[llvm] [SPIR-V] Do not use OpenCL metadata for ptr element type resolution (PR #82678)

[Justin Bogner via llvm-commits]

================
@@ -567,22 +608,20 @@ void SPIRVEmitIntrinsics::processGlobalValue(GlobalVariable &GV) {
 
 void SPIRVEmitIntrinsics::insertAssignPtrTypeIntrs(Instruction *I) {
   reportFatalOnTokenType(I);
-  if (I->getType()->isVoidTy() || !requireAssignPtrType(I))
+  if (!I->getType()->isPointerTy() || !requireAssignType(I) ||
+      isa<BitCastInst>(I))
     return;
 
   setInsertPointSkippingPhis(*IRB, I->getNextNode());
 
   Constant *EltTyConst;
-  unsigned AddressSpace = 0;
-  if (auto *AI = dyn_cast<AllocaInst>(I)) {
+  unsigned AddressSpace = I->getType()->getPointerAddressSpace();
+  if (auto *AI = dyn_cast<AllocaInst>(I))
     EltTyConst = UndefValue::get(AI->getAllocatedType());
-    AddressSpace = AI->getAddressSpace();
-  } else if (auto *GEP = dyn_cast<GetElementPtrInst>(I)) {
+  else if (auto *GEP = dyn_cast<GetElementPtrInst>(I))
     EltTyConst = UndefValue::get(GEP->getResultElementType());
-    AddressSpace = GEP->getPointerAddressSpace();
-  } else {
-    llvm_unreachable("Unexpected instruction!");
-  }
+  else if (I->getType()->isPointerTy())
+    EltTyConst = UndefValue::get(IntegerType::getInt8Ty(I->getContext()));
----------------
bogner wrote:

Dropping the else/llvm_unreachable case here results in a `-Wsometimes-uninitialized` warning. We probably want to add it back to get a reliable crash in debug builds rather than UB.
```
llvm/lib/Target/SPIRV/SPIRVEmitIntrinsics.cpp:623:12: error: variable 'EltTyConst' is used uninitialized whenever 'if' condition is false [-Werror,-Wsometimes-uninitialized]
  else if (I->getType()->isPointerTy())
           ^~~~~~~~~~~~~~~~~~~~~~~~~~~
llvm/lib/Target/SPIRV/SPIRVEmitIntrinsics.cpp:626:67: note: uninitialized use occurs here
  buildIntrWithMD(Intrinsic::spv_assign_ptr_type, {I->getType()}, EltTyConst, I,
                                                                  ^~~~~~~~~~
llvm/lib/Target/SPIRV/SPIRVEmitIntrinsics.cpp:623:8: note: remove the 'if' if its condition is always true
  else if (I->getType()->isPointerTy())
       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
llvm/lib/Target/SPIRV/SPIRVEmitIntrinsics.cpp:617:23: note: initialize the variable 'EltTyConst' to silence this warning
  Constant *EltTyConst;
                      ^
                       = nullptr
```

https://github.com/llvm/llvm-project/pull/82678