[clang] [llvm] [clang][OpenMP][SPIR-V] Fix addrspace of globals and global constants (PR #134399)

[Nick Sarnie via llvm-commits]

================
@@ -5384,6 +5384,11 @@ LangAS CodeGenModule::GetGlobalVarAddressSpace(const VarDecl *D) {
     LangAS AS;
     if (OpenMPRuntime->hasAllocateAttributeForGlobalVar(D, AS))
       return AS;
+    if (LangOpts.OpenMPIsTargetDevice && getTriple().isSPIRV())
----------------
sarnex wrote:

Yep, I see the problem with the string even with pure `spirv64-unknown-unknown`. Repro:
```
extern int printf(const char*);
int main() {
    printf("foo");
return 0;
}
```
```
clang++ -cc1 -triple spirv64-unknown-unknown -emit-llvm test.cpp -o -
```
```
; ModuleID = 'test.cpp'
source_filename = "test.cpp"
target datalayout = "e-i64:64-v16:16-v24:32-v32:32-v48:64-v96:128-v192:256-v256:256-v512:512-v1024:1024-n8:16:32:64-G1"
target triple = "spirv64-unknown-unknown"

@.str = private unnamed_addr constant [4 x i8] c"foo\00", align 1

; Function Attrs: mustprogress noinline norecurse nounwind optnone
define noundef i32 @main() #0 {
entry:
  %retval = alloca i32, align 4
  store i32 0, ptr %retval, align 4
  %call = call spir_func noundef i32 @_Z6printfPKc(ptr noundef @.str)
  ret i32 0
}

declare spir_func noundef i32 @_Z6printfPKc(ptr noundef) #1

attributes #0 = { mustprogress noinline norecurse nounwind optnone "no-trapping-math"="true" "stack-protector-buffer-size"="8" }
attributes #1 = { "no-trapping-math"="true" "stack-protector-buffer-size"="8" }

!llvm.module.flags = !{!0}
!llvm.ident = !{!1}

!0 = !{i32 1, !"wchar_size", i32 4}
!1 = !{!"clang version 21.0.0git (https://github.com/llvm/llvm-project.git 06bfbba877c26630b6c5b0ffef7f6623aa2e9ee8)"}

```

[Here](https://github.com/llvm/llvm-project/blob/10bef367a5643bc41d0172b02e080645c68f821a/clang/lib/CodeGen/CodeGenModule.cpp#L6600C1-L6605C44)'s where we get the addrspace from:
```
 unsigned AddrSpace = CGM.getContext().getTargetAddressSpace(
      CGM.GetGlobalConstantAddressSpace());
```

In `GetGlobalConstantAddressSpace`, we [do](https://github.com/llvm/llvm-project/blob/10bef367a5643bc41d0172b02e080645c68f821a/clang/lib/CodeGen/CodeGenModule.cpp#L5391)
```
if (auto AS = getTarget().getConstantAddressSpace())
    return *AS;
```

and since there's no override for SPIR-V we just [get](https://github.com/llvm/llvm-project/blob/10bef367a5643bc41d0172b02e080645c68f821a/clang/include/clang/Basic/TargetInfo.h#L1670) the default:
```
 virtual std::optional<LangAS> getConstantAddressSpace() const {
    return LangAS::Default;
  }
```

If you see something wrong in this callstack let me know, I'm happy to fix it!



https://github.com/llvm/llvm-project/pull/134399