[clang] [clang][CodeGen][OpenCL] Fix `alloca` handling & `sret`when compiling for (PR #113930)

[Alex Voicu via cfe-commits]

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@@ -108,11 +108,15 @@ RawAddress CodeGenFunction::CreateTempAlloca(llvm::Type *Ty, CharUnits Align,
   if (AllocaAddr)
     *AllocaAddr = Alloca;
   llvm::Value *V = Alloca.getPointer();
+  assert((!getLangOpts().OpenCL ||
+          CGM.getTarget().getTargetAddressSpace(getASTAllocaAddressSpace()) ==
+              CGM.getTarget().getTargetAddressSpace(LangAS::opencl_private)) &&
+         "For OpenCL allocas must allocate in the private address space!");
   // Alloca always returns a pointer in alloca address space, which may
   // be different from the type defined by the language. For example,
   // in C++ the auto variables are in the default address space. Therefore
   // cast alloca to the default address space when necessary.
-  if (getASTAllocaAddressSpace() != LangAS::Default) {
+  if (!getLangOpts().OpenCL && getASTAllocaAddressSpace() != LangAS::Default) {
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AlexVlx wrote:

The language factors in here because you cannot multi-purpose / multi-map LangAS::Default, which is why we (and others) used the hacked AS map that had private as default. Maybe there's a more elegant solution to this that does things upstream, and perhaps we'll implement it later, but this is borderline NFC to deal with dropping the privateIsDefault hacked AS maps. As for the rest of the code, I've not authored it, so I cannot comment one way or the other.

https://github.com/llvm/llvm-project/pull/113930