[clang] [SPIR-V] Add hlsl_private address space for HLSL/SPIR-V (PR #122103)

[Nathan Gauër via cfe-commits]

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@@ -83,6 +84,7 @@ const LangASMap AMDGPUTargetInfo::AMDGPUDefIsPrivMap = {
     llvm::AMDGPUAS::FLAT_ADDRESS, // ptr32_uptr
     llvm::AMDGPUAS::FLAT_ADDRESS, // ptr64
     llvm::AMDGPUAS::FLAT_ADDRESS, // hlsl_groupshared
+    llvm::AMDGPUAS::FLAT_ADDRESS, // hlsl_private
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Keenuts wrote:

HLSL documentation for those is currently this: https://learn.microsoft.com/en-us/windows/win32/direct3dhlsl/dx-graphics-hlsl-variable-syntax

FXC/DXC implementation of a `static int my_global` would be equivalent to a c++ `static thread_local int my_global`. Initialized once, thread local.

If this is not available in AMDGPU yet, what value shall be picked?

https://github.com/llvm/llvm-project/pull/122103