From: Jakub Jelinek <jakub@redhat.com>
Date: Tue, 18 Dec 2007 00:13:29 +0000 (+0100)
Subject: re PR rtl-optimization/34490 (r128833 causes miscompilation of glibc clock_gettime.c)
X-Git-Tag: releases/gcc-4.3.0~918
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=dc7c279e97760bba05fa4d637d5652f8559eab3a;p=thirdparty%2Fgcc.git

re PR rtl-optimization/34490 (r128833 causes miscompilation of glibc clock_gettime.c)

	PR rtl-optimization/34490
	* simplify-rtx.c (simplify_const_relational_operation): If !sign,
	don't reduce mmin/mmax using num_sign_bit_copies.

	* gcc.c-torture/execute/20071216-1.c: New test.

From-SVN: r131023
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index c71729dc02c3..c3595a4dc61f 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2007-12-18  Jakub Jelinek  <jakub@redhat.com>
+
+	PR rtl-optimization/34490
+	* simplify-rtx.c (simplify_const_relational_operation): If !sign,
+	don't reduce mmin/mmax using num_sign_bit_copies.
+
 2007-12-17  Kaveh R. Ghazi  <ghazi@caip.rutgers.edu>
 
 	* doc/install.texi: Change recommended MPFR from 2.2.1 > 2.3.0.
diff --git a/gcc/simplify-rtx.c b/gcc/simplify-rtx.c
index 0371339d5405..fd14e407dc84 100644
--- a/gcc/simplify-rtx.c
+++ b/gcc/simplify-rtx.c
@@ -4233,15 +4233,17 @@ simplify_const_relational_operation (enum rtx_code code,
       else
 	{
 	  rtx mmin_rtx, mmax_rtx;
-	  unsigned int sign_copies = num_sign_bit_copies (trueop0, mode);
 	  get_mode_bounds (mode, sign, mode, &mmin_rtx, &mmax_rtx);
 
-	  /* Since unsigned mmin will never be interpreted as negative, use
-	     INTVAL (and an arithmetic right shift).  */
-	  mmin = INTVAL (mmin_rtx) >> (sign_copies - 1);
-	  /* Since signed mmax will always be positive, use UINTVAL (and
-	     a logical right shift).  */
-	  mmax = UINTVAL (mmax_rtx) >> (sign_copies - 1);
+	  mmin = INTVAL (mmin_rtx);
+	  mmax = INTVAL (mmax_rtx);
+	  if (sign)
+	    {
+	      unsigned int sign_copies = num_sign_bit_copies (trueop0, mode);
+
+	      mmin >>= (sign_copies - 1);
+	      mmax >>= (sign_copies - 1);
+	    }
 	}
 
       switch (code)
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 1650e37b85c0..d42c3345884b 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2007-12-18  Jakub Jelinek  <jakub@redhat.com>
+
+	PR rtl-optimization/34490
+	* gcc.c-torture/execute/20071216-1.c: New test.
+
 2007-12-17  Kaveh R. Ghazi  <ghazi@caip.rutgers.edu>
 
 	* gcc.dg/torture/builtin-math-4.c: Remove XFAIL.
diff --git a/gcc/testsuite/gcc.c-torture/execute/20071216-1.c b/gcc/testsuite/gcc.c-torture/execute/20071216-1.c
new file mode 100644
index 000000000000..a337b773af8f
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/20071216-1.c
@@ -0,0 +1,38 @@
+/* PR rtl-optimization/34490 */
+
+extern void abort (void);
+
+static int x;
+
+int
+__attribute__((noinline))
+bar (void)
+{
+  return x;
+}
+
+int
+foo (void)
+{
+  long int b = bar ();
+  if ((unsigned long) b < -4095L)
+    return b;
+  if (-b != 38)
+    b = -2;
+  return b + 1;
+}
+
+int
+main (void)
+{
+  x = 26;
+  if (foo () != 26)
+    abort ();
+  x = -39;
+  if (foo () != -1)
+    abort ();
+  x = -38;
+  if (foo () != -37)
+    abort ();
+  return 0;
+}