Re: [PATCH] RISC-V: Fix single-step expansion [PR126550].

On 8/4/2026 5:03 AM, Robin Dapp wrote:
> Hi,
>
> In expand_const_vector_single_step_npatterns, we use a second vector
> builder that is derived from the main one, in order to create a
> different alternating pattern for constant synthesis.  We later use the
> second builder's number of patterns for creating an intermediate
> operation. The second builder can have a different number of patterns
> than the first one, however, for example when its "global" pattern is
> simpler.
>
> This patch uses npatterns from the original builder.
>
> Regtested on rv64gcv_zvl512b.
>
> It's surprising that this went unnoticed for so long.  Definitely
> requires backporting to 16, 15, and maybe 14.
>
> Regards
>   Robin
>
>
> 	PR target/126550
>
> gcc/ChangeLog:
>
> 	* config/riscv/riscv-v.cc (expand_const_vector_single_step_npatterns):
> 	User global builder's npatterns.
>
> gcc/testsuite/ChangeLog:
>
> 	* gcc.target/riscv/rvv/autovec/pr126550-2.c: New test.
> 	* gcc.target/riscv/rvv/autovec/pr126550.c: New test.
LGTM.
jeff