[Bug target/81763] Issues with BMI on 32bit x86 apps on GCC 7.1+

[ubizjak at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81763

--- Comment #24 from Uroš Bizjak <ubizjak at gmail dot com> ---
(In reply to Jakub Jelinek from comment #22)
> Wonder though if it wouldn't give the RA more choices by also including
> another
> &r <- (r, m) alternative with bmi2 isa attribute.

This would be worse than r <- (0, m) alternative on register starved x86_32
architecture. The above approach can use up to 6 registers, while r <- (0, m)
uses up to 4.