[llvm] [DirectX] Add support for Raw Buffer Loads and Stores for scalars and vectors of doubles and i64s in SM6.2 and earlier (PR #146627)

[Justin Bogner via llvm-commits]

================
@@ -544,63 +555,81 @@ static Value *expandRadiansIntrinsic(CallInst *Orig) {
   return Builder.CreateFMul(X, PiOver180);
 }
 
-static bool expandTypedBufferLoadIntrinsic(CallInst *Orig) {
+static bool expandBufferLoadIntrinsic(CallInst *Orig, bool IsRaw) {
   IRBuilder<> Builder(Orig);
 
   Type *BufferTy = Orig->getType()->getStructElementType(0);
   Type *ScalarTy = BufferTy->getScalarType();
   bool IsDouble = ScalarTy->isDoubleTy();
   assert(IsDouble || ScalarTy->isIntegerTy(64) &&
                          "Only expand double or int64 scalars or vectors");
+  bool IsVector = isa<FixedVectorType>(BufferTy);
 
   unsigned ExtractNum = 2;
   if (auto *VT = dyn_cast<FixedVectorType>(BufferTy)) {
-    assert(VT->getNumElements() == 2 &&
-           "TypedBufferLoad vector must be size 2");
-    ExtractNum = 4;
+    if (!IsRaw)
+      assert(VT->getNumElements() == 2 &&
+             "TypedBufferLoad vector must be size 2");
+    ExtractNum = 2 * VT->getNumElements();
----------------
bogner wrote:

Maybe debatable if it's clearer or not, but it saves some typing to calculate the number of things to extract first:
```suggestion
    ExtractNum = 2 * VT->getNumElements();
    if (!IsRaw)
      assert(ExtractNum == 4 && "TypedBufferLoad vector must be size 2");
```

https://github.com/llvm/llvm-project/pull/146627