On 8/4/25 3:09 AM, Robin Dapp wrote:
Hi,
In PR121334 we are asked to expand a const_vector of size 4 with
poly_int elements. It has 2 elts per pattern so is neither a
const_vector_duplicate nor a const_vector_stepped.
We don't allow this kind of constant in legitimate_constant_p but expr
apparently still wants us to expand it under certain conditions.
This patch implements a basic expander for such kinds of patterns.
As slide1up is used to build the individual vectors it also adds
a helper function expand_slide1up.
I regtested on rv64gcv_zvl512b but unfortunately the newly created
pattern is not even executed. I tried some variations of the original
code but didn't manage to trigger it.
Regards
Robin
PR target/121334
gcc/ChangeLog:
* config/riscv/riscv-v.cc (expand_slide1up): New function.
(expand_vector_init_trailing_same_elem): Use new function.
(expand_const_vector_onestep): New function.
(expand_const_vector): Uew expand_slide1up.
(expand_vector_init_merge_repeating_sequence): Ditto.
(shuffle_off_by_one_patterns): Ditto.
gcc/testsuite/ChangeLog:
* gcc.target/riscv/rvv/autovec/pr121334.c: New test.
As Palmer noted, b4 will grok this, so I used that, fixed the ChangeLog
to get past the hooks and pushed this to the trunk.
Thanks for the hint on b4. It's not something I generally use, though
I'm definitely aware of it.
jeff
