From: Richard Guenther <rguenther@suse.de>
Date: Tue, 9 May 2006 16:01:53 +0000 (+0000)
Subject: re PR middle-end/27136 (Compile failure with -O -ffast-math)
X-Git-Tag: releases/gcc-4.0.4~709
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2da60f1c6f14f3fc6cea91315a4c2d7fa505962e;p=thirdparty%2Fgcc.git

re PR middle-end/27136 (Compile failure with -O -ffast-math)

2006-05-09  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/27136
	* tree-ssa-loop-niter.c (get_val_for): Correct function
	comment, assert requirements.
	(loop_niter_by_eval): Stop processing if the iterated
	value did not simplify.

	* gcc.dg/torture/pr27136.c: New testcase.

From-SVN: r113657
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 0c5f5893ac26..be18f843ad61 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,11 @@
+2006-05-09  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/27136
+	* tree-ssa-loop-niter.c (get_val_for): Correct function
+	comment, assert requirements.
+	(loop_niter_by_eval): Stop processing if the iterated
+	value did not simplify.
+
 2006-05-03  Roger Sayle  <roger@eyesopen.com>
 
 	PR c/25309
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 3644eff079b3..97da8e57a636 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2006-05-09  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/27136
+	* gcc.dg/torture/pr27136.c: New testcase.
+
 2006-05-07  Volker Reichelt  <reichelt@igpm.rwth-aachen.de>
 
 	* g++.dg/template/incomplete2.C: Fix error marker.
diff --git a/gcc/testsuite/gcc.dg/torture/pr27136.c b/gcc/testsuite/gcc.dg/torture/pr27136.c
new file mode 100644
index 000000000000..32b7bf123ef7
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr27136.c
@@ -0,0 +1,10 @@
+/* { dg-do compile } */
+/* { dg-options "-ffast-math" } */
+
+void foo()
+{
+  double x;
+
+  for (x = 2; x < 10; x *= x)
+    ;
+}
diff --git a/gcc/tree-ssa-loop-niter.c b/gcc/tree-ssa-loop-niter.c
index 58a00e4c74e5..b994b5b1f384 100644
--- a/gcc/tree-ssa-loop-niter.c
+++ b/gcc/tree-ssa-loop-niter.c
@@ -947,7 +947,7 @@ get_base_for (struct loop *loop, tree x)
 
 /* Given an expression X, then 
  
-   * if BASE is NULL_TREE, X must be a constant and we return X.
+   * if X is NULL_TREE, we return the constant BASE.
    * otherwise X is a SSA name, whose value in the considered loop is derived
      by a chain of operations with constant from a result of a phi node in
      the header of the loop.  Then we return value of X when the value of the
@@ -960,6 +960,8 @@ get_val_for (tree x, tree base)
   use_optype uses;
   use_operand_p op;
 
+  gcc_assert (is_gimple_min_invariant (base));
+
   if (!x)
     return base;
 
@@ -1057,7 +1059,11 @@ loop_niter_by_eval (struct loop *loop, edge exit)
 	}
 
       for (j = 0; j < 2; j++)
-	val[j] = get_val_for (next[j], val[j]);
+	{
+	  val[j] = get_val_for (next[j], val[j]);
+	  if (!is_gimple_min_invariant (val[j]))
+	    return chrec_dont_know;
+	}
     }
 
   return chrec_dont_know;