[OpenMP] Do not create offloading entries for internal or hidden symbols

[jhuber6]

Summary

Currently we create offloading entries to register device variables with
the host. When we register a variable we will look up the symbol in the
device image and map the device address to the host address. This is a
problem when the symbol is declared with hidden visibility or internal
linkage. This means the symbol is not accessible externally and we
cannot get its address. We should still allow static variables to be
declared on the device, but ew should not create an offloading entry for
them so they exist independently on the host and device.

Fixes #54309

[jhuber6]

Adding new test

[jdoerfert]

LG

[JonChesterfield]

Sounds good to me too, thanks!

clang/lib/CodeGen/CGOpenMPRuntime.cpp

if (const auto *CE =
               DiagnosticsEngine::Error,
               "Offloading entry for declare target variable is incorrect: the "
               "address is invalid.");
           CGM.getDiags().Report(DiagID);
           continue;
         }
         break;
       }
+
+      // Hidden or internal symbols on the device are not externally visible. We
+      // should not attempt to register them by creating an offloading entry.
+      if (auto *GV = dyn_cast<llvm::GlobalValue>(CE->getAddress()))
+        if (GV->hasLocalLinkage() || GV->hasHiddenVisibility())
+          continue;
+
       createOffloadEntry(CE->getAddress(), CE->getAddress(),
                          CE->getVarSize().getQuantity(), Flags,
                          CE->getLinkage());
     } else {
       llvm_unreachable("Unsupported entry kind.");
     }
   }
 }

clang/test/OpenMP/declare_target_visibility_codegen.cpp

+// RUN: %clang_cc1 -verify -fopenmp -fopenmp-version=45 -fopenmp-targets=powerpc64le-ibm-linux-gnu -x c++ -triple x86_64-unknown-unknown -emit-llvm %s -o - | FileCheck %s --check-prefix=HOST
+
+// expected-no-diagnostics
+class C {
+public:
+//.
+// HOST: @[[C:.+]] = internal global %class.C zeroinitializer, align 4
+// HOST: @[[X:.+]] = internal global i32 0, align 4
+// HOST: @y = hidden global i32 0
+// HOST: @z = global i32 0
+// HOST-NOT: @.omp_offloading.entry.c
+// HOST-NOT: @.omp_offloading.entry.x
+// HOST-NOT: @.omp_offloading.entry.y
+// HOST: @.omp_offloading.entry.z
+  C() : x(0) {}
+
+  int x;
+};
+
+static C c;
+#pragma omp declare target(c)
+
+static int x;
+#pragma omp declare target(x)
+
+int __attribute__((visibility("hidden"))) y;
+#pragma omp declare target(y)
+
+int z;
+#pragma omp declare target(z)

clang/test/OpenMP/nvptx_declare_target_var_ctor_dtor_codegen.cpp

 // DEVICE-DAG: call noundef i32 [[CAZ]]()
 // DEVICE-DAG: ret void
 
 // HOST-DAG: @[[CD_DTOR:__omp_offloading__.+_cd_l61_dtor]] = private constant i8 0
 // DEVICE-DAG: define internal void [[CD_DTOR:@__omp_offloading__.+_cd_l61_dtor]]()
 // DEVICE-DAG: call void
 // DEVICE-DAG: ret void
 
-// HOST-DAG: @.omp_offloading.entry_name{{.*}} = internal unnamed_addr constant [{{[0-9]+}} x i8] c"[[C_ADDR]]\00"
-// HOST-DAG: @.omp_offloading.entry.[[C_ADDR]] = weak{{.*}} constant %struct.__tgt_offload_entry { i8* bitcast (i32* @[[C_ADDR]] to i8*), i8* getelementptr inbounds ([{{[0-9]+}} x i8], [{{[0-9]+}} x i8]* @.omp_offloading.entry_name{{.*}}, i32 0, i32 0), i64 4, i32 0, i32 0 }, section "omp_offloading_entries", align 1
 // HOST-DAG: @.omp_offloading.entry_name{{.*}} = internal unnamed_addr constant [{{[0-9]+}} x i8] c"[[CD_ADDR]]\00"
 // HOST-DAG: @.omp_offloading.entry.[[CD_ADDR]] = weak{{.*}} constant %struct.__tgt_offload_entry { i8* bitcast (%struct.S* @[[CD_ADDR]] to i8*), i8* getelementptr inbounds ([{{[0-9]+}} x i8], [{{[0-9]+}} x i8]* @.omp_offloading.entry_name{{.*}}, i32 0, i32 0), i64 4, i32 0, i32 0 }, section "omp_offloading_entries", align 1
 // HOST-DAG: @.omp_offloading.entry_name{{.*}} = internal unnamed_addr constant [{{[0-9]+}} x i8] c"[[C_CTOR]]\00"
 // HOST-DAG: @.omp_offloading.entry.[[C_CTOR]] = weak{{.*}} constant %struct.__tgt_offload_entry { i8* @[[C_CTOR]], i8* getelementptr inbounds ([{{[0-9]+}} x i8], [{{[0-9]+}} x i8]* @.omp_offloading.entry_name{{.*}}, i32 0, i32 0), i64 0, i32 2, i32 0 }, section "omp_offloading_entries", align 1
 // HOST-DAG: @.omp_offloading.entry_name{{.*}}= internal unnamed_addr constant [{{[0-9]+}} x i8] c"[[CD_CTOR]]\00"
 // HOST-DAG: @.omp_offloading.entry.[[CD_CTOR]] = weak{{.*}} constant %struct.__tgt_offload_entry { i8* @[[CD_CTOR]], i8* getelementptr inbounds ([{{[0-9]+}} x i8], [{{[0-9]+}} x i8]* @.omp_offloading.entry_name{{.*}}, i32 0, i32 0), i64 0, i32 2, i32 0 }, section "omp_offloading_entries", align 1
 // HOST-DAG: @.omp_offloading.entry_name{{.*}}= internal unnamed_addr constant [{{[0-9]+}} x i8] c"[[CD_DTOR]]\00"
 // HOST-DAG: @.omp_offloading.entry.[[CD_DTOR]] = weak{{.*}} constant %struct.__tgt_offload_entry { i8* @[[CD_DTOR]], i8* getelementptr inbounds ([{{[0-9]+}} x i8], [{{[0-9]+}} x i8]* @.omp_offloading.entry_name{{.*}}, i32 0, i32 0), i64 0, i32 4, i32 0 }, section "omp_offloading_entries", align 1