[PATCH] Fix PRs 65063 and 63593

[Richard Biener <rguenther at suse dot de>]

Predictive commoning happens to re-use SSA names it released while
there are still uses of them (oops), confusing the hell out of
other code (expected).  Fixed thus.

Bootstrap and regtest running on x86_64-unknown-linux-gnu.

Richard.

2015-02-16  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/63593
	PR tree-optimization/65063
	* tree-predcom.c (execute_pred_commoning_chain): Delay removing
	stmts and releasing SSA names until...
	(execute_pred_commoning): ... after processing all chains.

	* gcc.dg/pr63593.c: New testcase.
	* gcc.dg/pr65063.c: Likewise.

Index: gcc/tree-predcom.c
===================================================================
--- gcc/tree-predcom.c	(revision 220731)
+++ gcc/tree-predcom.c	(working copy)
@@ -1745,9 +1745,8 @@ execute_pred_commoning_chain (struct loo
   if (chain->combined)
     {
       /* For combined chains, just remove the statements that are used to
-	 compute the values of the expression (except for the root one).  */
-      for (i = 1; chain->refs.iterate (i, &a); i++)
-	remove_stmt (a->stmt);
+	 compute the values of the expression (except for the root one).
+	 We delay this until after all chains are processed.  */
     }
   else
     {
@@ -1811,6 +1810,21 @@ execute_pred_commoning (struct loop *loo
 	execute_pred_commoning_chain (loop, chain, tmp_vars);
     }
 
+  FOR_EACH_VEC_ELT (chains, i, chain)
+    {
+      if (chain->type == CT_INVARIANT)
+	;
+      else if (chain->combined)
+	{
+	  /* For combined chains, just remove the statements that are used to
+	     compute the values of the expression (except for the root one).  */
+	  dref a;
+	  unsigned j;
+	  for (j = 1; chain->refs.iterate (j, &a); j++)
+	    remove_stmt (a->stmt);
+	}
+    }
+
   update_ssa (TODO_update_ssa_only_virtuals);
 }
 
Index: gcc/testsuite/gcc.dg/pr63593.c
===================================================================
--- gcc/testsuite/gcc.dg/pr63593.c	(revision 0)
+++ gcc/testsuite/gcc.dg/pr63593.c	(working copy)
@@ -0,0 +1,20 @@
+/* { dg-do compile } */
+/* { dg-options "-O3 -fno-tree-vectorize" } */
+
+int in[2 * 4][4];
+int out[4];
+
+void
+foo (void)
+{
+  int sum;
+  int i, j, k;
+  for (k = 0; k < 4; k++)
+    {
+      sum = 1;
+      for (j = 0; j < 4; j++)
+	for (i = 0; i < 4; i++)
+	  sum *= in[i + k][j];
+      out[k] = sum;
+    }
+}
Index: gcc/testsuite/gcc.dg/pr65063.c
===================================================================
--- gcc/testsuite/gcc.dg/pr65063.c	(revision 0)
+++ gcc/testsuite/gcc.dg/pr65063.c	(working copy)
@@ -0,0 +1,33 @@
+/* { dg-do run } */
+/* { dg-options "-O3 -fno-tree-loop-ivcanon -fno-tree-vectorize" } */
+
+static int in[8][4];
+static int out[4];
+static const int check_result[] = {0, 16, 256, 4096};
+
+static inline void foo ()
+{
+  int sum;
+  int i, j, k;
+  for (k = 0; k < 4; k++)
+    {
+      sum = 1;
+      for (j = 0; j < 4; j++)
+	for (i = 0; i < 4; i++)
+	  sum *= in[i + k][j];
+      out[k] = sum;
+    }
+}
+
+int main ()
+{
+  int i, j, k;
+  for (i = 0; i < 8; i++)
+    for (j = 0; j < 4; j++)
+      in[i][j] = (i + 2) / 3;
+  foo ();
+  for (k = 0; k < 4; k++)
+    if (out[k] != check_result[k])
+      __builtin_abort ();
+  return 0;
+}