[clang] [llvm] [SPIRV] Pack 64-bit vec2 typed buffers into 4x32-bit images (PR #208626)

[Farzon Lotfi via cfe-commits]

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@@ -890,6 +890,14 @@ llvm::Type *CommonSPIRTargetCodeGenInfo::getSPIRVImageTypeFromHLSLResource(
          "The element type for a SPIR-V resource must be a scalar integer or "
          "floating point type.");
 
+  // SPIR-V has no 64-bit multi-component image format, so pack a 2-component
+  // 64-bit typed buffer into a 4-component 32-bit image. The backend
+  // reinterprets it with OpBitcast on load and store.
+  if (SampledType->isIntegerTy(64) && NumChannels == 2) {
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farzonl wrote:

what if we got  a 64bit type with 3 components or 4? Should we explicitly reject unsupported 64-bit configurations if we can't handle them like this case does?

https://github.com/llvm/llvm-project/pull/208626