From: Thomas Preud'homme <thomas.preudhomme@arm.com>
Date: Wed, 12 Mar 2014 10:15:29 +0000 (+0000)
Subject: re PR tree-optimization/60454 (Code mistakenly detected as doing bswap)
X-Git-Tag: releases/gcc-4.9.0~486
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=882a5fbe3c0e81734257bfd8bc0f5c41a769394b;p=thirdparty%2Fgcc.git

re PR tree-optimization/60454 (Code mistakenly detected as doing bswap)

	PR tree-optimization/60454
	* tree-ssa-math-opts.c (find_bswap_1): Fix bswap detection.

	* gcc.c-torture/execute/pr60454.c: New test.

From-SVN: r208509
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index cc980d95ddec..c76fc807dd41 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2014-03-12  Thomas Preud'homme  <thomas.preudhomme@arm.com>
+
+	PR tree-optimization/60454
+	* tree-ssa-math-opts.c (find_bswap_1): Fix bswap detection.
+
 2014-03-12  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
 
 	* config.gcc (aarch64*-*-*): Use ISA flags from aarch64-arches.def.
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 24d0d9ad81cb..dde17b02a9ef 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2014-03-12  Thomas Preud'homme  <thomas.preudhomme@arm.com>
+
+	PR tree-optimization/60454
+	* gcc.c-torture/execute/pr60454.c: New test.
+
 2014-03-12  Jakub Jelinek  <jakub@redhat.com>
 	    Marc Glisse  <marc.glisse@inria.fr>
 
diff --git a/gcc/testsuite/gcc.c-torture/execute/pr60454.c b/gcc/testsuite/gcc.c-torture/execute/pr60454.c
new file mode 100644
index 000000000000..ceec45e699ff
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/pr60454.c
@@ -0,0 +1,31 @@
+#ifdef __UINT32_TYPE__
+typedef __UINT32_TYPE__ uint32_t;
+#else
+typedef unsigned uint32_t;
+#endif
+
+#define __fake_const_swab32(x) ((uint32_t)(			      \
+        (((uint32_t)(x) & (uint32_t)0x000000ffUL) << 24) |            \
+        (((uint32_t)(x) & (uint32_t)0x0000ff00UL) <<  8) |            \
+        (((uint32_t)(x) & (uint32_t)0x000000ffUL) <<  8) |            \
+        (((uint32_t)(x) & (uint32_t)0x0000ff00UL)      ) |            \
+        (((uint32_t)(x) & (uint32_t)0xff000000UL) >> 24)))
+
+/* Previous version of bswap optimization would detect byte swap when none
+   happen. This test aims at catching such wrong detection to avoid
+   regressions.  */
+
+__attribute__ ((noinline, noclone)) uint32_t
+fake_swap32 (uint32_t in)
+{
+  return __fake_const_swab32 (in);
+}
+
+int main(void)
+{
+  if (sizeof (uint32_t) * __CHAR_BIT__ != 32)
+    return 0;
+  if (fake_swap32 (0x12345678UL) != 0x78567E12UL)
+    __builtin_abort ();
+  return 0;
+}
diff --git a/gcc/tree-ssa-math-opts.c b/gcc/tree-ssa-math-opts.c
index 8e372ede741b..9ff857cd6571 100644
--- a/gcc/tree-ssa-math-opts.c
+++ b/gcc/tree-ssa-math-opts.c
@@ -1801,7 +1801,9 @@ find_bswap_1 (gimple stmt, struct symbolic_number *n, int limit)
 
   if (rhs_class == GIMPLE_BINARY_RHS)
     {
+      int i;
       struct symbolic_number n1, n2;
+      unsigned HOST_WIDEST_INT mask;
       tree source_expr2;
 
       if (code != BIT_IOR_EXPR)
@@ -1827,6 +1829,15 @@ find_bswap_1 (gimple stmt, struct symbolic_number *n, int limit)
 	    return NULL_TREE;
 
 	  n->size = n1.size;
+	  for (i = 0, mask = 0xff; i < n->size; i++, mask <<= BITS_PER_UNIT)
+	    {
+	      unsigned HOST_WIDEST_INT masked1, masked2;
+
+	      masked1 = n1.n & mask;
+	      masked2 = n2.n & mask;
+	      if (masked1 && masked2 && masked1 != masked2)
+		return NULL_TREE;
+	    }
 	  n->n = n1.n | n2.n;
 
 	  if (!verify_symbolic_number_p (n, stmt))