re PR tree-optimization/43186 (A loop in tree_unroll_loops_completely never ends)

2010-02-27  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/43186
	* params.def (PARAM_MAX_UNROLL_ITERATIONS): New param.
	* doc/invoke.texi (max-completely-peel-loop-nest-depth): Document.
	* tree-ssa-loop-ivcanon.c (tree_unroll_loops_completely): Limit
	unroller iterations.

	* gcc.c-torture/compile/pr43186.c: Adjust testcase.

From-SVN: r157114

6 files changed, 25 insertions, 2 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index f6cdb86..049729b 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,11 @@
+2010-02-27  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/43186
+	* params.def (PARAM_MAX_UNROLL_ITERATIONS): New param.
+	* doc/invoke.texi (max-completely-peel-loop-nest-depth): Document.
+	* tree-ssa-loop-ivcanon.c (tree_unroll_loops_completely): Limit
+	unroller iterations.
+
 2010-02-27  H.J. Lu  <hongjiu.lu@intel.com>
 
 	* config.gcc: Set the default 32bit/64bit archs if 64bit ISA is
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 6a6bd92..36580fb 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -8094,6 +8094,9 @@ The maximum number of insns of a completely peeled loop.
 @item max-completely-peel-times
 The maximum number of iterations of a loop to be suitable for complete peeling.
 
+@item max-completely-peel-loop-nest-depth
+The maximum depth of a loop nest suitable for complete peeling.
+
 @item max-unswitch-insns
 The maximum number of insns of an unswitched loop.
 
diff --git a/gcc/params.def b/gcc/params.def
index 21dcb44..07bfb90 100644
--- a/gcc/params.def
+++ b/gcc/params.def
@@ -266,6 +266,11 @@ DEFPARAM(PARAM_MAX_ONCE_PEELED_INSNS,
 	"max-once-peeled-insns",
 	"The maximum number of insns of a peeled loop that rolls only once",
 	400, 0, 0)
+/* The maximum depth of a loop nest we completely peel.  */
+DEFPARAM(PARAM_MAX_UNROLL_ITERATIONS,
+	 "max-completely-peel-loop-nest-depth",
+	 "The maximum depth of a loop nest we completely peel",
+	 8, 0, 0)
 
 /* The maximum number of insns of an unswitched loop.  */
 DEFPARAM(PARAM_MAX_UNSWITCH_INSNS,
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 8884795..bf0b7ce8 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2010-02-27  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/43186
+	* gcc.c-torture/compile/pr43186.c: Adjust testcase.
+
 2010-02-27  Kaz Kojima  <kkojima@gcc.gnu.org>
 
 	* g++.dg/abi/packed1.C: Expect warning on the SH.
diff --git a/gcc/testsuite/gcc.c-torture/compile/pr43186.c b/gcc/testsuite/gcc.c-torture/compile/pr43186.c
index d235e97..7171e6a 100644
--- a/gcc/testsuite/gcc.c-torture/compile/pr43186.c
+++ b/gcc/testsuite/gcc.c-torture/compile/pr43186.c
@@ -5,7 +5,7 @@ void foo (int i)
   int a, b;
 
   if (!i)
-    for (a = 1; a < 3; a++)
+    for (a = 1; a < 4; a++)
       if (a)
 	for (b = 1; b < 3; b++)
 	  foo (b);
diff --git a/gcc/tree-ssa-loop-ivcanon.c b/gcc/tree-ssa-loop-ivcanon.c
index df48dfd..e9841f5 100644
--- a/gcc/tree-ssa-loop-ivcanon.c
+++ b/gcc/tree-ssa-loop-ivcanon.c
@@ -522,6 +522,7 @@ tree_unroll_loops_completely (bool may_increase_size, bool unroll_outer)
   struct loop *loop;
   bool changed;
   enum unroll_level ul;
+  int iteration = 0;
 
   do
     {
@@ -554,7 +555,8 @@ tree_unroll_loops_completely (bool may_increase_size, bool unroll_outer)
 	  scev_reset ();
 	}
     }
-  while (changed);
+  while (changed
+	 && ++iteration <= PARAM_VALUE (PARAM_MAX_UNROLL_ITERATIONS));
 
   return 0;
 }