From: Jun Ma <JunMa@linux.alibaba.com>
Date: Thu, 27 Jun 2019 09:50:35 +0000 (+0000)
Subject: re PR tree-optimization/89772 (memchr for a character not in constant nul-padded... 
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=5fd336bbd7b273408018dfbb7a170e1d54facb8e;p=gcc.git

re PR tree-optimization/89772 (memchr for a character not in constant nul-padded string not folded)

	PR tree-optimization/89772
	* gimple-fold.c (gimple_fold_builtin_memchr): consider trailing nuls in
	out-of-bound accesses checking.

	gcc/testsuite
	* gcc.dg/builtin-memchr-4.c: New test.

From-SVN: r272740
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index a1bd7985efa..44f9850b671 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2019-06-27  Jun Ma <JunMa@linux.alibaba.com>
+
+	PR tree-optimization/89772
+	* gimple-fold.c (gimple_fold_builtin_memchr): consider trailing nuls in
+	out-of-bound accesses checking.
+
 2019-06-27  Martin Liska  <mliska@suse.cz>
 
 	PR tree-optimization/91014
diff --git a/gcc/gimple-fold.c b/gcc/gimple-fold.c
index dfb31a02078..118718a59ee 100644
--- a/gcc/gimple-fold.c
+++ b/gcc/gimple-fold.c
@@ -2543,7 +2543,15 @@ gimple_fold_builtin_memchr (gimple_stmt_iterator *gsi)
       const char *r = (const char *)memchr (p1, c, MIN (length, string_length));
       if (r == NULL)
 	{
-	  if (length <= string_length)
+	  tree mem_size, offset_node;
+	  string_constant (arg1, &offset_node, &mem_size, NULL);
+	  unsigned HOST_WIDE_INT offset = (offset_node == NULL_TREE)
+					  ? 0 : tree_to_uhwi (offset_node);
+	  /* MEM_SIZE is the size of the array the string literal
+	     is stored in.  */
+	  unsigned HOST_WIDE_INT string_size = tree_to_uhwi (mem_size) - offset;
+	  gcc_checking_assert (string_length <= string_size);
+	  if (length <= string_size)
 	    {
 	      replace_call_with_value (gsi, build_int_cst (ptr_type_node, 0));
 	      return true;
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index c48ceefebe4..3c459a406d2 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2019-06-27  Jun Ma  <JunMa@linux.alibaba.com>
+
+	PR tree-optimization/89772
+	* gcc.dg/builtin-memchr-4.c: New test.
+
 2019-06-27  Martin Liska  <mliska@suse.cz>
 
 	PR tree-optimization/91014
diff --git a/gcc/testsuite/gcc.dg/builtin-memchr-4.c b/gcc/testsuite/gcc.dg/builtin-memchr-4.c
new file mode 100644
index 00000000000..58a3b444b63
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/builtin-memchr-4.c
@@ -0,0 +1,40 @@
+/* PR tree-optimization/89772
+   Verify that memchr calls with a pointer to a constant character
+   are folded as expected.
+   { dg-do compile }
+   { dg-options "-O1 -Wall -fdump-tree-release_ssa" } */
+
+typedef __SIZE_TYPE__  size_t;
+typedef __WCHAR_TYPE__ wchar_t;
+
+extern void* memchr (const void*, int, size_t);
+extern int printf (const char*, ...);
+extern void abort (void);
+
+#define A(expr)						\
+  ((expr)						\
+   ? (void)0						\
+   : (printf ("assertion failed on line %i: %s\n",	\
+	      __LINE__, #expr),				\
+      abort ()))
+
+const char a[8] = {'a',0,'b'};
+const char b[3] = {'a','b'};
+const char c[8] = {'a','b','c'};
+
+void test_memchr_cst_char (void)
+{
+  A (!memchr (a, 'c', 2));
+  A (!memchr (a, 'c', 5));
+  A (!memchr (a, 'c', sizeof a));
+  A (&a[1] == memchr (a, 0, sizeof a));
+
+  A (!memchr (b, 0, 2));
+  A (&b[2] == memchr (b, 0, sizeof b));
+
+  A (!memchr (c, 0, 2));
+  A (&c[3] == memchr (c, 0, 4));
+  A (&c[3] == memchr (c, 0, sizeof a));
+}
+
+/* { dg-final { scan-tree-dump-not "abort" "release_ssa" } } */