Hi!
As mentioned in the PR, giving up for all vector mode extensions
is unnecessary, but unlike scalar integer extensions, where the low part
of the extended value is the original value, for vectors this is not true,
thus the old value is lost. Which means we can perform REE, but only if
all uses of the definition are the same (code+mode) extension.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2015-01-12 Jakub Jelinek <jakub@redhat.com>
PR rtl-optimization/64286
* ree.c (add_removable_extension): Don't add vector mode
extensions if all uses of the source register aren't the same
vector extensions.
* gcc.target/i386/avx2-pr64286.c: New test.