[clang] [OpenMP] Remove NVPTX local addrspace on parameters (PR #183195)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang-codegen

Author: Jameson Nash (vtjnash)

<details>
<summary>Changes</summary>

In CGOpenMPRuntimeGPU::translateParameter, reference-type captured variables were translated to pointer parameters with two address-space annotations:

1. LangAS::opencl_global on the pointee (for map'd variables), which correctly produces ptr addrspace(1) in NVPTX IR.
2. getLangASFromTargetAS(NVPTX_local_addr=5) on the pointer itself, annotating the parameter as living in NVPTX local (stack) memory.

The second annotation is incorrect at the Clang type-system level: EmitParmDecl only supports parameters to be in LangAS::Default (or the special cases for OpenCL).

Temporarily add an assert in EmitParmDecl that catches parameters with non-default address spaces in non-OpenCL compilations, and fix the violation by dropping the NVPTX_local_addr addAddressSpace call.

Should fix the issue noticed in
https://github.com/llvm/llvm-project/pull/181256#discussion_r2821894122, allowing removing the special case there for OpenMP, though I haven't tested the combination yet. That PR will fix EmitParmDecl to actually support non-default address spaces from Sema, and will remove this assert again.

---
Full diff: https://github.com/llvm/llvm-project/pull/183195.diff


2 Files Affected:

- (modified) clang/lib/CodeGen/CGDecl.cpp (+2) 
- (modified) clang/lib/CodeGen/CGOpenMPRuntimeGPU.cpp (-2) 


``````````diff
diff --git a/clang/lib/CodeGen/CGDecl.cpp b/clang/lib/CodeGen/CGDecl.cpp
index a7bd2f0470cc0..8b5ffde1b73f3 100644
--- a/clang/lib/CodeGen/CGDecl.cpp
+++ b/clang/lib/CodeGen/CGDecl.cpp
@@ -2685,6 +2685,8 @@ void CodeGenFunction::EmitParmDecl(const VarDecl &D, ParamValue Arg,
     Arg.getAnyValue()->setName(D.getName());
 
   QualType Ty = D.getType();
+  assert((getLangOpts().OpenCL || Ty.getAddressSpace() == LangAS::Default) &&
+         "parameter has non-default address space in non-OpenCL mode");
 
   // Use better IR generation for certain implicit parameters.
   if (auto IPD = dyn_cast<ImplicitParamDecl>(&D)) {
diff --git a/clang/lib/CodeGen/CGOpenMPRuntimeGPU.cpp b/clang/lib/CodeGen/CGOpenMPRuntimeGPU.cpp
index 0d7714ecbcc76..61f7470acb117 100644
--- a/clang/lib/CodeGen/CGOpenMPRuntimeGPU.cpp
+++ b/clang/lib/CodeGen/CGOpenMPRuntimeGPU.cpp
@@ -1816,8 +1816,6 @@ CGOpenMPRuntimeGPU::translateParameter(const FieldDecl *FD,
   }
   ArgType = CGM.getContext().getPointerType(PointeeTy);
   QC.addRestrict();
-  enum { NVPTX_local_addr = 5 };
-  QC.addAddressSpace(getLangASFromTargetAS(NVPTX_local_addr));
   ArgType = QC.apply(CGM.getContext(), ArgType);
   if (isa<ImplicitParamDecl>(NativeParam))
     return ImplicitParamDecl::Create(

``````````

</details>


https://github.com/llvm/llvm-project/pull/183195