tree-opt: Fix bootstrap failure in tree-ssa-forwprop.c some more PR90838

2020-01-13  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/90838
	* tree-ssa-forwprop.c (simplify_count_trailing_zeroes): Use
	SCALAR_INT_TYPE_MODE directly in CTZ_DEFINED_VALUE_AT_ZERO macro
	argument rather than to initialize temporary for targets that
	don't use the mode argument at all.  Initialize ctzval to avoid
	warning at -O0.

gcc/ChangeLog

+2020-01-13  Jakub Jelinek  <jakub@redhat.com>
+
+	PR tree-optimization/90838
+	* tree-ssa-forwprop.c (simplify_count_trailing_zeroes): Use
+	SCALAR_INT_TYPE_MODE directly in CTZ_DEFINED_VALUE_AT_ZERO macro
+	argument rather than to initialize temporary for targets that
+	don't use the mode argument at all.  Initialize ctzval to avoid
+	warning at -O0.
+
 2020-01-10  Thomas Schwinge  <thomas@codesourcery.com>
 
 	* tree.h (OMP_CLAUSE_USE_DEVICE_PTR_IF_PRESENT): New definition.

gcc/tree-ssa-forwprop.c

@@ -1920,10 +1920,10 @@ simplify_count_trailing_zeroes (gimple_stmt_iterator *gsi)
 				      res_ops[1], res_ops[2], zero_val))
     {
       tree type = TREE_TYPE (res_ops[0]);
-      HOST_WIDE_INT ctzval;
+      HOST_WIDE_INT ctzval = 0;
       HOST_WIDE_INT type_size = tree_to_shwi (TYPE_SIZE (type));
-      scalar_int_mode mode = SCALAR_INT_TYPE_MODE (type);
-      bool zero_ok = CTZ_DEFINED_VALUE_AT_ZERO (mode, ctzval) == 2;
+      bool zero_ok
+	= CTZ_DEFINED_VALUE_AT_ZERO (SCALAR_INT_TYPE_MODE (type), ctzval) == 2;
 
       /* Skip if there is no value defined at zero, or if we can't easily
 	 return the correct value for zero.  */