Limit SH strncmp inline expansion (PR target/78460).

GCC mainline built for sh4-linux-gnu runs out of memory building a
glibc test, which calls strncmp with very large constant size
argument, resulting in the SH inline strncmp expansion trying to
inline a fully unrolled expansion of strncmp for that size.

This patch limits that fully unrolled expansion to the case of less
than 32 bytes.  This is explicitly *not* trying to be optimal in any
way (very likely a lower threshold makes sense), just to limit enough
to avoid the out-of-memory issue in the glibc testsuite.

I have *not* run the GCC testsuite for SH.  I have verified that this
allows the glibc testsuite to build OK, with both GCC mainline and GCC
7 branch (and that the included test builds quickly with patched GCC,
runs out of memory with unpatched GCC).

	PR target/78460
	PR target/67712
gcc:
	* config/sh/sh-mem.cc (sh_expand_cmpnstr): Only unroll for
	constant count if that count is less than 32.

gcc/testsuite:
	* gcc.c-torture/compile/string-large-1.c: New test.

From-SVN: r251108

4 files changed, 134 insertions, 2 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index c95dc28..14fc3db 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+2017-08-15  Joseph Myers  <joseph@codesourcery.com>
+
+	PR target/78460
+	PR target/67712
+	* config/sh/sh-mem.cc (sh_expand_cmpnstr): Only unroll for
+	constant count if that count is less than 32.
+
 2017-08-15  Nathan Sidwell  <nathan@acm.org>
 
 	* gcc.c (execute): Emit friendlier message if inferior is killed
diff --git a/gcc/config/sh/sh-mem.cc b/gcc/config/sh/sh-mem.cc
index 3f7041c..8fce979 100644
--- a/gcc/config/sh/sh-mem.cc
+++ b/gcc/config/sh/sh-mem.cc
@@ -349,12 +349,13 @@ sh_expand_cmpnstr (rtx *operands)
 
   rtx len = copy_to_mode_reg (SImode, operands[3]);
   int constp = CONST_INT_P (operands[3]);
+  HOST_WIDE_INT bytes = constp ? INTVAL (operands[3]) : 0;
 
   const unsigned int addr1_alignment = MEM_ALIGN (operands[1]) / BITS_PER_UNIT;
   const unsigned int addr2_alignment = MEM_ALIGN (operands[2]) / BITS_PER_UNIT;
 
   /* Loop on a register count.  */
-  if (constp)
+  if (constp && bytes >= 0 && bytes < 32)
     {
       rtx tmp0 = gen_reg_rtx (SImode);
       rtx tmp3 = gen_reg_rtx (SImode);
@@ -363,7 +364,6 @@ sh_expand_cmpnstr (rtx *operands)
       rtx_code_label *L_loop_long = gen_label_rtx ();
       rtx_code_label *L_end_loop_long = gen_label_rtx ();
 
-      int bytes = INTVAL (operands[3]);
       int witers = bytes / 4;
 
       if (witers > 1)
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index f13f9b0..835a8f4 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2017-08-15  Joseph Myers  <joseph@codesourcery.com>
+
+	PR target/78460
+	PR target/67712
+	* gcc.c-torture/compile/string-large-1.c: New test.
+
 2017-08-15  Richard Biener  <rguenther@suse.de>
 
 	PR tree-optimization/81790
diff --git a/gcc/testsuite/gcc.c-torture/compile/string-large-1.c b/gcc/testsuite/gcc.c-torture/compile/string-large-1.c
new file mode 100644
index 0000000..ddac0d5
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/compile/string-large-1.c
@@ -0,0 +1,119 @@
+/* Test built-in string functions with large sizes.  PR 78460.  */
+
+typedef __SIZE_TYPE__ size_t;
+
+#define SIZE1 ((size_t) -1)
+#define SIZE2 (SIZE1 >> 1)
+#define SIZE3 ((unsigned int) -1)
+#define SIZE4 (SIZE3 >> 1)
+
+volatile int v1, v2, v3, v4;
+void *volatile vp1, *volatile vp2, *volatile vp3, *volatile vp4;
+
+void
+test_memchr (const void *a, int b)
+{
+  vp1 = __builtin_memchr (a, b, SIZE1);
+  vp2 = __builtin_memchr (a, b, SIZE2);
+  vp3 = __builtin_memchr (a, b, SIZE3);
+  vp4 = __builtin_memchr (a, b, SIZE4);
+}
+
+void
+test_memcmp (const void *a, const void *b)
+{
+  v1 = __builtin_memcmp (a, b, SIZE1);
+  v2 = __builtin_memcmp (a, b, SIZE2);
+  v3 = __builtin_memcmp (a, b, SIZE3);
+  v4 = __builtin_memcmp (a, b, SIZE4);
+}
+
+void
+test_memcpy (void *a, const void *b)
+{
+  vp1 = __builtin_memcpy (a, b, SIZE1);
+  vp2 = __builtin_memcpy (a, b, SIZE2);
+  vp3 = __builtin_memcpy (a, b, SIZE3);
+  vp4 = __builtin_memcpy (a, b, SIZE4);
+}
+
+void
+test_memmove (void *a, const void *b)
+{
+  vp1 = __builtin_memmove (a, b, SIZE1);
+  vp2 = __builtin_memmove (a, b, SIZE2);
+  vp3 = __builtin_memmove (a, b, SIZE3);
+  vp4 = __builtin_memmove (a, b, SIZE4);
+}
+
+void
+test_mempcpy (void *a, const void *b)
+{
+  vp1 = __builtin_mempcpy (a, b, SIZE1);
+  vp2 = __builtin_mempcpy (a, b, SIZE2);
+  vp3 = __builtin_mempcpy (a, b, SIZE3);
+  vp4 = __builtin_mempcpy (a, b, SIZE4);
+}
+
+void
+test_memset (void *a, int b)
+{
+  vp1 = __builtin_memset (a, b, SIZE1);
+  vp2 = __builtin_memset (a, b, SIZE2);
+  vp3 = __builtin_memset (a, b, SIZE3);
+  vp4 = __builtin_memset (a, b, SIZE4);
+}
+
+void
+test_stpncpy (char *a, const char *b)
+{
+  vp1 = __builtin_stpncpy (a, b, SIZE1);
+  vp2 = __builtin_stpncpy (a, b, SIZE2);
+  vp3 = __builtin_stpncpy (a, b, SIZE3);
+  vp4 = __builtin_stpncpy (a, b, SIZE4);
+}
+
+void
+test_strndup (const char *a)
+{
+  vp1 = __builtin_strndup (a, SIZE1);
+  vp2 = __builtin_strndup (a, SIZE2);
+  vp3 = __builtin_strndup (a, SIZE3);
+  vp4 = __builtin_strndup (a, SIZE4);
+}
+
+void
+test_strncasecmp (const char *a, const char *b)
+{
+  v1 = __builtin_strncasecmp (a, b, SIZE1);
+  v2 = __builtin_strncasecmp (a, b, SIZE2);
+  v3 = __builtin_strncasecmp (a, b, SIZE3);
+  v4 = __builtin_strncasecmp (a, b, SIZE4);
+}
+
+void
+test_strncat (char *a, const char *b)
+{
+  vp1 = __builtin_strncat (a, b, SIZE1);
+  vp2 = __builtin_strncat (a, b, SIZE2);
+  vp3 = __builtin_strncat (a, b, SIZE3);
+  vp4 = __builtin_strncat (a, b, SIZE4);
+}
+
+void
+test_strncmp (const char *a, const char *b)
+{
+  v1 = __builtin_strncmp (a, b, SIZE1);
+  v2 = __builtin_strncmp (a, b, SIZE2);
+  v3 = __builtin_strncmp (a, b, SIZE3);
+  v4 = __builtin_strncmp (a, b, SIZE4);
+}
+
+void
+test_strncpy (char *a, const char *b)
+{
+  vp1 = __builtin_strncpy (a, b, SIZE1);
+  vp2 = __builtin_strncpy (a, b, SIZE2);
+  vp3 = __builtin_strncpy (a, b, SIZE3);
+  vp4 = __builtin_strncpy (a, b, SIZE4);
+}