[clang] [OpenCL] Put constant initializer globals into constant addrspace (PR #90048)

[Changpeng Fang via cfe-commits]

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@@ -535,20 +535,23 @@ void AggExprEmitter::EmitArrayInit(Address DestPtr, llvm::ArrayType *AType,
       elementType.isTriviallyCopyableType(CGF.getContext())) {
     CodeGen::CodeGenModule &CGM = CGF.CGM;
     ConstantEmitter Emitter(CGF);
-    LangAS AS = ArrayQTy.getAddressSpace();
+    QualType GVArrayQTy = CGM.getContext().getAddrSpaceQualType(
+        CGM.getContext().removeAddrSpaceQualType(ArrayQTy),
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changpeng wrote:

We saw a regression caused by this PR. It is a soft hang in CGM.getContext().removeAddrSpaceQualType.
Specifically it is in the following while loop:
while (T.hasAddressSpace()) {
    TypeNode = Quals.strip(T);

    // If the type no longer has an address space after stripping qualifiers,
    // jump out.
    if (!QualType(TypeNode, 0).hasAddressSpace())
      break;

    // There might be sugar in the way. Strip it and try again.
    T = T.getSingleStepDesugaredType(*this);
  }
We found that "T == T.getSingleStepDesugaredType(*this);" and this it could not proceed.

I am not sure whether we should break out this loop when "T == T.getSingleStepDesugaredType(*this)"
or something else is wrong that we should never see such case.

Here is the dump of T:
ConstantArrayType 0x555565b40640 '__private ulong[16]' 16
`-QualType 0x555565b403f8 '__private ulong' __private
  `-ElaboratedType 0x555565b3ff40 'ulong' sugar imported
    `-TypedefType 0x555565b3fef0 'ulong' sugar imported
      |-Typedef 0x555565b3fe80 'ulong'
      `-BuiltinType 0x55556583f430 'unsigned long'

https://github.com/llvm/llvm-project/pull/90048