Support swizzle indexing. (#139)

tools/clang/lib/CodeGen/CGExprCXX.cpp

@@ -221,7 +221,32 @@ RValue CodeGenFunction::EmitCXXMemberOrOperatorMemberCallExpr(
 
       llvm::Value *This = nullptr;
       if (Base->getValueKind() != ExprValueKind::VK_RValue) {
+        LValue LV = EmitLValue(Base);
+        if (LV.isSimple()) {
           This = EmitLValue(Base).getAddress();
+          if (isa<ExtMatrixElementExpr>(Base)) {
+            llvm::Value *Val = Builder.CreateLoad(This);
+            This = Builder.CreateAlloca(Val->getType());
+            Builder.CreateStore(Val, This);
+          }
+        } else {
+          assert(LV.isExtVectorElt() && "must be ext vector here");
+          This = LV.getExtVectorAddr();
+          llvm::Constant *Elts = LV.getExtVectorElts();
+          llvm::Type *Ty = ConvertType(LV.getType());
+
+          llvm::Constant *zero = Builder.getInt32(0);
+          llvm::Value *TmpThis = Builder.CreateAlloca(Ty);
+          for (unsigned i = 0; i < Ty->getVectorNumElements(); i++) {
+            llvm::Value *EltIdx = Elts->getAggregateElement(i);
+            llvm::Value *EltGEP = Builder.CreateGEP(This, {zero, EltIdx});
+            llvm::Value *TmpEltGEP =
+                Builder.CreateGEP(TmpThis, {zero, Builder.getInt32(i)});
+            llvm::Value *Elt = Builder.CreateLoad(EltGEP);
+            Builder.CreateStore(Elt, TmpEltGEP);
+          }
+          This = TmpThis;
+        }
       } else {
         llvm::Value *Val = EmitScalarExpr(Base);
         This = Builder.CreateAlloca(Val->getType());

tools/clang/test/CodeGenHLSL/swizzleIndexing.hlsl

@@ -0,0 +1,10 @@
+// RUN: %dxc -E main -T ps_6_0 %s | FileCheck %s
+
+// CHECK: @main
+
+float4x4 m;
+uint4 main(uint4 a : AAA, uint4 b : BBB) : SV_Target
+{
+  float4x4 tm = m;
+  return a.wzyx[b.x] + tm._m00_m11[b.x];
+}

tools/clang/unittests/HLSL/CompilerTest.cpp

@@ -529,6 +529,7 @@ public:
   TEST_METHOD(CodeGenSwizzle2)
   TEST_METHOD(CodeGenSwizzleAtomic)
   TEST_METHOD(CodeGenSwizzleAtomic2)
+  TEST_METHOD(CodeGenSwizzleIndexing)
   TEST_METHOD(CodeGenTemp1)
   TEST_METHOD(CodeGenTemp2)
   TEST_METHOD(CodeGenTexSubscript)
@@ -2811,6 +2812,10 @@ TEST_F(CompilerTest, CodeGenSwizzleAtomic2) {
   CodeGenTestCheck(L"..\\CodeGenHLSL\\swizzleAtomic2.hlsl");
 }
 
+TEST_F(CompilerTest, CodeGenSwizzleIndexing) {
+  CodeGenTestCheck(L"..\\CodeGenHLSL\\swizzleIndexing.hlsl");
+}
+
 TEST_F(CompilerTest, CodeGenTemp1) {
   CodeGenTest(L"..\\CodeGenHLSL\\temp1.hlsl");
 }