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RE: [PATCH] Fix PR61375: cancel bswap optimization when value doesn't fit in a HOST_WIDE_INT
- From: "Thomas Preud'homme" <thomas dot preudhomme at arm dot com>
- To: "'Richard Biener'" <richard dot guenther at gmail dot com>
- Cc: "GCC Patches" <gcc-patches at gcc dot gnu dot org>
- Date: Fri, 20 Jun 2014 18:41:41 +0800
- Subject: RE: [PATCH] Fix PR61375: cancel bswap optimization when value doesn't fit in a HOST_WIDE_INT
- Authentication-results: sourceware.org; auth=none
- References: <002c01cf8453$e32b4710$a981d530$ at arm dot com> <CAFiYyc3F==SQgWMWp2NOXAQvdB5UNQ1j6pJGDC6ebs-e9rnduw at mail dot gmail dot com>
> From: Richard Biener [mailto:richard.guenther@gmail.com]
> Sent: Tuesday, June 10, 2014 5:05 PM
>
> Backports are welcome - please post a patch.
>
Sorry for the delay. Here you are:
diff --git a/gcc/testsuite/gcc.c-torture/execute/pr61375.c b/gcc/testsuite/gcc.c-torture/execute/pr61375.c
new file mode 100644
index 0000000..d3b54a8
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/pr61375.c
@@ -0,0 +1,35 @@
+#ifdef __UINT64_TYPE__
+typedef __UINT64_TYPE__ uint64_t;
+#else
+typedef unsigned long long uint64_t;
+#endif
+
+#ifndef __SIZEOF_INT128__
+#define __int128 long long
+#endif
+
+/* Some version of bswap optimization would ICE when analyzing a mask constant
+ too big for an HOST_WIDE_INT (PR61375). */
+
+__attribute__ ((noinline, noclone)) uint64_t
+uint128_central_bitsi_ior (unsigned __int128 in1, uint64_t in2)
+{
+ __int128 mask = (__int128)0xffff << 56;
+ return ((in1 & mask) >> 56) | in2;
+}
+
+int
+main (int argc)
+{
+ __int128 in = 1;
+#ifdef __SIZEOF_INT128__
+ in <<= 64;
+#endif
+ if (sizeof (uint64_t) * __CHAR_BIT__ != 64)
+ return 0;
+ if (sizeof (unsigned __int128) * __CHAR_BIT__ != 128)
+ return 0;
+ if (uint128_central_bitsi_ior (in, 2) != 0x102)
+ __builtin_abort ();
+ return 0;
+}
diff --git a/gcc/tree-ssa-math-opts.c b/gcc/tree-ssa-math-opts.c
index 9ff857c..9d64205 100644
--- a/gcc/tree-ssa-math-opts.c
+++ b/gcc/tree-ssa-math-opts.c
@@ -1741,6 +1741,8 @@ find_bswap_1 (gimple stmt, struct symbolic_number *n, int limit)
if (n->size % BITS_PER_UNIT != 0)
return NULL_TREE;
n->size /= BITS_PER_UNIT;
+ if (n->size > (int)sizeof (unsigned HOST_WIDEST_INT))
+ return NULL_TREE;
n->n = (sizeof (HOST_WIDEST_INT) < 8 ? 0 :
(unsigned HOST_WIDEST_INT)0x08070605 << 32 | 0x04030201);
@@ -1781,6 +1783,8 @@ find_bswap_1 (gimple stmt, struct symbolic_number *n, int limit)
type_size = TYPE_PRECISION (gimple_expr_type (stmt));
if (type_size % BITS_PER_UNIT != 0)
return NULL_TREE;
+ if (type_size > (int)HOST_BITS_PER_WIDEST_INT)
+ return NULL_TREE;
if (type_size / BITS_PER_UNIT < (int)(sizeof (HOST_WIDEST_INT)))
{
Ok for GCC 4.8 and GCC 4.9 branches?
Best regards,
Thomas