[llvm] [SPIR-V] Fix validation errors for function pointers with CodeSectionINTEL storage class (PR #192973)

[Arseniy Obolenskiy via llvm-commits]

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@@ -2829,13 +2829,15 @@ bool SPIRVInstructionSelector::selectAddrSpaceCast(Register ResVReg,
     // are expressed by OpSpecConstantOp with an Opcode.
     // TODO: maybe insert a check whether the Kernel capability was declared and
     // so PtrCastToGeneric/GenericCastToPtr are available.
-    unsigned SpecOpcode =
-        DstSC == SPIRV::StorageClass::Generic && isGenericCastablePtr(SrcSC)
-            ? static_cast<uint32_t>(SPIRV::Opcode::PtrCastToGeneric)
-            : (SrcSC == SPIRV::StorageClass::Generic &&
-                       isGenericCastablePtr(DstSC)
-                   ? static_cast<uint32_t>(SPIRV::Opcode::GenericCastToPtr)
-                   : 0);
+    unsigned SpecOpcode = [&]() -> unsigned {
+      if (SrcSC == SPIRV::StorageClass::CodeSectionINTEL)
+        return static_cast<uint32_t>(SPIRV::Opcode::Bitcast);
+      if (DstSC == SPIRV::StorageClass::Generic && isGenericCastablePtr(SrcSC))
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aobolensk wrote:

OpSpecConstantOp PtrCastToGeneric requires the source and result pointee types to match, but getUcharPtrTypeReg always produces a generic uchar* type, which doesn't match a function-pointer's pointee type.

https://github.com/llvm/llvm-project/pull/192973