re PR tree-optimization/34825 (ICE with -funsafe-math-optimizations)

2008-01-17  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/34825
	* tree-ssa-math-opts.c (is_division_by): Do not recognize
	x / x as division to handle.

	* gcc.dg/pr34825.c: New testcase.

From-SVN: r131595

gcc/ChangeLog

+2008-01-17  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/34825
+	* tree-ssa-math-opts.c (is_division_by): Do not recognize
+	x / x as division to handle.
+
 2008-01-16  John David Anglin  <dave.anglin@nrc-cnrc.gc.ca>
 
 	* pa64-hpux.h (LIB_SPEC): Add "-lpthread" in shared links if "-mt" or

gcc/testsuite/ChangeLog

 2008-01-17  Richard Guenther  <rguenther@suse.de>
 
+	PR tree-optimization/34825
+	* gcc.dg/pr34825.c: New testcase.
+
+2008-01-17  Richard Guenther  <rguenther@suse.de>
+
 	* gcc.c-torture/execute/20080117-1.c: New testcase.
 
 2008-01-17  Revital Eres  <eres@il.ibm.com>

gcc/testsuite/gcc.dg/pr34825.c

+/* { dg-do compile } */
+/* { dg-options "-O -funsafe-math-optimizations" } */
+
+double foo(double x, double y)
+{
+  return x == y ? x/y*x/y : 0;
+}
+

gcc/tree-ssa-math-opts.c

@@ -275,7 +275,11 @@ is_division_by (tree use_stmt, tree def)
 {
   return TREE_CODE (use_stmt) == GIMPLE_MODIFY_STMT
 	 && TREE_CODE (GIMPLE_STMT_OPERAND (use_stmt, 1)) == RDIV_EXPR
-	 && TREE_OPERAND (GIMPLE_STMT_OPERAND (use_stmt, 1), 1) == def;
+	 && TREE_OPERAND (GIMPLE_STMT_OPERAND (use_stmt, 1), 1) == def
+	 /* Do not recognize x / x as valid division, as we are getting
+	    confused later by replacing all immediate uses x in such
+	    a stmt.  */
+	 && TREE_OPERAND (GIMPLE_STMT_OPERAND (use_stmt, 1), 0) != def;
 }
 
 /* Walk the subset of the dominator tree rooted at OCC, setting the