[llvm] [DirectX] Add support for typedBufferLoad and Store for RWBuffer<double2> and RWBuffer<double> (PR #139996)

[Justin Bogner via llvm-commits]

================
@@ -532,6 +541,89 @@ static Value *expandRadiansIntrinsic(CallInst *Orig) {
   return Builder.CreateFMul(X, PiOver180);
 }
 
+static Value *expandTypedBufferLoadIntrinsic(CallInst *Orig) {
+  IRBuilder<> Builder(Orig);
+
+  Type *BufferTy = Orig->getType()->getStructElementType(0);
+
+  unsigned ExtractNum = 2;
+  if (auto *VT = dyn_cast<FixedVectorType>(BufferTy)) {
+    assert(VT->getNumElements() == 2 &&
+           "TypedBufferLoad double vector has wrong size");
+    ExtractNum = 4;
+  }
+
+  Type *Ty = VectorType::get(Builder.getInt32Ty(), ExtractNum, false);
+
+  Type *LoadType = StructType::get(Ty, Builder.getInt1Ty());
+  CallInst *Load =
+      Builder.CreateIntrinsic(LoadType, Intrinsic::dx_resource_load_typedbuffer,
+                              {Orig->getOperand(0), Orig->getOperand(1)});
+
+  // extract the buffer load's result
+  Value *Extract = Builder.CreateExtractValue(Load, {0});
+
+  SmallVector<Value *> ExtractElements;
+  for (unsigned I = 0; I < ExtractNum; ++I)
+    ExtractElements.push_back(
+        Builder.CreateExtractElement(Extract, (uint64_t)I));
----------------
bogner wrote:

Better to use the `i32` overloads of extractelement by creating the constant explicitly, rather than using the i64 helper.
```suggestion
    ExtractElements.push_back(
        Builder.CreateExtractElement(Extract, Builder.getInt32(I)));
```

This comes up a few times elsewhere with extract- and insertelement as well.

https://github.com/llvm/llvm-project/pull/139996