@@ -7990,18 +7990,9 @@ make_compound_operation_int (machine_mode mode, rtx *x_ptr,
XEXP (inner_x0, 1),
i, 1, 0, in_code == COMPARE);
- if (new_rtx)
- {
- /* If we narrowed the mode when dropping the subreg, then
- we must zero-extend to keep the semantics of the AND. */
- if (GET_MODE_SIZE (inner_mode) >= GET_MODE_SIZE (mode))
- ;
- else if (SCALAR_INT_MODE_P (inner_mode))
- new_rtx = simplify_gen_unary (ZERO_EXTEND, mode,
- new_rtx, inner_mode);
- else
- new_rtx = NULL;
- }
+ /* If we narrowed the mode when dropping the subreg, then we lose. */
+ if (GET_MODE_SIZE (inner_mode) < GET_MODE_SIZE (mode))
+ new_rtx = NULL;
/* If that didn't give anything, see if the AND simplifies on
its own. */
We here have an AND of a SUBREG of an LSHIFTRT. If that SUBREG is paradoxical, the extraction we form is the length of the size of the inner mode, which includes some bits that should not be in the result. Just give up in that case. Tested on powerpc64-linux {-m32,-m64} and on x86_64-linux. Committing to trunk. Segher 2018-07-18 Segher Boessenkool <segher@kernel.crashing.org> PR rtl-optimization/81423 * combine.c (make_compound_operation_int): Don't try to optimize the AND of a SUBREG of an LSHIFTRT if that SUBREG is paradoxical. --- gcc/combine.c | 15 +++------------ 1 file changed, 3 insertions(+), 12 deletions(-)