[clang] [OpenMP] Prevent AMDGPU from overriding visibility on DT_nohost variables (PR #68264)

[Joseph Huber via cfe-commits]

https://github.com/jhuber6 created https://github.com/llvm/llvm-project/pull/68264

Summary:
There's some logic in the AMDGPU target that manually resets the
requested visibility of certain variables. This was triggering when we
set a constant variable in OpenMP. However, we shouldn't do this for
OpenMP when the variable has the `nohost` type. That implies that the
variable is not visible to the host and therefore does not need to be
visible, so we should respect the original value of it.


>From 52d11d0d975f03a3cd2760b42236b5ec8097331b Mon Sep 17 00:00:00 2001
From: Joseph Huber <jhuber6 at vols.utk.edu>
Date: Wed, 4 Oct 2023 16:50:20 -0500
Subject: [PATCH] [OpenMP] Prevent AMDGPU from overriding visibility on
 DT_nohost variables

Summary:
There's some logic in the AMDGPU target that manually resets the
requested visibility of certain variables. This was triggering when we
set a constant variable in OpenMP. However, we shouldn't do this for
OpenMP when the variable has the `nohost` type. That implies that the
variable is not visible to the host and therefore does not need to be
visible, so we should respect the original value of it.
---
 clang/lib/CodeGen/Targets/AMDGPU.cpp    | 4 ++++
 clang/test/OpenMP/target_visibility.cpp | 6 +++++-
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/clang/lib/CodeGen/Targets/AMDGPU.cpp b/clang/lib/CodeGen/Targets/AMDGPU.cpp
index dc628b7345f59fd..70f906a42e6d9c4 100644
--- a/clang/lib/CodeGen/Targets/AMDGPU.cpp
+++ b/clang/lib/CodeGen/Targets/AMDGPU.cpp
@@ -308,6 +308,10 @@ static bool requiresAMDGPUProtectedVisibility(const Decl *D,
   if (GV->getVisibility() != llvm::GlobalValue::HiddenVisibility)
     return false;
 
+  if (auto *Attr = D->getAttr<OMPDeclareTargetDeclAttr>())
+    if (OMPDeclareTargetDeclAttr::DT_NoHost == Attr->getDevType())
+      return false;
+
   return D->hasAttr<OpenCLKernelAttr>() ||
          (isa<FunctionDecl>(D) && D->hasAttr<CUDAGlobalAttr>()) ||
          (isa<VarDecl>(D) &&
diff --git a/clang/test/OpenMP/target_visibility.cpp b/clang/test/OpenMP/target_visibility.cpp
index 938d164df89bffb..2ed90d4b8ba9a77 100644
--- a/clang/test/OpenMP/target_visibility.cpp
+++ b/clang/test/OpenMP/target_visibility.cpp
@@ -1,5 +1,5 @@
 // RUN: %clang_cc1 -debug-info-kind=limited -verify -fopenmp -x c++ -triple nvptx64-unknown-unknown -fopenmp-targets=nvptx64-nvidia-cuda -emit-llvm %s -fopenmp-is-target-device -o - | FileCheck %s
-// RUN: %clang_cc1 -debug-info-kind=limited -verify -fopenmp -x c++ -triple nvptx-unknown-unknown -fopenmp-targets=nvptx-nvidia-cuda -emit-llvm %s -fopenmp-is-target-device -o - | FileCheck %s
+// RUN: %clang_cc1 -debug-info-kind=limited -verify -fopenmp -x c++ -triple amdgcn-amd-amdhsa -fopenmp-targets=amdgcn-amd-amdhsa -emit-llvm %s -fopenmp-is-target-device -o - | FileCheck %s
 // expected-no-diagnostics
 
 
@@ -21,6 +21,10 @@ void B::bar() { A a; a.foo(); }
 void B::sbar() { A::sfoo(); }
 #pragma omp declare target to(B::bar, B::sbar)
 
+[[gnu::visibility("hidden")]] extern const int x = 0;
+#pragma omp declare target to(x) device_type(nohost)
+
+// CHECK-DAG: @x = hidden{{.*}} constant i32 0
 // CHECK-DAG: define hidden void @_ZN1B4sbarEv()
 // CHECK-DAG: define linkonce_odr hidden void @_ZN1A4sfooEv()
 // CHECK-DAG: define hidden void @_ZN1B3barEv(