#include "config.h"#include "system.h"#include "coretypes.h"#include "tm.h"#include "tree.h"#include "flags.h"#include "tm_p.h"#include "target.h"#include "ggc.h"#include "langhooks.h"#include "basic-block.h"#include "function.h"#include "gimple-pretty-print.h"#include "pointer-set.h"#include "gimple.h"#include "gimple-ssa.h"#include "tree-phinodes.h"#include "ssa-iterators.h"#include "tree-ssanames.h"#include "tree-ssa-loop-manip.h"#include "tree-into-ssa.h"#include "tree-ssa.h"#include "tree-inline.h"#include "hashtab.h"#include "tree-pass.h"#include "diagnostic-core.h"#include "cfgloop.h"
Data Structures | |
| struct | count_ptr_d |
Variables | |
| static struct pointer_map_t * | edge_var_maps |
Function Documentation
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Helper for count_uses_and_derefs. Called by walk_tree to look for (ALIGN/MISALIGNED_)INDIRECT_REF nodes for the pointer passed in DATA.
Do not walk inside ADDR_EXPR nodes. In the expression &ptr->fld, pointer 'ptr' is not dereferenced, it is simply used to compute the address of 'fld' as 'ptr + offsetof(fld)'.
References walk_stmt_info::is_lhs, count_ptr_d::num_loads, and count_ptr_d::num_stores.
Referenced by count_uses_and_derefs().
| void count_uses_and_derefs | ( | tree | ptr, |
| gimple | stmt, | ||
| unsigned * | num_uses_p, | ||
| unsigned * | num_loads_p, | ||
| unsigned * | num_stores_p | ||
| ) |
Count the number of direct and indirect uses for pointer PTR in statement STMT. The number of direct uses is stored in *NUM_USES_P. Indirect references are counted separately depending on whether they are store or load operations. The counts are stored in *NUM_STORES_P and *NUM_LOADS_P.
Find out the total number of uses of PTR in STMT.
Now count the number of indirect references to PTR. This is truly awful, but we don't have much choice. There are no parent pointers inside INDIRECT_REFs, so an expression like '*x_1 = foo (x_1, *x_1)' needs to be traversed piece by piece to find all the indirect and direct uses of x_1 inside. The only shortcut we can take is the fact that GIMPLE only allows INDIRECT_REFs inside the expressions below.
References count, count_ptr_derefs(), walk_stmt_info::info, count_ptr_d::num_loads, count_ptr_d::num_stores, count_ptr_d::ptr, and walk_gimple_op().
| void delete_tree_ssa | ( | void | ) |
Deallocate memory associated with SSA data structures for FNDECL.
We no longer maintain the SSA operand cache at this point.
We no longer need the edge variable maps.
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Do the actions required to initialize internal data structures used in tree-ssa optimization passes.
Allocate hash tables, arrays and other structures.
References cfun, fini_ssa_operands(), fini_ssanames(), and ssa_operands_active().
| void execute_update_addresses_taken | ( | void | ) |
Compute TREE_ADDRESSABLE and DECL_GIMPLE_REG_P for local variables.
Collect into ADDRESSES_TAKEN all variables whose address is taken within the function body.
Note all addresses taken by the stmt.
If we have a call or an assignment, see if the lhs contains
a local decl that requires not to be a gimple register. We cannot move required conversions from
the lhs to the rhs in asm statements, so
require we do not need any. We cannot iterate over all referenced vars because that can contain unused vars from BLOCK trees, which causes code generation differences for -g vs. -g0.
Operand caches need to be recomputed for operands referencing the updated variables and operands need to be rewritten to expose bare symbols.
Re-write TARGET_MEM_REFs of symbols we want to
rewrite into SSA form. We shouldn't have any fancy wrapping of
component-refs on the LHS, but look through
VIEW_CONVERT_EXPRs as that is easy. Rewrite the RHS and make sure the resulting assignment
is validly typed. For var ={v} {CLOBBER}; where var lost
TREE_ADDRESSABLE just remove the stmt. Update SSA form here, we are called as non-pass as well.
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Called via walk_tree, look for SSA_NAMEs that have already been released.
References FOR_EACH_IMM_USE_FAST, MAY_HAVE_DEBUG_STMTS, name_registered_for_update_p(), NULL, and USE_STMT.
| void flush_pending_stmts | ( | ) |
Add PHI arguments queued in PENDING_STMT list on edge E to edge E->dest.
References add_phi_arg(), gsi_stmt(), redirect_edge_var_map_def(), and redirect_edge_var_map_location().
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Used by redirect_edge_var_map_destroy to free all memory.
References NULL, pointer_map_destroy(), and pointer_map_traverse().
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Gate for IPCP optimization.
Do nothing for funcions that was produced already in SSA form.
Referenced by init_tree_ssa().
| void gimple_replace_ssa_lhs | ( | ) |
Replace the LHS of STMT, an assignment, either a GIMPLE_ASSIGN or a GIMPLE_CALL, with NLHS, in preparation for modifying the RHS to an expression with a different value.
This will update any annotations (say debug bind stmts) referring to the original LHS, so that they use the RHS instead. This is done even if NLHS and LHS are the same, for it is understood that the RHS will be modified afterwards, and NLHS will not be assigned an equivalent value.
Adjusting any non-annotation uses of the LHS, if needed, is a responsibility of the caller.
The effect of this call should be pretty much the same as that of inserting a copy of STMT before STMT, and then removing the original stmt, at which time gsi_remove() would have update annotations, but using this function saves all the inserting, copying and removing.
References DECL_HAS_VALUE_EXPR_P, DECL_VALUE_EXPR, MAY_HAVE_DEBUG_STMTS, NULL_TREE, SSA_NAME_VAR, target_for_debug_bind(), TREE_CODE, and VAR_DECL_IS_VIRTUAL_OPERAND.
| void init_tree_ssa | ( | ) |
Initialize global DFA and SSA structures.
References gate_init_datastructures().
| void insert_debug_temp_for_var_def | ( | ) |
Insert a DEBUG BIND stmt before the DEF of VAR if VAR is referenced by other DEBUG stmts, and replace uses of the DEF with the newly-created debug temp.
If this name has already been registered for replacement, do nothing as anything that uses this name isn't in SSA form.
Check whether there are debug stmts that reference this variable and, if there are, decide whether we should use a debug temp.
Count this as an additional use, so as to make sure we
use a temp unless VAR's definition has a SINGLE_RHS that
can be shared. If we didn't get an insertion point, and the stmt has already been removed, we won't be able to insert the debug bind stmt, so we'll have to drop debug information.
error_mark_node is what fixup_noreturn_call changes PHI arguments
to. When removing blocks without following reverse dominance
order, we may sometimes encounter SSA_NAMEs that have
already been released, referenced in other SSA_DEFs that
we're about to release. Consider:
<bb X>:
v_1 = foo;
<bb Y>:
w_2 = v_1 + bar;
# DEBUG w => w_2
If we deleted BB X first, propagating the value of w_2
won't do us any good. It's too late to recover their
original definition of v_1: when it was deleted, it was
only referenced in other DEFs, it couldn't possibly know
it should have been retained, and propagating every
single DEF just in case it might have to be propagated
into a DEBUG STMT would probably be too wasteful.
When dominator information is not readily available, we
check for and accept some loss of debug information. But
if it is available, there's no excuse for us to remove
blocks in the wrong order, so we don't even check for
dead SSA NAMEs. SSA verification shall catch any
errors. If there's a single use of VAR, and VAR is the entire debug
expression (usecount would have been incremented again
otherwise), and the definition involves only constants and
SSA names, then we can propagate VALUE into this single use,
avoiding the temp.
We can also avoid using a temp if VALUE can be shared and
propagated into all uses, without generating expressions that
wouldn't be valid gimple RHSs.
Other cases that would require unsharing or non-gimple RHSs
are deferred to a debug temp, although we could avoid temps
at the expense of duplication of expressions. unshare_expr is not needed here. vexpr is either a
SINGLE_RHS, that can be safely shared, some other RHS
that was unshared when we found it had a single debug
use, or a DEBUG_EXPR_DECL, that can be safely
shared. If we didn't replace uses with a debug decl fold the
resulting expression. Otherwise we end up with invalid IL.
Referenced by release_ssa_name().
| void insert_debug_temps_for_defs | ( | ) |
Insert a DEBUG BIND stmt before STMT for each DEF referenced by other DEBUG stmts, and replace uses of the DEF with the newly-created debug temp.
References DEF_FROM_PTR, FOR_EACH_IMM_USE_STMT, gimple_debug_bind_p(), gimple_debug_bind_reset_value(), TREE_CODE, and update_stmt().
| gimple_opt_pass* make_pass_init_datastructures | ( | ) |
| gimple_opt_pass* make_pass_update_address_taken | ( | ) |
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When possible, clear TREE_ADDRESSABLE bit or set DECL_GIMPLE_REG_P bit and mark the variable VAR for conversion into SSA. Return true when updating stmts is required.
Global Variables, result decls cannot be changed.
Do not change TREE_ADDRESSABLE if we need to preserve var as
a non-register. Otherwise we are confused and forget to
add virtual operands for it.
References bitmap_set_bit, DECL_P, DECL_UID, get_base_address(), gimple_get_lhs(), non_rewritable_lvalue_p(), and TREE_CODE.
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If necessary, rewrite the base of the reference tree *TP from a MEM_REF to a plain or converted symbol.
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For an lvalue tree LHS return true if it cannot be rewritten into SSA form. Otherwise return true.
A plain decl is always rewritable.
A decl that is wrapped inside a MEM-REF that covers it full is also rewritable. ??? The following could be relaxed allowing component references that do not change the access size.
Referenced by maybe_optimize_var().
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For a tree REF return its base if it is the base of a MEM_REF that cannot be rewritten into SSA form. Otherwise return NULL_TREE.
A plain decl does not need it set.
But watch out for MEM_REFs we cannot lower to a VIEW_CONVERT_EXPR or a BIT_FIELD_REF.
References bitmap_bit_p, bitmap_set_bit, DECL_GIMPLE_REG_P, DECL_HARD_REGISTER, DECL_UID, dump_file, is_gimple_reg(), is_gimple_reg_type(), is_global_var(), print_generic_expr(), TREE_ADDRESSABLE, TREE_CODE, TREE_THIS_VOLATILE, and TREE_TYPE.
| void redirect_edge_var_map_add | ( | ) |
Add a mapping with PHI RESULT and PHI DEF associated with edge E.
| void redirect_edge_var_map_clear | ( | ) |
Clear the var mappings in edge E.
Referenced by redirect_edge_var_map_destroy(), and remove_branch().
| void redirect_edge_var_map_destroy | ( | void | ) |
Clear the edge variable mappings.
References edge_def::dest, gsi_end_p(), gsi_next(), gsi_start_phis(), and redirect_edge_var_map_clear().
| void redirect_edge_var_map_dup | ( | ) |
Duplicate the redirected var mappings in OLDE in NEWE.
Since we can't remove a mapping, let's just duplicate it. This assumes a pointer_map can have multiple edges mapping to the same var_map (many to one mapping), since we don't remove the previous mappings.
| edge_var_map_vector* redirect_edge_var_map_vector | ( | ) |
Return the variable mappings for a given edge. If there is none, return NULL.
Hey, what kind of idiot would... you'd be surprised.
Referenced by remove_forwarder_block_with_phi().
| void release_defs_bitset | ( | ) |
Delete SSA DEFs for SSA versions in the TOREMOVE bitmap, removing dominated stmts before their dominators, so that release_ssa_defs stands a chance of propagating DEFs into debug bind stmts.
Performing a topological sort is probably overkill, this will most likely run in slightly superlinear time, rather than the pathological quadratic worst case.
We can't propagate PHI nodes into debug stmts.
If we find another definition to remove that uses
the one we're looking at, defer the removal of this
one, so that it can be propagated into debug stmts
after the other is.
| void reset_debug_uses | ( | ) |
Reset all debug stmts that use SSA_NAME(s) defined in STMT.
References bitmap_bit_p, bitmap_empty_p(), DEF_FROM_PTR, EXECUTE_IF_SET_IN_BITMAP, FOR_EACH_IMM_USE_STMT, FOR_EACH_SSA_DEF_OPERAND, is_gimple_debug(), ssa_name, SSA_NAME_VERSION, and SSA_OP_DEF.
| edge ssa_redirect_edge | ( | ) |
Remove the corresponding arguments from the PHI nodes in E's destination block and redirect it to DEST. Return redirected edge. The list of removed arguments is stored in a vector accessed through edge_var_maps.
Remove the appropriate PHI arguments in E's destination block.
| bool ssa_undefined_value_p | ( | ) |
Return true if T, an SSA_NAME, has an undefined value.
Parameters get their initial value from the function entry.
When returning by reference the return address is actually a hidden parameter.
Hard register variables get their initial value from the ether.
The value is undefined iff its definition statement is empty.
Referenced by do_partial_partial_insertion().
| tree target_for_debug_bind | ( | ) |
Given a tree for an expression for which we might want to emit locations or values in debug information (generally a variable, but we might deal with other kinds of trees in the future), return the tree that should be used as the variable of a DEBUG_BIND STMT or VAR_LOCATION INSN or NOTE. Return NULL if VAR is not to be tracked.
var-tracking only tracks registers.
Referenced by debug_tree_ssa_stats(), find_def_blocks_for(), and gimple_replace_ssa_lhs().
| tree tree_ssa_strip_useless_type_conversions | ( | ) |
Strip conversions from EXP according to tree_ssa_useless_type_conversion and return the resulting expression.
References build1, integer_zerop(), TREE_OPERAND, and TREE_TYPE.
| bool tree_ssa_useless_type_conversion | ( | ) |
Return true if EXPR is a useless type conversion, otherwise return false.
If we have an assignment that merely uses a NOP_EXPR to change the top of the RHS to the type of the LHS and the type conversion is "safe", then strip away the type conversion so that we can enter LHS = RHS into the const_and_copies table.
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Return true if the DECL_UID in both trees are equal.
References GIMPLE_PASS, OPTGROUP_NONE, PROP_cfg, and TV_NONE.
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Hash a tree in a uid_decl_map.
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Return true if the definition of SSA_NAME at block BB is malformed.
STMT is the statement where SSA_NAME is created.
DEFINITION_BLOCK is an array of basic blocks indexed by SSA_NAME version numbers. If DEFINITION_BLOCK[SSA_NAME_VERSION] is set, it means that the block in that array slot contains the definition of SSA_NAME.
IS_VIRTUAL is true if SSA_NAME is created by a VDEF.
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Return true if any of the arguments for PHI node PHI at block BB is malformed.
DEFINITION_BLOCK is an array of basic blocks indexed by SSA_NAME version numbers. If DEFINITION_BLOCK[SSA_NAME_VERSION] is set, it means that the block in that array slot contains the definition of SSA_NAME.
References error(), handled_component_p(), TREE_ADDRESSABLE, TREE_CODE, and TREE_OPERAND.
| DEBUG_FUNCTION void verify_ssa | ( | ) |
Verify common invariants in the SSA web. TODO: verify the variable annotations.
Keep track of SSA names present in the IL.
Now verify all the uses and make sure they agree with the definitions found in the previous pass.
Make sure that all edges have a clear 'aux' field.
Verify the arguments for every PHI node in the block.
Now verify all the uses and vuses in every statement of the block.
Restore the dominance information to its prior known state, so that we do not perturb the compiler's subsequent behavior.
References edge_def::aux, edge_def::dest, error(), basic_block_def::index, and edge_def::src.
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Return true if SSA_NAME is malformed and mark it visited.
IS_VIRTUAL is true if this SSA_NAME was found inside a virtual operand.
References error().
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Return true if the use of SSA_NAME at statement STMT in block BB is malformed.
DEF_BB is the block where SSA_NAME was found to be created.
IDOM contains immediate dominator information for the flowgraph.
CHECK_ABNORMAL is true if the caller wants to check whether this use is flowing through an abnormal edge (only used when checking PHI arguments).
If NAMES_DEFINED_IN_BB is not NULL, it contains a bitmap of ssa names that are defined before STMT in basic block BB.
Make sure the use is in an appropriate list by checking the previous element to make sure it's the same.
References error().
Variable Documentation
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Miscellaneous SSA utility functions. Copyright (C) 2001-2013 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/. Pointer map of variable mappings, keyed by edge.
