From: Jakub Jelinek <jakub@redhat.com>
Date: Mon, 18 Oct 2010 10:08:47 +0000 (+0200)
Subject: re PR middle-end/46019 (x / (0x200000000ULL << y) miscompilation with 32-bit HWI)
X-Git-Tag: releases/gcc-4.4.6~308
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3cac8db81e3a7dc06e8384dd3c3f82805e15ddff;p=thirdparty%2Fgcc.git

re PR middle-end/46019 (x / (0x200000000ULL << y) miscompilation with 32-bit HWI)

	PR middle-end/46019
	* fold-const.c (fold_binary_loc): If integer_pow2p has
	TREE_INT_CST_LOW zero, look at TREE_INT_CST_HIGH.

	* gcc.c-torture/execute/pr46019.c: New test.

From-SVN: r165621
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 63fdea3f3f26..aff534d49fde 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2010-10-18  Jakub Jelinek  <jakub@redhat.com>
+
+	PR middle-end/46019
+	* fold-const.c (fold_binary_loc): If integer_pow2p has
+	TREE_INT_CST_LOW zero, look at TREE_INT_CST_HIGH.
+
 2010-10-07  John David Anglin  <dave.anglin@nrc-cnrc.gc.ca>
 
 	PR target/45820
diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index 4d5e70d4b268..5c549c589bc4 100644
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -11658,7 +11658,13 @@ fold_binary (enum tree_code code, tree type, tree op0, tree op1)
 	  if (integer_pow2p (sval) && tree_int_cst_sgn (sval) > 0)
 	    {
 	      tree sh_cnt = TREE_OPERAND (arg1, 1);
-	      unsigned long pow2 = exact_log2 (TREE_INT_CST_LOW (sval));
+	      unsigned long pow2;
+
+	      if (TREE_INT_CST_LOW (sval))
+		pow2 = exact_log2 (TREE_INT_CST_LOW (sval));
+	      else
+		pow2 = exact_log2 (TREE_INT_CST_HIGH (sval))
+		       + HOST_BITS_PER_WIDE_INT;
 
 	      if (strict_overflow_p)
 		fold_overflow_warning (("assuming signed overflow does not "
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 0f41aa67bbe6..dae7bfcca655 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2010-10-18  Jakub Jelinek  <jakub@redhat.com>
+
+	PR middle-end/46019
+	* gcc.c-torture/execute/pr46019.c: New test.
+
 2010-10-16  John David Anglin  <dave.anglin@nrc-cnrc.gc.ca>
 
 	Backport from mainline
diff --git a/gcc/testsuite/gcc.c-torture/execute/pr46019.c b/gcc/testsuite/gcc.c-torture/execute/pr46019.c
new file mode 100644
index 000000000000..b0365576ac85
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/pr46019.c
@@ -0,0 +1,14 @@
+/* PR middle-end/46019 */
+
+extern void abort (void);
+
+int
+main (void)
+{
+  unsigned long long l = 0x40000000000ULL;
+  int n;
+  for (n = 0; n < 8; n++)
+    if (l / (0x200000000ULL << n) != (0x200 >> n))
+      abort ();
+  return 0;
+}