From: Uros Bizjak <ubizjak@gmail.com>
Date: Sun, 16 Aug 2015 17:52:51 +0000 (+0200)
Subject: backport: re PR target/66648 (incorrect memcpy expansion with unrolled_loop strategy... 
X-Git-Tag: releases/gcc-4.9.4~646
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b1ef35e2ad76abb245be2a75f94234c92872ac46;p=thirdparty%2Fgcc.git

backport: re PR target/66648 (incorrect memcpy expansion with unrolled_loop strategy at -O2)

	Backport from mainline:
	2015-07-25  Uros Bizjak  <ubizjak@gmail.com>

	PR target/66648
	* config/i386/i386.c (ix86_expand_set_or_movmem): Emit main loop
	execution guard when min_size is less than size_needed.

testsuite/ChangeLog:

	Backport from mainline:
	2015-07-25  Uros Bizjak  <ubizjak@gmail.com>

	PR target/66648
	* gcc.target/i386/pr66648.c: New test.

From-SVN: r226926
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 41755d790719..5959f9dab298 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,12 @@
+2015-08-16  Uros Bizjak  <ubizjak@gmail.com>
+
+	Backport from mainline:
+	2015-07-25  Uros Bizjak  <ubizjak@gmail.com>
+
+	PR target/66648
+	* config/i386/i386.c (ix86_expand_set_or_movmem): Emit main loop
+	execution guard when min_size is less than size_needed.
+
 2015-08-04  Szabolcs Nagy  <szabolcs.nagy@arm.com>
 
 	Backport from mainline:
diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index 716b766e4ad5..1a06d46cebbe 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -24419,7 +24419,8 @@ ix86_expand_set_or_movmem (rtx dst, rtx src, rtx count_exp, rtx val_exp,
       dst = change_address (dst, BLKmode, destreg);
       set_mem_align (dst, desired_align * BITS_PER_UNIT);
       epilogue_size_needed = 0;
-      if (need_zero_guard && !min_size)
+      if (need_zero_guard
+	  && min_size < (unsigned HOST_WIDE_INT) size_needed)
 	{
 	  /* It is possible that we copied enough so the main loop will not
 	     execute.  */
@@ -24551,7 +24552,7 @@ ix86_expand_set_or_movmem (rtx dst, rtx src, rtx count_exp, rtx val_exp,
 	  max_size -= align_bytes;
 	}
       if (need_zero_guard
-	  && !min_size
+	  && min_size < (unsigned HOST_WIDE_INT) size_needed
 	  && (count < (unsigned HOST_WIDE_INT) size_needed
 	      || (align_bytes == 0
 		  && count < ((unsigned HOST_WIDE_INT) size_needed
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index b9213d2ad34a..d90d3d7ea99d 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,11 @@
+2015-08-16  Uros Bizjak  <ubizjak@gmail.com>
+
+	Backport from mainline:
+	2015-07-25  Uros Bizjak  <ubizjak@gmail.com>
+
+	PR target/66648
+	* gcc.target/i386/pr66648.c: New test.
+
 2015-08-07  Mikael Morin  <mikael@gcc.gnu.org>
 
 	PR fortran/66929
diff --git a/gcc/testsuite/gcc.target/i386/pr66648.c b/gcc/testsuite/gcc.target/i386/pr66648.c
new file mode 100644
index 000000000000..88c126fff8c0
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr66648.c
@@ -0,0 +1,33 @@
+/* { dg-do run } */
+/* { dg-options "-O2 -mstringop-strategy=unrolled_loop -mtune=nocona" } */
+
+#define PATTERN 0xdeadbeef
+#define SIZE    32
+
+struct S { int i; char str[SIZE]; int j; };
+
+void __attribute__((noclone, noinline))
+my_memcpy (char *, const char *, unsigned int);
+
+void
+my_memcpy (char *dst, const char *src, unsigned int len)
+{
+  if (len < 8)
+    __builtin_abort ();
+
+  __builtin_memcpy (dst, src, len);
+}
+
+int
+main (void)
+{
+  const char str[SIZE]= "1234567890123456789012345678901";
+  struct S *s = __builtin_malloc (sizeof (struct S));
+
+  s->j = PATTERN;
+  my_memcpy (s->str, str, SIZE);
+  if (s->j != PATTERN)
+    __builtin_abort ();
+
+  return 0;
+}