http://gcc.gnu.org/bugzilla/show_bug.cgi?id=61010
--- Comment #7 from Richard Biener <rguenth at gcc dot gnu.org> ---
Like
Index: gcc/fold-const.c
===================================================================
--- gcc/fold-const.c (revision 209928)
+++ gcc/fold-const.c (working copy)
@@ -11426,7 +11426,6 @@ fold_binary_loc (location_t loc,
{
double_int c1, c2, c3, msk;
int width = TYPE_PRECISION (type), w;
- bool try_simplify = true;
c1 = tree_to_double_int (TREE_OPERAND (arg0, 1));
c2 = tree_to_double_int (arg1);
@@ -11463,20 +11462,7 @@ fold_binary_loc (location_t loc,
}
}
- /* If X is a tree of the form (Y * K1) & K2, this might conflict
- with that optimization from the BIT_AND_EXPR optimizations.
- This could end up in an infinite recursion. */
- if (TREE_CODE (TREE_OPERAND (arg0, 0)) == MULT_EXPR
- && TREE_CODE (TREE_OPERAND (TREE_OPERAND (arg0, 0), 1))
- == INTEGER_CST)
- {
- tree t = TREE_OPERAND (TREE_OPERAND (arg0, 0), 1);
- double_int masked = mask_with_tz (type, c3, tree_to_double_int
(t));
-
- try_simplify = (masked != c1);
- }
-
- if (try_simplify && c3 != c1)
+ if (c3 != c1)
return fold_build2_loc (loc, BIT_IOR_EXPR, type,
fold_build2_loc (loc, BIT_AND_EXPR, type,
TREE_OPERAND (arg0, 0),
@@ -11866,16 +11852,25 @@ fold_binary_loc (location_t loc,
&& TREE_CODE (arg0) == MULT_EXPR
&& TREE_CODE (TREE_OPERAND (arg0, 1)) == INTEGER_CST)
{
+ double_int darg1 = tree_to_double_int (arg1);
double_int masked
- = mask_with_tz (type, tree_to_double_int (arg1),
+ = mask_with_tz (type, darg1,
tree_to_double_int (TREE_OPERAND (arg0, 1)));
if (masked.is_zero ())
return omit_two_operands_loc (loc, type, build_zero_cst (type),
arg0, arg1);
- else if (masked != tree_to_double_int (arg1))
- return fold_build2_loc (loc, code, type, op0,
- double_int_to_tree (type, masked));
+ else if (masked != darg1)
+ {
+ /* Avoid the transform if arg1 is a mask of some
+ mode which allows further optimizations. */
+ int pop = darg1.popcount ();
+ if (!(pop >= BITS_PER_UNIT
+ && exact_log2 (pop) != -1
+ && double_int::mask (pop) == darg1))
+ return fold_build2_loc (loc, code, type, op0,
+ double_int_to_tree (type, masked));
+ }
}
/* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
