dwarf2cfi.c File Reference
#include "expr.h"
Include dependency graph for dwarf2cfi.c:
Data Structures | |
| struct | dw_cfi_row_struct |
| struct | reg_saved_in_data_struct |
| struct | dw_trace_info |
| struct | trace_info_hasher |
| struct | queued_reg_save |
Typedefs | |
| typedef struct dw_cfi_row_struct | dw_cfi_row |
| typedef struct reg_saved_in_data_struct | reg_saved_in_data |
| typedef dw_trace_info * | dw_trace_info_ref |
Variables | |
| static vec< dw_trace_info > | trace_info |
| static vec< dw_trace_info_ref > | trace_work_list |
| static hash_table < trace_info_hasher > | trace_index |
| cfi_vec | cie_cfi_vec |
| static dw_cfi_row * | cie_cfi_row |
| static reg_saved_in_data * | cie_return_save |
| static unsigned long | dwarf2out_cfi_label_num |
| static rtx | add_cfi_insn |
| static cfi_vec * | add_cfi_vec |
| static dw_trace_info * | cur_trace |
| static dw_cfi_row * | cur_row |
| static dw_cfa_location * | cur_cfa |
| static vec< queued_reg_save > | queued_reg_saves |
| static bool | any_cfis_emitted |
| static unsigned | dw_stack_pointer_regnum |
| static unsigned | dw_frame_pointer_regnum |
| static signed char | saved_do_cfi_asm = 0 |
Typedef Documentation
| typedef struct dw_cfi_row_struct dw_cfi_row |
A collected description of an entire row of the abstract CFI table.
| typedef dw_trace_info* dw_trace_info_ref |
| typedef struct reg_saved_in_data_struct reg_saved_in_data |
The caller's ORIG_REG is saved in SAVED_IN_REG.
Function Documentation
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Add CFI either to the current insn stream or to a vector, or both.
References dw_cfi_row_struct::reg_save, vec_safe_grow_cleared(), and vec_safe_length().
Referenced by copy_cfi_row(), and dwarf2out_cfi_label().
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While we can occasionally have args_size < 0 internally, this state
should not persist at a point we actually need an opcode.
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Walk the function, looking for NOTE_INSN_CFI notes. Add the CFIs to the function's FDE, adding CFI labels and set_loc/advance_loc opcodes as necessary.
We always start with a function_begin label.
Don't attempt to advance_loc4 between labels
in different sections. Set the location counter to the new label.
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Return the insn before the first NOTE_INSN_CFI after START.
References dw_trace_info::head, dw_trace_info::id, memset(), and dw_trace_info::switch_sections.
| bool cfa_equal_p | ( | ) |
Determine if two dw_cfa_location structures define the same data.
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Determine if two CFI entries are identical.
Make things easier for our callers, including missing operands.
Obviously, the opcodes must match.
Compare the two operands, re-using the type of the operands as
already exposed elsewhere.
Referenced by cfi_oprnd_equal_p().
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Examine CFI and return true if a cfi label and set_loc is needed beforehand. Even when generating CFI assembler instructions, we still have to add the cfi to the list so that lookup_cfa_1 works later on. When -g2 and above we even need to force emitting of CFI labels and add to list a DW_CFA_set_loc for convert_cfa_to_fb_loc_list purposes. If we're generating DWARF3 output we use DW_OP_call_frame_cfa and so don't use convert_cfa_to_fb_loc_list.
References dw_cfi_row_struct::cfa, cur_row, cur_trace, dw_trace_info::end_true_args_size, HOST_WIDE_INT, maybe_record_trace_start(), cfa_loc::offset, and cfa_loc::reg.
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Determine if two CFI operands are identical.
References dw_cfi_row_struct::cfa_cfi, and cfi_equal_p().
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Determine if two CFI_ROW structures are identical.
Referenced by change_cfi_row().
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Emit CFI info to change the state from OLD_ROW to NEW_ROW.
References dw_trace_info::args_size_undefined, dw_trace_info::beg_row, dw_trace_info::beg_true_args_size, dw_trace_info::cfa_store, dw_trace_info::cfa_temp, cfi_row_equal_p(), copy_cfi_row(), cur_row, cur_trace, dump_file, dw_trace_info::end_true_args_size, get_trace_info(), HOST_WIDE_INT, dw_trace_info::id, dw_trace_info::regs_saved_in_regs, and rtx_name.
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Does INSN clobber any register which QUEUED_REG_SAVES lists a saved location for? Or, does it clobber a register which we've previously said that some other register is saved in, and for which we now have a new location for?
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Compare X and Y for equivalence. The inputs may be REGs or PC_RTX.
Referenced by notice_eh_throw(), and record_reg_saved_in_reg().
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Insert CFI notes between traces to properly change state between them.
??? Ideally, we should have both queued and processed every trace.
However the current representation of constant pools on various targets
is indistinguishable from unreachable code. Assume for the moment that
we can simply skip over such traces. ??? Consider creating a DATA_INSN rtx code to indicate that
these are not "real" instructions, and should not be considered.
This could be generically useful for tablejump data as well. Remove all unprocessed traces from the list.
Work from the end back to the beginning. This lets us easily insert
remember/restore_state notes in the correct order wrt other notes. In dwarf2out_switch_text_section, we'll begin a new FDE
for the portion of the function in the alternate text
section. The row state at the very beginning of that
new FDE will be exactly the row state from the CIE. If there's no change from the previous end state, fine.
Otherwise check for the common case of sharing state with
the beginning of an epilogue, but not the end. Insert
remember/restore opcodes in that case. Note that if we blindly insert the remember at the
start of the trace, we can wind up increasing the
size of the unwind info due to extra advance opcodes.
Instead, put the remember immediately before the next
state change. We know there must be one, because the
state at the beginning and head of the trace differ. Otherwise, we'll simply change state from the previous end.
Connect args_size between traces that have can_throw_internal insns.
??? Search back to previous CFI note.
References dump_file, hash_table< Descriptor, Allocator >::find_slot_with_hash(), dw_trace_info::head, rtx_name, and dw_trace_info::switch_sections.
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Return a copy of an existing CFI row.
References add_cfi(), dw_cfi_oprnd_struct::dw_cfi_offset, dw_cfi_struct::dw_cfi_opc, dw_cfi_struct::dw_cfi_oprnd1, and new_cfi().
Referenced by change_cfi_row().
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Scan the function and create the initial set of CFI notes.
Always begin at the entry trace.
References save_point_p().
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On entry, the Canonical Frame Address is at SP.
For a few targets, we have the return address incoming into a
register, but choose a different return column. This will result
in a DW_CFA_register for the return, and an entry in
regs_saved_in_regs to match. If the target later stores that
return address register to the stack, we want to be able to emit
the DW_CFA_offset against the return column, not the intermediate
save register. Save the contents of regs_saved_in_regs so that
we can re-initialize it at the start of each function.
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Set up the pseudo-cfg of instruction traces, as described at the block comment at the top of the file.
The first trace begins at the start of the function,
and begins with the CIE row state. Walk all the insns, collecting start of trace locations.
We should have just seen a barrier.
Watch out for save_point notes between basic blocks.
In particular, a note after a barrier. Do not record these,
delaying trace creation until the label. Create the trace index after we've finished building trace_info,
avoiding stale pointer problems due to reallocation.
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Propagate CUR_TRACE state to the destinations implied by INSN.
??? Sadly, this is in large part a duplicate of make_edges.
Sibling calls don't have edges inside this function.
Process non-local goto edges.
Process EH edges.
References add_cfi_insn, dw_cfi_row_struct::cfa, cur_cfa, cur_row, cur_trace, dw_trace_info::end_true_args_size, HOST_WIDE_INT, dw_cfi_row_struct::reg_save, scan_insn_after(), and vec_safe_copy().
| void debug_cfi_row | ( | dw_cfi_row * | row | ) |
| void debug_cfi_row | ( | ) |
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The CFA is now calculated from NEW_CFA. Consider OLD_CFA in determining what opcode to emit. Returns the CFI opcode to effect the change, or NULL if NEW_CFA == OLD_CFA.
If nothing changed, no need to issue any call frame instructions.
Construct a "DW_CFA_def_cfa_offset <offset>" instruction, indicating
the CFA register did not change but the offset did. The data
factoring for DW_CFA_def_cfa_offset_sf happens in output_cfi, or
in the assembler via the .cfi_def_cfa_offset directive. Construct a "DW_CFA_def_cfa_register <register>" instruction,
indicating the CFA register has changed to <register> but the
offset has not changed. Construct a "DW_CFA_def_cfa <register> <offset>" instruction,
indicating the CFA register has changed to <register> with
the specified offset. The data factoring for DW_CFA_def_cfa_sf
happens in output_cfi, or in the assembler via the .cfi_def_cfa
directive. Construct a DW_CFA_def_cfa_expression instruction to
calculate the CFA using a full location expression since no
register-offset pair is available.
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Similarly, but take OLD_CFA from CUR_ROW, and update it after the fact.
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Divide OFF by DWARF_CIE_DATA_ALIGNMENT, asserting no remainder.
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Generate a new label for the CFI info to refer to.
References add_cfi(), dw_cfi_struct::dw_cfi_opc, dw_cfi_struct::dw_cfi_oprnd1, dw_cfi_oprnd_struct::dw_cfi_reg_num, and new_cfi().
| bool dwarf2out_do_cfi_asm | ( | void | ) |
Decide whether to emit frame unwind via assembler directives.
Assume failure for a moment.
Make sure the personality encoding is one the assembler can support.
In particular, aligned addresses can't be handled. If we can't get the assembler to emit only .debug_frame, and we don't need
dwarf2 unwind info for exceptions, then emit .debug_frame by hand. Success!
Referenced by append_entry_to_tmpl_value_parm_die_table().
| bool dwarf2out_do_frame | ( | void | ) |
Decide whether we want to emit frame unwind information for the current translation unit.
We want to emit correct CFA location expressions or lists, so we
have to return true if we're going to output debug info, even if
we're not going to output frame or unwind info.
| void dwarf2out_emit_cfi | ( | ) |
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Output all the entries in QUEUED_REG_SAVES.
References cfa_loc::base_offset, cur_cfa, dwf_regno(), cfa_loc::indirect, memset(), cfa_loc::offset, and cfa_loc::reg.
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Record call frame debugging information for INSN, which either sets SP or FP (adjusting how we calculate the frame address) or saves a register to the stack.
The actual flush happens elsewhere.
Check again. A parallel can save and update the same register.
We could probably check just once, here, but this is safer than
removing the check at the start of the function.
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A subroutine of dwarf2out_frame_debug, process a REG_ADJUST_CFA note.
References dwf_regno(), and reg_save().
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A subroutine of dwarf2out_frame_debug, process a REG_CFA_EXPRESSION note.
??? We'd like to use queue_reg_save, were the interface different,
and, as above, we could manage flushing for epilogues.
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A subroutine of dwarf2out_frame_debug, process a REG_CFA_OFFSET note.
As documented, only consider extremely simple addresses.
??? We'd like to use queue_reg_save, but we need to come up with
a different flushing heuristic for epilogues. We have a PARALLEL describing where the contents of SRC live.
Queue register saves for each piece of the PARALLEL.
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A subroutine of dwarf2out_frame_debug, process a REG_CFA_REGISTER note.
??? We'd like to use queue_reg_save, but we need to come up with
a different flushing heuristic for epilogues.
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A subroutine of dwarf2out_frame_debug, process a REG_CFA_RESTORE note.
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A subroutine of dwarf2out_frame_debug, process a REG_CFA_WINDOW_SAVE. ??? Perhaps we should note in the CIE where windows are saved (instead of assuming 0(cfa)) and what registers are in the window.
References dw_trace_info::cfa_temp, cfun, cur_cfa, cur_trace, dwarf2out_frame_debug_expr(), dwf_regno(), function::fde, HOST_WIDE_INT, limit, cfa_loc::offset, offset, cfa_loc::reg, reg_saved_in(), SET, and dw_fde_struct::stack_realign.
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A subroutine of dwarf2out_frame_debug, process a REG_DEF_CFA note.
??? If this fails, we could be calling into the _loc functions to
define a full expression. So far no port does that.
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Record call frame debugging information for an expression EXPR,
which either sets SP or FP (adjusting how we calculate the frame
address) or saves a register to the stack or another register.
LABEL indicates the address of EXPR.
This function encodes a state machine mapping rtxes to actions on
cfa, cfa_store, and cfa_temp.reg. We describe these rules so
users need not read the source code.
The High-Level Picture
Changes in the register we use to calculate the CFA: Currently we
assume that if you copy the CFA register into another register, we
should take the other one as the new CFA register; this seems to
work pretty well. If it's wrong for some target, it's simple
enough not to set RTX_FRAME_RELATED_P on the insn in question.
Changes in the register we use for saving registers to the stack:
This is usually SP, but not always. Again, we deduce that if you
copy SP into another register (and SP is not the CFA register),
then the new register is the one we will be using for register
saves. This also seems to work.
Register saves: There's not much guesswork about this one; if
RTX_FRAME_RELATED_P is set on an insn which modifies memory, it's a
register save, and the register used to calculate the destination
had better be the one we think we're using for this purpose.
It's also assumed that a copy from a call-saved register to another
register is saving that register if RTX_FRAME_RELATED_P is set on
that instruction. If the copy is from a call-saved register to
the *same* register, that means that the register is now the same
value as in the caller.
Except: If the register being saved is the CFA register, and the
offset is nonzero, we are saving the CFA, so we assume we have to
use DW_CFA_def_cfa_expression. If the offset is 0, we assume that
the intent is to save the value of SP from the previous frame.
In addition, if a register has previously been saved to a different
register,
Invariants / Summaries of Rules
cfa current rule for calculating the CFA. It usually
consists of a register and an offset. This is
actually stored in *cur_cfa, but abbreviated
for the purposes of this documentation.
cfa_store register used by prologue code to save things to the stack
cfa_store.offset is the offset from the value of
cfa_store.reg to the actual CFA
cfa_temp register holding an integral value. cfa_temp.offset
stores the value, which will be used to adjust the
stack pointer. cfa_temp is also used like cfa_store,
to track stores to the stack via fp or a temp reg.
Rules 1- 4: Setting a register's value to cfa.reg or an expression
with cfa.reg as the first operand changes the cfa.reg and its
cfa.offset. Rule 1 and 4 also set cfa_temp.reg and
cfa_temp.offset.
Rules 6- 9: Set a non-cfa.reg register value to a constant or an
expression yielding a constant. This sets cfa_temp.reg
and cfa_temp.offset.
Rule 5: Create a new register cfa_store used to save items to the
stack.
Rules 10-14: Save a register to the stack. Define offset as the
difference of the original location and cfa_store's
location (or cfa_temp's location if cfa_temp is used).
Rules 16-20: If AND operation happens on sp in prologue, we assume
stack is realigned. We will use a group of DW_OP_XXX
expressions to represent the location of the stored
register instead of CFA+offset.
The Rules
"{a,b}" indicates a choice of a xor b.
"<reg>:cfa.reg" indicates that <reg> must equal cfa.reg.
Rule 1:
(set <reg1> <reg2>:cfa.reg)
effects: cfa.reg = <reg1>
cfa.offset unchanged
cfa_temp.reg = <reg1>
cfa_temp.offset = cfa.offset
Rule 2:
(set sp ({minus,plus,losum} {sp,fp}:cfa.reg
{<const_int>,<reg>:cfa_temp.reg}))
effects: cfa.reg = sp if fp used
cfa.offset += {+/- <const_int>, cfa_temp.offset} if cfa.reg==sp
cfa_store.offset += {+/- <const_int>, cfa_temp.offset}
if cfa_store.reg==sp
Rule 3:
(set fp ({minus,plus,losum} <reg>:cfa.reg <const_int>))
effects: cfa.reg = fp
cfa_offset += +/- <const_int>
Rule 4:
(set <reg1> ({plus,losum} <reg2>:cfa.reg <const_int>))
constraints: <reg1> != fp
<reg1> != sp
effects: cfa.reg = <reg1>
cfa_temp.reg = <reg1>
cfa_temp.offset = cfa.offset
Rule 5:
(set <reg1> (plus <reg2>:cfa_temp.reg sp:cfa.reg))
constraints: <reg1> != fp
<reg1> != sp
effects: cfa_store.reg = <reg1>
cfa_store.offset = cfa.offset - cfa_temp.offset
Rule 6:
(set <reg> <const_int>)
effects: cfa_temp.reg = <reg>
cfa_temp.offset = <const_int>
Rule 7:
(set <reg1>:cfa_temp.reg (ior <reg2>:cfa_temp.reg <const_int>))
effects: cfa_temp.reg = <reg1>
cfa_temp.offset |= <const_int>
Rule 8:
(set <reg> (high <exp>))
effects: none
Rule 9:
(set <reg> (lo_sum <exp> <const_int>))
effects: cfa_temp.reg = <reg>
cfa_temp.offset = <const_int>
Rule 10:
(set (mem ({pre,post}_modify sp:cfa_store (???? <reg1> <const_int>))) <reg2>)
effects: cfa_store.offset -= <const_int>
cfa.offset = cfa_store.offset if cfa.reg == sp
cfa.reg = sp
cfa.base_offset = -cfa_store.offset
Rule 11:
(set (mem ({pre_inc,pre_dec,post_dec} sp:cfa_store.reg)) <reg>)
effects: cfa_store.offset += -/+ mode_size(mem)
cfa.offset = cfa_store.offset if cfa.reg == sp
cfa.reg = sp
cfa.base_offset = -cfa_store.offset
Rule 12:
(set (mem ({minus,plus,losum} <reg1>:{cfa_store,cfa_temp} <const_int>))
<reg2>)
effects: cfa.reg = <reg1>
cfa.base_offset = -/+ <const_int> - {cfa_store,cfa_temp}.offset
Rule 13:
(set (mem <reg1>:{cfa_store,cfa_temp}) <reg2>)
effects: cfa.reg = <reg1>
cfa.base_offset = -{cfa_store,cfa_temp}.offset
Rule 14:
(set (mem (post_inc <reg1>:cfa_temp <const_int>)) <reg2>)
effects: cfa.reg = <reg1>
cfa.base_offset = -cfa_temp.offset
cfa_temp.offset -= mode_size(mem)
Rule 15:
(set <reg> {unspec, unspec_volatile})
effects: target-dependent
Rule 16:
(set sp (and: sp <const_int>))
constraints: cfa_store.reg == sp
effects: cfun->fde.stack_realign = 1
cfa_store.offset = 0
fde->drap_reg = cfa.reg if cfa.reg != sp and cfa.reg != fp
Rule 17:
(set (mem ({pre_inc, pre_dec} sp)) (mem (plus (cfa.reg) (const_int))))
effects: cfa_store.offset += -/+ mode_size(mem)
Rule 18:
(set (mem ({pre_inc, pre_dec} sp)) fp)
constraints: fde->stack_realign == 1
effects: cfa_store.offset = 0
cfa.reg != HARD_FRAME_POINTER_REGNUM
Rule 19:
(set (mem ({pre_inc, pre_dec} sp)) cfa.reg)
constraints: fde->stack_realign == 1
&& cfa.offset == 0
&& cfa.indirect == 0
&& cfa.reg != HARD_FRAME_POINTER_REGNUM
effects: Use DW_CFA_def_cfa_expression to define cfa
cfa.reg == fde->drap_reg If RTX_FRAME_RELATED_P is set on a PARALLEL, process each member of
the PARALLEL independently. The first element is always processed if
it is a SET. This is for backward compatibility. Other elements
are processed only if they are SETs and the RTX_FRAME_RELATED_P
flag is set in them. PARALLELs have strict read-modify-write semantics, so we
ought to evaluate every rvalue before changing any lvalue.
It's cumbersome to do that in general, but there's an
easy approximation that is enough for all current users:
handle register saves before register assignments. Setting FP from SP.
Rule 1
Update the CFA rule wrt SP or FP. Make sure src is
relative to the current CFA register.
We used to require that dest be either SP or FP, but the
ARM copies SP to a temporary register, and from there to
FP. So we just rely on the backends to only set
RTX_FRAME_RELATED_P on appropriate insns. Saving a register in a register.
For the SPARC and its register window.
After stack is aligned, we can only save SP in FP
if drap register is used. In this case, we have
to restore stack pointer with the CFA value and we
don't generate this DWARF information. Rule 2
Adjusting SP.
Restoring SP from FP in the epilogue.
Assume we've set the source reg of the LO_SUM from sp.
Rule 3
Either setting the FP from an offset of the SP,
or adjusting the FP Rule 4
Setting a temporary CFA register that will be copied
into the FP later on. Or used to save regs to the stack.
Rule 5
Setting a scratch register that we will use instead
of SP for saving registers to the stack. Rule 9
Rule 6
Rule 7
Skip over HIGH, assuming it will be followed by a LO_SUM,
which will fill in all of the bits. Rule 8
Rule 15
All unspecs should be represented by REG_CFA_* notes.
Rule 16
If this AND operation happens on stack pointer in prologue,
we assume the stack is realigned and we extract the
alignment. We interpret reg_save differently with stack_realign set.
Thus we must flush whatever we have queued first. Saving a register to the stack. Make sure dest is relative to the
CFA register. Rule 10
With a push.
We can't handle variable size modifications.
Rule 11
Rule 18: If stack is aligned, we will use FP as a
reference to represent the address of the stored
regiser. Rule 12
With an offset.
Rule 13
Without an offset.
Rule 14
Rule 17
If the source operand of this MEM operation is a memory,
we only care how much stack grew. We're storing the current CFA reg into the stack.
Rule 19
If stack is aligned, putting CFA reg into stack means
we can no longer use reg + offset to represent CFA.
Here we use DW_CFA_def_cfa_expression instead. The
result of this expression equals to the original CFA
value. If the source register is exactly the CFA, assume
we're saving SP like any other register; this happens
on the ARM. Otherwise, we'll need to look in the stack to
calculate the CFA. We have a PARALLEL describing where the contents of SRC live.
Queue register saves for each piece of the PARALLEL.
Referenced by dwarf2out_frame_debug_cfa_window_save().
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Convert a DWARF call frame info. operation to its string name
References asm_out_file.
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Short-hand inline for the very common D_F_R (REGNO (x)) operation.
??? This ought to go into dwarf2out.h, except that dwarf2out.h is used in places where rtl is prohibited.
References pc_rtx, record_reg_saved_in_reg(), queued_reg_save::reg, and queued_reg_save::saved_reg.
Referenced by dwarf2out_flush_queued_reg_saves(), dwarf2out_frame_debug_adjust_cfa(), dwarf2out_frame_debug_cfa_window_save(), and reg_saved_in().
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Annotate the function with NOTE_INSN_CFI notes to record the CFI state at each location within the function. These notes will be emitted during pass_final.
The first time we're called, compute the incoming frame state.
Do the work.
Free all the data we allocated.
| rtx expand_builtin_dwarf_sp_column | ( | void | ) |
Hook used by __throw.
References choose_hard_reg_mode(), and HOST_WIDE_INT.
| void expand_builtin_init_dwarf_reg_sizes | ( | ) |
Generate code to initialize the register size table.
References targetm.
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Targets which still implement the prologue in assembler text
cannot use the generic dwarf2 unwinding. ??? What to do for UI_TARGET unwinding? They might be able to benefit
from the optimized shrink-wrapping annotations that we will compute.
For now, only produce the CFI notes for dwarf2.
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This function fills in aa dw_cfa_location structure from a dwarf location descriptor sequence.
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Referenced by change_cfi_row().
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MEM is a memory reference for the register size table, each element of which has mode MODE. Initialize column C as a return address column.
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Record the initial position of the return address. RTL is INCOMING_RETURN_ADDR_RTX.
RA is in a register.
RA is on the stack.
The return address is at some offset from any value we can
actually load. For instance, on the SPARC it is in %i7+8. Just
ignore the offset for now; it doesn't matter for unwinding frames.
| void lookup_cfa_1 | ( | ) |
Find the previous value for the CFA, iteratively. CFI is the opcode to interpret, *LOC will be updated as necessary, *REMEMBER is used for one level of remember/restore state processing.
References dw_cfi_oprnd_struct::dw_cfi_addr, dw_cfi_oprnd_struct::dw_cfi_loc, dw_cfi_oprnd_struct::dw_cfi_offset, dw_cfi_oprnd_addr, dw_cfi_oprnd_loc, dw_cfi_oprnd_offset, dw_cfi_oprnd_reg_num, dw_cfi_oprnd_unused, dw_cfi_oprnd_struct::dw_cfi_reg_num, and loc_descr_equal_p().
| rtl_opt_pass* make_pass_dwarf2_frame | ( | ) |
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If LABEL is the start of a trace, then initialize the state of that trace from CUR_TRACE and CUR_ROW.
This is the first time we've encountered this trace. Propagate
state across the edge and push the trace onto the work list. We ought to have the same state incoming to a given trace no
matter how we arrive at the trace. Anything else means we've
got some kind of optimization error. The args_size is allowed to conflict if it isn't actually used.
Referenced by cfi_label_required_p().
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Similarly, but handle the args_size and CFA reset across EH and non-local goto edges.
Convert a change in args_size (always a positive in the
direction of stack growth) to a change in stack pointer.
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Return true if we need a signed version of a given opcode (e.g. DW_CFA_offset_extended_sf vs DW_CFA_offset_extended).
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Return a pointer to a newly allocated Call Frame Instruction.
Referenced by copy_cfi_row(), and dwarf2out_cfi_label().
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Return a newly allocated CFI row, with no defined data.
References add_cfi_insn, and emit_note_after().
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A subroutine of scan_trace. Check INSN for a REG_ARGS_SIZE note and adjust data structures to match.
If the CFA is computed off the stack pointer, then we must adjust
the computation of the CFA as well. Convert a change in args_size (always a positive in the
direction of stack growth) to a change in stack pointer.
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A subroutine of scan_trace. INSN is can_throw_internal. Update the data within the trace related to EH insns and args_size.
??? If the CFA is the stack pointer, search backward for the last
CFI note and insert there. Given that the stack changed for the
args_size change, there *must* be such a note in between here and
the last eh insn.
References compare_reg_or_pc(), and queued_reg_save::reg.
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This routine will generate the correct assembly data for a location description based on a cfi entry with a complex address.
Output the size of the block.
Now output the operations themselves.
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Similar, but used for .cfi_escape.
Output the size of the block.
Now output the operations themselves.
| void output_cfi | ( | ) |
Output a Call Frame Information opcode and its operand(s).
Obsoleted by DW_CFA_offset_extended_sf.
References dw2_asm_output_data_uleb128_raw(), dw_cfi_oprnd_struct::dw_cfi_offset, dw_cfi_struct::dw_cfi_oprnd1, and HOST_WIDE_INT_PRINT_DEC.
| void output_cfi_directive | ( | ) |
Similar, but do it via assembler directives instead.
Should only be created in a code path not followed when emitting
via directives. The assembler is going to take care of this for
us. But this routines is also used for debugging dumps, so
print something. FALLTHRU
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Add an entry to QUEUED_REG_SAVES saying that REG is now saved at SREG, or if SREG is NULL then it is saved at OFFSET to the CFA.
Duplicates waste space, but it's also necessary to remove them
for correctness, since the queue gets output in reverse order.
References cur_trace, reg_saved_in_data_struct::orig_reg, queued_reg_save::reg, dw_trace_info::regs_saved_in_regs, reg_saved_in_data_struct::saved_in_reg, and queued_reg_save::saved_reg.
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Record SRC as being saved in DEST. DEST may be null to delete an existing entry. SRC may be a register or PC_RTX.
References compare_reg_or_pc(), cur_trace, modified_in_p(), reg_saved_in_data_struct::orig_reg, queued_reg_save::reg, dw_trace_info::regs_saved_in_regs, and reg_saved_in_data_struct::saved_in_reg.
Referenced by dwf_regno().
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Add the CFI for saving a register. REG is the CFA column number. If SREG is -1, the register is saved at OFFSET from the CFA; otherwise it is saved in SREG.
When stack is aligned, store REG using DW_CFA_expression with FP.
While we could emit something like DW_CFA_same_value or
DW_CFA_restore, we never expect to see something like that
in a prologue. This is more likely to be a bug. A backend
can always bypass this by using REG_CFA_RESTORE directly.
References cur_cfa, cfa_loc::indirect, and cfa_loc::offset.
Referenced by dwarf2out_frame_debug_adjust_cfa().
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What register, if any, is currently saved in REG?
References cur_cfa, dwf_regno(), HOST_WIDE_INT, cfa_loc::offset, offset, and cfa_loc::reg.
Referenced by dwarf2out_frame_debug_cfa_window_save().
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Labels, except those that are really jump tables.
We split traces at the prologue/epilogue notes because those
are points at which the unwind info is usually stable. This
makes it easier to find spots with identical unwind info so
that we can use remember/restore_state opcodes.
Referenced by create_cfi_notes().
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A subroutine of scan_trace. Do what needs to be done "after" INSN.
Referenced by create_trace_edges().
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Scan the trace beginning at INSN and create the CFI notes for the instructions therein.
Do everything that happens "before" the insn.
Notice the end of a trace.
Don't bother saving the unneeded queued registers at all.
Propagate across fallthru edges.
Handle all changes to the row state. Sequences require special
handling for the positioning of the notes. ??? Hopefully multiple delay slots are not annulled.
If ELT is an instruction from target of an annulled
branch, the effects are for the target only and so
the args_size and CFA along the current path
shouldn't change. ??? Should we instead save the entire row state?
If ELT is a annulled branch-taken instruction (i.e.
executed only when branch is not taken), the args_size
and CFA should not change through the jump. Update and continue with the trace.
The insns in the delay slot should all be considered to happen
"before" a call insn. Consider a call with a stack pointer
adjustment in the delay slot. The backtrace from the callee
should include the sp adjustment. Unfortunately, that leaves
us with an unavoidable unwinding error exactly at the call insn
itself. For jump insns we'd prefer to avoid this error by
placing the notes after the sequence. Make sure any register saves are visible at the jump target.
However, if there is some adjustment on the call itself, e.g.
a call_pop, that action should be considered to happen after
the call returns. Flush data before calls and jumps, and of course if necessary.
Between frame-related-p and args_size we might have otherwise
emitted two cfa adjustments. Do it now. Minimize the number of advances by emitting the entire queue
once anything is emitted. Note that a test for control_flow_insn_p does exactly the
same tests as are done to actually create the edges. So
always call the routine and let it not create edges for
non-control-flow insns.
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Perform ROW->REG_SAVE[COLUMN] = CFI. CFI may be null, indicating that the register column is no longer saved.
Variable Documentation
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The insn after which a new CFI note should be emitted.
Referenced by create_trace_edges(), and new_cfi_row().
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When non-null, add_cfi will add the CFI to this vector.
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True if any CFI directives were emitted at the current insn.
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The state of the first row of the FDE table, which includes the state provided by the CIE.
| cfi_vec cie_cfi_vec |
A vector of call frame insns for the CIE.
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A copy of the current CFA, for use during the processing of a single insn.
Referenced by create_trace_edges(), dwarf2out_flush_queued_reg_saves(), dwarf2out_frame_debug_cfa_window_save(), reg_save(), and reg_saved_in().
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The current, i.e. most recently generated, row of the CFI table.
Referenced by cfi_label_required_p(), change_cfi_row(), and create_trace_edges().
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The current instruction trace.
Referenced by cfi_label_required_p(), change_cfi_row(), create_trace_edges(), dwarf2out_frame_debug_cfa_window_save(), queue_reg_save(), and record_reg_saved_in_reg().
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Short-hand for commonly used register numbers.
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Save the result of dwarf2out_do_frame across PCH. This variable is tri-state, with 0 unset, >0 true, <0 false.
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The variables making up the pseudo-cfg, as described above.
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