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target/arm: Fix MVE VSLI by 0 and VSRI by <dt> 

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>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Peter Maydell 2021-08-13 17:11:47 +01:00
parent aa29190826
commit c88ff88498
1 changed files with 5 additions and 4 deletions
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9
target/arm/mve_helper.c
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@ -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; \
} \