From: Richard Biener <rguenther@suse.de>
Date: Fri, 21 Apr 2017 12:47:02 +0000 (+0000)
Subject: re PR tree-optimization/79547 (duplicate strlen calls with same argument not folded)
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=2fd30fbe0d3a9525ec14e0102f3ebb0e80a2736e;p=gcc.git

re PR tree-optimization/79547 (duplicate strlen calls with same argument not folded)

2017-04-21  Richard Biener  <rguenther@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.

From-SVN: r247062
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 359273ef092..30b22d6e55d 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,11 @@
+2017-04-21  Richard Biener  <rguenther@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.
+
 2017-04-21  Richard Biener  <rguenther@suse.de>
 
 	PR tree-optimization/78847
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 414f27972bf..84d1074c8d4 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2017-04-21  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/79547
+	* gcc.dg/tree-ssa/strlen-2.c: New testcase.
+
 2017-04-21  Richard Biener  <rguenther@suse.de>
 
 	PR tree-optimization/78847
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/strlen-2.c b/gcc/testsuite/gcc.dg/tree-ssa/strlen-2.c
new file mode 100644
index 00000000000..1bca06fb1a4
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/strlen-2.c
@@ -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" 0 "strlen" } } */
diff --git a/gcc/tree-ssa-structalias.c b/gcc/tree-ssa-structalias.c
index 77736f51153..7b1bf10e1cf 100644
--- a/gcc/tree-ssa-structalias.c
+++ b/gcc/tree-ssa-structalias.c
@@ -4474,6 +4474,40 @@ find_func_aliases_for_builtin_call (struct function *fn, gcall *t)
 	    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: