[HIP] Allow partial linking for -fgpu-rdc

clang/lib/CodeGen/CGCUDANV.cpp

@@ -760,10 +760,10 @@ llvm::Function *CGNVCUDARuntime::makeModuleCtorFunction() {
       // to contain the fat binary but will be populated somewhere else,
       // e.g. by lld through link script.
       FatBinStr = new llvm::GlobalVariable(
-        CGM.getModule(), CGM.Int8Ty,
-        /*isConstant=*/true, llvm::GlobalValue::ExternalLinkage, nullptr,
-        "__hip_fatbin", nullptr,
-        llvm::GlobalVariable::NotThreadLocal);
+          CGM.getModule(), CGM.Int8Ty,
+          /*isConstant=*/true, llvm::GlobalValue::ExternalLinkage, nullptr,
+          "__hip_fatbin_" + CGM.getContext().getCUIDHash(), nullptr,
+          llvm::GlobalVariable::NotThreadLocal);
       cast<llvm::GlobalVariable>(FatBinStr)->setSection(FatbinConstantName);
     }
 
@@ -816,8 +816,8 @@ llvm::Function *CGNVCUDARuntime::makeModuleCtorFunction() {
   // thread safety of the loaded program. Therefore we can assume sequential
   // execution of constructor functions here.
   if (IsHIP) {
-    auto Linkage = CudaGpuBinary ? llvm::GlobalValue::InternalLinkage :
-        llvm::GlobalValue::LinkOnceAnyLinkage;
+    auto Linkage = CudaGpuBinary ? llvm::GlobalValue::InternalLinkage
+                                 : llvm::GlobalValue::ExternalLinkage;
     llvm::BasicBlock *IfBlock =
         llvm::BasicBlock::Create(Context, "if", ModuleCtorFunc);
     llvm::BasicBlock *ExitBlock =
@@ -826,11 +826,11 @@ llvm::Function *CGNVCUDARuntime::makeModuleCtorFunction() {
     // of HIP ABI.
     GpuBinaryHandle = new llvm::GlobalVariable(
         TheModule, PtrTy, /*isConstant=*/false, Linkage,
-        /*Initializer=*/llvm::ConstantPointerNull::get(PtrTy),
-        "__hip_gpubin_handle");
-    if (Linkage == llvm::GlobalValue::LinkOnceAnyLinkage)
-      GpuBinaryHandle->setComdat(
-          CGM.getModule().getOrInsertComdat(GpuBinaryHandle->getName()));
+        /*Initializer=*/
+        CudaGpuBinary ? llvm::ConstantPointerNull::get(PtrTy) : nullptr,
+        CudaGpuBinary
+            ? "__hip_gpubin_handle"
+            : "__hip_gpubin_handle_" + CGM.getContext().getCUIDHash());
     GpuBinaryHandle->setAlignment(CGM.getPointerAlign().getAsAlign());
     // Prevent the weak symbol in different shared libraries being merged.
     if (Linkage != llvm::GlobalValue::InternalLinkage)

clang/lib/CodeGen/CodeGenModule.cpp

@@ -915,7 +915,15 @@ void CodeGenModule::Release() {
         llvm::ConstantArray::get(ATy, UsedArray), "__clang_gpu_used_external");
     addCompilerUsedGlobal(GV);
   }
-
+  if (LangOpts.HIP) {
+    // Emit a unique ID so that host and device binaries from the same
+    // compilation unit can be associated.
+    auto *GV = new llvm::GlobalVariable(
+        getModule(), Int8Ty, false, llvm::GlobalValue::ExternalLinkage,
+        llvm::Constant::getNullValue(Int8Ty),
+        "__hip_cuid_" + getContext().getCUIDHash());
+    addCompilerUsedGlobal(GV);
+  }
   emitLLVMUsed();
   if (SanStats)
     SanStats->finish();

clang/lib/Driver/OffloadBundler.cpp

@@ -588,8 +588,15 @@ class ObjectFileHandler final : public FileHandler {
     StringRef Content = *ContentOrErr;
 
     // Copy fat object contents to the output when extracting host bundle.
-    if (Content.size() == 1u && Content.front() == 0)
-      Content = StringRef(Input.getBufferStart(), Input.getBufferSize());
+    std::string ModifiedContent;
+    if (Content.size() == 1u && Content.front() == 0) {
+      auto HostBundleOrErr = getHostBundle();
+      if (!HostBundleOrErr)
+        return HostBundleOrErr.takeError();
+
+      ModifiedContent = std::move(*HostBundleOrErr);
+      Content = ModifiedContent;
+    }
 
     OS.write(Content.data(), Content.size());
     return Error::success();
@@ -692,6 +699,35 @@ class ObjectFileHandler final : public FileHandler {
     }
     return Error::success();
   }
+
+  Expected<std::string> getHostBundle() {
+    TempFileHandlerRAII TempFiles;
+
+    auto ModifiedObjPathOrErr = TempFiles.Create(std::nullopt);
+    if (!ModifiedObjPathOrErr)
+      return ModifiedObjPathOrErr.takeError();
+    StringRef ModifiedObjPath = *ModifiedObjPathOrErr;
+
+    BumpPtrAllocator Alloc;
+    StringSaver SS{Alloc};
+    SmallVector<StringRef, 16> ObjcopyArgs{"llvm-objcopy"};
+
+    ObjcopyArgs.push_back("--regex");
+    ObjcopyArgs.push_back("--remove-section=__CLANG_OFFLOAD_BUNDLE__.*");
+    ObjcopyArgs.push_back("--");
+    ObjcopyArgs.push_back(BundlerConfig.InputFileNames.front());
+    ObjcopyArgs.push_back(ModifiedObjPath);
+
+    if (Error Err = executeObjcopy(BundlerConfig.ObjcopyPath, ObjcopyArgs))
+      return std::move(Err);
+
+    auto BufOrErr = MemoryBuffer::getFile(ModifiedObjPath);
+    if (!BufOrErr)
+      return createStringError(BufOrErr.getError(),
+                               "Failed to read back the modified object file");
+
+    return BufOrErr->get()->getBuffer().str();
+  }
 };
 
 /// Handler for text files. The bundled file will have the following format.