[OpenMP] Do not link the bitcode OpenMP runtime when targeting AMDGPU.

[jhuber6]

Summary

The AMDGPU target can only emit LLVM-IR, so we can always rely on LTO to
link the static version of the runtime optimally. Using the static
library only has a few advantages. Namely, it avoids several known bugs
and allows us to optimize out more functions. This is legal since the
changes in D142486 and D142484

Depends on D142486 D142484

[jdoerfert]

LG, not linking in something seems fine if it works and the direction is what we always wanted.

[arsenm]

Well the library still doesn't 100% work unless using -mlink-builtin-bitcode. It's taking forever to make progress on fixing that

[jhuber6]

In D142491#4078400, @arsenm wrote:

Well the library still doesn't 100% work unless using -mlink-builtin-bitcode. It's taking forever to make progress on fixing that

This is the OpenMP DeviceRTL, the AMD one is still shoved into each TU via -mlink-builtin-bitcode. I'm still interested in addressing that however, my ultimate desire is for linking on the device to be sane and match the host pretty closely.

clang/lib/Driver/ToolChains/AMDGPUOpenMP.cpp

for (auto BCFile : getDeviceLibs(DriverArgs)) {
     CC1Args.push_back(BCFile.ShouldInternalize ? "-mlink-builtin-bitcode"
                                                : "-mlink-bitcode-file");
     CC1Args.push_back(DriverArgs.MakeArgString(BCFile.Path));
   }
 
   // Link the bitcode library late if we're using device LTO.
   if (getDriver().isUsingLTO(/* IsOffload */ true))
     return;
-
-  addOpenMPDeviceRTL(getDriver(), DriverArgs, CC1Args, GPUArch, getTriple());
 }
 
 llvm::opt::DerivedArgList *AMDGPUOpenMPToolChain::TranslateArgs(
     const llvm::opt::DerivedArgList &Args, StringRef BoundArch,
     Action::OffloadKind DeviceOffloadKind) const {
   DerivedArgList *DAL =
       HostTC.TranslateArgs(Args, BoundArch, DeviceOffloadKind);
   if (!DAL)

clang/test/Driver/amdgpu-openmp-toolchain.c

 // REQUIRES: x86-registered-target
 // REQUIRES: amdgpu-registered-target
 // RUN:   %clang -### --target=x86_64-unknown-linux-gnu -fopenmp -fopenmp-targets=amdgcn-amd-amdhsa \
 // RUN:          -Xopenmp-target=amdgcn-amd-amdhsa -march=gfx906 --libomptarget-amdgpu-bc-path=%S/Inputs/hip_dev_lib %s 2>&1 \
 // RUN:   | FileCheck %s
 // RUN:   %clang -### --target=x86_64-unknown-linux-gnu -fopenmp -fopenmp-targets=amdgcn-amd-amdhsa \
 // RUN:          --offload-arch=gfx906 --libomptarget-amdgpu-bc-path=%S/Inputs/hip_dev_lib %s 2>&1 \
 // RUN:   | FileCheck %s
 
 // verify the tools invocations
 // CHECK: "-cc1" "-triple" "x86_64-unknown-linux-gnu"{{.*}}"-emit-llvm-bc"{{.*}}"-x" "c"
-// CHECK: "-cc1" "-triple" "amdgcn-amd-amdhsa" "-aux-triple" "x86_64-unknown-linux-gnu"{{.*}}"-target-cpu" "gfx906"{{.*}}"-fcuda-is-device"{{.*}}"-mlink-builtin-bitcode" "{{.*}}libomptarget-amdgpu-gfx906.bc"
+// CHECK: "-cc1" "-triple" "amdgcn-amd-amdhsa" "-aux-triple" "x86_64-unknown-linux-gnu"{{.*}}"-target-cpu" "gfx906"{{.*}}"-fcuda-is-device"{{.*}}
 // CHECK: "-cc1" "-triple" "x86_64-unknown-linux-gnu"{{.*}}"-emit-obj"
 // CHECK: clang-linker-wrapper{{.*}}"--"{{.*}} "-o" "a.out"
 
 // RUN:   %clang -ccc-print-phases --target=x86_64-unknown-linux-gnu -fopenmp -fopenmp-targets=amdgcn-amd-amdhsa -Xopenmp-target=amdgcn-amd-amdhsa -march=gfx906 %s 2>&1 \
 // RUN:   | FileCheck --check-prefix=CHECK-PHASES %s
 // CHECK-PHASES: 0: input, "[[INPUT:.+]]", c, (host-openmp)
 // CHECK-PHASES: 1: preprocessor, {0}, cpp-output, (host-openmp)
 // CHECK-PHASES: 2: compiler, {1}, ir, (host-openmp)
 // CHECK-PHASES: 3: input, "[[INPUT]]", c, (device-openmp)
 // CHECK-PHASES: 4: preprocessor, {3}, cpp-output, (device-openmp)
 // CHECK-PHASES: 5: compiler, {4}, ir, (device-openmp)
 // CHECK-PHASES: 6: offload, "host-openmp (x86_64-unknown-linux-gnu)" {2}, "device-openmp (amdgcn-amd-amdhsa)" {5}, ir
 // CHECK-PHASES: 7: backend, {6}, ir, (device-openmp)
 // CHECK-PHASES: 8: offload, "device-openmp (amdgcn-amd-amdhsa)" {7}, ir
 // CHECK-PHASES: 9: clang-offload-packager, {8}, image, (device-openmp)
 // CHECK-PHASES: 10: offload, "host-openmp (x86_64-unknown-linux-gnu)" {2}, "device-openmp (x86_64-unknown-linux-gnu)" {9}, ir
 // CHECK-PHASES: 11: backend, {10}, assembler, (host-openmp)
 // CHECK-PHASES: 12: assembler, {11}, object, (host-openmp)
 // CHECK-PHASES: 13: clang-linker-wrapper, {12}, image, (host-openmp)
 
-// handling of --libomptarget-amdgpu-bc-path
-// RUN:   %clang -### --target=x86_64-unknown-linux-gnu -fopenmp -fopenmp-targets=amdgcn-amd-amdhsa -Xopenmp-target=amdgcn-amd-amdhsa -march=gfx803 --libomptarget-amdgpu-bc-path=%S/Inputs/hip_dev_lib/libomptarget-amdgpu-gfx803.bc %s 2>&1 | FileCheck %s --check-prefix=CHECK-LIBOMPTARGET
-// CHECK-LIBOMPTARGET: "-cc1" "-triple" "amdgcn-amd-amdhsa"{{.*}}"-target-cpu" "gfx803" "-fcuda-is-device" "-mlink-builtin-bitcode"{{.*}}Inputs/hip_dev_lib/libomptarget-amdgpu-gfx803.bc"{{.*}}
-
-// RUN:   %clang -### --target=x86_64-unknown-linux-gnu -fopenmp -fopenmp-targets=amdgcn-amd-amdhsa -Xopenmp-target=amdgcn-amd-amdhsa -march=gfx803 -nogpulib %s 2>&1 | FileCheck %s --check-prefix=CHECK-NOGPULIB
-// CHECK-NOGPULIB-NOT: "-cc1" "-triple" "amdgcn-amd-amdhsa"{{.*}}"-target-cpu" "gfx803" "-fcuda-is-device" "-mlink-builtin-bitcode"{{.*}}libomptarget-amdgpu-gfx803.bc"{{.*}}
-
 // RUN:   %clang -### --target=x86_64-unknown-linux-gnu -ccc-print-bindings -fopenmp -fopenmp-targets=amdgcn-amd-amdhsa -Xopenmp-target=amdgcn-amd-amdhsa -march=gfx803 -nogpulib %s 2>&1 | FileCheck %s --check-prefix=CHECK-BINDINGS
 // RUN:   %clang -### --target=x86_64-unknown-linux-gnu -ccc-print-bindings -fopenmp -fopenmp-targets=amdgcn-amd-amdhsa --offload-arch=gfx803 -nogpulib %s 2>&1 | FileCheck %s --check-prefix=CHECK-BINDINGS
 // CHECK-BINDINGS: "x86_64-unknown-linux-gnu" - "clang", inputs: ["[[INPUT:.+]]"], output: "[[HOST_BC:.+]]"
 // CHECK-BINDINGS: "amdgcn-amd-amdhsa" - "clang", inputs: ["[[INPUT]]", "[[HOST_BC]]"], output: "[[DEVICE_BC:.+]]"
 // CHECK-BINDINGS: "x86_64-unknown-linux-gnu" - "Offload::Packager", inputs: ["[[DEVICE_BC]]"], output: "[[BINARY:.+]]"
 // CHECK-BINDINGS: "x86_64-unknown-linux-gnu" - "clang", inputs: ["[[HOST_BC]]", "[[BINARY]]"], output: "[[HOST_OBJ:.+]]"
 // CHECK-BINDINGS: "x86_64-unknown-linux-gnu" - "Offload::Linker", inputs: ["[[HOST_OBJ]]"], output: "a.out"
 

openmp/libomptarget/test/lit.cfg

elif config.operating_system == 'Darwin':
     config.test_flags += " -Wl,-rpath," + config.omp_host_rtl_directory
 else: # Unices
     config.test_flags += " -Wl,-rpath," + config.library_dir
     config.test_flags += " -Wl,-rpath," + config.omp_host_rtl_directory
     config.test_flags += " -Wl,-rpath," + config.llvm_lib_directory
     if config.cuda_libdir:
         config.test_flags += " -Wl,-rpath," + config.cuda_libdir
     if config.libomptarget_current_target.startswith('amdgcn'):
-        config.test_flags += " --libomptarget-amdgcn-bc-path=" + config.library_dir
-    if config.libomptarget_current_target.startswith('nvptx'):
         config.test_flags += " --libomptarget-nvptx-bc-path=" + config.library_dir
     if config.libomptarget_current_target.endswith('-LTO'):
         config.test_flags += " -foffload-lto"
     if config.libomptarget_current_target.endswith('-JIT-LTO') and evaluate_bool_env(
         config.environment['LIBOMPTARGET_NEXTGEN_PLUGINS']
     ):
         config.test_flags += " -foffload-lto"
         config.test_flags += " -Wl,--embed-bitcode"