDR_ADDR reloads never conflict with RELOAD_FOR_OPERAND_ADDRESS reloads. This is true for a single pair of RELOAD_FOR_OPADDR_ADDR/RELOAD_FOR_OPERAND_ADDRESS reloads. However, if there is more than one RELOAD_FOR_OPERAND_ADDRESS reload, then a RELOAD_FOR_OPADDR_ADDR reload conflicts with all RELOAD_FOR_OPERAND_ADDRESS reloads other than the one that uses it. This is complicated by the fact that a single operand can have more than one RELOAD_FOR_OPERAND_ADDRESS reload. It is very difficult to fix choose_reload_regs without affecting code quality, and cases that actually fail are extremely rare, so it turns out to be better to fix the problem here by not generating cases that choose_reload_regs will fail for.
There is a similar problem with RELOAD_FOR_INPUT_ADDRESS / RELOAD_FOR_OUTPUT_ADDRESS when there is more than one of a kind for a single operand. We can reduce the register pressure by exploiting that a RELOAD_FOR_X_ADDR_ADDR that precedes all RELOAD_FOR_X_ADDRESS reloads does not conflict with any of them, if it is only used for the first of the RELOAD_FOR_X_ADDRESS reloads.
We use last_op_addr_reload and the contents of the above arrays first as flags - -2 means no instance encountered, -1 means exactly one instance encountered. If more than one instance has been encountered, we store the reload number of the first reload of the kind in question; reload numbers are known to be non-negative.
Check if the only TYPE reload that uses reload I is
reload FIRST_NUM. See if we have any reloads that are now allowed to be merged because we've changed when the reload is needed to RELOAD_FOR_OPERAND_ADDRESS or RELOAD_FOR_OTHER_ADDRESS. Only check for the most common cases.
Compute reload_mode and reload_nregs.
Special case a simple move with an input reload and a destination of a hard reg, if the hard reg is ok, use it.
References recog_data_d::operand, operands_match_p(), and recog_data.
Referenced by maybe_fix_stack_asms().
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Record all reloads needed for handling memory address AD which appears in *LOC in a memory reference to mode MODE which itself is found in location *MEMREFLOC. Note that we take shortcuts assuming that no multi-reg machine mode occurs as part of an address.
OPNUM and TYPE specify the purpose of this reload.
IND_LEVELS says how many levels of indirect addressing this machine supports.
INSN, if nonzero, is the insn in which we do the reload. It is used to determine if we may generate output reloads, and where to put USEs for pseudos that we have to replace with stack slots.
Value is one if this address is reloaded or replaced as a whole; it is zero if the top level of this address was not reloaded or replaced, and it is -1 if it may or may not have been reloaded or replaced.
Note that there is no verification that the address will be valid after this routine does its work. Instead, we rely on the fact that the address was valid when reload started. So we need only undo things that reload could have broken. These are wrong register types, pseudos not allocated to a hard register, and frame pointer elimination.
If the address is a register, see if it is a legitimate address and reload if not. We first handle the cases where we need not reload or where we must reload in a non-standard way.
We can avoid a reload if the register's equivalent memory
expression is valid as an indirect memory address.
But not all addresses are valid in a mem used as an indirect
address: only reg or reg+constant. TEM is not the same as what we'll be replacing the
pseudo with after reload, put a USE in front of INSN
in the final reload pass. We mark the USE with QImode so that we
recognize it as one that can be safely
deleted at the end of reload. This doesn't really count as replacing the address
as a whole, since it is still a memory access. The only remaining case where we can avoid a reload is if this is a
hard register that is valid as a base register and which is not the
subject of a CLOBBER in this insn. If we do not have one of the cases above, we must do the reload.
The address appears valid, so reloads are not needed.
But the address may contain an eliminable register.
This can happen because a machine with indirect addressing
may consider a pseudo register by itself a valid address even when
it has failed to get a hard reg.
So do a tree-walk to find and eliminate all such regs. But first quickly dispose of a common case.
Check result for validity after substitution.
The address is not valid. We have to figure out why. First see if we have an outer AND and remove it if so. Then analyze what's inside.
One possibility for why the address is invalid is that it is itself a MEM. This can happen when the frame pointer is being eliminated, a pseudo is not allocated to a hard register, and the offset between the frame and stack pointers is not its initial value. In that case the pseudo will have been replaced by a MEM referring to the stack pointer.
First ensure that the address in this MEM is valid. Then, unless
indirect addresses are valid, reload the MEM into a register. If tem was changed, then we must create a new memory reference to
hold it and store it back into memrefloc. Check similar cases as for indirect addresses as above except
that we can allow pseudos and a MEM since they should have been
taken care of above. Must use TEM here, not AD, since it is the one that will
have any subexpressions reloaded, if needed. If we have address of a stack slot but it's not valid because the displacement is too large, compute the sum in a register. Handle all base registers here, not just fp/ap/sp, because on some targets (namely SH) we can also get too large displacements from big-endian corrections.
Similarly, if we were to reload the base register and the
mem+offset address is still invalid, then we want to reload
the whole address, not just the base register. Unshare the MEM rtx so we can safely alter it.
Unshare the sum as well.
Reload the displacement into an index reg.
We assume the frame pointer or arg pointer is a base reg. If the sum of two regs is not necessarily valid,
reload the sum into a base reg.
That will at least work. If we have an indexed stack slot, there are three possible reasons why it might be invalid: The index might need to be reloaded, the address might have been made by frame pointer elimination and hence have a constant out of range, or both reasons might apply. We can easily check for an index needing reload, but even if that is the case, we might also have an invalid constant. To avoid making the conservative assumption and requiring two reloads, we see if this address is valid when not interpreted strictly. If it is, the only problem is that the index needs a reload and find_reloads_address_1 will take care of it. Handle all base registers here, not just fp/ap/sp, because on some targets (namely SPARC) we can also get invalid addresses from preventive subreg big-endian corrections made by find_reloads_toplev. We can also get expressions involving LO_SUM (rather than PLUS) from find_reloads_subreg_address. If we decide to do something, it must be that `double_reg_address_ok' is true. We generate a reload of the base register + constant and rework the sum so that the reload register will be added to the index. This is safe because we know the address isn't shared. We check for the base register as both the first and second operand of the innermost PLUS and/or LO_SUM.
Form the adjusted address.
See if address becomes valid when an eliminable register in a sum is replaced.
Ok, we win that way. Replace any additional eliminable
registers. Make sure that didn't make the address invalid again.
If constants aren't valid addresses, reload the constant address into a register.
If AD is an address in the constant pool, the MEM rtx may be shared.
Unshare it so we can safely alter it.
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Record the pseudo registers we must reload into hard registers in a subexpression of a would-be memory address, X referring to a value in mode MODE. (This function is not called if the address we find is strictly valid.)
CONTEXT = 1 means we are considering regs as index regs, = 0 means we are considering them as base regs. OUTER_CODE is the code of the enclosing RTX, typically a MEM, a PLUS, or an autoinc code. If CONTEXT == 0 and OUTER_CODE is a PLUS or LO_SUM, then INDEX_CODE is the code of the index part of the address. Otherwise, pass SCRATCH for this argument. OPNUM and TYPE specify the purpose of any reloads made.
IND_LEVELS says how many levels of indirect addressing are supported at this point in the address.
INSN, if nonzero, is the insn in which we do the reload. It is used to determine if we may generate output reloads.
We return nonzero if X, as a whole, is reloaded or replaced. Note that we take shortcuts assuming that no multi-reg machine mode occurs as part of an address. Also, this is not fully machine-customizable; it works for machines such as VAXen and 68000's and 32000's, but other possible machines could have addressing modes that this does not handle right. If you add push_reload calls here, you need to make sure gen_reload handles those cases gracefully.
??? Why is this given op1's mode and above for ??? op0 SUBREGs we use word_mode?
Plus in the index register may be created only as a result of
register rematerialization for expression like &localvar*4. Reload it.
It may be possible to combine the displacement on the outer level,
but it is probably not worthwhile to do so.
Currently, we only support {PRE,POST}_MODIFY constructs
where a base register is {inc,dec}remented by the contents
of another register or by a constant value. Thus, these
operands must match. Require index register (or constant). Let's just handle the
register case in the meantime... If the target allows
auto-modify by a constant then we could try replacing a pseudo
register with its equivalent constant where applicable.
We also handle the case where the register was eliminated
resulting in a PLUS subexpression.
If we later decide to reload the whole PRE_MODIFY or
POST_MODIFY, inc_for_reload might clobber the reload register
before reading the index. The index register might therefore
need to live longer than a TYPE reload normally would, so be
conservative and class it as RELOAD_OTHER. A register that is incremented cannot be constant!
Handle a register that is equivalent to a memory location
which cannot be addressed directly. First reload the memory location's address.
We can't use ADDR_TYPE (type) here, because we need to
write back the value after reading it, hence we actually
need two registers. Then reload the memory location into a base
register. We require a base register here...
A register that is incremented cannot be constant!
Handle a register that is equivalent to a memory location
which cannot be addressed directly. First reload the memory location's address.
We can't use ADDR_TYPE (type) here, because we need to
write back the value after reading it, hence we actually
need two registers. Put this inside a new increment-expression.
Proceed to reload that, as if it contained a register.
If we have a hard register that is ok in this incdec context,
don't make a reload. If the register isn't nice enough for
autoincdec, we can reload it. But, if an autoincrement of a
register that we here verified as playing nice, still outside
isn't "valid", it must be that no autoincrement is "valid".
If that is true and something made an autoincrement anyway,
this must be a special context where one is allowed.
(For example, a "push" instruction.)
We can't improve this address, so leave it alone. Otherwise, reload the autoincrement into a suitable hard reg
and record how much to increment by. If we can output the register afterwards, do so, this
saves the extra update.
We can do so if we have an INSN - i.e. no JUMP_INSN nor
CALL_INSN - and it does not set CC0.
But don't do this if we cannot directly address the
memory location, since this will make it harder to
reuse address reloads, and increases register pressure.
Also don't do this if we can probably update x directly. We use the original pseudo for loc, so that
emit_reload_insns() knows which pseudo this
reload refers to and updates the pseudo rtx, not
its equivalent memory location, as well as the
corresponding entry in reg_last_reload_reg. Look for parts to reload in the inner expression and reload them
too, in addition to this operation. Reloading all inner parts in
addition to this one shouldn't be necessary, but at this point,
we don't know if we can possibly omit any part that *can* be
reloaded. Targets that are better off reloading just either part
(or perhaps even a different part of an outer expression), should
define LEGITIMIZE_RELOAD_ADDRESS. This is probably the result of a substitution, by eliminate_regs, of
an equivalent address for a pseudo that was not allocated to a hard
register. Verify that the specified address is valid and reload it
into a register.
Since we know we are going to reload this item, don't decrement for
the indirection level.
Note that this is actually conservative: it would be slightly more
efficient to use the value of SPILL_INDIRECT_LEVELS from
reload1.c here. If a register appearing in an address is the subject of a CLOBBER
in this insn, reload it into some other register to be safe.
The CLOBBER is supposed to make the register unavailable
from before this insn to after it. If this is a SUBREG of a hard register and the resulting register
is of the wrong class, reload the whole SUBREG. This avoids
needless copies if SUBREG_REG is multi-word. If this is a SUBREG of a pseudo-register, and the pseudo-register
is larger than the class size, then reload the whole SUBREG. If the inner register will be replaced by a memory
reference, we can do this only if we can replace the
whole subreg by a (narrower) memory reference. If
this is not possible, fall through and reload just
the inner register (including address reloads). Pass SCRATCH for INDEX_CODE, since CODE can never be a PLUS once
we get here.
Referenced by maybe_memory_address_addr_space_p().
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X, which is found at *LOC, is a part of an address that needs to be reloaded into a register of class RCLASS. If X is a constant, or if X is a PLUS that contains a constant, check that the constant is a legitimate operand and that we are supposed to be able to load it into the register.
If not, force the constant into memory and reload the MEM instead.
MODE is the mode to use, in case X is an integer constant.
OPNUM and TYPE describe the purpose of any reloads made.
IND_LEVELS says how many levels of indirect addressing this machine supports.
Referenced by maybe_memory_address_addr_space_p().
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X, a subreg of a pseudo, is a part of an address that needs to be reloaded, and the pseusdo is equivalent to a memory location.
Attempt to replace the whole subreg by a (possibly narrower or wider) memory reference. If this is possible, return this new memory reference, and push all required address reloads. Otherwise, return NULL.
OPNUM and TYPE identify the purpose of the reload.
IND_LEVELS says how many levels of indirect addressing are supported at this point in the address.
INSN, if nonzero, is the insn in which we do the reload. It is used to determine where to put USEs for pseudos that we have to replace with stack slots.
We cannot replace the subreg with a modified memory reference if: - we have a paradoxical subreg that implicitly acts as a zero or sign extension operation due to LOAD_EXTEND_OP; - we have a subreg that is implicitly supposed to act on the full register due to WORD_REGISTER_OPERATIONS (see also eliminate_regs); - the address of the equivalent memory location is mode-dependent; or - we have a paradoxical subreg and the resulting memory is not sufficiently aligned to allow access in the wider mode. In addition, we choose not to perform the replacement for <em>any</em> paradoxical subreg, even if it were possible in principle. This is to avoid generating wider memory references than necessary. This corresponds to how previous versions of reload used to handle paradoxical subregs where no address reload was required.
Since we don't attempt to handle paradoxical subregs, we can just call into simplify_subreg, which will handle all remaining checks for us.
Now push all required address reloads, if any.
??? Do we need to handle nonzero offsets somehow?
For some processors an address may be valid in the original mode but not in a smaller mode. For example, ARM accepts a scaled index register in SImode but not in HImode. Note that this is only a problem if the address in reg_equiv_mem is already invalid in the new mode; other cases would be fixed by find_reloads_address as usual. ??? We attempt to handle such cases here by doing an additional reload of the full address after the usual processing by find_reloads_address. Note that this may not work in the general case, but it seems to cover the cases where this situation currently occurs. A more general fix might be to reload the *value* instead of the address, but this would not be expected by the callers of this routine as-is. If find_reloads_address already completed replaced the address, there is nothing further to do.
If this is not a toplevel operand, find_reloads doesn't see this substitution. We have to emit a USE of the pseudo so that delete_output_reload can see it.
We mark the USE with QImode so that we recognize it as one that can be safely deleted at the end of reload.
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Scan X for memory references and scan the addresses for reloading. Also checks for references to "constant" regs that we want to eliminate and replaces them with the values they stand for. We may alter X destructively if it contains a reference to such. If X is just a constant reg, we return the equivalent value instead of X.
IND_LEVELS says how many levels of indirect addressing this machine supports.
OPNUM and TYPE identify the purpose of the reload.
IS_SET_DEST is true if X is the destination of a SET, which is not appropriate to be replaced by a constant.
INSN, if nonzero, is the insn in which we do the reload. It is used to determine if we may generate output reloads, and where to put USEs for pseudos that we have to replace with stack slots.
ADDRESS_RELOADED. If nonzero, is a pointer to where we put the result of find_reloads_address.
This code is duplicated for speed in find_reloads.
If this is not a toplevel operand, find_reloads doesn't see
this substitution. We have to emit a USE of the pseudo so
that delete_output_reload can see it. We mark the USE with QImode so that we recognize it
as one that can be safely deleted at the end of
reload. Check for SUBREG containing a REG that's equivalent to a
constant. If the constant has a known value, truncate it
right now. Similarly if we are extracting a single-word of a
multi-word constant. If the constant is symbolic, allow it
to be substituted normally. push_reload will strip the
subreg later. The constant must not be VOIDmode, because we
will lose the mode of the register (this should never happen
because one of the cases above should handle it). If the subreg contains a reg that will be converted to a mem,
attempt to convert the whole subreg to a (narrower or wider)
memory reference instead. If this succeeds, we're done –
otherwise fall through to check whether the inner reg still
needs address reloads anyway. If we have replaced a reg with it's equivalent memory loc -
that can still be handled here e.g. if it's in a paradoxical
subreg - we must make the change in a copy, rather than using
a destructive change. This way, find_reloads can still elect
not to do the change.
References ADDR_SPACE_GENERIC_P, copy_rtx(), GET_MODE, move_replacements(), and XEXP.
| rtx find_replacement | ( | ) |
If LOC was scheduled to be replaced by something, return the replacement. Otherwise, return *LOC.
If *LOC is a PLUS, MINUS, or MULT, see if a replacement is scheduled for what's inside and make a new rtl if so.
References in_hard_reg_set_p(), and reg_class_contents.
Referenced by do_output_reload().
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Return the number of a previously made reload that can be combined with a new one, or n_reloads if none of the existing reloads can be used. OUT, RCLASS, TYPE and OPNUM are the same arguments as passed to push_reload, they determine the kind of the new reload that we try to combine. P_IN points to the corresponding value of IN, which can be modified by this function. DONT_SHARE is nonzero if we can't share any input-only reload for IN.
We can't merge two reloads if the output of either one is earlyclobbered.
We can use an existing reload if the class is right and at least one of IN and OUT is a match and the other is at worst neutral. (A zero compared against anything is neutral.) For targets with small register classes, don't use existing reloads unless they are for the same thing since that can cause us to need more reload registers than we otherwise would.
If the existing reload has a register, it must fit our class.
Reloading a plain reg for input can match a reload to postincrement that reg, since the postincrement's value is the right value. Likewise, it can match a preincrement reload, since we regard the preincrementation as happening before any ref in this insn to that register.
If the existing reload has a register, it must fit our
class. Make sure reload_in ultimately has the increment,
not the plain register.
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Find the largest class which has at least one register valid in mode INNER, and which for every such register, that register number plus N is also valid in OUTER (if in range) and is cheap to move into REGNO. Such a class must exist.
References gcc_assert, in_hard_reg_set_p(), reg_class_contents, reg_class_size, and register_move_cost().
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We are trying to reload a subreg of something that is not a register. Find the largest class which contains only registers valid in mode MODE. OUTER is the mode of the subreg, DEST_CLASS the class in which we would eventually like to obtain the object.
References earlyclobber_operand_p(), MATCHES, MERGABLE_RELOADS, n_reloads, reg_class_contents, reg_class_subset_p(), REG_P, rld, small_register_class_p(), targetm, TEST_HARD_REG_BIT, and true_regnum().
| rtx form_sum | ( | ) |
Compute the sum of X and Y, making canonicalizations assumed in an address, namely: sum constant integers, surround the sum of two constants with a CONST, put the constant as the second operand, and group the constant on the outermost sum.
This routine assumes both inputs are already in canonical form.
Note that if the operands of Y are specified in the opposite order in the recursive calls below, infinite recursion will occur.
If both constant, encapsulate sum. Otherwise, just form sum. A constant will have been placed second.
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Return 1 if expression X alters a hard reg in the range from BEG_REGNO (inclusive) to END_REGNO (exclusive), either explicitly or in the guise of a pseudo-reg allocated to REGNO. X should be the body of an instruction.
See if this reg overlaps range under consideration.
References CASE_CONST_UNIQUE, XEXP, and XSTR.
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Return 1 if altering Y will not modify the value of X. Y is also described by YDATA, which should be decompose (Y).
If Y is memory and X is not, Y can't affect X.
If bases are distinct symbolic constants, there is no overlap.
Constants and stack slots never overlap.
If either base is variable, we don't know anything.
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Return a mem ref for the memory equivalent of reg REGNO. This mem ref is not shared with anything.
We must rerun eliminate_regs, in case the elimination offsets have changed.
If TEM might contain a pseudo, we must copy it to avoid modifying it when we do the substitution for the reload.
Copy the result if it's still the same as the equivalence, to avoid modifying it when we do the substitution for the reload.
References CONST_INT_P, frame_pointer_rtx, GET_CODE, HARD_FRAME_POINTER_IS_FRAME_POINTER, REG_P, REGNO, regno_ok_for_base_p(), and XEXP.
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Returns true if AD could be turned into a valid memory reference to mode MODE in address space AS by reloading the part pointed to by PART into a register.
References base_reg_class(), find_reloads_address_1(), find_reloads_address_part(), GET_CODE, GET_MODE, INTVAL, plus_constant(), and XEXP.
| void move_replacements | ( | ) |
Change any replacements being done to *X to be done to *Y.
Referenced by find_reloads_toplev().
| int operands_match_p | ( | ) |
Like rtx_equal_p except that it allows a REG and a SUBREG to match if they are the same hard reg, and has special hacks for autoincrement and autodecrement. This is specifically intended for find_reloads to use in determining whether two operands match. X is the operand whose number is the lower of the two.
The value is 2 if Y contains a pre-increment that matches a non-incrementing address in X. ??? To be completely correct, we should arrange to pass for X the output operand and for Y the input operand. For now, we assume that the output operand has the lower number because that is natural in (SET output (... input ...)).
On a REG_WORDS_BIG_ENDIAN machine, point to the last register of a multiple hard register group of scalar integer registers, so that for example (reg:DI 0) and (reg:SI 1) will be considered the same register.
If two operands must match, because they are really a single operand of an assembler insn, then two postincrements are invalid because the assembler insn would increment only once. On the other hand, a postincrement matches ordinary indexing if the postincrement is the output operand. Two preincrements are invalid because the assembler insn would increment only once. On the other hand, a preincrement matches ordinary indexing if the preincrement is the input operand. In this case, return 2, since some callers need to do special things when this happens.
Now we have disposed of all the cases in which different rtx codes can match.
(MULT:SI x y) and (MULT:HI x y) are NOT equivalent.
MEMs referring to different address space are not equivalent.
Compare the elements. If any pair of corresponding elements fail to match, return 0 for the whole things.
If any subexpression returns 2,
we should return 2 if we are successful. It is believed that rtx's at this level will never
contain anything but integers and other rtx's,
except for within LABEL_REFs and SYMBOL_REFs.
References decomposition::base, const0_rtx, CONST_INT_P, CONSTANT_P, decompose(), decomposition::end, end_hard_regno(), gcc_assert, GET_CODE, GET_MODE, GET_MODE_SIZE, INTVAL, NULL_RTX, offset, decomposition::reg_flag, REG_P, REGNO, decomposition::safe, decomposition::start, subreg_nregs(), SUBREG_REG, true_regnum(), and XEXP.
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Add NEW to reg_equiv_alt_mem_list[REGNO] if it's not present in the list yet.
References RELOAD_FOR_INPADDR_ADDRESS, RELOAD_FOR_INPUT_ADDRESS, RELOAD_FOR_OUTADDR_ADDRESS, RELOAD_FOR_OUTPUT_ADDRESS, and type().
| int push_reload | ( | rtx | in, |
| rtx | out, | ||
| rtx * | inloc, | ||
| rtx * | outloc, | ||
| enum reg_class | rclass, | ||
| enum machine_mode | inmode, | ||
| enum machine_mode | outmode, | ||
| int | strict_low, | ||
| int | optional, | ||
| int | opnum, | ||
| enum reload_type | type | ||
| ) |
Record one reload that needs to be performed. IN is an rtx saying where the data are to be found before this instruction. OUT says where they must be stored after the instruction. (IN is zero for data not read, and OUT is zero for data not written.) INLOC and OUTLOC point to the places in the instructions where IN and OUT were found. If IN and OUT are both nonzero, it means the same register must be used to reload both IN and OUT.
RCLASS is a register class required for the reloaded data. INMODE is the machine mode that the instruction requires for the reg that replaces IN and OUTMODE is likewise for OUT.
If IN is zero, then OUT's location and mode should be passed as INLOC and INMODE.
STRICT_LOW is the 1 if there is a containing STRICT_LOW_PART rtx.
OPTIONAL nonzero means this reload does not need to be performed: it can be discarded if that is more convenient.
OPNUM and TYPE say what the purpose of this reload is.
The return value is the reload-number for this reload.
If both IN and OUT are nonzero, in some rare cases we might want to make two separate reloads. (Actually we never do this now.) Therefore, the reload-number for OUT is stored in output_reloadnum when we return; the return value applies to IN. Usually (presently always), when IN and OUT are nonzero, the two reload-numbers are equal, but the caller should be careful to distinguish them.
INMODE and/or OUTMODE could be VOIDmode if no mode has been specified for the operand. In that case, use the operand's mode as the mode to reload.
If find_reloads and friends until now missed to replace a pseudo with a constant of reg_equiv_constant something went wrong beforehand. Note that it can't simply be done here if we missed it earlier since the constant might need to be pushed into the literal pool and the resulting memref would probably need further reloading.
reg_equiv_constant only contains constants which are obviously not appropriate as destination. So if we would need to replace the destination pseudo with a constant we are in real trouble.
If we have a read-write operand with an address side-effect, change either IN or OUT so the side-effect happens only once.
If we are reloading a (SUBREG constant ...), really reload just the inside expression in its own mode. Similarly for (SUBREG (PLUS ...)). If we have (SUBREG:M1 (MEM:M2 ...) ...) (or an inner REG that is still a pseudo and hence will become a MEM) with M1 wider than M2 and the register is a pseudo, also reload the inside expression. For machines that extend byte loads, do this for any SUBREG of a pseudo where both M1 and M2 are a word or smaller, M1 is wider than M2, and M2 is an integral mode that gets extended when loaded. Similar issue for (SUBREG:M1 (REG:M2 ...) ...) for a hard register R where either M1 is not valid for R or M2 is wider than a word but we only need one register to store an M2-sized quantity in R. (However, if OUT is nonzero, we need to reload the reg *and* the subreg, so do nothing here, and let following statement handle it.) Note that the case of (SUBREG (CONST_INT...)...) is handled elsewhere; we can't handle it here because CONST_INT does not indicate a mode. Similarly, we must reload the inside expression if we have a STRICT_LOW_PART (presumably, in == out in this case). Also reload the inner expression if it does not require a secondary reload but the SUBREG does. Finally, reload the inner expression if it is a register that is in the class whose registers cannot be referenced in a different size and M1 is not the same size as M2. If subreg_lowpart_p is false, we cannot reload just the inside since we might end up with the wrong register class. But if it is inside a STRICT_LOW_PART, we have no choice, so we hope we do get the right register class there.
The case where out is nonzero
is handled differently in the following statement. This is supposed to happen only for paradoxical subregs made by
combine.c. (SUBREG (MEM)) isn't supposed to occur other ways. Similar issue for (SUBREG:M1 (REG:M2 ...) ...) for a hard register R where M1 is not valid for R if it was not handled by the code above. Similar issue for (SUBREG constant ...) if it was not handled by the code above. This can happen if SUBREG_BYTE != 0. However, we must reload the inner reg *as well as* the subreg in that case.
This relies on the fact that emit_reload_insns outputs the
instructions for input reloads of type RELOAD_OTHER in the same
order as the reloads. Thus if the outer reload is also of type
RELOAD_OTHER, we are guaranteed that this inner reload will be
output before the outer reload. Similarly for paradoxical and problematical SUBREGs on the output. Note that there is no reason we need worry about the previous value of SUBREG_REG (out); even if wider than out, storing in a subreg is entitled to clobber it all (except in the case of a word mode subreg or of a STRICT_LOW_PART, in that latter case the constraint should label it input-output.)
The case of a word mode subreg
is handled differently in the following statement. Similar issue for (SUBREG:M1 (REG:M2 ...) ...) for a hard register R where either M1 is not valid for R or M2 is wider than a word but we only need one register to store an M2-sized quantity in R. However, we must reload the inner reg *as well as* the subreg in that case and the inner reg is an in-out reload.
This relies on the fact that emit_reload_insns outputs the
instructions for output reloads of type RELOAD_OTHER in reverse
order of the reloads. Thus if the outer reload is also of type
RELOAD_OTHER, we are guaranteed that this inner reload will be
output after the outer reload. If IN appears in OUT, we can't share any input-only reload for IN.
If IN is a SUBREG of a hard register, make a new REG. This simplifies some of the cases below.
Similarly for OUT.
Narrow down the class of register wanted if that is desirable on this machine for efficiency.
Output reloads may need analogous treatment, different in detail.
Discard what the target said if we cannot do it.
Make sure we use a class that can handle the actual pseudo inside any subreg. For example, on the 386, QImode regs can appear within SImode subregs. Although GENERAL_REGS can handle SImode, QImode needs a smaller class.
Verify that this class is at least possible for the mode that is specified.
Avoid further trouble with this insn.
We used to continue here setting class to ALL_REGS, but it triggers
sanity check on i386 for:
void foo(long double d)
{
asm("" :: "a" (d));
}
Returning zero here ought to be safe as we take care in
find_reloads to not process the reloads when instruction was
replaced by USE. Optional output reloads are always OK even if we have no register class, since the function of these reloads is only to have spill_reg_store etc. set, so that the storing insn can be deleted later.
See if we need a secondary reload register to move between CLASS
and IN or CLASS and OUT. Get the icode and push any required reloads
needed for each of them if so. We found no existing reload suitable for re-use.
So add an additional reload. We are reusing an existing reload,
but we may have additional information for it.
For example, we may now have both IN and OUT
while the old one may have just one of them. The modes can be different. If they are, we want to reload in
the larger mode, so that the value is valid for both modes. If we merge reloads for two distinct rtl expressions that
are identical in content, there might be duplicate address
reloads. Remove the extra set now, so that if we later find
that we can inherit this reload, we can get rid of the
address reloads altogether.
Do not do this if both reloads are optional since the result
would be an optional reload which could potentially leave
unresolved address replacements.
It is not sufficient to call transfer_replacements since
choose_reload_regs will remove the replacements for address
reloads of inherited reloads which results in the same
problem. We must keep the address reload with the lower operand
number alive. When emitting reloads we don't necessarily look at the in-
and outmode, but also directly at the operands (in and out).
So we can't simply overwrite them with whatever we have found
for this (to-be-merged) reload, we have to "merge" that too.
Reusing another reload already verified that we deal with the
same operands, just possibly in different modes. So we
overwrite the operands only when the new mode is larger.
See also PR33613. If the ostensible rtx being reloaded differs from the rtx found in the location to substitute, this reload is not safe to combine because we cannot reliably tell whether it appears in the insn.
If we will replace IN and OUT with the reload-reg, record where they are located so that substitution need not do a tree walk.
If this reload is just being introduced and it has both an incoming quantity and an outgoing quantity that are supposed to be made to match, see if either one of the two can serve as the place to reload into. If one of them is acceptable, set rld[i].reg_rtx to that one.
If the outgoing register already contains the same value
as the incoming one, we can dispense with loading it.
The easiest way to tell the caller that is to give a phony
value for the incoming operand (same as outgoing one). If this is an input reload and the operand contains a register that dies in this insn and is used nowhere else, see if it is the right class to be used for this reload. Use it if so. (This occurs most commonly in the case of paradoxical SUBREGs and in-out reloads). We cannot do this if it is also an output reload that mentions the register unless the output is a SUBREG that clobbers an entire register. Note that the operand might be one of the spill regs, if it is a pseudo reg and we are in a block where spilling has not taken place. But if there is no spilling in this block, that is OK. An explicitly used hard reg cannot be a spill reg.
Check that a former pseudo is valid; see find_dummy_reload.
If this is also an output reload, IN cannot be used as
the reload register if it is set in this insn unless IN
is also OUT. ??? Why is this code so different from the previous?
Is there any simple coherent way to describe the two together?
What's going on here. Make sure the operand fits in the reg that dies.
Referenced by update_auto_inc_notes().
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Record an additional place we must replace a value for which we have already recorded a reload. RELOADNUM is the value returned by push_reload when the reload was recorded. This is used in insn patterns that use match_dup.
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Determine if any secondary reloads are needed for loading (if IN_P is nonzero) or storing (if IN_P is zero) X to or from a reload register of register class RELOAD_CLASS in mode RELOAD_MODE. If secondary reloads are needed, push them.
Return the reload number of the secondary reload we made, or -1 if we didn't need one. *PICODE is set to the insn_code to use if we do need a secondary reload.
If X is a paradoxical SUBREG, use the inner value to determine both the mode and object being reloaded.
If X is a pseudo-register that has an equivalent MEM (actually, if it is still a pseudo-register by now, it *must* have an equivalent MEM but we don't want to assume that), use that equivalent when seeing if a secondary reload is needed since whether or not a reload is needed might be sensitive to the form of the MEM.
If we don't need any secondary registers, done.
If we will be using an insn, the secondary reload is for a scratch register.
If IN_P is nonzero, the reload register will be the output in
operand 0. If IN_P is zero, the reload register will be the input
in operand 1. Outputs should have an initial "=", which we must
skip. ??? It would be useful to be able to handle only two, or more than
three, operands, but for now we can only handle the case of having
exactly three: output, input and one temp/scratch. ??? We currently have no way to represent a reload that needs
an icode to reload from an intermediate tertiary reload register.
We should probably have a new field in struct reload to tag a
chain of scratch operand reloads onto. This case isn't valid, so fail. Reload is allowed to use the same register for RELOAD_FOR_INPUT_ADDRESS and RELOAD_FOR_INPUT reloads, but in the case of a secondary register, we actually need two different registers for correct code. We fail here to prevent the possibility of silently generating incorrect code later. The convention is that secondary input reloads are valid only if the secondary_class is different from class. If you have such a case, you can not use secondary reloads, you must work around the problem some other way. Allow this when a reload_in/out pattern is being used. I.e. assume that the generated code handles this case.
See if we can reuse an existing secondary reload.
We need to make a new secondary reload for this register class.
Maybe we could combine these, but it seems too tricky.
References GET_MODE, and SUBREG_REG.
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Return nonzero if anything in X contains a MEM. Look also for pseudo registers.
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Return nonzero if register in range [REGNO, ENDREGNO) appears either explicitly or implicitly in X other than being stored into (except for earlyclobber operands).
References contained within the substructure at LOC do not count. LOC may be zero, meaning don't ignore anything.
This is similar to refers_to_regno_p in rtlanal.c except that we look at equivalences for pseudos that didn't get hard registers.
If this is a pseudo, a hard register must not have been allocated.
X must therefore either be a constant or be in memory.
If this is a SUBREG of a hard reg, we can see exactly which
registers are being modified. Otherwise, handle normally. Note setting a SUBREG counts as referring to the REG it is in for
a pseudo but not for hard registers since we can
treat each word individually. If the output is an earlyclobber operand, this is
a conflict. X does not match, so try its subexpressions.
| int reg_overlap_mentioned_for_reload_p | ( | ) |
Nonzero if modifying X will affect IN. If X is a register or a SUBREG, we check if any register number in X conflicts with the relevant register numbers. If X is a constant, return 0. If X is a MEM, return 1 iff IN contains a MEM (we don't bother checking for memory addresses that can't conflict because we expect this to be a rare case.
This function is similar to reg_overlap_mentioned_p in rtlanal.c except that we look at equivalences for pseudos that didn't get hard registers.
Overly conservative.
If either argument is a constant, then modifying X can not affect IN.
If this is a pseudo, it must not have been assigned a hard register.
Therefore, it must either be in memory or be a constant. We actually want to know if X is mentioned somewhere inside IN.
We must not say that (plus (sp) (const_int 124)) is in
(plus (sp) (const_int 64)), since that can lead to incorrect reload
allocation when spuriously changing a RELOAD_FOR_OUTPUT_ADDRESS
into a RELOAD_OTHER on behalf of another RELOAD_OTHER.
Referenced by copy_replacements_1().
| int regno_clobbered_p | ( | unsigned int | regno, |
| rtx | insn, | ||
| enum machine_mode | mode, | ||
| int | sets | ||
| ) |
Return 1 if register REGNO is the subject of a clobber in insn INSN. If SETS is 1, also consider SETs. If SETS is 2, enable checking REG_INC. REGNO must refer to a hard register.
regno must be a hard register.
| rtx reload_adjust_reg_for_mode | ( | ) |
Find the low part, with mode MODE, of a hard regno RELOADREG.
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Return true if X is a SUBREG that will need reloading of its SUBREG_REG expression. MODE is the mode that X will be used in. OUTPUT is true if the function is invoked for the output part of an enclosing reload.
Only SUBREGs are problematical.
If INNER is a constant or PLUS, then INNER will need reloading.
If INNER is not a hard register, then INNER will not need reloading.
If INNER is not ok for MODE, then INNER will need reloading.
If this is for an output, and the outer part is a word or smaller, INNER is larger than a word and the number of registers in INNER is not the same as the number of words in INNER, then INNER will need reloading (with an in-out reload).
| int remove_address_replacements | ( | ) |
IN_RTX is the value loaded by a reload that we now decided to inherit, or a subpart of it. If we have any replacements registered for IN_RTX, cancel the reloads that were supposed to load them. Return nonzero if we canceled any reloads.
Note that the following store must be done before the recursive calls.
References reg_class_subset_p(), RELOAD_OTHER, rld, and targetm.
| int safe_from_earlyclobber | ( | ) |
Similar, but calls decompose.
References gcc_assert, and this_insn_is_asm.
| enum reg_class scratch_reload_class | ( | ) |
ICODE is the insn_code of a reload pattern. Check that it has exactly three operands, verify that operand 2 is an output operand, and return its register class. ??? We'd like to be able to handle any pattern with at least 2 operands, for zero or more scratch registers, but that needs more infrastructure.
| reg_class_t secondary_reload_class | ( | bool | in_p, |
| reg_class_t | rclass, | ||
| enum machine_mode | mode, | ||
| rtx | x | ||
| ) |
If a secondary reload is needed, return its class. If both an intermediate register and a scratch register is needed, we return the class of the intermediate register.
If there are no secondary reloads at all, we return NO_REGS. If an intermediate register is needed, we return its class.
No intermediate register is needed, but we have a special reload pattern, which we assume for now needs a scratch register.
Referenced by deallocate_reload_reg().
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True if C is a non-empty register class that has too few registers to be safely used as a reload target class.
Referenced by find_valid_class_1().
| int strict_memory_address_addr_space_p | ( | enum machine_mode | mode, |
| rtx | addr, | ||
| addr_space_t | as | ||
| ) |
Return 1 if ADDR is a valid memory address for mode MODE in address space AS, and check that each pseudo reg has the proper kind of hard reg.
References operands_match_p(), and XVECEXP.
Referenced by subreg_lowpart_offset().
|
static |
If ADDR is a sum containing a pseudo register that should be replaced with a constant (from reg_equiv_constant), return the result of doing so, and also apply the associative law so that the result is more likely to be a valid address. (But it is not guaranteed to be one.)
Note that at most one register is replaced, even if more are replaceable. Also, we try to put the result into a canonical form so it is more likely to be a valid address.
In all other cases, return ADDR.
Try to find a register to replace.
Pick out up to three things to add.
Compute the sum.
|
static |
Find all pseudo regs appearing in AD that are eliminable in favor of equivalent values and do not have hard regs; replace them by their equivalents. INSN, if nonzero, is the insn in which we do the reload. We put USEs in front of it for pseudos that we have to replace with stack slots.
We mark the USE with QImode so that we recognize it
as one that can be safely deleted at the end of
reload.
Quickly dispose of a common case.
| void subst_reloads | ( | ) |
Substitute into the current INSN the registers into which we have reloaded the things that need reloading. The array `replacements' contains the locations of all pointers that must be changed and says what to replace them with.
Return the rtx that X translates into; usually X, but modified.
If we're replacing a LABEL_REF with a register, there must
already be an indication (to e.g. flow) which label this
register refers to.
Encapsulate RELOADREG so its machine mode matches what
used to be there. Note that gen_lowpart_common will
do the wrong thing if RELOADREG is multi-word. RELOADREG
will always be a REG here. If reload got no reg and isn't optional, something's wrong.
References CONSTANT_P, DEBUG_INSN_P, frame_pointer_rtx, GET_CODE, GET_MODE, LABEL_P, MEM_P, MEM_VOLATILE_P, PARAM_VALUE, PREV_INSN, REG_P, REGNO, SCALAR_FLOAT_MODE_P, stack_pointer_rtx, replacement::where, and XEXP.
| void transfer_replacements | ( | ) |
Transfer all replacements that used to be in reload FROM to be in reload TO.
References targetm.
|
static |
Update the REG_INC notes for an insn. It updates all REG_INC notes for the instruction which refer to REGNO the to refer to the reload number.
INSN is the insn for which any REG_INC notes need updating.
REGNO is the register number which has been reloaded.
RELOADNUM is the reload number.
References GET_MODE, push_reload(), RELOAD_OTHER, and XEXP.
Variable Documentation
|
static |
If hard_regs_live_known is nonzero, we can tell which hard regs are currently live, at least enough to succeed in choosing dummy reloads.
| int n_earlyclobbers |
All the "earlyclobber" operands of the current insn are recorded here.
| int n_reloads |
All reloads of the current insn are recorded here. See reload.h for comments.
Referenced by find_valid_class_1(), gen_reload_chain_without_interm_reg_p(), and maybe_fix_stack_asms().
|
static |
Number of replacements currently recorded.
|
static |
On return from push_reload, holds the reload-number for the OUT operand, which can be different for that from the input operand.
| rtx reload_earlyclobbers[MAX_RECOG_OPERANDS] |
| int reload_n_operands |
Save the number of operands.
|
static |
|
static |
Replacing reloads.
If `replace_reloads' is nonzero, then as each reload is recorded an entry is made for it in the table `replacements'. Then later `subst_reloads' can look through that table and perform all the replacements needed. Nonzero means record the places to replace.
|
static |
| struct reload rld[MAX_RELOADS] |
Referenced by find_reusable_reload(), find_valid_class_1(), reloads_unique_chain_p(), and remove_address_replacements().
|
static |
Indexed by hard reg number, element is nonnegative if hard reg has been spilled. This vector is passed to `find_reloads' as an argument and is not changed here.
|
static |
Set to 1 in subst_reg_equivs if it changes anything.
|
static |
The instruction we are doing reloads for; so we can test whether a register dies in it.
|
static |
Nonzero if this instruction is a user-specified asm with operands.
Referenced by safe_from_earlyclobber().
