On Thu, 16 Feb 2017, Richard Biener wrote:
>
> I am testing the following patch for PR79547. Those builtins do not
> return anything that can be used to re-construct the pointer(s) passed
> to them.
>
> Queued for GCC 8.
Actually we need calluse constraints. Thus adjusted as follows.
Richard.
2017-02-17 Richard Biener <rguent...@suse.de>
PR tree-optimization/79547
* tree-ssa-structalias.c (find_func_aliases_for_builtin_call):
Handle strlen, strcmp, strncmp, strcasecmp, strncasecmp, memcmp,
bcmp, strspn, strcspn, __builtin_object_size and __builtin_constant_p
without any constraints.
* gcc.dg/tree-ssa/strlen-2.c: New testcase.
Index: gcc/testsuite/gcc.dg/tree-ssa/strlen-2.c
===================================================================
--- gcc/testsuite/gcc.dg/tree-ssa/strlen-2.c (nonexistent)
+++ gcc/testsuite/gcc.dg/tree-ssa/strlen-2.c (working copy)
@@ -0,0 +1,15 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-strlen" } */
+
+void f (unsigned);
+
+void f3 (void)
+{
+ char s[] = "1234";
+
+ f (__builtin_strlen (s));
+ f (__builtin_strlen (s));
+ f (__builtin_strlen (s));
+}
+
+/* { dg-final { scan-tree-dump-times "strlen" 1 "strlen" } } */
Index: gcc/tree-ssa-structalias.c
===================================================================
--- gcc/tree-ssa-structalias.c (revision 245501)
+++ gcc/tree-ssa-structalias.c (working copy)
@@ -4474,6 +4474,40 @@ find_func_aliases_for_builtin_call (stru
process_all_all_constraints (lhsc, rhsc);
}
return true;
+ /* Pure functions that return something not based on any object and
+ that use the memory pointed to by their arguments (but not
+ transitively). */
+ case BUILT_IN_STRCMP:
+ case BUILT_IN_STRNCMP:
+ case BUILT_IN_STRCASECMP:
+ case BUILT_IN_STRNCASECMP:
+ case BUILT_IN_MEMCMP:
+ case BUILT_IN_BCMP:
+ case BUILT_IN_STRSPN:
+ case BUILT_IN_STRCSPN:
+ {
+ varinfo_t uses = get_call_use_vi (t);
+ make_any_offset_constraints (uses);
+ make_constraint_to (uses->id, gimple_call_arg (t, 0));
+ make_constraint_to (uses->id, gimple_call_arg (t, 1));
+ /* No constraints are necessary for the return value. */
+ return true;
+ }
+ case BUILT_IN_STRLEN:
+ {
+ varinfo_t uses = get_call_use_vi (t);
+ make_any_offset_constraints (uses);
+ make_constraint_to (uses->id, gimple_call_arg (t, 0));
+ /* No constraints are necessary for the return value. */
+ return true;
+ }
+ case BUILT_IN_OBJECT_SIZE:
+ case BUILT_IN_CONSTANT_P:
+ {
+ /* No constraints are necessary for the return value or the
+ arguments. */
+ return true;
+ }
/* Trampolines are special - they set up passing the static
frame. */
case BUILT_IN_INIT_TRAMPOLINE:
