On 10/6/25 2:40 PM, Robin Dapp wrote:
Hi,
In shuffle_series_pattern we use series_p to determine if the permute
mask is a simple series. This didn't take into account that series_p
also returns true for e.g. {0, 3, 2, 1} where the step is 3 and the
indices form a series modulo 4.
We emit
vid + vmul
in order to synthesize a series. In order to be always correct we would
need a vrem afterwards still which does not seem worth it.
This patch adds the modulo for VLA permutes and punts if we wrap around
for VLS permutes. I'm not really certain whether we'll really see a wrapping
VLA series (certainly we haven't so far in the test suite) but as we observed
a VLS one here now it appears conservatively correct to module the indices.
Regtested on rv64gcv_zvl512b.
Regards
Robin
PR target/121845
gcc/ChangeLog:
* config/riscv/riscv-v.cc (shuffle_series_patterns):
Modulo indices for VLA and punt when wrapping for VLS.
gcc/testsuite/ChangeLog:
* gcc.target/riscv/rvv/autovec/pr121845.c: New test.
I've pushed this to the trunk as well. I'll take care of patchwork and
BZ momentarily.
jeff
