re PR tree-optimization/23049 (ICE with -O3 -ftree-vectorize on 4.1.x)

2005-10-05  Steven Bosscher  <stevenb@suse.de>
gcc/
	PR tree-optimization/23049
	* tree-ssa-dom.c (thread_across_edge): Make sure that the condition
	of a COND_EXPR is folded before calling fold on the whole rhs of a
	conditional assignment.
	* doc/tree-ssa.texi: Update the GIMPLE grammar for a valid rhs to
	document that a COND_EXPR may appear there.

testsuite/
	* gcc.dg/pr23049.c: New test.

	* gcc.dg/ucnid-4.c: Fix test.

From-SVN: r104938

gcc/ChangeLog

@@ -1,3 +1,12 @@
+2005-10-05  Steven Bosscher  <stevenb@suse.de>
+
+	PR tree-optimization/23049
+	* tree-ssa-dom.c (thread_across_edge): Make sure that the condition
+	of a COND_EXPR is folded before calling fold on the whole rhs of a
+	conditional assignment.
+	* doc/tree-ssa.texi: Update the GIMPLE grammar for a valid rhs to
+	document that a COND_EXPR may appear there.
+
 2005-10-03  Diego Novillo  <dnovillo@redhat.com>
 
 	PR 23445

gcc/doc/tree-ssa.texi

@@ -728,6 +728,10 @@ void f()
                 | RELOP
                         op0 -> val
                         op1 -> val
+		| COND_EXPR
+			op0 -> condition
+			op1 -> val
+			op2 -> val
 @end smallexample
 
 @node Annotations

gcc/testsuite/ChangeLog

@@ -1,3 +1,9 @@
+2005-10-05  Steven Bosscher  <stevenb@suse.de>
+
+	* gcc.dg/pr23049.c: New test.
+
+	* gcc.dg/ucnid-4.c: Fix test.
+
 2005-10-03  Diego Novillo  <dnovillo@redhat.com>
 
 	PR 23445

gcc/testsuite/gcc.dg/pr23049.c

@@ -0,0 +1,26 @@
+/* This was an ICE in fold where we tried to fold something like,
+
+     a = 0 == 0 ? 0 : 3988292384
+
+   after doing if-conversion for the vectorizer.  Folding "0 == 0"
+   should have been done before calling fold on the whole rhs of
+   the above expression.  */
+
+/* { dg-do compile } */
+/* { dg-options "-O3 -ftree-vectorize" } */
+
+static unsigned short int crc_table[256];
+void AC3_encode_init(void)
+{
+  unsigned int c, n, k;
+  for(n=0;  n<256; n++)
+  {
+    c = n << 8;
+    for (k = 0; k < 8; k++)
+    {
+      if (c & (1 << 15))
+       c = ((c << 1) & 0xffff) ^ (((1 << 0) | (1 << 2) | (1 << 15) | (1 << 16)) & 0xffff);
+    }
+    crc_table[n] = c;
+  }
+}

gcc/testsuite/gcc.dg/ucnid-4.c

@@ -1,4 +1,4 @@
-/* { dg-do run */
+/* { dg-do run } */
 /* { dg-xfail-if "" { "powerpc-ibm-aix*" } { "*" } { "" } } */
 /* { dg-options "-std=c99 -fextended-identifiers" } */
 void abort (void);

gcc/tree-ssa-dom.c

@@ -666,7 +666,7 @@ thread_across_edge (struct dom_walk_data *walk_data, edge e)
      statements.  This does not prevent threading through E->dest.  */
   for (bsi = bsi_start (e->dest); ! bsi_end_p (bsi); bsi_next (&bsi))
     {
-      tree cached_lhs;
+      tree cached_lhs = NULL;
 
       stmt = bsi_stmt (bsi);
 
@@ -705,7 +705,7 @@ thread_across_edge (struct dom_walk_data *walk_data, edge e)
       else
 	{
 	  /* Copy the operands.  */
-	  tree *copy;
+	  tree *copy, pre_fold_expr;
 	  ssa_op_iter iter;
 	  use_operand_p use_p;
 	  unsigned int num, i = 0;
@@ -729,12 +729,31 @@ thread_across_edge (struct dom_walk_data *walk_data, edge e)
 
 	  /* Try to fold/lookup the new expression.  Inserting the
 	     expression into the hash table is unlikely to help
-	     simplify anything later, so just query the hashtable.  */
-	  cached_lhs = fold (TREE_OPERAND (stmt, 1));
-	  if (TREE_CODE (cached_lhs) != SSA_NAME
-	      && !is_gimple_min_invariant (cached_lhs))
-	    cached_lhs = lookup_avail_expr (stmt, false);
+	     Sadly, we have to handle conditional assignments specially
+	     here, because fold expects all the operands of an expression
+	     to be folded before the expression itself is folded, but we
+	     can't just substitute the folded condition here.  */
+	  if (TREE_CODE (TREE_OPERAND (stmt, 1)) == COND_EXPR)
+	    {
+	      tree cond = COND_EXPR_COND (TREE_OPERAND (stmt, 1));
+	      cond = fold (cond);
+	      if (cond == boolean_true_node)
+		pre_fold_expr = COND_EXPR_THEN (TREE_OPERAND (stmt, 1));
+	      else if (cond == boolean_false_node)
+		pre_fold_expr = COND_EXPR_ELSE (TREE_OPERAND (stmt, 1));
+	      else
+		pre_fold_expr = TREE_OPERAND (stmt, 1);
+	    }
+	  else
+	    pre_fold_expr = TREE_OPERAND (stmt, 1);
 
+	  if (pre_fold_expr)
+	    {
+	      cached_lhs = fold (pre_fold_expr);
+	      if (TREE_CODE (cached_lhs) != SSA_NAME
+		  && !is_gimple_min_invariant (cached_lhs))
+	        cached_lhs = lookup_avail_expr (stmt, false);
+	    }
 
 	  /* Restore the statement's original uses/defs.  */
 	  i = 0;