From: Roger Sayle <roger@eyesopen.com>
Date: Mon, 4 Aug 2003 23:46:34 +0000 (+0000)
Subject: re PR middle-end/11771 (Segfault with simple double arithmetics)
X-Git-Tag: releases/gcc-3.4.0~4396
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=02a1994cbad7e89f535ee982c80def2bd6e7d9bf;p=thirdparty%2Fgcc.git

re PR middle-end/11771 (Segfault with simple double arithmetics)


	PR middle-end/11771
	* fold-const.c (negate_expr_p <MINUS_EXPR>): Change to match the
	logic in negate_expr, i.e. we don't invert (A-B) for floating
	point types unless flag_unsafe_math_optimizations.

	* gcc.c-torture/compile/20030804-1.c: New test case.

From-SVN: r70159
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index daf0bec3424e..60bfb0289e43 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+2003-08-04  Roger Sayle  <roger@eyesopen.com>
+
+	PR middle-end/11771
+	* fold-const.c (negate_expr_p <MINUS_EXPR>): Change to match the
+	logic in negate_expr, i.e. we don't invert (A-B) for floating
+	point types unless flag_unsafe_math_optimizations.
+
 2003-08-04  Roger Sayle  <roger@eyesopen.com>
 
 	* fold-const.c (fold <PLUS_EXPR>): Transform x+x into x*2.0.
diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index 4dd606f68bf5..9333c5907477 100644
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -841,9 +841,12 @@ negate_expr_p (tree t)
 
     case REAL_CST:
     case NEGATE_EXPR:
-    case MINUS_EXPR:
       return true;
 
+    case MINUS_EXPR:
+      /* We can't turn -(A-B) into B-A when we honor signed zeros.  */
+      return ! FLOAT_TYPE_P (type) || flag_unsafe_math_optimizations;
+
     default:
       break;
     }
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index ba19bc89283a..86e12c522c41 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2003-08-04  Roger Sayle  <roger@eyesopen.com>
+
+	PR middle-end/11771
+	* gcc.c-torture/compile/20030804-1.c: New test case.
+
 2003-08-04  Roger Sayle  <roger@eyesopen.com>
 
 	* gcc.dg/20030804-1.c: New test case.
diff --git a/gcc/testsuite/gcc.c-torture/compile/20030804-1.c b/gcc/testsuite/gcc.c-torture/compile/20030804-1.c
new file mode 100644
index 000000000000..189fde3cee5f
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/compile/20030804-1.c
@@ -0,0 +1,9 @@
+/* Extracted from PR middle-end/11771.  */
+/* The following testcase used to ICE without -ffast-math from unbounded
+   recursion in fold.  This was due to the logic in negate_expr_p not
+   matching that in negate_expr.  */
+
+double f(double x) {
+    return -(1 - x) + (x ? -(1 - x) : 0);
+}
+