Commit Graph

3 Commits

Author SHA1 Message Date
Craig Topper bc8148f7b0 [X86] Lower v16i16->v8i16 truncate using an 'and' with 255, an extract_subvector, and a packuswb instruction.
Summary: This is an improvement over the two pshufbs and punpcklqdq we'd get otherwise.

Reviewers: RKSimon, spatel

Reviewed By: RKSimon

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D54671

llvm-svn: 347171
2018-11-18 17:59:28 +00:00
Craig Topper 553ac560aa [X86] Add some custom type legalization rules for truncate with -x86-experimental-vector-widening-legalization.
This avoids some nasty shuffles when we have avx512. It will also prevent using zmm truncate instructions when a ymm instruction that zeroes part of an xmm register will do. Also avoid using avx512 truncate instructions when the input is 128 bits or less. These instructions are 2 uops on skx so we can probably find a better single uop shuffle like pshufb.

llvm-svn: 346936
2018-11-15 08:23:40 +00:00
Craig Topper 333ab7d08b [X86] Add more tests for -x86-experimental-vector-widening-legalization
I'm looking into whether we can make this the default legalization strategy. Adding these tests to help cover the changes that will be necessary.

This patch adds copies of some tests with the command line switch enabled. By making copies its easier to compare the two legalization strategies.

I've also removed RUN lines from some of these tests that already had -x86-experimental-vector-widening-legalization

llvm-svn: 346745
2018-11-13 07:47:52 +00:00