tree cfb56c94b308b0175927bd383706d3166b5fc8c1
parent 64045042b801685e6e4f25613eada86ee2f7d71a
author John Porto <jpp@chromium.org> 1461243222 -0700
committer John Porto <jpp@chromium.org> 1461243222 -0700

Subzero. Rematerializes shufflevector instructions.

This CL is a first step towards optimizing vector shuffles in
Subzero.

PNaCl bitcode does not support the shufflevector instruction,
so pnacl-clang emits a series of extractelement/insertelement.
pnacl-llc is then responsible for performing a pattern match
on the output bitcode and rematerialize the shufflevector.

With this CL, we enable shufflevector rematerialization in
Subzero. To keep this CL simple, we introduce no efficient
shufflevector lowering. Instead, we scalarize the
rematerialized instructions.

BUG= https://bugs.chromium.org/p/nativeclient/issues/detail?id=4136
R=stichnot@chromium.org

Review URL: https://codereview.chromium.org/1897243002 .