[llvm] [SPIR-V] Emit builtin variable OpVariable into entry block (PR #189958)

[Arseniy Obolenskiy via llvm-commits]

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@@ -6114,11 +6114,16 @@ bool SPIRVInstructionSelector::loadVec3BuiltinInputID(
   MIRBuilder.getMRI()->setType(NewRegister, LLT::pointer(0, 64));
   GR.assignSPIRVTypeToVReg(PtrType, NewRegister, MIRBuilder.getMF());
 
-  // Build global variable with the necessary decorations for the input ID
-  // builtin variable.
+  // Emit the OpVariable into the entry block to ensure the def dominates
+  // all uses across all MBBs.
+  MachineBasicBlock &EntryBB = MIRBuilder.getMF().front();
+  MachineIRBuilder GVBuilder(MIRBuilder.getState());
+  if (&GVBuilder.getMBB() != &EntryBB)
+    GVBuilder.setInsertPt(EntryBB, EntryBB.getFirstTerminator());
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aobolensk wrote:

Yes, done

https://github.com/llvm/llvm-project/pull/189958