re PR tree-optimization/56962 (SLSR caused miscompilation of fftw)

	PR tree-optimization/56962
	* gimple-ssa-strength-reduction.c (record_increment): Only set
	initializer if gimple_assign_rhs_code is {,POINTER_}PLUS_EXPR and
	either rhs1 or rhs2 is equal to c->base_expr.

	* gcc.c-torture/execute/pr56962.c: New test.

From-SVN: r197978

gcc/ChangeLog

+2013-04-15  Jakub Jelinek  <jakub@redhat.com>
+
+	PR tree-optimization/56962
+	* gimple-ssa-strength-reduction.c (record_increment): Only set
+	initializer if gimple_assign_rhs_code is {,POINTER_}PLUS_EXPR and
+	either rhs1 or rhs2 is equal to c->base_expr.
+
 2013-04-15  Richard Biener  <rguenther@suse.de>
 
 	PR tree-optimization/56933

gcc/gimple-ssa-strength-reduction.c

@@ -1829,16 +1829,20 @@ record_increment (slsr_cand_t c, double_int increment)
       if (c->kind == CAND_ADD
 	  && c->index == increment
 	  && (increment.sgt (double_int_one)
-	      || increment.slt (double_int_minus_one)))
+	      || increment.slt (double_int_minus_one))
+	  && (gimple_assign_rhs_code (c->cand_stmt) == PLUS_EXPR
+	      || gimple_assign_rhs_code (c->cand_stmt) == POINTER_PLUS_EXPR))
 	{
-	  tree t0;
+	  tree t0 = NULL_TREE;
 	  tree rhs1 = gimple_assign_rhs1 (c->cand_stmt);
 	  tree rhs2 = gimple_assign_rhs2 (c->cand_stmt);
 	  if (operand_equal_p (rhs1, c->base_expr, 0))
 	    t0 = rhs2;
-	  else
+	  else if (operand_equal_p (rhs2, c->base_expr, 0))
 	    t0 = rhs1;
-	  if (SSA_NAME_DEF_STMT (t0) && gimple_bb (SSA_NAME_DEF_STMT (t0)))
+	  if (t0
+	      && SSA_NAME_DEF_STMT (t0)
+	      && gimple_bb (SSA_NAME_DEF_STMT (t0)))
 	    {
 	      incr_vec[incr_vec_len].initializer = t0;
 	      incr_vec[incr_vec_len++].init_bb

gcc/testsuite/ChangeLog

+2013-04-15  Jakub Jelinek  <jakub@redhat.com>
+
+	PR tree-optimization/56962
+	* gcc.c-torture/execute/pr56962.c: New test.
+
 2013-04-15  Richard Biener  <rguenther@suse.de>
 
 	PR tree-optimization/56933

gcc/testsuite/gcc.c-torture/execute/pr56962.c

+/* PR tree-optimization/56962 */
+
+extern void abort (void);
+long long v[144];
+
+__attribute__((noinline, noclone)) void
+bar (long long *x)
+{
+  if (x != &v[29])
+    abort ();
+}
+
+__attribute__((noinline, noclone)) void
+foo (long long *x, long y, long z)
+{
+  long long a, b, c;
+  a = x[z * 4 + y * 3];
+  b = x[z * 5 + y * 3];
+  c = x[z * 5 + y * 4];
+  x[y * 4] = a;
+  bar (&x[z * 5 + y]);
+  x[z * 5 + y * 5] = b + c;
+}
+
+int
+main ()
+{
+  foo (v, 24, 1);
+  return 0;
+}