[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]

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@@ -620,8 +649,12 @@ static bool expandTypedBufferLoadIntrinsic(CallInst *Orig) {
     } else {
       // Use of the check bit
       assert(Indices[0] == 1 && "Unexpected type for typedbufferload");
-      if (!CheckBit)
-        CheckBit = Builder.CreateExtractValue(Load, {1});
+      if (!CheckBit) {
+        SmallVector<Value *, 2> CheckBits;
+        for (Value *L : Loads)
+          CheckBits.push_back(Builder.CreateExtractValue(L, {1}));
+        CheckBit = Builder.CreateAnd(CheckBits);
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bogner wrote:

Might be worth a comment about the intentional difference from DXC. That is:
```c++
        // Note: This does not always match the historical behaviour of DXC.
        // See https://github.com/microsoft/DirectXShaderCompiler/issues/7622
```

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