On 4/19/23 21:58, liuhongt via Gcc-patches wrote:
Use swap_communattive_operands_p for canonicalization. When both value
has same operand precedence value, then first bit in the mask should
select first operand.
The canonicalization should help backends for pattern match. .i.e. x86
backend has lots of vec_merge patterns, combine will create any form
of vec_merge(mask, or inverted mask), then backend need to add 2
patterns to match exact 1 instruction. The canonicalization can
simplify 2 patterns to 1.
Bootstrapped and regtested on x86_64-pc-linux-gnu{-m32,}, aarch64-linux-gnu.
Ok for trunk?
gcc/ChangeLog:
* combine.cc (maybe_swap_commutative_operands): Canonicalize
vec_merge when mask is constant.
ISTM that if we're going to call this the canonical form, then we should
document it in rtl.texi.
Otherwise it looks pretty good to me. So let's get the docs updated and
get this installed.
jeff
