diff options
Diffstat (limited to 'gcc/tree-ssa-alias.c')
| -rw-r--r-- | gcc/tree-ssa-alias.c | 36 |
1 files changed, 34 insertions, 2 deletions
diff --git a/gcc/tree-ssa-alias.c b/gcc/tree-ssa-alias.c index 7b25778307f..032e79b8ba0 100644 --- a/gcc/tree-ssa-alias.c +++ b/gcc/tree-ssa-alias.c @@ -1483,6 +1483,16 @@ refs_may_alias_p_1 (ao_ref *ref1, ao_ref *ref2, bool tbaa_p) ao_ref_alias_set (ref2))) return false; + /* If the reference is based on a pointer that points to memory + that may not be written to then the other reference cannot possibly + clobber it. */ + if ((TREE_CODE (TREE_OPERAND (base2, 0)) == SSA_NAME + && SSA_NAME_POINTS_TO_READONLY_MEMORY (TREE_OPERAND (base2, 0))) + || (ind1_p + && TREE_CODE (TREE_OPERAND (base1, 0)) == SSA_NAME + && SSA_NAME_POINTS_TO_READONLY_MEMORY (TREE_OPERAND (base1, 0)))) + return false; + /* Dispatch to the pointer-vs-decl or pointer-vs-pointer disambiguators. */ if (var1_p && ind2_p) return indirect_ref_may_alias_decl_p (ref2->ref, base2, @@ -1991,6 +2001,14 @@ call_may_clobber_ref_p_1 (gcall *call, ao_ref *ref) || !is_global_var (base))) return false; + /* If the reference is based on a pointer that points to memory + that may not be written to then the call cannot possibly clobber it. */ + if ((TREE_CODE (base) == MEM_REF + || TREE_CODE (base) == TARGET_MEM_REF) + && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME + && SSA_NAME_POINTS_TO_READONLY_MEMORY (TREE_OPERAND (base, 0))) + return false; + callee = gimple_call_fndecl (call); /* Handle those builtin functions explicitly that do not act as @@ -2722,7 +2740,14 @@ next:; if (arg1 == arg0) ; else if (! maybe_skip_until (phi, arg0, ref, arg1, cnt, visited, - abort_on_visited, translate, data)) + abort_on_visited, + /* Do not translate when walking over + backedges. */ + dominated_by_p + (CDI_DOMINATORS, + gimple_bb (SSA_NAME_DEF_STMT (arg1)), + phi_bb) + ? NULL : translate, data)) return NULL_TREE; } @@ -2783,7 +2808,14 @@ walk_non_aliased_vuses (ao_ref *ref, tree vuse, break; if (valueize) - vuse = valueize (vuse); + { + vuse = valueize (vuse); + if (!vuse) + { + res = NULL; + break; + } + } def_stmt = SSA_NAME_DEF_STMT (vuse); if (gimple_nop_p (def_stmt)) break; |