commit 802f8d0f4f85a6a58c8e387c803fb6e8358c0e1b
author Craig Topper <craig.topper@intel.com> Sat Feb 23 08:34:10 2019 +0000
committer Craig Topper <craig.topper@intel.com> Sat Feb 23 08:34:10 2019 +0000
tree d91ffafe6fe689604037183be9956dddf2d68f01
parent a56275251b761bac1045528ce3e4a1c4d5863b26

[X86] Sign extend the 8-bit immediate when commuting blend instructions to match isel.

Conversion from ConstantSDNode to MachineInstr sign extends immediates from their APInt representation to int64_t.

This commit makes sure we do the same for commuting. The tests changes show how this improves CSE. This issue was made worse by the MachineCSE using commuteInstruction to undo a commute. So we virtually guarantee the sign extend from isel would be lost.

The improved CSE also occurred with r354363, but that was reverted. I'm working to undo the revert, but wanted to get this fix in while it was easy to see the results.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@354724 91177308-0d34-0410-b5e6-96231b3b80d8