tree 05dd72cac5db2ea5ce140e84cde1801ff099ebe5
parent cceef2f73676f56a4985b838ce8734cc193d6a4d
author Matt Arsenault <Matthew.Arsenault@amd.com> 1549568264 +0000
committer Matt Arsenault <Matthew.Arsenault@amd.com> 1549568264 +0000

GlobalISel: Implement narrowScalar for shift main type

This is pretty much directly ported from SelectionDAG. Doesn't include
the shift by non-constant but known bits version, since there isn't a
globalisel version of computeKnownBits yet.

This shows a disadvantage of targets not specifically which type
should be used for the shift amount. If type 0 is legalized before
type 1, the operations on the shift amount type use the wider type
(which are also less likely to legalize). This can be avoided by
targets specifying legalization actions on type 1 earlier than for
type 0.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@353455 91177308-0d34-0410-b5e6-96231b3b80d8