Patchwork Fix PR middle-end/55219

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Submitter Eric Botcazou
Date Nov. 7, 2012, 10:21 p.m.
Message ID <5336214.jMX7Aekqkv@polaris>
Download mbox | patch
Permalink /patch/197734/
State New
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Comments

Eric Botcazou - Nov. 7, 2012, 10:21 p.m.
This is a regression present on the mainline and 4.7 branch.  For expressions 
of the form:

  h = (g ? c : g ? f : g ? e : g ? i : g ? f : g ? e : g ? d : x)
      + (a ? : a ? : a ? : a ? : a ? : a ? : a ? : a ? : a ? : a ? : a
         ? j : a ? : 0 ? : a ? : a ? : a ? : a ? : a ? : a ? k : a ? : x);

there is a memory explosion in the folder: fold_binary_op_with_conditional_arg 
is distributing the + inside the conditional expressions at each level 
recursively.  The transformation was originally applied only if the argument 
was TREE_CONSTANT, but during 4.7 development I extended it to more general 
arguments to help Ada.

Fixed by disabling recursion entirely, as it was originally.


Bootstrapped/regtested on x86_64-suse-linux, applied on mainline and 4.7 
branch as obvious.


2012-11-07  Eric Botcazou  <ebotcazou@adacore.com>

	PR middle-end/55219
	* fold-const.c (fold_binary_op_with_conditional_arg): Do not fold if
	the argument is itself a conditional expression.


2012-11-07  Eric Botcazou  <ebotcazou@adacore.com>

	* gcc.c-torture/compile/20121107-1.c: New test.

Patch

Index: fold-const.c
===================================================================
--- fold-const.c	(revision 193280)
+++ fold-const.c	(working copy)
@@ -5987,10 +5987,11 @@  fold_binary_op_with_conditional_arg (loc
     cond_code = VEC_COND_EXPR;
 
   /* This transformation is only worthwhile if we don't have to wrap ARG
-     in a SAVE_EXPR and the operation can be simplified on at least one
-     of the branches once its pushed inside the COND_EXPR.  */
+     in a SAVE_EXPR and the operation can be simplified without recursing
+     on at least one of the branches once its pushed inside the COND_EXPR.  */
   if (!TREE_CONSTANT (arg)
       && (TREE_SIDE_EFFECTS (arg)
+	  || TREE_CODE (arg) == COND_EXPR || TREE_CODE (arg) == VEC_COND_EXPR
 	  || TREE_CONSTANT (true_value) || TREE_CONSTANT (false_value)))
     return NULL_TREE;