[clang] [llvm] [Offload][CUDA] Allow CUDA kernels to use LLVM/Offload (PR #94549)

via cfe-commits cfe-commits at lists.llvm.org
Wed Jun 5 17:27:07 PDT 2024


llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-backend-amdgpu

@llvm/pr-subscribers-clang

Author: Johannes Doerfert (jdoerfert)

<details>
<summary>Changes</summary>

Through the new `-foffload-via-llvm` flag, CUDA kernels can now be
lowered to the LLVM/Offload API. On the Clang side, this is simply done
by using the OpenMP offload toolchain and emitting calls to `llvm*`
functions to orchestrate the kernel launch rather than `cuda*`
functions. These `llvm*` functions are implemented on top of the
existing LLVM/Offload API.

As we are about to redefine the Offload API, this wil help us in the
design process as a second offload language.

We do not support any CUDA APIs yet, however, we could:
  https://www.osti.gov/servlets/purl/1892137

For proper host execution we need to resurrect/rebase
  https://tianshilei.me/wp-content/uploads/2021/12/llpp-2021.pdf
(which was designed for debugging).

```
❯❯❯ cat test.cu
extern "C" {
void *llvm_omp_target_alloc_shared(size_t Size, int DeviceNum);
void llvm_omp_target_free_shared(void *DevicePtr, int DeviceNum);
}

__global__ void square(int *A) { *A = 42; }

int main(int argc, char **argv) {
  int DevNo = 0;
  int *Ptr = reinterpret_cast<int *>(llvm_omp_target_alloc_shared(4, DevNo));
  *Ptr = 7;
  printf("Ptr %p, *Ptr %i\n", Ptr, *Ptr);
  square<<<1, 1>>>(Ptr);
  printf("Ptr %p, *Ptr %i\n", Ptr, *Ptr);
  llvm_omp_target_free_shared(Ptr, DevNo);
}

❯❯❯ clang++ test.cu -O3 -o test123 -foffload-via-llvm --offload-arch=native

❯❯❯ llvm-objdump --offloading test123

test123:        file format elf64-x86-64

OFFLOADING IMAGE [0]:
kind            elf
arch            gfx90a
triple          amdgcn-amd-amdhsa
producer        openmp

❯❯❯ LIBOMPTARGET_INFO=16 ./test123
Ptr 0x155448ac8000, *Ptr 7
Ptr 0x155448ac8000, *Ptr 42
```

---

Patch is 30.82 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/94549.diff


23 Files Affected:

- (modified) clang/include/clang/Basic/LangOptions.def (+1) 
- (modified) clang/include/clang/Driver/Options.td (+6) 
- (modified) clang/lib/CodeGen/CGCUDANV.cpp (+24-10) 
- (modified) clang/lib/Driver/Driver.cpp (+12-7) 
- (modified) clang/lib/Driver/ToolChains/Clang.cpp (+22-4) 
- (modified) clang/lib/Driver/ToolChains/CommonArgs.cpp (+6-1) 
- (modified) clang/lib/Headers/CMakeLists.txt (+3) 
- (modified) clang/lib/Headers/openmp_wrappers/__clang_openmp_device_functions.h (+2-4) 
- (added) clang/lib/Headers/openmp_wrappers/__llvm_offload.h (+31) 
- (added) clang/lib/Headers/openmp_wrappers/__llvm_offload_device.h (+10) 
- (added) clang/lib/Headers/openmp_wrappers/__llvm_offload_host.h (+15) 
- (modified) clang/lib/Sema/SemaCUDA.cpp (+3) 
- (added) clang/test/Driver/cuda-via-liboffload.cu (+23) 
- (modified) offload/include/Shared/APITypes.h (+19-14) 
- (modified) offload/include/omptarget.h (+1-1) 
- (modified) offload/plugins-nextgen/amdgpu/src/rtl.cpp (+11-1) 
- (modified) offload/plugins-nextgen/common/src/PluginInterface.cpp (+11-3) 
- (modified) offload/src/CMakeLists.txt (+1) 
- (added) offload/src/KernelLanguage/API.cpp (+76) 
- (modified) offload/src/exports (+3) 
- (added) offload/test/offloading/CUDA/basic_launch.cu (+29) 
- (added) offload/test/offloading/CUDA/basic_launch_blocks_and_threads.cu (+30) 
- (added) offload/test/offloading/CUDA/basic_launch_multi_arg.cu (+33) 


``````````diff
diff --git a/clang/include/clang/Basic/LangOptions.def b/clang/include/clang/Basic/LangOptions.def
index 4061451b2150a..8aff98867202e 100644
--- a/clang/include/clang/Basic/LangOptions.def
+++ b/clang/include/clang/Basic/LangOptions.def
@@ -288,6 +288,7 @@ LANGOPT(GPUMaxThreadsPerBlock, 32, 1024, "default max threads per block for kern
 LANGOPT(GPUDeferDiag, 1, 0, "defer host/device related diagnostic messages for CUDA/HIP")
 LANGOPT(GPUExcludeWrongSideOverloads, 1, 0, "always exclude wrong side overloads in overloading resolution for CUDA/HIP")
 LANGOPT(OffloadingNewDriver, 1, 0, "use the new driver for generating offloading code.")
+LANGOPT(OffloadViaLLVM, 1, 0, "target LLVM/Offload as portable offloading runtime.")
 
 LANGOPT(SYCLIsDevice      , 1, 0, "Generate code for SYCL device")
 LANGOPT(SYCLIsHost        , 1, 0, "SYCL host compilation")
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index 57f37c5023110..a09d75917ff98 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -1275,6 +1275,12 @@ def no_offload_compress : Flag<["--"], "no-offload-compress">;
 def offload_compression_level_EQ : Joined<["--"], "offload-compression-level=">,
   Flags<[HelpHidden]>,
   HelpText<"Compression level for offload device binaries (HIP only)">;
+
+defm offload_via_llvm : BoolFOption<"offload-via-llvm",
+  LangOpts<"OffloadViaLLVM">, DefaultFalse,
+  PosFlag<SetTrue, [], [ClangOption, CC1Option], "Use">,
+  NegFlag<SetFalse, [], [ClangOption], "Don't use">,
+  BothFlags<[], [ClangOption], " LLVM/Offload as portable offloading runtime.">>;
 }
 
 // CUDA options
diff --git a/clang/lib/CodeGen/CGCUDANV.cpp b/clang/lib/CodeGen/CGCUDANV.cpp
index 43dfbbb90dd52..acbc7e9e43635 100644
--- a/clang/lib/CodeGen/CGCUDANV.cpp
+++ b/clang/lib/CodeGen/CGCUDANV.cpp
@@ -19,6 +19,7 @@
 #include "clang/Basic/Cuda.h"
 #include "clang/CodeGen/CodeGenABITypes.h"
 #include "clang/CodeGen/ConstantInitBuilder.h"
+#include "llvm/ADT/StringRef.h"
 #include "llvm/Frontend/Offloading/Utility.h"
 #include "llvm/IR/BasicBlock.h"
 #include "llvm/IR/Constants.h"
@@ -36,6 +37,11 @@ constexpr unsigned HIPFatMagic = 0x48495046; // "HIPF"
 
 class CGNVCUDARuntime : public CGCUDARuntime {
 
+  /// The prefix used for function calls and section names (CUDA, HIP, LLVM)
+  StringRef Prefix;
+  /// TODO: We should transition the OpenMP section to LLVM/Offload
+  StringRef SectionPrefix;
+
 private:
   llvm::IntegerType *IntTy, *SizeTy;
   llvm::Type *VoidTy;
@@ -191,15 +197,11 @@ class CGNVCUDARuntime : public CGCUDARuntime {
 } // end anonymous namespace
 
 std::string CGNVCUDARuntime::addPrefixToName(StringRef FuncName) const {
-  if (CGM.getLangOpts().HIP)
-    return ((Twine("hip") + Twine(FuncName)).str());
-  return ((Twine("cuda") + Twine(FuncName)).str());
+  return (Prefix + FuncName).str();
 }
 std::string
 CGNVCUDARuntime::addUnderscoredPrefixToName(StringRef FuncName) const {
-  if (CGM.getLangOpts().HIP)
-    return ((Twine("__hip") + Twine(FuncName)).str());
-  return ((Twine("__cuda") + Twine(FuncName)).str());
+  return ("__" + Prefix + FuncName).str();
 }
 
 static std::unique_ptr<MangleContext> InitDeviceMC(CodeGenModule &CGM) {
@@ -227,6 +229,14 @@ CGNVCUDARuntime::CGNVCUDARuntime(CodeGenModule &CGM)
   SizeTy = CGM.SizeTy;
   VoidTy = CGM.VoidTy;
   PtrTy = CGM.UnqualPtrTy;
+
+  if (CGM.getLangOpts().OffloadViaLLVM) {
+    Prefix = "llvm";
+    SectionPrefix = "omp";
+  } else if (CGM.getLangOpts().HIP)
+    SectionPrefix = Prefix = "hip";
+  else
+    SectionPrefix = Prefix = "cuda";
 }
 
 llvm::FunctionCallee CGNVCUDARuntime::getSetupArgumentFn() const {
@@ -305,7 +315,8 @@ void CGNVCUDARuntime::emitDeviceStub(CodeGenFunction &CGF,
   }
   if (CudaFeatureEnabled(CGM.getTarget().getSDKVersion(),
                          CudaFeature::CUDA_USES_NEW_LAUNCH) ||
-      (CGF.getLangOpts().HIP && CGF.getLangOpts().HIPUseNewLaunchAPI))
+      (CGF.getLangOpts().HIP && CGF.getLangOpts().HIPUseNewLaunchAPI) ||
+      (CGF.getLangOpts().OffloadViaLLVM))
     emitDeviceStubBodyNew(CGF, Args);
   else
     emitDeviceStubBodyLegacy(CGF, Args);
@@ -1129,8 +1140,9 @@ void CGNVCUDARuntime::transformManagedVars() {
 // registered. The linker will provide a pointer to this section so we can
 // register the symbols with the linked device image.
 void CGNVCUDARuntime::createOffloadingEntries() {
-  StringRef Section = CGM.getLangOpts().HIP ? "hip_offloading_entries"
-                                            : "cuda_offloading_entries";
+  SmallVector<char, 32> Out;
+  StringRef Section = (SectionPrefix + "_offloading_entries").toStringRef(Out);
+
   llvm::Module &M = CGM.getModule();
   for (KernelInfo &I : EmittedKernels)
     llvm::offloading::emitOffloadingEntry(
@@ -1199,7 +1211,9 @@ llvm::Function *CGNVCUDARuntime::finalizeModule() {
     }
     return nullptr;
   }
-  if (CGM.getLangOpts().OffloadingNewDriver && RelocatableDeviceCode)
+  if (CGM.getLangOpts().OffloadViaLLVM)
+    createOffloadingEntries();
+  else if (CGM.getLangOpts().OffloadingNewDriver && RelocatableDeviceCode)
     createOffloadingEntries();
   else
     return makeModuleCtorFunction();
diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
index f5ea73a04ae5c..815149a49d018 100644
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -792,11 +792,13 @@ void Driver::CreateOffloadingDeviceToolChains(Compilation &C,
                    }) ||
       C.getInputArgs().hasArg(options::OPT_hip_link) ||
       C.getInputArgs().hasArg(options::OPT_hipstdpar);
+  bool UseLLVMOffload = C.getInputArgs().hasArg(
+      options::OPT_foffload_via_llvm, options::OPT_fno_offload_via_llvm, false);
   if (IsCuda && IsHIP) {
     Diag(clang::diag::err_drv_mix_cuda_hip);
     return;
   }
-  if (IsCuda) {
+  if (IsCuda && !UseLLVMOffload) {
     const ToolChain *HostTC = C.getSingleOffloadToolChain<Action::OFK_Host>();
     const llvm::Triple &HostTriple = HostTC->getTriple();
     auto OFK = Action::OFK_Cuda;
@@ -818,7 +820,7 @@ void Driver::CreateOffloadingDeviceToolChains(Compilation &C,
         CudaInstallation.WarnIfUnsupportedVersion();
     }
     C.addOffloadDeviceToolChain(CudaTC.get(), OFK);
-  } else if (IsHIP) {
+  } else if (IsHIP && !UseLLVMOffload) {
     if (auto *OMPTargetArg =
             C.getInputArgs().getLastArg(options::OPT_fopenmp_targets_EQ)) {
       Diag(clang::diag::err_drv_unsupported_opt_for_language_mode)
@@ -842,10 +844,11 @@ void Driver::CreateOffloadingDeviceToolChains(Compilation &C,
   // We need to generate an OpenMP toolchain if the user specified targets with
   // the -fopenmp-targets option or used --offload-arch with OpenMP enabled.
   bool IsOpenMPOffloading =
-      C.getInputArgs().hasFlag(options::OPT_fopenmp, options::OPT_fopenmp_EQ,
-                               options::OPT_fno_openmp, false) &&
-      (C.getInputArgs().hasArg(options::OPT_fopenmp_targets_EQ) ||
-       C.getInputArgs().hasArg(options::OPT_offload_arch_EQ));
+      ((IsCuda || IsHIP) && UseLLVMOffload) ||
+      (C.getInputArgs().hasFlag(options::OPT_fopenmp, options::OPT_fopenmp_EQ,
+                                options::OPT_fno_openmp, false) &&
+       (C.getInputArgs().hasArg(options::OPT_fopenmp_targets_EQ) ||
+        C.getInputArgs().hasArg(options::OPT_offload_arch_EQ)));
   if (IsOpenMPOffloading) {
     // We expect that -fopenmp-targets is always used in conjunction with the
     // option -fopenmp specifying a valid runtime with offloading support, i.e.
@@ -873,7 +876,7 @@ void Driver::CreateOffloadingDeviceToolChains(Compilation &C,
       for (StringRef T : OpenMPTargets->getValues())
         OpenMPTriples.insert(T);
     } else if (C.getInputArgs().hasArg(options::OPT_offload_arch_EQ) &&
-               !IsHIP && !IsCuda) {
+               ((!IsHIP && !IsCuda) || UseLLVMOffload)) {
       const ToolChain *HostTC = C.getSingleOffloadToolChain<Action::OFK_Host>();
       auto AMDTriple = getHIPOffloadTargetTriple(*this, C.getInputArgs());
       auto NVPTXTriple = getNVIDIAOffloadTargetTriple(*this, C.getInputArgs(),
@@ -4138,6 +4141,8 @@ void Driver::BuildActions(Compilation &C, DerivedArgList &Args,
 
   bool UseNewOffloadingDriver =
       C.isOffloadingHostKind(Action::OFK_OpenMP) ||
+      Args.hasFlag(options::OPT_foffload_via_llvm,
+                   options::OPT_fno_offload_via_llvm, false) ||
       Args.hasFlag(options::OPT_offload_new_driver,
                    options::OPT_no_offload_new_driver, false);
 
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index 4e1c52462e584..07b7e60caa2b4 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -1125,6 +1125,18 @@ void Clang::AddPreprocessingOptions(Compilation &C, const JobAction &JA,
     CmdArgs.push_back("__clang_openmp_device_functions.h");
   }
 
+  if (Args.hasArg(options::OPT_foffload_via_llvm)) {
+    CmdArgs.push_back("-include");
+    SmallString<128> P(D.ResourceDir);
+    llvm::sys::path::append(P, "include");
+    llvm::sys::path::append(P, "openmp_wrappers");
+    if (JA.isDeviceOffloading(Action::OFK_OpenMP))
+      llvm::sys::path::append(P, "__llvm_offload_device.h");
+    else
+      llvm::sys::path::append(P, "__llvm_offload_host.h");
+    CmdArgs.push_back(Args.MakeArgString(P));
+  }
+
   // Add -i* options, and automatically translate to
   // -include-pch/-include-pth for transparent PCH support. It's
   // wonky, but we include looking for .gch so we can support seamless
@@ -6672,11 +6684,17 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
     Args.addOptOutFlag(CmdArgs, options::OPT_fopenmp_extensions,
                        options::OPT_fno_openmp_extensions);
   }
-
-  // Forward the new driver to change offloading code generation.
-  if (Args.hasFlag(options::OPT_offload_new_driver,
-                   options::OPT_no_offload_new_driver, false))
+  // Forward the offload runtime change to code generation, liboffload implies
+  // new driver. Otherwise, check if we should forward the new driver to change
+  // offloading code generation.
+  if (Args.hasFlag(options::OPT_foffload_via_llvm,
+                   options::OPT_fno_offload_via_llvm, false)) {
+    CmdArgs.push_back("--offload-new-driver");
+    CmdArgs.push_back("-foffload-via-llvm");
+  } else if (Args.hasFlag(options::OPT_offload_new_driver,
+                          options::OPT_no_offload_new_driver, false)) {
     CmdArgs.push_back("--offload-new-driver");
+  }
 
   SanitizeArgs.addArgs(TC, Args, CmdArgs, InputType);
 
diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 71e993119436a..74a69f65f7ad5 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -1144,8 +1144,13 @@ bool tools::addOpenMPRuntime(const Compilation &C, ArgStringList &CmdArgs,
                              bool ForceStaticHostRuntime, bool IsOffloadingHost,
                              bool GompNeedsRT) {
   if (!Args.hasFlag(options::OPT_fopenmp, options::OPT_fopenmp_EQ,
-                    options::OPT_fno_openmp, false))
+                    options::OPT_fno_openmp, false)) {
+    // We need libomptarget (liboffload) if it's the choosen offloading runtime.
+    if (Args.hasFlag(options::OPT_foffload_via_llvm,
+                     options::OPT_fno_offload_via_llvm, false))
+      CmdArgs.push_back("-lomptarget");
     return false;
+  }
 
   Driver::OpenMPRuntimeKind RTKind = TC.getDriver().getOpenMPRuntime(Args);
 
diff --git a/clang/lib/Headers/CMakeLists.txt b/clang/lib/Headers/CMakeLists.txt
index d3090e488306f..215dfe207c228 100644
--- a/clang/lib/Headers/CMakeLists.txt
+++ b/clang/lib/Headers/CMakeLists.txt
@@ -323,6 +323,9 @@ set(openmp_wrapper_files
   openmp_wrappers/__clang_openmp_device_functions.h
   openmp_wrappers/complex_cmath.h
   openmp_wrappers/new
+  openmp_wrappers/__llvm_offload.h
+  openmp_wrappers/__llvm_offload_host.h
+  openmp_wrappers/__llvm_offload_device.h
 )
 
 set(llvm_libc_wrapper_files
diff --git a/clang/lib/Headers/openmp_wrappers/__clang_openmp_device_functions.h b/clang/lib/Headers/openmp_wrappers/__clang_openmp_device_functions.h
index d5b6846b03488..889d607557ecb 100644
--- a/clang/lib/Headers/openmp_wrappers/__clang_openmp_device_functions.h
+++ b/clang/lib/Headers/openmp_wrappers/__clang_openmp_device_functions.h
@@ -10,14 +10,11 @@
 #ifndef __CLANG_OPENMP_DEVICE_FUNCTIONS_H__
 #define __CLANG_OPENMP_DEVICE_FUNCTIONS_H__
 
-#ifndef _OPENMP
-#error "This file is for OpenMP compilation only."
-#endif
-
 #ifdef __cplusplus
 extern "C" {
 #endif
 
+#ifdef __NVPTX__
 #pragma omp begin declare variant match(                                       \
     device = {arch(nvptx, nvptx64)}, implementation = {extension(match_any)})
 
@@ -34,6 +31,7 @@ extern "C" {
 #undef __CUDA__
 
 #pragma omp end declare variant
+#endif
 
 #ifdef __AMDGCN__
 #pragma omp begin declare variant match(device = {arch(amdgcn)})
diff --git a/clang/lib/Headers/openmp_wrappers/__llvm_offload.h b/clang/lib/Headers/openmp_wrappers/__llvm_offload.h
new file mode 100644
index 0000000000000..d78e3b41f99a5
--- /dev/null
+++ b/clang/lib/Headers/openmp_wrappers/__llvm_offload.h
@@ -0,0 +1,31 @@
+/*===------ LLVM/Offload helpers for kernel languages (CUDA/HIP) -*- c++ -*-===
+ *
+ * Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+ * See https://llvm.org/LICENSE.txt for license information.
+ * SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+ *
+ *===-----------------------------------------------------------------------===
+ */
+
+#include <stdlib.h>
+
+#define __host__ __attribute__((host))
+#define __device__ __attribute__((device))
+#define __global__ __attribute__((global))
+#define __shared__ __attribute__((shared))
+#define __constant__ __attribute__((constant))
+#define __managed__ __attribute__((managed))
+
+extern "C" {
+
+typedef struct dim3 {
+  dim3() {}
+  dim3(unsigned x) : x(x) {}
+  unsigned x = 0, y = 0, z = 0;
+} dim3;
+
+// TODO: For some reason the CUDA device compilation requires this declaration
+// to be present but it should not.
+unsigned __llvmPushCallConfiguration(dim3 gridDim, dim3 blockDim,
+                                     size_t sharedMem = 0, void *stream = 0);
+}
diff --git a/clang/lib/Headers/openmp_wrappers/__llvm_offload_device.h b/clang/lib/Headers/openmp_wrappers/__llvm_offload_device.h
new file mode 100644
index 0000000000000..1a813b331515b
--- /dev/null
+++ b/clang/lib/Headers/openmp_wrappers/__llvm_offload_device.h
@@ -0,0 +1,10 @@
+/*===------ LLVM/Offload helpers for kernel languages (CUDA/HIP) -*- c++ -*-===
+ *
+ * Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+ * See https://llvm.org/LICENSE.txt for license information.
+ * SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+ *
+ *===-----------------------------------------------------------------------===
+ */
+
+#include "__llvm_offload.h"
diff --git a/clang/lib/Headers/openmp_wrappers/__llvm_offload_host.h b/clang/lib/Headers/openmp_wrappers/__llvm_offload_host.h
new file mode 100644
index 0000000000000..160289d169b55
--- /dev/null
+++ b/clang/lib/Headers/openmp_wrappers/__llvm_offload_host.h
@@ -0,0 +1,15 @@
+/*===------ LLVM/Offload helpers for kernel languages (CUDA/HIP) -*- c++ -*-===
+ *
+ * Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+ * See https://llvm.org/LICENSE.txt for license information.
+ * SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+ *
+ *===-----------------------------------------------------------------------===
+ */
+
+#include "__llvm_offload.h"
+
+extern "C" {
+unsigned llvmLaunchKernel(const void *func, dim3 gridDim, dim3 blockDim,
+                          void **args, size_t sharedMem = 0, void *stream = 0);
+}
diff --git a/clang/lib/Sema/SemaCUDA.cpp b/clang/lib/Sema/SemaCUDA.cpp
index 80ea43dc5316e..b507e19556363 100644
--- a/clang/lib/Sema/SemaCUDA.cpp
+++ b/clang/lib/Sema/SemaCUDA.cpp
@@ -1059,6 +1059,9 @@ void SemaCUDA::inheritTargetAttrs(FunctionDecl *FD,
 }
 
 std::string SemaCUDA::getConfigureFuncName() const {
+  if (getLangOpts().OffloadViaLLVM)
+    return "__llvmPushCallConfiguration";
+
   if (getLangOpts().HIP)
     return getLangOpts().HIPUseNewLaunchAPI ? "__hipPushCallConfiguration"
                                             : "hipConfigureCall";
diff --git a/clang/test/Driver/cuda-via-liboffload.cu b/clang/test/Driver/cuda-via-liboffload.cu
new file mode 100644
index 0000000000000..68dc963e906b2
--- /dev/null
+++ b/clang/test/Driver/cuda-via-liboffload.cu
@@ -0,0 +1,23 @@
+// RUN: %clang -### -target x86_64-linux-gnu -foffload-via-llvm -ccc-print-bindings \
+// RUN:        --offload-arch=sm_35 --offload-arch=sm_70 %s 2>&1 \
+// RUN: | FileCheck -check-prefix BINDINGS %s
+
+//      BINDINGS: "x86_64-unknown-linux-gnu" - "clang", inputs: ["[[INPUT:.+]]"], output: "[[HOST_BC:.+]]"
+// BINDINGS-NEXT: "nvptx64-nvidia-cuda" - "clang", inputs: ["[[INPUT]]", "[[HOST_BC]]"], output: "[[PTX_SM_35:.+]]"
+// BINDINGS-NEXT: "nvptx64-nvidia-cuda" - "NVPTX::Assembler", inputs: ["[[PTX_SM_35]]"], output: "[[CUBIN_SM_35:.+]]"
+// BINDINGS-NEXT: "nvptx64-nvidia-cuda" - "clang", inputs: ["[[INPUT]]", "[[HOST_BC]]"], output: "[[PTX_SM_70:.+]]"
+// BINDINGS-NEXT: "nvptx64-nvidia-cuda" - "NVPTX::Assembler", inputs: ["[[PTX_SM_70:.+]]"], output: "[[CUBIN_SM_70:.+]]"
+// BINDINGS-NEXT: "x86_64-unknown-linux-gnu" - "Offload::Packager", inputs: ["[[CUBIN_SM_35]]", "[[CUBIN_SM_70]]"], output: "[[BINARY:.+]]"
+// BINDINGS-NEXT: "x86_64-unknown-linux-gnu" - "clang", inputs: ["[[HOST_BC]]", "[[BINARY]]"], output: "[[HOST_OBJ:.+]]"
+// BINDINGS-NEXT: "x86_64-unknown-linux-gnu" - "Offload::Linker", inputs: ["[[HOST_OBJ]]"], output: "a.out"
+
+// RUN: %clang -### -target x86_64-linux-gnu -foffload-via-llvm -ccc-print-bindings \
+// RUN:        --offload-arch=sm_35 --offload-arch=sm_70 %s 2>&1 \
+// RUN: | FileCheck -check-prefix BINDINGS-DEVICE %s
+
+// BINDINGS-DEVICE: # "nvptx64-nvidia-cuda" - "clang", inputs: ["[[INPUT:.+]]"], output: "[[PTX:.+]]"
+// BINDINGS-DEVICE: # "nvptx64-nvidia-cuda" - "NVPTX::Assembler", inputs: ["[[PTX]]"], output: "[[CUBIN:.+]]"
+
+// RUN: %clang -### -target x86_64-linux-gnu -ccc-print-bindings --offload-link -foffload-via-llvm %s 2>&1 | FileCheck -check-prefix DEVICE-LINK %s
+
+// DEVICE-LINK: "x86_64-unknown-linux-gnu" - "Offload::Linker", inputs: ["[[INPUT:.+]]"], output: "a.out"
diff --git a/offload/include/Shared/APITypes.h b/offload/include/Shared/APITypes.h
index e8fc27785b6c2..2c41a6e2ba43c 100644
--- a/offload/include/Shared/APITypes.h
+++ b/offload/include/Shared/APITypes.h
@@ -89,22 +89,27 @@ struct __tgt_async_info {
 
 /// This struct contains all of the arguments to a target kernel region launch.
 struct KernelArgsTy {
-  uint32_t Version;   // Version of this struct for ABI compatibility.
-  uint32_t NumArgs;   // Number of arguments in each input pointer.
-  void **ArgBasePtrs; // Base pointer of each argument (e.g. a struct).
-  void **ArgPtrs;     // Pointer to the argument data.
-  int64_t *ArgSizes;  // Size of the argument data in bytes.
-  int64_t *ArgTypes;  // Type of the data (e.g. to / from).
-  void **ArgNames;    // Name of the data for debugging, possibly null.
-  void **ArgMappers;  // User-defined mappers, possibly null.
-  uint64_t Tripcount; // Tripcount for the teams / distribute loop, 0 otherwise.
+  uint32_t Version = 0; // Version of this struct for ABI compatibility.
+  uint32_t NumArgs = 0; // Number of arguments in each input pointer.
+  void **ArgBasePtrs =
+      nullptr;                 // Base pointer of each argument (e.g. a struct).
+  void **ArgPtrs = nullptr;    // Pointer to the argument data.
+  int64_t *ArgSizes = nullptr; // Size of the argument data in bytes.
+  int64_t *ArgTypes = nullptr; // Type of the data (e.g. to / from).
+  void **ArgNames = nullptr;   // Name of the data for debugging, possibly null.
+  void **ArgMappers = nullptr; // User-defined mappers, possibly null.
+  uint64_t Tripcount =
+      0; // Tripcount for the teams / distribute loop, 0 otherwise.
   struct {
     uint64_t NoWait : 1; // Was this kernel spawned with a `nowait` clause.
-    uint64_t Unused : 63;
-  } Flags;
-  uint32_t NumTeams[3];    // The number of teams (for x,y,z dimension).
-  ...
[truncated]

``````````

</details>


https://github.com/llvm/llvm-project/pull/94549


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