AMDGPU: Support for SimplifyDemandedVectorElts for load intrinsics

llvm-svn: 297408

1 files changed, 41 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
index d8824b473a6..78ee9d5de3f 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
@@ -1561,6 +1561,47 @@ Value *InstCombiner::SimplifyDemandedVectorElts(Value *V, APInt DemandedElts,
     case Intrinsic::x86_sse4a_insertqi:
       UndefElts |= APInt::getHighBitsSet(VWidth, VWidth / 2);
       break;
+    case Intrinsic::amdgcn_buffer_load:
+    case Intrinsic::amdgcn_buffer_load_format: {
+      if (VWidth == 1 || !APIntOps::isMask(DemandedElts))
+        return nullptr;
+
+      // TODO: Handle 3 vectors when supported in code gen.
+      unsigned NewNumElts = PowerOf2Ceil(DemandedElts.countTrailingOnes());
+      if (NewNumElts == VWidth)
+        return nullptr;
+
+      Module *M = II->getParent()->getParent()->getParent();
+      Type *EltTy = V->getType()->getVectorElementType();
+
+      Type *NewTy = (NewNumElts == 1) ? EltTy :
+        VectorType::get(EltTy, NewNumElts);
+
+      Function *NewIntrin = Intrinsic::getDeclaration(M, II->getIntrinsicID(),
+                                                      NewTy);
+
+      SmallVector<Value *, 5> Args;
+      for (unsigned I = 0, E = II->getNumArgOperands(); I != E; ++I)
+        Args.push_back(II->getArgOperand(I));
+
+      CallInst *NewCall = Builder->CreateCall(NewIntrin, Args);
+      NewCall->takeName(II);
+      NewCall->copyMetadata(*II);
+      if (NewNumElts == 1) {
+        return Builder->CreateInsertElement(UndefValue::get(V->getType()),
+                                            NewCall, static_cast<uint64_t>(0));
+      }
+
+      SmallVector<uint32_t, 8> EltMask;
+      for (unsigned I = 0; I < VWidth; ++I)
+        EltMask.push_back(I);
+
+      Value *Shuffle = Builder->CreateShuffleVector(
+        NewCall, UndefValue::get(NewTy), EltMask);
+
+      MadeChange = true;
+      return Shuffle;
+    }
     }
     break;
   }