Remove redundant movs for waveShuffle

Change-Id: I9dd157dcde2b0ecd13d9801d9f74fe46aaf25d9d

Author: fftzeng

IGC/Compiler/CustomSafeOptPass.cpp

@@ -446,6 +446,11 @@ void CustomSafeOptPass::visitCallInst(CallInst& C)
             break;
         }
 
+        case GenISAIntrinsic::GenISA_WaveShuffleIndex:
+        {
+            visitWaveShuffleIndex(inst);
+            break;
+        }
         default:
             break;
         }
@@ -1173,6 +1178,15 @@ void IGC::CustomSafeOptPass::visitLdptr(llvm::CallInst* inst)
     }
 }
 
+void IGC::CustomSafeOptPass::visitWaveShuffleIndex(llvm::CallInst* inst)
+{
+    llvm::Constant* src1 = llvm::dyn_cast<llvm::Constant>(inst->getOperand(1));
+    llvm::Constant* src2 = llvm::dyn_cast<llvm::Constant>(inst->getOperand(2));
+    if (src1 && src2 && src1->isZeroValue() && src2->isZeroValue())
+    {
+        inst->replaceAllUsesWith(inst->getOperand(0));
+    }
+}
 
 void IGC::CustomSafeOptPass::visitLdRawVec(llvm::CallInst* inst)
 {

IGC/Compiler/CustomSafeOptPass.hpp

@@ -82,6 +82,7 @@ namespace IGC
         void visitLdptr(llvm::CallInst* inst);
         void visitLdRawVec(llvm::CallInst* inst);
         void visitLoadInst(llvm::LoadInst& I);
+        void visitWaveShuffleIndex(llvm::CallInst* inst);
 
         //
         // IEEE Floating point arithmetic is not associative.  Any pattern