Fix folding of memcmp("a", "a", 2) (PR, tree-optimization/78257)

From d7c46e5eb4d295d7653eae188cae04a8f7f0719f Mon Sep 17 00:00:00 2001
From: marxin <mliska@suse.cz>
Date: Wed, 9 Nov 2016 10:33:43 +0100
Subject: [PATCH] Fix folding of memcmp("a", "a", 2) (PR
 tree-optimization/78257)

gcc/ChangeLog:

2016-11-09  Martin Liska  <mliska@suse.cz>

	* fold-const-call.c (fold_const_call): Fix the folding.

gcc/testsuite/ChangeLog:

2016-11-09  Martin Liska  <mliska@suse.cz>

	* gcc.dg/tree-ssa/builtins-folding-generic.c (main): Add new
	test-case for memcmp.
	* gcc.dg/tree-ssa/builtins-folding-gimple.c: Likewise.
---
 gcc/fold-const-call.c                                    | 10 +++++-----
 gcc/gimplify.c                                           |  1 -
 gcc/testsuite/gcc.dg/tree-ssa/builtins-folding-generic.c |  5 +++++
 gcc/testsuite/gcc.dg/tree-ssa/builtins-folding-gimple.c  |  6 ++++++
 4 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/gcc/fold-const-call.c b/gcc/fold-const-call.c
index 1b3a755..38f9717 100644
--- a/gcc/fold-const-call.c
+++ b/gcc/fold-const-call.c
@@ -1506,7 +1506,7 @@  tree
 fold_const_call (combined_fn fn, tree type, tree arg0, tree arg1, tree arg2)
 {
   const char *p0, *p1;
-  size_t s2 = 0;
+  size_t s0, s1, s2 = 0;
   switch (fn)
     {
     case CFN_BUILT_IN_STRNCMP:
@@ -1538,11 +1538,11 @@  fold_const_call (combined_fn fn, tree type, tree arg0, tree arg1, tree arg2)
       }
     case CFN_BUILT_IN_BCMP:
     case CFN_BUILT_IN_MEMCMP:
-      if ((p0 = c_getstr (arg0))
-	  && (p1 = c_getstr (arg1))
+      if ((p0 = c_getstr (arg0, &s0))
+	  && (p1 = c_getstr (arg1, &s1))
 	  && host_size_t_cst_p (arg2, &s2)
-	  && s2 <= strlen (p0)
-	  && s2 <= strlen (p1))
+	  && s2 <= s0
+	  && s2 <= s1)
 	return build_cmp_result (type, memcmp (p0, p1, s2));
       return NULL_TREE;
 
diff --git a/gcc/gimplify.c b/gcc/gimplify.c
index e5930e6..15976e2 100644
--- a/gcc/gimplify.c
+++ b/gcc/gimplify.c
@@ -2266,7 +2266,6 @@  gimplify_switch_expr (tree *expr_p, gimple_seq *pre_p)
 
       labels = gimplify_ctxp->case_labels;
       gimplify_ctxp->case_labels = saved_labels;
-      gcc_assert (gimplify_ctxp->live_switch_vars->elements () == 0);
       delete gimplify_ctxp->live_switch_vars;
       gimplify_ctxp->live_switch_vars = saved_live_switch_vars;
 
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/builtins-folding-generic.c b/gcc/testsuite/gcc.dg/tree-ssa/builtins-folding-generic.c
index 175feff..3c7e001 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/builtins-folding-generic.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/builtins-folding-generic.c
@@ -66,6 +66,10 @@  main (void)
   if (__builtin_strncasecmp ("aab", "aac", 2) != 0)
     __builtin_abort ();
 
+  /* MEMCMP.  */
+  if (__builtin_memcmp ("aaaaa", "aaaaa", 6) != 0)
+    __builtin_abort ();
+
   return 0;
 }
 
@@ -74,3 +78,4 @@  main (void)
 /* { dg-final { scan-tree-dump-not "__builtin_strncmp" "original" } } */
 /* { dg-final { scan-tree-dump-not "__builtin_strncasecmp" "original" } } */
 /* { dg-final { scan-tree-dump-not "__builtin_memchr" "original" } } */
+/* { dg-final { scan-tree-dump-not "__builtin_memcmp" "original" } } */
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/builtins-folding-gimple.c b/gcc/testsuite/gcc.dg/tree-ssa/builtins-folding-gimple.c
index 283bd1c..d08ced5 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/builtins-folding-gimple.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/builtins-folding-gimple.c
@@ -63,6 +63,7 @@  main (void)
 
   const char *aaaaa = "aaaaa";
   const char *hello = "hello";
+  const char *hello2 = "hello";
   const char *empty = "";
   const char *ab = "ab";
   const char *ba = "ba";
@@ -151,6 +152,10 @@  main (void)
   if (__builtin_strncasecmp (++s2, ++s3+2, 0) != 0 || s2 != s1+1 || s3 != s1+5)
     __builtin_abort();
 
+  /* MEMCMP.  */
+  if (__builtin_memcmp (hello, hello2, 6) != 0)
+    __builtin_abort ();
+
   return 0;
 }
 
@@ -158,4 +163,5 @@  main (void)
 /* { dg-final { scan-tree-dump-not "__builtin_strcasecmp" "optimized" } } */
 /* { dg-final { scan-tree-dump-not "__builtin_strncmp" "optimized" } } */
 /* { dg-final { scan-tree-dump-not "__builtin_memchr" "optimized" } } */
+/* { dg-final { scan-tree-dump-not "__builtin_memcmp" "optimized" } } */
 /* { dg-final { scan-tree-dump-times "__builtin_strncasecmp" 3 "optimized" } } */
-- 
2.10.1