AMDGPU/GlobalISel: Remove unnecessary legality constraint for G_EXTRACT

Summary:
We were marking G_EXTRACT operations unsupported if the output type
was larger than the input type.  I don't see how this could ever actually
happen, so I dropped the constraint.  Doing this makes it possible to
reuse the same legality code for G_INSERT.

Reviewers: arsenm

Reviewed By: arsenm

Subscribers: kzhuravl, wdng, nhaehnle, yaxunl, rovka, kristof.beyls, dstuttard, tpr, t-tye, llvm-commits

Differential Revision: https://reviews.llvm.org/D49600

llvm-svn: 337794

llvm/lib/Target/AMDGPU/AMDGPULegalizerInfo.cpp

@@ -173,9 +173,6 @@ AMDGPULegalizerInfo::AMDGPULegalizerInfo(const GCNSubtarget &ST,
 
   // FIXME: Doesn't handle extract of illegal sizes.
   getActionDefinitionsBuilder(G_EXTRACT)
-    .unsupportedIf([=](const LegalityQuery &Query) {
-        return Query.Types[0].getSizeInBits() >= Query.Types[1].getSizeInBits();
-      })
     .legalIf([=](const LegalityQuery &Query) {
         const LLT &Ty0 = Query.Types[0];
         const LLT &Ty1 = Query.Types[1];