[GlobalISel] CSEMIRBuilder: Add support for G_GEP

Summary:
This patch adds G_GEP to `shouldCSEOpc` so that it can be CSEd. It also refactors
`translateGetElementPtr` by replacing `createGenericVirtualRegister` calls with types.

Reviewers: aditya_nandakumar, arsenm, dsanders, paquette, aemerson

Reviewed By: aditya_nandakumar

Subscribers: wdng, rovka, javed.absar, hiraditya, Petar.Avramovic, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D66316

llvm-svn: 369070

1 files changed, 7 insertions, 14 deletions

diff --git a/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp b/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
index 81ea7b539be..e1d0dc718b7 100644
--- a/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
@@ -1076,36 +1076,29 @@ bool IRTranslator::translateGetElementPtr(const User &U,
       }
 
       if (Offset != 0) {
-        Register NewBaseReg = MRI->createGenericVirtualRegister(PtrTy);
         LLT OffsetTy = getLLTForType(*OffsetIRTy, *DL);
         auto OffsetMIB = MIRBuilder.buildConstant({OffsetTy}, Offset);
-        MIRBuilder.buildGEP(NewBaseReg, BaseReg, OffsetMIB.getReg(0));
-
-        BaseReg = NewBaseReg;
+        BaseReg =
+            MIRBuilder.buildGEP(PtrTy, BaseReg, OffsetMIB.getReg(0)).getReg(0);
         Offset = 0;
       }
 
       Register IdxReg = getOrCreateVReg(*Idx);
-      if (MRI->getType(IdxReg) != OffsetTy) {
-        Register NewIdxReg = MRI->createGenericVirtualRegister(OffsetTy);
-        MIRBuilder.buildSExtOrTrunc(NewIdxReg, IdxReg);
-        IdxReg = NewIdxReg;
-      }
+      if (MRI->getType(IdxReg) != OffsetTy)
+        IdxReg = MIRBuilder.buildSExtOrTrunc(OffsetTy, IdxReg).getReg(0);
 
       // N = N + Idx * ElementSize;
       // Avoid doing it for ElementSize of 1.
       Register GepOffsetReg;
       if (ElementSize != 1) {
-        GepOffsetReg = MRI->createGenericVirtualRegister(OffsetTy);
         auto ElementSizeMIB = MIRBuilder.buildConstant(
             getLLTForType(*OffsetIRTy, *DL), ElementSize);
-        MIRBuilder.buildMul(GepOffsetReg, ElementSizeMIB.getReg(0), IdxReg);
+        GepOffsetReg =
+            MIRBuilder.buildMul(OffsetTy, ElementSizeMIB, IdxReg).getReg(0);
       } else
         GepOffsetReg = IdxReg;
 
-      Register NewBaseReg = MRI->createGenericVirtualRegister(PtrTy);
-      MIRBuilder.buildGEP(NewBaseReg, BaseReg, GepOffsetReg);
-      BaseReg = NewBaseReg;
+      BaseReg = MIRBuilder.buildGEP(PtrTy, BaseReg, GepOffsetReg).getReg(0);
     }
   }