re PR middle-end/55555 (miscompilation at -O2 (number_of_iterations))

2012-12-18  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/55555
	* tree-ssa-loop-niter.c (idx_infer_loop_bounds): Properly
	analyze evolution of the index for the loop it is used in.
	* tree-scalar-evolution.c (instantiate_scev_name): Take
	inner loop we will be creating a chrec for.  Generalize
	fix for PR40281 and prune invalid SCEVs.
	(instantiate_scev_poly): Likewise - pass down inner loop
	we will be creating a chrec for.
	(instantiate_scev_binary): Take and pass through inner loop.
	(instantiate_array_ref): Likewise.
	(instantiate_scev_convert): Likewise.
	(instantiate_scev_not): Likewise.
	(instantiate_scev_3): Likewise.
	(instantiate_scev_2): Likewise.
	(instantiate_scev_1): Likewise.
	(instantiate_scev_r): Likewise.
	(resolve_mixers): Adjust.
	(instantiate_scev): Likewise.

	* gcc.dg/torture/pr55555.c: New testcase.
	* gcc.dg/vect/vect-iv-11.c: Adjust.

From-SVN: r194578

gcc/ChangeLog

+2012-12-18  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/55555
+	* tree-ssa-loop-niter.c (idx_infer_loop_bounds): Properly
+	analyze evolution of the index for the loop it is used in.
+	* tree-scalar-evolution.c (instantiate_scev_name): Take
+	inner loop we will be creating a chrec for.  Generalize
+	fix for PR40281 and prune invalid SCEVs.
+	(instantiate_scev_poly): Likewise - pass down inner loop
+	we will be creating a chrec for.
+	(instantiate_scev_binary): Take and pass through inner loop.
+	(instantiate_array_ref): Likewise.
+	(instantiate_scev_convert): Likewise.
+	(instantiate_scev_not): Likewise.
+	(instantiate_scev_3): Likewise.
+	(instantiate_scev_2): Likewise.
+	(instantiate_scev_1): Likewise.
+	(instantiate_scev_r): Likewise.
+	(resolve_mixers): Adjust.
+	(instantiate_scev): Likewise.
+
 2012-12-18  Jakub Jelinek  <jakub@redhat.com>
 
 	PR debug/55717

gcc/testsuite/ChangeLog

+2012-12-18  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/55555
+	* gcc.dg/torture/pr55555.c: New testcase.
+	* gcc.dg/vect/vect-iv-11.c: Adjust.
+
 2012-12-18  Jakub Jelinek  <jakub@redhat.com>
 
 	PR debug/55717

gcc/testsuite/gcc.dg/torture/pr55555.c

+/* { dg-do run } */
+
+double s[4] = { 1.0, 2.0, 3.0, 4.0 }, pol_x[2] = { 5.0, 6.0 };
+
+__attribute__((noinline)) int
+foo (void)
+{
+  double coef_x[8] = { 0, 0, 0, 0, 0, 0, 0, 0 };
+  int lxp = 0;
+  if (lxp <= 1)
+    do
+      {
+	double t = pol_x[lxp];
+	long S;
+	long l = lxp * 4L - 1;
+	for (S = 1; S <= 4; S++)
+	  coef_x[S + l] = coef_x[S + l] + s[S - 1] * t;
+      }
+    while (lxp++ != 1);
+  asm volatile ("" : : "r" (coef_x) : "memory");
+  for (lxp = 0; lxp < 8; lxp++)
+    if (coef_x[lxp] != ((lxp & 3) + 1) * (5.0 + (lxp >= 4)))
+      __builtin_abort ();
+  return 1;
+}
+
+int
+main ()
+{
+  asm volatile ("" : : : "memory");
+  if (!foo ())
+    __builtin_abort ();
+  return 0;
+}

gcc/testsuite/gcc.dg/vect/vect-iv-11.c

@@ -3,7 +3,8 @@
 #include <stdarg.h>
 #include "tree-vect.h"
 
-int main1 (int len)
+int __attribute__((noinline,noclone))
+main1 (int len)
 {  
   int s = 0;
   int i = len;

gcc/tree-ssa-loop-niter.c

@@ -2671,7 +2671,12 @@ idx_infer_loop_bounds (tree base, tree *idx, void *dta)
       upper = false;
     }
 
-  ev = instantiate_parameters (loop, analyze_scalar_evolution (loop, *idx));
+  struct loop *dloop = loop_containing_stmt (data->stmt);
+  if (!dloop)
+    return true;
+
+  ev = analyze_scalar_evolution (dloop, *idx);
+  ev = instantiate_parameters (loop, ev);
   init = initial_condition (ev);
   step = evolution_part_in_loop_num (ev, loop->num);