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| author | Richard Biener <rguenther@suse.de> | 2016-04-29 08:36:49 +0000 |
|---|---|---|
| committer | Richard Biener <rguenth@gcc.gnu.org> | 2016-04-29 08:36:49 +0000 |
| commit | 98998245d99f06946b4d5ed6744c77c3760f1141 (patch) | |
| tree | 1858d6d18d0408f87683330cd1b7664179f40c81 /gcc/tree-ssa-alias.c | |
| parent | 59cf7a415cf212da56ea3ebd5b34063e84b9275f (diff) | |
| download | gcc-98998245d99f06946b4d5ed6744c77c3760f1141.zip gcc-98998245d99f06946b4d5ed6744c77c3760f1141.tar.gz gcc-98998245d99f06946b4d5ed6744c77c3760f1141.tar.bz2 | |
re PR tree-optimization/13962 ([tree-ssa] make "fold" use alias information to optimize pointer comparisons)
2016-04-29 Richard Biener <rguenther@suse.de>
PR tree-optimization/13962
PR tree-optimization/65686
* tree-ssa-alias.h (ptrs_compare_unequal): Declare.
* tree-ssa-alias.c (ptrs_compare_unequal): New function
using PTA to compare pointers.
* match.pd: Add pattern for pointer equality compare simplification
using ptrs_compare_unequal.
* gcc.dg/uninit-pr65686.c: New testcase.
From-SVN: r235622
Diffstat (limited to 'gcc/tree-ssa-alias.c')
| -rw-r--r-- | gcc/tree-ssa-alias.c | 60 |
1 files changed, 60 insertions, 0 deletions
diff --git a/gcc/tree-ssa-alias.c b/gcc/tree-ssa-alias.c index 08f10e5..f801b01 100644 --- a/gcc/tree-ssa-alias.c +++ b/gcc/tree-ssa-alias.c @@ -321,6 +321,66 @@ ptr_deref_may_alias_ref_p_1 (tree ptr, ao_ref *ref) return true; } +/* Returns true if PTR1 and PTR2 compare unequal because of points-to. */ + +bool +ptrs_compare_unequal (tree ptr1, tree ptr2) +{ + /* First resolve the pointers down to a SSA name pointer base or + a VAR_DECL, PARM_DECL or RESULT_DECL. This explicitely does + not yet try to handle LABEL_DECLs, FUNCTION_DECLs, CONST_DECLs + or STRING_CSTs which needs points-to adjustments to track them + in the points-to sets. */ + tree obj1 = NULL_TREE; + tree obj2 = NULL_TREE; + if (TREE_CODE (ptr1) == ADDR_EXPR) + { + tree tem = get_base_address (TREE_OPERAND (ptr1, 0)); + if (! tem) + return false; + if (TREE_CODE (tem) == VAR_DECL + || TREE_CODE (tem) == PARM_DECL + || TREE_CODE (tem) == RESULT_DECL) + obj1 = tem; + else if (TREE_CODE (tem) == MEM_REF) + ptr1 = TREE_OPERAND (tem, 0); + } + if (TREE_CODE (ptr2) == ADDR_EXPR) + { + tree tem = get_base_address (TREE_OPERAND (ptr2, 0)); + if (! tem) + return false; + if (TREE_CODE (tem) == VAR_DECL + || TREE_CODE (tem) == PARM_DECL + || TREE_CODE (tem) == RESULT_DECL) + obj2 = tem; + else if (TREE_CODE (tem) == MEM_REF) + ptr2 = TREE_OPERAND (tem, 0); + } + + if (obj1 && obj2) + /* Other code handles this correctly, no need to duplicate it here. */; + else if (obj1 && TREE_CODE (ptr2) == SSA_NAME) + { + struct ptr_info_def *pi = SSA_NAME_PTR_INFO (ptr2); + if (!pi) + return false; + return !pt_solution_includes (&pi->pt, obj1); + } + else if (TREE_CODE (ptr1) == SSA_NAME && obj2) + { + struct ptr_info_def *pi = SSA_NAME_PTR_INFO (ptr1); + if (!pi) + return false; + return !pt_solution_includes (&pi->pt, obj2); + } + + /* ??? We'd like to handle ptr1 != NULL and ptr1 != ptr2 + but those require pt.null to be conservatively correct. */ + + return false; +} + /* Returns whether reference REF to BASE may refer to global memory. */ static bool |