| Message ID | 20210729111512.16541-4-peter.maydell@linaro.org |
|---|---|
| State | Superseded |
| Headers | show |
| Series | target/arm: MVE slices 3 and 4 | expand |
On 7/29/21 1:14 AM, Peter Maydell wrote: > In the MVE shift-and-insert insns, we special case VSLI by 0 > and VSRI by <dt>. VSRI by <dt> means "don't update the destination", > which is what we've implemented. However VSLI by 0 is "set > destination to the input", so we don't want to use the same > special-casing that we do for VSRI by <dt>. > > Since the generic logic gives the right answer for a shift > by 0, just use that. > > Signed-off-by: Peter Maydell<peter.maydell@linaro.org> > --- > target/arm/mve_helper.c | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) Reviewed-by: Richard Henderson <richard.henderson@linaro.org> r~
diff --git a/target/arm/mve_helper.c b/target/arm/mve_helper.c index db5d6220854..f14fa914b68 100644 --- a/target/arm/mve_helper.c +++ b/target/arm/mve_helper.c @@ -1279,11 +1279,12 @@ DO_2SHIFT_S(vrshli_s, DO_VRSHLS) uint16_t mask; \ uint64_t shiftmask; \ unsigned e; \ - if (shift == 0 || shift == ESIZE * 8) { \ + if (shift == ESIZE * 8) { \ /* \ - * Only VSLI can shift by 0; only VSRI can shift by <dt>. \ - * The generic logic would give the right answer for 0 but \ - * fails for <dt>. \ + * Only VSRI can shift by <dt>; it should mean "don't \ + * update the destination". The generic logic can't handle \ + * this because it would try to shift by an out-of-range \ + * amount, so special case it here. \ */ \ goto done; \ } \
In the MVE shift-and-insert insns, we special case VSLI by 0 and VSRI by <dt>. VSRI by <dt> means "don't update the destination", which is what we've implemented. However VSLI by 0 is "set destination to the input", so we don't want to use the same special-casing that we do for VSRI by <dt>. Since the generic logic gives the right answer for a shift by 0, just use that. Signed-off-by: Peter Maydell <peter.maydell@linaro.org> --- target/arm/mve_helper.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) -- 2.20.1