[clang] [llvm] [SPIR-V] Implement SPV_KHR_untyped_pointers extension (PR #201233)

[Dmitry Sidorov via cfe-commits]

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@@ -6917,11 +7040,33 @@ bool SPIRVInstructionSelector::selectFrameIndex(Register ResVReg,
   // Change order of instructions if needed: all OpVariable instructions in a
   // function must be the first instructions in the first block
   auto It = getOpVariableMBBIt(*I.getMF());
-  BuildMI(*It->getParent(), It, It->getDebugLoc(), TII.get(SPIRV::OpVariable))
-      .addDef(ResVReg)
-      .addUse(GR.getSPIRVTypeID(ResType))
-      .addImm(static_cast<uint32_t>(SPIRV::StorageClass::Function))
-      .constrainAllUses(TII, TRI, RBI);
+
+  // Pointers to opaque types stay typed even with the extension on, so emit the
+  // untyped variant only when the result is actually an untyped pointer.
+  bool UseUntypedPointers =
+      ResType->getOpcode() == SPIRV::OpTypeUntypedPointerKHR;
+  unsigned Opcode =
+      UseUntypedPointers ? SPIRV::OpUntypedVariableKHR : SPIRV::OpVariable;
+
+  auto MIB = BuildMI(*It->getParent(), It, It->getDebugLoc(), TII.get(Opcode))
+                 .addDef(ResVReg)
+                 .addUse(GR.getSPIRVTypeID(ResType));
+
+  // Add storage class (comes before DataType for OpUntypedVariableKHR).
+  MIB.addImm(static_cast<uint32_t>(SPIRV::StorageClass::Function));
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MrSidims wrote:

reworded with addImm folded

https://github.com/llvm/llvm-project/pull/201233