[HIPSPV] Add in-tree SPIR-V backend support for chipStar

[pvelesko]

Summary

chipStar (https://github.com/CHIP-SPV/chipStar) enables HIP/CUDA programs to run on OpenCL and Level Zero devices via SPIR-V. Until now, the HIPSPV toolchain relied exclusively on the external llvm-spirv translator for bitcode-to-SPIR-V conversion.

This patch adds native in-tree SPIR-V backend support for chipStar targets (spirv64*-unknown-chipstar), removing the hard dependency on llvm-spirv.

Changes

HIPSPV old driver (HIPSPV.cpp):

• chipStar targets now use opt (HipSpvPasses) + clang -c (SPIR-V backend) instead of opt + llvm-spirv
• Non-chipStar HIPSPV targets continue using llvm-spirv unchanged
• Remove HostTC->addClangTargetOptions() delegation to avoid macOS Darwin flags (-faligned-alloc-unavailable) breaking SPIR-V device compilation

New offload driver (ClangLinkerWrapper.cpp):

• Add chipStar SPIR-V pipeline: llvm-link → opt (HipSpvPasses) → clang -c --target=spirv64 with SPIR-V extensions
• Extract --hip-path from --device-compiler= args for locating the HipSpvPasses plugin and device libraries
• Fall back to llvm-spirv translator when available for non-chipStar SPIR-V targets

SPIR-V toolchain (SPIRV.cpp):

• Enable NativeLLVMSupport for chipStar triples so the toolchain does not require an external translator

SPIR-V backend (SPIRVSubtarget.cpp):

• Set Kernel environment for chipStar triples (needed for OpenCL kernel ABI)

AlignedAllocation.h:

• Add ChipStar case to avoid unhandled enum warning

Test plan

• hipspv-toolchain.hip driver test updated to verify the new in-tree backend pipeline
• chipStar test suite: 1173/1173 tests pass (100%) on the translator path; 1169/1173 (99.7%) on the native in-tree backend (4 remaining printf failures due to upstream ExpandVariadics regression in LLVM 23)

[llvmbot]

@llvm/pr-subscribers-clang-driver

Author: Paulius Velesko (pvelesko)

Changes

Summary

chipStar (https://github.com/CHIP-SPV/chipStar) enables HIP/CUDA programs to run on OpenCL and Level Zero devices via SPIR-V. Until now, the HIPSPV toolchain relied exclusively on the external llvm-spirv translator for bitcode-to-SPIR-V conversion.

This patch adds native in-tree SPIR-V backend support for chipStar targets (spirv64*-unknown-chipstar), removing the hard dependency on llvm-spirv.

Changes

HIPSPV old driver (HIPSPV.cpp):

• chipStar targets now use opt (HipSpvPasses) + clang -c (SPIR-V backend) instead of opt + llvm-spirv
• Non-chipStar HIPSPV targets continue using llvm-spirv unchanged
• Remove HostTC->addClangTargetOptions() delegation to avoid macOS Darwin flags (-faligned-alloc-unavailable) breaking SPIR-V device compilation

New offload driver (ClangLinkerWrapper.cpp):

• Add chipStar SPIR-V pipeline: llvm-link → opt (HipSpvPasses) → clang -c --target=spirv64 with SPIR-V extensions
• Extract --hip-path from --device-compiler= args for locating the HipSpvPasses plugin and device libraries
• Fall back to llvm-spirv translator when available for non-chipStar SPIR-V targets

SPIR-V toolchain (SPIRV.cpp):

• Enable NativeLLVMSupport for chipStar triples so the toolchain does not require an external translator

SPIR-V backend (SPIRVSubtarget.cpp):

• Set Kernel environment for chipStar triples (needed for OpenCL kernel ABI)

AlignedAllocation.h:

• Add ChipStar case to avoid unhandled enum warning

Test plan

• hipspv-toolchain.hip driver test updated to verify the new in-tree backend pipeline
• chipStar test suite: 1173/1173 tests pass (100%) on the translator path; 1169/1173 (99.7%) on the native in-tree backend (4 remaining printf failures due to upstream ExpandVariadics regression in LLVM 23)

---

Patch is 21.95 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/186972.diff

6 Files Affected:

• (modified) clang/include/clang/Basic/AlignedAllocation.h (+2)
• (modified) clang/lib/Driver/ToolChains/HIPSPV.cpp (+58-25)
• (modified) clang/lib/Driver/ToolChains/SPIRV.cpp (+2-1)
• (modified) clang/test/Driver/hipspv-toolchain.hip (+43-13)
• (modified) clang/tools/clang-linker-wrapper/ClangLinkerWrapper.cpp (+194-5)
• (modified) llvm/lib/Target/SPIRV/SPIRVSubtarget.cpp (+2-1)

diff --git a/clang/include/clang/Basic/AlignedAllocation.h b/clang/include/clang/Basic/AlignedAllocation.h
index ac26eb4a276da..9b84d07286d52 100644
--- a/clang/include/clang/Basic/AlignedAllocation.h
+++ b/clang/include/clang/Basic/AlignedAllocation.h
@@ -35,6 +35,8 @@ inline llvm::VersionTuple alignedAllocMinVersion(llvm::Triple::OSType OS) {
     return llvm::VersionTuple(4U);
   case llvm::Triple::ZOS:
     return llvm::VersionTuple(); // All z/OS versions have no support.
+  case llvm::Triple::ChipStar:
+    return llvm::VersionTuple(); // No version constraint for device targets.
   }
 
   llvm_unreachable("Unexpected OS");
diff --git a/clang/lib/Driver/ToolChains/HIPSPV.cpp b/clang/lib/Driver/ToolChains/HIPSPV.cpp
index 8bdb7ab042b2b..70f831c3ade87 100644
--- a/clang/lib/Driver/ToolChains/HIPSPV.cpp
+++ b/clang/lib/Driver/ToolChains/HIPSPV.cpp
@@ -72,10 +72,56 @@ void HIPSPV::Linker::constructLinkAndEmitSpirvCommand(
   tools::constructLLVMLinkCommand(C, *this, JA, Inputs, LinkArgs, Output, Args,
                                   TempFile);
 
-  // Post-link HIP lowering.
+  auto T = getToolChain().getTriple();
+
+  if (T.getOS() == llvm::Triple::ChipStar) {
+    // chipStar: run HipSpvPasses via opt, then use the in-tree SPIR-V backend
+    // for codegen (replaces the external llvm-spirv translator).
+
+    // Run HipSpvPasses plugin via opt (must run on LLVM IR before
+    // the SPIR-V backend lowers to MIR).
+    auto PassPluginPath = findPassPlugin(C.getDriver(), Args);
+    if (!PassPluginPath.empty()) {
+      const char *PassPathCStr = C.getArgs().MakeArgString(PassPluginPath);
+      const char *OptOutput = HIP::getTempFile(C, Name + "-lower", "bc");
+      ArgStringList OptArgs{TempFile,     "-load-pass-plugin",
+                            PassPathCStr, "-passes=hip-post-link-passes",
+                            "-o",         OptOutput};
+      const char *Opt =
+          Args.MakeArgString(getToolChain().GetProgramPath("opt"));
+      C.addCommand(std::make_unique<Command>(
+          JA, *this, ResponseFileSupport::None(), Opt, OptArgs, Inputs,
+          Output));
+      TempFile = OptOutput;
+    }
 
-  // Run LLVM IR passes to lower/expand/emulate HIP code that does not translate
-  // to SPIR-V (E.g. dynamic shared memory).
+    // Compile processed bitcode to SPIR-V using the in-tree backend.
+    ArgStringList ClangArgs;
+    ClangArgs.push_back("--no-default-config");
+    ClangArgs.push_back("-c");
+    ClangArgs.push_back(
+        C.getArgs().MakeArgString("--target=" + T.getTriple()));
+
+    ClangArgs.push_back("-mllvm");
+    ClangArgs.push_back("-spirv-ext=+SPV_INTEL_function_pointers"
+                        ",+SPV_INTEL_subgroups"
+                        ",+SPV_EXT_relaxed_printf_string_address_space"
+                        ",+SPV_KHR_bit_instructions"
+                        ",+SPV_EXT_shader_atomic_float_add");
+
+    ClangArgs.push_back(TempFile);
+    ClangArgs.push_back("-o");
+    ClangArgs.push_back(Output.getFilename());
+
+    const char *Clang =
+        C.getArgs().MakeArgString(C.getDriver().getClangProgramPath());
+    C.addCommand(std::make_unique<Command>(
+        JA, *this, ResponseFileSupport::None(), Clang, ClangArgs, Inputs,
+        Output));
+    return;
+  }
+
+  // Non-chipStar: run HIP passes via opt, then translate with llvm-spirv.
   auto PassPluginPath = findPassPlugin(C.getDriver(), Args);
   if (!PassPluginPath.empty()) {
     const char *PassPathCStr = C.getArgs().MakeArgString(PassPluginPath);
@@ -89,27 +135,11 @@ void HIPSPV::Linker::constructLinkAndEmitSpirvCommand(
     TempFile = OptOutput;
   }
 
-  // Emit SPIR-V binary.
+  // Emit SPIR-V binary via llvm-spirv translator (non-chipStar targets).
   llvm::opt::ArgStringList TrArgs;
-  auto T = getToolChain().getTriple();
-  bool HasNoSubArch = T.getSubArch() == llvm::Triple::NoSubArch;
-  if (T.getOS() == llvm::Triple::ChipStar) {
-    // chipStar needs 1.2 for supporting warp-level primitivies via sub-group
-    // extensions.  Strictly put we'd need 1.3 for the standard non-extension
-    // shuffle operations, but it's not supported by any backend driver of the
-    // chipStar.
-    if (HasNoSubArch)
-      TrArgs.push_back("--spirv-max-version=1.2");
-    TrArgs.push_back("--spirv-ext=-all"
-                     // Needed for experimental indirect call support.
-                     ",+SPV_INTEL_function_pointers"
-                     // Needed for shuffles below SPIR-V 1.3
-                     ",+SPV_INTEL_subgroups");
-  } else {
-    if (HasNoSubArch)
-      TrArgs.push_back("--spirv-max-version=1.1");
-    TrArgs.push_back("--spirv-ext=+all");
-  }
+  if (T.getSubArch() == llvm::Triple::NoSubArch)
+    TrArgs.push_back("--spirv-max-version=1.1");
+  TrArgs.push_back("--spirv-ext=+all");
 
   InputInfo TrInput = InputInfo(types::TY_LLVM_BC, TempFile, "");
   SPIRV::constructTranslateCommand(C, *this, JA, Output, TrInput, TrArgs);
@@ -152,14 +182,17 @@ HIPSPVToolChain::HIPSPVToolChain(const Driver &D, const llvm::Triple &Triple,
 void HIPSPVToolChain::addClangTargetOptions(
     const llvm::opt::ArgList &DriverArgs, llvm::opt::ArgStringList &CC1Args,
     Action::OffloadKind DeviceOffloadingKind) const {
-
   if (!HostTC) {
     assert(DeviceOffloadingKind == Action::OFK_None &&
            "Need host toolchain for offloading!");
     return;
   }
 
-  HostTC->addClangTargetOptions(DriverArgs, CC1Args, DeviceOffloadingKind);
+  // NOTE: Unlike other HIP toolchains, we do NOT delegate to
+  // HostTC.addClangTargetOptions() here. On macOS (Darwin), the host toolchain
+  // adds flags like -faligned-alloc-unavailable that are specific to macOS
+  // libc++ and break SPIR-V device compilation. SPIR-V device code doesn't
+  // have the same stdlib limitations as the host.
 
   assert(DeviceOffloadingKind == Action::OFK_HIP &&
          "Only HIP offloading kinds are supported for GPUs.");
diff --git a/clang/lib/Driver/ToolChains/SPIRV.cpp b/clang/lib/Driver/ToolChains/SPIRV.cpp
index a59bd05cac0cf..e6a04e00af87b 100644
--- a/clang/lib/Driver/ToolChains/SPIRV.cpp
+++ b/clang/lib/Driver/ToolChains/SPIRV.cpp
@@ -185,7 +185,8 @@ SPIRVToolChain::SPIRVToolChain(const Driver &D, const llvm::Triple &Triple,
     : ToolChain(D, Triple, Args) {
   // TODO: Revisit need/use of --sycl-link option once SYCL toolchain is
   // available and SYCL linking support is moved there.
-  NativeLLVMSupport = Args.hasArg(options::OPT_sycl_link) || D.isUsingLTO();
+  NativeLLVMSupport = Args.hasArg(options::OPT_sycl_link) || D.isUsingLTO() ||
+                      Triple.getOS() == llvm::Triple::ChipStar;
 
   // Lookup binaries into the driver directory.
   getProgramPaths().push_back(getDriver().Dir);
diff --git a/clang/test/Driver/hipspv-toolchain.hip b/clang/test/Driver/hipspv-toolchain.hip
index ae8d65313abfb..9af64ca4bdaa4 100644
--- a/clang/test/Driver/hipspv-toolchain.hip
+++ b/clang/test/Driver/hipspv-toolchain.hip
@@ -59,17 +59,50 @@
 // RUN: llvm-offload-binary -o %t.dev.out \
 // RUN:   --image=file=%t.dev.bc,kind=hip,triple=spirv64-unknown-chipstar,arch=generic
 
-// RUN: clang-linker-wrapper --dry-run \
+// Test the in-tree SPIR-V backend path (no llvm-spirv available).
+// Run from a directory that doesn't contain llvm-spirv and use
+// --no-canonical-prefixes so getExecutableDir() looks there instead of
+// the build bin dir. Empty PATH ensures PATH lookup also fails.
+// RUN: mkdir -p %t/no-spirv %t/empty
+// RUN: ln -sf clang-linker-wrapper %t/no-spirv/clang-linker-wrapper
+// RUN: env "PATH=%t/empty" %t/no-spirv/clang-linker-wrapper \
+// RUN:   --no-canonical-prefixes --dry-run \
 // RUN:   --device-compiler=spirv64-unknown-chipstar=--hip-path="%S/Inputs/hipspv" \
 // RUN:   --host-triple=spirv64-unknown-chipstar \
 // RUN:   --linker-path=clang-offload-bundler \
 // RUN:   --emit-fatbin-only -o /dev/null %t.dev.out \
 // RUN: 2>&1 | FileCheck %s --check-prefix=WRAPPER -DHIP_PATH=%S/Inputs/hipspv
 
-// WRAPPER: clang{{.*}}" --no-default-config -o {{[^ ]*.img}}
+// The linker wrapper runs opt (HipSpvPasses) then uses the in-tree SPIR-V
+// backend when llvm-spirv is not available.
+// WRAPPER: "{{.*}}opt" {{.*}}-load-pass-plugin
+// WRAPPER-SAME: {{.*}}libLLVMHipSpvPasses.so
+// WRAPPER-SAME: -passes=hip-post-link-passes
+
+// WRAPPER: "{{.*}}clang{{.*}}" --no-default-config -o
 // WRAPPER-SAME: --target=spirv64-unknown-chipstar
-// WRAPPER-SAME: {{[^ ]*.o}}
-// WRAPPER-SAME: --hip-path=[[HIP_PATH]]
+// WRAPPER-SAME: -mllvm -spirv-ext=+SPV_INTEL_function_pointers,+SPV_INTEL_subgroups,+SPV_EXT_relaxed_printf_string_address_space,+SPV_KHR_bit_instructions,+SPV_EXT_shader_atomic_float_add
+// WRAPPER-SAME: -c -x ir
+
+// Test the llvm-spirv translator path (llvm-spirv available in executable dir).
+// Place a fake llvm-spirv next to the clang-linker-wrapper symlink.
+// RUN: mkdir -p %t/with-spirv
+// RUN: ln -sf clang-linker-wrapper %t/with-spirv/clang-linker-wrapper
+// RUN: touch %t/with-spirv/llvm-spirv && chmod +x %t/with-spirv/llvm-spirv
+// RUN: env "PATH=%t/empty" %t/with-spirv/clang-linker-wrapper \
+// RUN:   --no-canonical-prefixes --dry-run \
+// RUN:   --device-compiler=spirv64-unknown-chipstar=--hip-path="%S/Inputs/hipspv" \
+// RUN:   --host-triple=spirv64-unknown-chipstar \
+// RUN:   --linker-path=clang-offload-bundler \
+// RUN:   --emit-fatbin-only -o /dev/null %t.dev.out \
+// RUN: 2>&1 | FileCheck %s --check-prefix=WRAPPER-TR
+
+// WRAPPER-TR: "{{.*}}opt" {{.*}}-load-pass-plugin
+// WRAPPER-TR-SAME: {{.*}}libLLVMHipSpvPasses.so
+// WRAPPER-TR-SAME: -passes=hip-post-link-passes
+
+// WRAPPER-TR: "{{.*}}llvm-spirv" {{.*}}--spirv-max-version=1.2
+// WRAPPER-TR-SAME: --spirv-ext=-all,+SPV_INTEL_function_pointers,+SPV_INTEL_subgroups
 
 // RUN: touch %t.dummy.o
 // RUN: %clang -### --no-default-config -o %t.dummy.img \
@@ -84,8 +117,9 @@
 // CHIPSTAR-SAME: "[[HIP_PATH]]/lib/libLLVMHipSpvPasses.so"
 // CHIPSTAR-SAME: "-passes=hip-post-link-passes" "-o" [[LOWER_BC:".*bc"]]
 
-//      CHIPSTAR: {{".*llvm-spirv"}} "--spirv-max-version=1.2"
-// CHIPSTAR-SAME: "--spirv-ext=-all,+SPV_INTEL_function_pointers,+SPV_INTEL_subgroups"
+//      CHIPSTAR: {{".*clang.*"}} "--no-default-config" "-c"
+// CHIPSTAR-SAME: "--target=spirv64-unknown-chipstar"
+// CHIPSTAR-SAME: "-mllvm" "-spirv-ext=+SPV_INTEL_function_pointers,+SPV_INTEL_subgroups,+SPV_EXT_relaxed_printf_string_address_space,+SPV_KHR_bit_instructions,+SPV_EXT_shader_atomic_float_add"
 // CHIPSTAR-SAME: [[LOWER_BC]] "-o" "[[SPIRV_OUT:.*img]]"
 
 // RUN: %clang -### --no-default-config -o %t.dummy.img \
@@ -100,8 +134,9 @@
 // CHIPSTAR-SUBARCH-SAME: "[[HIP_PATH]]/lib/libLLVMHipSpvPasses.so"
 // CHIPSTAR-SUBARCH-SAME: "-passes=hip-post-link-passes" "-o" [[LOWER_BC:".*bc"]]
 
-//      CHIPSTAR-SUBARCH: {{".*llvm-spirv"}}
-// CHIPSTAR-SUBARCH-SAME: "--spirv-ext=-all,+SPV_INTEL_function_pointers,+SPV_INTEL_subgroups"
+//      CHIPSTAR-SUBARCH: {{".*clang.*"}} "--no-default-config" "-c"
+// CHIPSTAR-SUBARCH-SAME: "--target=spirv64v1.3-unknown-chipstar"
+// CHIPSTAR-SUBARCH-SAME: "-mllvm" "-spirv-ext=+SPV_INTEL_function_pointers,+SPV_INTEL_subgroups,+SPV_EXT_relaxed_printf_string_address_space,+SPV_KHR_bit_instructions,+SPV_EXT_shader_atomic_float_add"
 // CHIPSTAR-SUBARCH-SAME: [[LOWER_BC]] "-o" "[[SPIRV_OUT:.*img]]"
 
 //-----------------------------------------------------------------------------
@@ -115,9 +150,4 @@
 // RUN:   | FileCheck -DVERSION=%llvm-version-major \
 // RUN:   --check-prefix=VERSIONED %s
 
-// RUN: env "PATH=%t/versioned" %clang -### --no-default-config \
-// RUN:  -o %t.dummy.img --target=spirv64-unknown-chipstar %t.dummy.o \
-// RUN:  --hip-path="%S/Inputs/hipspv" -o /dev/null 2>&1 \
-// RUN: | FileCheck -DVERSION=%llvm-version-major --check-prefix=VERSIONED %s
-
 // VERSIONED: {{.*}}llvm-spirv-[[VERSION]]
diff --git a/clang/tools/clang-linker-wrapper/ClangLinkerWrapper.cpp b/clang/tools/clang-linker-wrapper/ClangLinkerWrapper.cpp
index 9e24a9c26d897..2522d0ac71df1 100644
--- a/clang/tools/clang-linker-wrapper/ClangLinkerWrapper.cpp
+++ b/clang/tools/clang-linker-wrapper/ClangLinkerWrapper.cpp
@@ -125,6 +125,9 @@ static StringRef ExecutableName;
 /// Binary path for the CUDA installation.
 static std::string CudaBinaryPath;
 
+/// HIP installation path.
+static std::string HipPath;
+
 /// Mutex lock to protect writes to shared TempFiles in parallel.
 static std::mutex TempFilesMutex;
 
@@ -479,9 +482,25 @@ fatbinary(ArrayRef<std::tuple<StringRef, StringRef, StringRef>> InputFiles,
   SmallVector<StringRef> Targets = {
       Saver.save("-targets=host-" + HostTriple.normalize())};
   for (const auto &[File, TripleRef, Arch] : InputFiles) {
-    std::string NormalizedTriple =
-        normalizeForBundler(Triple(TripleRef), !Arch.empty());
-    Targets.push_back(Saver.save("hip-" + NormalizedTriple + "-" + Arch));
+    llvm::Triple T(TripleRef);
+    // For SPIR-V targets, derive arch from triple if not provided
+    StringRef EffectiveArch = Arch;
+    if (EffectiveArch.empty() && T.isSPIRV()) {
+      EffectiveArch = T.getArchName();
+    }
+    StringRef BundleID;
+    if (EffectiveArch == "amdgcnspirv") {
+      BundleID = Saver.save("hip-spirv64-amd-amdhsa--" + EffectiveArch);
+    } else if (T.isSPIRV()) {
+      // ChipStar and other SPIR-V HIP targets: use hip-spirv64-<vendor>-<os>--<arch>
+      BundleID = Saver.save("hip-spirv64-" + T.getVendorName() + "-" +
+                            T.getOSName() + "--" + EffectiveArch);
+    } else {
+      std::string NormalizedTriple =
+          normalizeForBundler(T, !Arch.empty());
+      BundleID = Saver.save("hip-" + NormalizedTriple + "-" + Arch);
+    }
+    Targets.push_back(BundleID);
   }
   CmdArgs.push_back(Saver.save(llvm::join(Targets, ",")));
 
@@ -554,7 +573,161 @@ Expected<StringRef> clang(ArrayRef<StringRef> InputFiles, const ArgList &Args,
   if (!Triple.isNVPTX() && !Triple.isSPIRV())
     CmdArgs.push_back("-Wl,--no-undefined");
 
-  for (StringRef InputFile : InputFiles)
+  // For non-chipStar SPIR-V targets, pass the HIP path to clang so it can
+  // find resources. For chipStar, passes are run via opt separately, so the
+  // inner clang doesn't need --hip-path (it just compiles IR to SPIR-V).
+  if (Triple.isSPIRV() && !HipPath.empty() &&
+      Triple.getOS() != llvm::Triple::ChipStar)
+    CmdArgs.push_back(Args.MakeArgString("--hip-path=" + HipPath));
+
+  // For chipStar targets: llvm-link (merge) → opt (HipSpvPasses) → clang
+  // (SPIR-V backend). The passes must operate on LLVM IR before the backend
+  // lowers to MIR, and all TU bitcode must be merged first for RDC support.
+  SmallVector<StringRef, 16> ProcessedInputFiles;
+  if (Triple.isSPIRV() && Triple.getOS() == llvm::Triple::ChipStar) {
+    // Step 1: Merge all input bitcode files with llvm-link (needed for RDC
+    // where functions can be defined across translation units).
+    StringRef MergedFile;
+    if (InputFiles.size() > 1) {
+      Expected<std::string> LinkPath =
+          findProgram("llvm-link", {getExecutableDir("llvm-link")});
+      if (!LinkPath)
+        return LinkPath.takeError();
+
+      auto LinkOutOrErr = createOutputFile(
+          sys::path::filename(ExecutableName) + ".merged", "bc");
+      if (!LinkOutOrErr)
+        return LinkOutOrErr.takeError();
+
+      SmallVector<StringRef, 16> LinkArgs{*LinkPath};
+      for (StringRef F : InputFiles)
+        LinkArgs.push_back(F);
+      LinkArgs.push_back("-o");
+      LinkArgs.push_back(*LinkOutOrErr);
+
+      if (Error Err = executeCommands(*LinkPath, LinkArgs))
+        return std::move(Err);
+
+      MergedFile = *LinkOutOrErr;
+    } else {
+      MergedFile = InputFiles[0];
+    }
+
+    // Step 2: Run HipSpvPasses via opt on the merged bitcode.
+    SmallString<128> PluginPath;
+    if (!HipPath.empty()) {
+      PluginPath.assign(HipPath);
+      sys::path::append(PluginPath, "lib", "libLLVMHipSpvPasses.so");
+      if (!sys::fs::exists(PluginPath)) {
+        PluginPath.assign(HipPath);
+        sys::path::append(PluginPath, "lib", "llvm",
+                          "libLLVMHipSpvPasses.so");
+      }
+      if (!sys::fs::exists(PluginPath))
+        PluginPath.clear();
+    }
+
+    StringRef OptOutputFile = MergedFile;
+    if (!PluginPath.empty()) {
+      Expected<std::string> OptPath =
+          findProgram("opt", {getExecutableDir("opt")});
+      if (!OptPath)
+        return OptPath.takeError();
+
+      auto OptOutOrErr = createOutputFile(
+          sys::path::filename(ExecutableName) + ".lowered", "bc");
+      if (!OptOutOrErr)
+        return OptOutOrErr.takeError();
+
+      SmallVector<StringRef, 16> OptArgs{
+          *OptPath,
+          MergedFile,
+          "-load-pass-plugin",
+          Args.MakeArgString(PluginPath),
+          "-passes=hip-post-link-passes",
+          "-o",
+          *OptOutOrErr,
+      };
+
+      if (Error Err = executeCommands(*OptPath, OptArgs))
+        return std::move(Err);
+
+      OptOutputFile = *OptOutOrErr;
+    }
+
+    // Step 3: Convert processed bitcode to SPIR-V.
+    // Check if llvm-spirv translator is available. If so, use it directly;
+    // otherwise use the in-tree SPIR-V backend via clang.
+    // Use sys::findProgramByName() instead of findProgram() to avoid the
+    // dry-run fallback that always "finds" programs by returning their name.
+    bool UseLLVMSpirvTranslator = false;
+    std::string LLVMSpirvPathStr;
+    {
+      ErrorOr<std::string> LLVMSpirvPath =
+          sys::findProgramByName("llvm-spirv", {getExecutableDir("llvm-spirv")});
+      if (!LLVMSpirvPath)
+        LLVMSpirvPath = sys::findProgramByName("llvm-spirv");
+      if (LLVMSpirvPath) {
+        LLVMSpirvPathStr = *LLVMSpirvPath;
+        UseLLVMSpirvTranslator = true;
+      }
+    }
+    if (UseLLVMSpirvTranslator) {
+      // Use llvm-spirv translator: BC → SPIR-V binary directly.
+      auto SpirvOutOrErr = createOutputFile(
+          sys::path::filename(ExecutableName) + ".spirv", "spv");
+      if (!SpirvOutOrErr)
+        return SpirvOutOrErr.takeError();
+
+      // Derive SPIR-V max version from the triple's sub-arch.
+      // chipStar needs v1.2 for sub-group extensions by default.
+      std::string MaxVerArg;
+      if (Triple.getSubArch() == llvm::Triple::SPIRVSubArch_v13)
+        MaxVerArg = "--spirv-max-version=1.3";
+      else if (Triple.getSubArch() == llvm::Triple::SPIRVSubArch_v12 ||
+               Triple.getOS() == llvm::Triple::ChipStar)
+        MaxVerArg = "--spirv-max-version=1.2";
+      else
+        MaxVerArg = "--spirv-max-version=1.1";
+
+      SmallVector<StringRef, 16> TranslateArgs{
+          LLVMSpirvPathStr,
+          OptOutputFile,
+          Args.MakeArgString(MaxVerArg),
+          "--spirv-ext=-all,+SPV_INTEL_function_pointers,+SPV_INTEL_subgroups",
+          "-o",
+          *SpirvOutOrErr,
+      };
+
+      if (Error Err = executeCommands(LLVMSpirvPathStr, TranslateArgs))
+        return std::move(Err);
+
+      // The SPIR-V binary is the final output; skip the inner clang
+      // compilation by returning it directly as the linked image.
+      return *SpirvOutOrErr;
+    }
+
+    // No llvm-spirv available; use the in-tree SPIR-V backend via clang.
+    ProcessedInputFiles.push_back(OptOutputFile);
+    CmdArgs.push_back("-mllvm");
+    CmdArgs.push_back("-spirv-ext=+SPV_INTEL_function_pointers"
+                      ",+SPV_INTEL_subgroups"
+                      ",+SPV_EXT_relaxed_printf_string_address_space"
+                      ",+SPV_KHR_bit_instructions"
+                      ",+SPV_EXT_shader_atomic_float_add");
+    // The extracted bitcode files have a .o extension which causes the driver
+    // to treat them as pre-compiled objects, skipping the Backend compilation
+    // step. Force the input language to LLVM IR so the SPIR-V backend runs.
+    // Use -c to skip the link phase — the SPIR-V backend output is the final
+    // binary; hitting HIPSPV::Linker would re-run the full pipeline.
+    CmdArgs.push_back("-c");
+    CmdArgs.push_back("-x");
+    CmdArgs.push_back("ir");
+  } else {
+    ProcessedInputFiles.append(InputFiles.begin(), InputFiles.end());
+  }
+
+  for (StringRef InputFile : ProcessedInputFiles)
     CmdArgs.push_back(InputFile);
 
   // If this is CPU offloading we copy the input libraries.
@@ -613,8 +786,14 @@ Expected<StringRef> clang(ArrayRef<StringRef> InputFiles, const ArgList &Args,
 
   for (StringRef Arg : Args.getA...
[truncated]

[llvmbot]

@llvm/pr-subscribers-backend-spir-v

Author: Paulius Velesko (pvelesko)

Changes

Summary

chipStar (https://github.com/CHIP-SPV/chipStar) enables HIP/CUDA programs to run on OpenCL and Level Zero devices via SPIR-V. Until now, the HIPSPV toolchain relied exclusively on the external llvm-spirv translator for bitcode-to-SPIR-V conversion.

This patch adds native in-tree SPIR-V backend support for chipStar targets (spirv64*-unknown-chipstar), removing the hard dependency on llvm-spirv.

Changes

HIPSPV old driver (HIPSPV.cpp):

• chipStar targets now use opt (HipSpvPasses) + clang -c (SPIR-V backend) instead of opt + llvm-spirv
• Non-chipStar HIPSPV targets continue using llvm-spirv unchanged
• Remove HostTC->addClangTargetOptions() delegation to avoid macOS Darwin flags (-faligned-alloc-unavailable) breaking SPIR-V device compilation

New offload driver (ClangLinkerWrapper.cpp):

• Add chipStar SPIR-V pipeline: llvm-link → opt (HipSpvPasses) → clang -c --target=spirv64 with SPIR-V extensions
• Extract --hip-path from --device-compiler= args for locating the HipSpvPasses plugin and device libraries
• Fall back to llvm-spirv translator when available for non-chipStar SPIR-V targets

SPIR-V toolchain (SPIRV.cpp):

• Enable NativeLLVMSupport for chipStar triples so the toolchain does not require an external translator

SPIR-V backend (SPIRVSubtarget.cpp):

• Set Kernel environment for chipStar triples (needed for OpenCL kernel ABI)

AlignedAllocation.h:

• Add ChipStar case to avoid unhandled enum warning

Test plan

• hipspv-toolchain.hip driver test updated to verify the new in-tree backend pipeline
• chipStar test suite: 1173/1173 tests pass (100%) on the translator path; 1169/1173 (99.7%) on the native in-tree backend (4 remaining printf failures due to upstream ExpandVariadics regression in LLVM 23)

---

Patch is 21.95 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/186972.diff

6 Files Affected:

• (modified) clang/include/clang/Basic/AlignedAllocation.h (+2)
• (modified) clang/lib/Driver/ToolChains/HIPSPV.cpp (+58-25)
• (modified) clang/lib/Driver/ToolChains/SPIRV.cpp (+2-1)
• (modified) clang/test/Driver/hipspv-toolchain.hip (+43-13)
• (modified) clang/tools/clang-linker-wrapper/ClangLinkerWrapper.cpp (+194-5)
• (modified) llvm/lib/Target/SPIRV/SPIRVSubtarget.cpp (+2-1)

diff --git a/clang/include/clang/Basic/AlignedAllocation.h b/clang/include/clang/Basic/AlignedAllocation.h
index ac26eb4a276da..9b84d07286d52 100644
--- a/clang/include/clang/Basic/AlignedAllocation.h
+++ b/clang/include/clang/Basic/AlignedAllocation.h
@@ -35,6 +35,8 @@ inline llvm::VersionTuple alignedAllocMinVersion(llvm::Triple::OSType OS) {
     return llvm::VersionTuple(4U);
   case llvm::Triple::ZOS:
     return llvm::VersionTuple(); // All z/OS versions have no support.
+  case llvm::Triple::ChipStar:
+    return llvm::VersionTuple(); // No version constraint for device targets.
   }
 
   llvm_unreachable("Unexpected OS");
diff --git a/clang/lib/Driver/ToolChains/HIPSPV.cpp b/clang/lib/Driver/ToolChains/HIPSPV.cpp
index 8bdb7ab042b2b..70f831c3ade87 100644
--- a/clang/lib/Driver/ToolChains/HIPSPV.cpp
+++ b/clang/lib/Driver/ToolChains/HIPSPV.cpp
@@ -72,10 +72,56 @@ void HIPSPV::Linker::constructLinkAndEmitSpirvCommand(
   tools::constructLLVMLinkCommand(C, *this, JA, Inputs, LinkArgs, Output, Args,
                                   TempFile);
 
-  // Post-link HIP lowering.
+  auto T = getToolChain().getTriple();
+
+  if (T.getOS() == llvm::Triple::ChipStar) {
+    // chipStar: run HipSpvPasses via opt, then use the in-tree SPIR-V backend
+    // for codegen (replaces the external llvm-spirv translator).
+
+    // Run HipSpvPasses plugin via opt (must run on LLVM IR before
+    // the SPIR-V backend lowers to MIR).
+    auto PassPluginPath = findPassPlugin(C.getDriver(), Args);
+    if (!PassPluginPath.empty()) {
+      const char *PassPathCStr = C.getArgs().MakeArgString(PassPluginPath);
+      const char *OptOutput = HIP::getTempFile(C, Name + "-lower", "bc");
+      ArgStringList OptArgs{TempFile,     "-load-pass-plugin",
+                            PassPathCStr, "-passes=hip-post-link-passes",
+                            "-o",         OptOutput};
+      const char *Opt =
+          Args.MakeArgString(getToolChain().GetProgramPath("opt"));
+      C.addCommand(std::make_unique<Command>(
+          JA, *this, ResponseFileSupport::None(), Opt, OptArgs, Inputs,
+          Output));
+      TempFile = OptOutput;
+    }
 
-  // Run LLVM IR passes to lower/expand/emulate HIP code that does not translate
-  // to SPIR-V (E.g. dynamic shared memory).
+    // Compile processed bitcode to SPIR-V using the in-tree backend.
+    ArgStringList ClangArgs;
+    ClangArgs.push_back("--no-default-config");
+    ClangArgs.push_back("-c");
+    ClangArgs.push_back(
+        C.getArgs().MakeArgString("--target=" + T.getTriple()));
+
+    ClangArgs.push_back("-mllvm");
+    ClangArgs.push_back("-spirv-ext=+SPV_INTEL_function_pointers"
+                        ",+SPV_INTEL_subgroups"
+                        ",+SPV_EXT_relaxed_printf_string_address_space"
+                        ",+SPV_KHR_bit_instructions"
+                        ",+SPV_EXT_shader_atomic_float_add");
+
+    ClangArgs.push_back(TempFile);
+    ClangArgs.push_back("-o");
+    ClangArgs.push_back(Output.getFilename());
+
+    const char *Clang =
+        C.getArgs().MakeArgString(C.getDriver().getClangProgramPath());
+    C.addCommand(std::make_unique<Command>(
+        JA, *this, ResponseFileSupport::None(), Clang, ClangArgs, Inputs,
+        Output));
+    return;
+  }
+
+  // Non-chipStar: run HIP passes via opt, then translate with llvm-spirv.
   auto PassPluginPath = findPassPlugin(C.getDriver(), Args);
   if (!PassPluginPath.empty()) {
     const char *PassPathCStr = C.getArgs().MakeArgString(PassPluginPath);
@@ -89,27 +135,11 @@ void HIPSPV::Linker::constructLinkAndEmitSpirvCommand(
     TempFile = OptOutput;
   }
 
-  // Emit SPIR-V binary.
+  // Emit SPIR-V binary via llvm-spirv translator (non-chipStar targets).
   llvm::opt::ArgStringList TrArgs;
-  auto T = getToolChain().getTriple();
-  bool HasNoSubArch = T.getSubArch() == llvm::Triple::NoSubArch;
-  if (T.getOS() == llvm::Triple::ChipStar) {
-    // chipStar needs 1.2 for supporting warp-level primitivies via sub-group
-    // extensions.  Strictly put we'd need 1.3 for the standard non-extension
-    // shuffle operations, but it's not supported by any backend driver of the
-    // chipStar.
-    if (HasNoSubArch)
-      TrArgs.push_back("--spirv-max-version=1.2");
-    TrArgs.push_back("--spirv-ext=-all"
-                     // Needed for experimental indirect call support.
-                     ",+SPV_INTEL_function_pointers"
-                     // Needed for shuffles below SPIR-V 1.3
-                     ",+SPV_INTEL_subgroups");
-  } else {
-    if (HasNoSubArch)
-      TrArgs.push_back("--spirv-max-version=1.1");
-    TrArgs.push_back("--spirv-ext=+all");
-  }
+  if (T.getSubArch() == llvm::Triple::NoSubArch)
+    TrArgs.push_back("--spirv-max-version=1.1");
+  TrArgs.push_back("--spirv-ext=+all");
 
   InputInfo TrInput = InputInfo(types::TY_LLVM_BC, TempFile, "");
   SPIRV::constructTranslateCommand(C, *this, JA, Output, TrInput, TrArgs);
@@ -152,14 +182,17 @@ HIPSPVToolChain::HIPSPVToolChain(const Driver &D, const llvm::Triple &Triple,
 void HIPSPVToolChain::addClangTargetOptions(
     const llvm::opt::ArgList &DriverArgs, llvm::opt::ArgStringList &CC1Args,
     Action::OffloadKind DeviceOffloadingKind) const {
-
   if (!HostTC) {
     assert(DeviceOffloadingKind == Action::OFK_None &&
            "Need host toolchain for offloading!");
     return;
   }
 
-  HostTC->addClangTargetOptions(DriverArgs, CC1Args, DeviceOffloadingKind);
+  // NOTE: Unlike other HIP toolchains, we do NOT delegate to
+  // HostTC.addClangTargetOptions() here. On macOS (Darwin), the host toolchain
+  // adds flags like -faligned-alloc-unavailable that are specific to macOS
+  // libc++ and break SPIR-V device compilation. SPIR-V device code doesn't
+  // have the same stdlib limitations as the host.
 
   assert(DeviceOffloadingKind == Action::OFK_HIP &&
          "Only HIP offloading kinds are supported for GPUs.");
diff --git a/clang/lib/Driver/ToolChains/SPIRV.cpp b/clang/lib/Driver/ToolChains/SPIRV.cpp
index a59bd05cac0cf..e6a04e00af87b 100644
--- a/clang/lib/Driver/ToolChains/SPIRV.cpp
+++ b/clang/lib/Driver/ToolChains/SPIRV.cpp
@@ -185,7 +185,8 @@ SPIRVToolChain::SPIRVToolChain(const Driver &D, const llvm::Triple &Triple,
     : ToolChain(D, Triple, Args) {
   // TODO: Revisit need/use of --sycl-link option once SYCL toolchain is
   // available and SYCL linking support is moved there.
-  NativeLLVMSupport = Args.hasArg(options::OPT_sycl_link) || D.isUsingLTO();
+  NativeLLVMSupport = Args.hasArg(options::OPT_sycl_link) || D.isUsingLTO() ||
+                      Triple.getOS() == llvm::Triple::ChipStar;
 
   // Lookup binaries into the driver directory.
   getProgramPaths().push_back(getDriver().Dir);
diff --git a/clang/test/Driver/hipspv-toolchain.hip b/clang/test/Driver/hipspv-toolchain.hip
index ae8d65313abfb..9af64ca4bdaa4 100644
--- a/clang/test/Driver/hipspv-toolchain.hip
+++ b/clang/test/Driver/hipspv-toolchain.hip
@@ -59,17 +59,50 @@
 // RUN: llvm-offload-binary -o %t.dev.out \
 // RUN:   --image=file=%t.dev.bc,kind=hip,triple=spirv64-unknown-chipstar,arch=generic
 
-// RUN: clang-linker-wrapper --dry-run \
+// Test the in-tree SPIR-V backend path (no llvm-spirv available).
+// Run from a directory that doesn't contain llvm-spirv and use
+// --no-canonical-prefixes so getExecutableDir() looks there instead of
+// the build bin dir. Empty PATH ensures PATH lookup also fails.
+// RUN: mkdir -p %t/no-spirv %t/empty
+// RUN: ln -sf clang-linker-wrapper %t/no-spirv/clang-linker-wrapper
+// RUN: env "PATH=%t/empty" %t/no-spirv/clang-linker-wrapper \
+// RUN:   --no-canonical-prefixes --dry-run \
 // RUN:   --device-compiler=spirv64-unknown-chipstar=--hip-path="%S/Inputs/hipspv" \
 // RUN:   --host-triple=spirv64-unknown-chipstar \
 // RUN:   --linker-path=clang-offload-bundler \
 // RUN:   --emit-fatbin-only -o /dev/null %t.dev.out \
 // RUN: 2>&1 | FileCheck %s --check-prefix=WRAPPER -DHIP_PATH=%S/Inputs/hipspv
 
-// WRAPPER: clang{{.*}}" --no-default-config -o {{[^ ]*.img}}
+// The linker wrapper runs opt (HipSpvPasses) then uses the in-tree SPIR-V
+// backend when llvm-spirv is not available.
+// WRAPPER: "{{.*}}opt" {{.*}}-load-pass-plugin
+// WRAPPER-SAME: {{.*}}libLLVMHipSpvPasses.so
+// WRAPPER-SAME: -passes=hip-post-link-passes
+
+// WRAPPER: "{{.*}}clang{{.*}}" --no-default-config -o
 // WRAPPER-SAME: --target=spirv64-unknown-chipstar
-// WRAPPER-SAME: {{[^ ]*.o}}
-// WRAPPER-SAME: --hip-path=[[HIP_PATH]]
+// WRAPPER-SAME: -mllvm -spirv-ext=+SPV_INTEL_function_pointers,+SPV_INTEL_subgroups,+SPV_EXT_relaxed_printf_string_address_space,+SPV_KHR_bit_instructions,+SPV_EXT_shader_atomic_float_add
+// WRAPPER-SAME: -c -x ir
+
+// Test the llvm-spirv translator path (llvm-spirv available in executable dir).
+// Place a fake llvm-spirv next to the clang-linker-wrapper symlink.
+// RUN: mkdir -p %t/with-spirv
+// RUN: ln -sf clang-linker-wrapper %t/with-spirv/clang-linker-wrapper
+// RUN: touch %t/with-spirv/llvm-spirv && chmod +x %t/with-spirv/llvm-spirv
+// RUN: env "PATH=%t/empty" %t/with-spirv/clang-linker-wrapper \
+// RUN:   --no-canonical-prefixes --dry-run \
+// RUN:   --device-compiler=spirv64-unknown-chipstar=--hip-path="%S/Inputs/hipspv" \
+// RUN:   --host-triple=spirv64-unknown-chipstar \
+// RUN:   --linker-path=clang-offload-bundler \
+// RUN:   --emit-fatbin-only -o /dev/null %t.dev.out \
+// RUN: 2>&1 | FileCheck %s --check-prefix=WRAPPER-TR
+
+// WRAPPER-TR: "{{.*}}opt" {{.*}}-load-pass-plugin
+// WRAPPER-TR-SAME: {{.*}}libLLVMHipSpvPasses.so
+// WRAPPER-TR-SAME: -passes=hip-post-link-passes
+
+// WRAPPER-TR: "{{.*}}llvm-spirv" {{.*}}--spirv-max-version=1.2
+// WRAPPER-TR-SAME: --spirv-ext=-all,+SPV_INTEL_function_pointers,+SPV_INTEL_subgroups
 
 // RUN: touch %t.dummy.o
 // RUN: %clang -### --no-default-config -o %t.dummy.img \
@@ -84,8 +117,9 @@
 // CHIPSTAR-SAME: "[[HIP_PATH]]/lib/libLLVMHipSpvPasses.so"
 // CHIPSTAR-SAME: "-passes=hip-post-link-passes" "-o" [[LOWER_BC:".*bc"]]
 
-//      CHIPSTAR: {{".*llvm-spirv"}} "--spirv-max-version=1.2"
-// CHIPSTAR-SAME: "--spirv-ext=-all,+SPV_INTEL_function_pointers,+SPV_INTEL_subgroups"
+//      CHIPSTAR: {{".*clang.*"}} "--no-default-config" "-c"
+// CHIPSTAR-SAME: "--target=spirv64-unknown-chipstar"
+// CHIPSTAR-SAME: "-mllvm" "-spirv-ext=+SPV_INTEL_function_pointers,+SPV_INTEL_subgroups,+SPV_EXT_relaxed_printf_string_address_space,+SPV_KHR_bit_instructions,+SPV_EXT_shader_atomic_float_add"
 // CHIPSTAR-SAME: [[LOWER_BC]] "-o" "[[SPIRV_OUT:.*img]]"
 
 // RUN: %clang -### --no-default-config -o %t.dummy.img \
@@ -100,8 +134,9 @@
 // CHIPSTAR-SUBARCH-SAME: "[[HIP_PATH]]/lib/libLLVMHipSpvPasses.so"
 // CHIPSTAR-SUBARCH-SAME: "-passes=hip-post-link-passes" "-o" [[LOWER_BC:".*bc"]]
 
-//      CHIPSTAR-SUBARCH: {{".*llvm-spirv"}}
-// CHIPSTAR-SUBARCH-SAME: "--spirv-ext=-all,+SPV_INTEL_function_pointers,+SPV_INTEL_subgroups"
+//      CHIPSTAR-SUBARCH: {{".*clang.*"}} "--no-default-config" "-c"
+// CHIPSTAR-SUBARCH-SAME: "--target=spirv64v1.3-unknown-chipstar"
+// CHIPSTAR-SUBARCH-SAME: "-mllvm" "-spirv-ext=+SPV_INTEL_function_pointers,+SPV_INTEL_subgroups,+SPV_EXT_relaxed_printf_string_address_space,+SPV_KHR_bit_instructions,+SPV_EXT_shader_atomic_float_add"
 // CHIPSTAR-SUBARCH-SAME: [[LOWER_BC]] "-o" "[[SPIRV_OUT:.*img]]"
 
 //-----------------------------------------------------------------------------
@@ -115,9 +150,4 @@
 // RUN:   | FileCheck -DVERSION=%llvm-version-major \
 // RUN:   --check-prefix=VERSIONED %s
 
-// RUN: env "PATH=%t/versioned" %clang -### --no-default-config \
-// RUN:  -o %t.dummy.img --target=spirv64-unknown-chipstar %t.dummy.o \
-// RUN:  --hip-path="%S/Inputs/hipspv" -o /dev/null 2>&1 \
-// RUN: | FileCheck -DVERSION=%llvm-version-major --check-prefix=VERSIONED %s
-
 // VERSIONED: {{.*}}llvm-spirv-[[VERSION]]
diff --git a/clang/tools/clang-linker-wrapper/ClangLinkerWrapper.cpp b/clang/tools/clang-linker-wrapper/ClangLinkerWrapper.cpp
index 9e24a9c26d897..2522d0ac71df1 100644
--- a/clang/tools/clang-linker-wrapper/ClangLinkerWrapper.cpp
+++ b/clang/tools/clang-linker-wrapper/ClangLinkerWrapper.cpp
@@ -125,6 +125,9 @@ static StringRef ExecutableName;
 /// Binary path for the CUDA installation.
 static std::string CudaBinaryPath;
 
+/// HIP installation path.
+static std::string HipPath;
+
 /// Mutex lock to protect writes to shared TempFiles in parallel.
 static std::mutex TempFilesMutex;
 
@@ -479,9 +482,25 @@ fatbinary(ArrayRef<std::tuple<StringRef, StringRef, StringRef>> InputFiles,
   SmallVector<StringRef> Targets = {
       Saver.save("-targets=host-" + HostTriple.normalize())};
   for (const auto &[File, TripleRef, Arch] : InputFiles) {
-    std::string NormalizedTriple =
-        normalizeForBundler(Triple(TripleRef), !Arch.empty());
-    Targets.push_back(Saver.save("hip-" + NormalizedTriple + "-" + Arch));
+    llvm::Triple T(TripleRef);
+    // For SPIR-V targets, derive arch from triple if not provided
+    StringRef EffectiveArch = Arch;
+    if (EffectiveArch.empty() && T.isSPIRV()) {
+      EffectiveArch = T.getArchName();
+    }
+    StringRef BundleID;
+    if (EffectiveArch == "amdgcnspirv") {
+      BundleID = Saver.save("hip-spirv64-amd-amdhsa--" + EffectiveArch);
+    } else if (T.isSPIRV()) {
+      // ChipStar and other SPIR-V HIP targets: use hip-spirv64-<vendor>-<os>--<arch>
+      BundleID = Saver.save("hip-spirv64-" + T.getVendorName() + "-" +
+                            T.getOSName() + "--" + EffectiveArch);
+    } else {
+      std::string NormalizedTriple =
+          normalizeForBundler(T, !Arch.empty());
+      BundleID = Saver.save("hip-" + NormalizedTriple + "-" + Arch);
+    }
+    Targets.push_back(BundleID);
   }
   CmdArgs.push_back(Saver.save(llvm::join(Targets, ",")));
 
@@ -554,7 +573,161 @@ Expected<StringRef> clang(ArrayRef<StringRef> InputFiles, const ArgList &Args,
   if (!Triple.isNVPTX() && !Triple.isSPIRV())
     CmdArgs.push_back("-Wl,--no-undefined");
 
-  for (StringRef InputFile : InputFiles)
+  // For non-chipStar SPIR-V targets, pass the HIP path to clang so it can
+  // find resources. For chipStar, passes are run via opt separately, so the
+  // inner clang doesn't need --hip-path (it just compiles IR to SPIR-V).
+  if (Triple.isSPIRV() && !HipPath.empty() &&
+      Triple.getOS() != llvm::Triple::ChipStar)
+    CmdArgs.push_back(Args.MakeArgString("--hip-path=" + HipPath));
+
+  // For chipStar targets: llvm-link (merge) → opt (HipSpvPasses) → clang
+  // (SPIR-V backend). The passes must operate on LLVM IR before the backend
+  // lowers to MIR, and all TU bitcode must be merged first for RDC support.
+  SmallVector<StringRef, 16> ProcessedInputFiles;
+  if (Triple.isSPIRV() && Triple.getOS() == llvm::Triple::ChipStar) {
+    // Step 1: Merge all input bitcode files with llvm-link (needed for RDC
+    // where functions can be defined across translation units).
+    StringRef MergedFile;
+    if (InputFiles.size() > 1) {
+      Expected<std::string> LinkPath =
+          findProgram("llvm-link", {getExecutableDir("llvm-link")});
+      if (!LinkPath)
+        return LinkPath.takeError();
+
+      auto LinkOutOrErr = createOutputFile(
+          sys::path::filename(ExecutableName) + ".merged", "bc");
+      if (!LinkOutOrErr)
+        return LinkOutOrErr.takeError();
+
+      SmallVector<StringRef, 16> LinkArgs{*LinkPath};
+      for (StringRef F : InputFiles)
+        LinkArgs.push_back(F);
+      LinkArgs.push_back("-o");
+      LinkArgs.push_back(*LinkOutOrErr);
+
+      if (Error Err = executeCommands(*LinkPath, LinkArgs))
+        return std::move(Err);
+
+      MergedFile = *LinkOutOrErr;
+    } else {
+      MergedFile = InputFiles[0];
+    }
+
+    // Step 2: Run HipSpvPasses via opt on the merged bitcode.
+    SmallString<128> PluginPath;
+    if (!HipPath.empty()) {
+      PluginPath.assign(HipPath);
+      sys::path::append(PluginPath, "lib", "libLLVMHipSpvPasses.so");
+      if (!sys::fs::exists(PluginPath)) {
+        PluginPath.assign(HipPath);
+        sys::path::append(PluginPath, "lib", "llvm",
+                          "libLLVMHipSpvPasses.so");
+      }
+      if (!sys::fs::exists(PluginPath))
+        PluginPath.clear();
+    }
+
+    StringRef OptOutputFile = MergedFile;
+    if (!PluginPath.empty()) {
+      Expected<std::string> OptPath =
+          findProgram("opt", {getExecutableDir("opt")});
+      if (!OptPath)
+        return OptPath.takeError();
+
+      auto OptOutOrErr = createOutputFile(
+          sys::path::filename(ExecutableName) + ".lowered", "bc");
+      if (!OptOutOrErr)
+        return OptOutOrErr.takeError();
+
+      SmallVector<StringRef, 16> OptArgs{
+          *OptPath,
+          MergedFile,
+          "-load-pass-plugin",
+          Args.MakeArgString(PluginPath),
+          "-passes=hip-post-link-passes",
+          "-o",
+          *OptOutOrErr,
+      };
+
+      if (Error Err = executeCommands(*OptPath, OptArgs))
+        return std::move(Err);
+
+      OptOutputFile = *OptOutOrErr;
+    }
+
+    // Step 3: Convert processed bitcode to SPIR-V.
+    // Check if llvm-spirv translator is available. If so, use it directly;
+    // otherwise use the in-tree SPIR-V backend via clang.
+    // Use sys::findProgramByName() instead of findProgram() to avoid the
+    // dry-run fallback that always "finds" programs by returning their name.
+    bool UseLLVMSpirvTranslator = false;
+    std::string LLVMSpirvPathStr;
+    {
+      ErrorOr<std::string> LLVMSpirvPath =
+          sys::findProgramByName("llvm-spirv", {getExecutableDir("llvm-spirv")});
+      if (!LLVMSpirvPath)
+        LLVMSpirvPath = sys::findProgramByName("llvm-spirv");
+      if (LLVMSpirvPath) {
+        LLVMSpirvPathStr = *LLVMSpirvPath;
+        UseLLVMSpirvTranslator = true;
+      }
+    }
+    if (UseLLVMSpirvTranslator) {
+      // Use llvm-spirv translator: BC → SPIR-V binary directly.
+      auto SpirvOutOrErr = createOutputFile(
+          sys::path::filename(ExecutableName) + ".spirv", "spv");
+      if (!SpirvOutOrErr)
+        return SpirvOutOrErr.takeError();
+
+      // Derive SPIR-V max version from the triple's sub-arch.
+      // chipStar needs v1.2 for sub-group extensions by default.
+      std::string MaxVerArg;
+      if (Triple.getSubArch() == llvm::Triple::SPIRVSubArch_v13)
+        MaxVerArg = "--spirv-max-version=1.3";
+      else if (Triple.getSubArch() == llvm::Triple::SPIRVSubArch_v12 ||
+               Triple.getOS() == llvm::Triple::ChipStar)
+        MaxVerArg = "--spirv-max-version=1.2";
+      else
+        MaxVerArg = "--spirv-max-version=1.1";
+
+      SmallVector<StringRef, 16> TranslateArgs{
+          LLVMSpirvPathStr,
+          OptOutputFile,
+          Args.MakeArgString(MaxVerArg),
+          "--spirv-ext=-all,+SPV_INTEL_function_pointers,+SPV_INTEL_subgroups",
+          "-o",
+          *SpirvOutOrErr,
+      };
+
+      if (Error Err = executeCommands(LLVMSpirvPathStr, TranslateArgs))
+        return std::move(Err);
+
+      // The SPIR-V binary is the final output; skip the inner clang
+      // compilation by returning it directly as the linked image.
+      return *SpirvOutOrErr;
+    }
+
+    // No llvm-spirv available; use the in-tree SPIR-V backend via clang.
+    ProcessedInputFiles.push_back(OptOutputFile);
+    CmdArgs.push_back("-mllvm");
+    CmdArgs.push_back("-spirv-ext=+SPV_INTEL_function_pointers"
+                      ",+SPV_INTEL_subgroups"
+                      ",+SPV_EXT_relaxed_printf_string_address_space"
+                      ",+SPV_KHR_bit_instructions"
+                      ",+SPV_EXT_shader_atomic_float_add");
+    // The extracted bitcode files have a .o extension which causes the driver
+    // to treat them as pre-compiled objects, skipping the Backend compilation
+    // step. Force the input language to LLVM IR so the SPIR-V backend runs.
+    // Use -c to skip the link phase — the SPIR-V backend output is the final
+    // binary; hitting HIPSPV::Linker would re-run the full pipeline.
+    CmdArgs.push_back("-c");
+    CmdArgs.push_back("-x");
+    CmdArgs.push_back("ir");
+  } else {
+    ProcessedInputFiles.append(InputFiles.begin(), InputFiles.end());
+  }
+
+  for (StringRef InputFile : ProcessedInputFiles)
     CmdArgs.push_back(InputFile);
 
   // If this is CPU offloading we copy the input libraries.
@@ -613,8 +786,14 @@ Expected<StringRef> clang(ArrayRef<StringRef> InputFiles, const ArgList &Args,
 
   for (StringRef Arg : Args.getA...
[truncated]

[github-actions]

✅ With the latest revision this PR passed the C/C++ code formatter.

[pvelesko]

The Test SPIR-V CI failure is pre-existing on main — confirmed by #186992 (no-op baseline PR on main that shows the same 5 pointer/SpecConstantOp test failures).

[pvelesko]

@linehill

[linehill]

I'm lost here - does this fix a breakage for chipStar? I have tested CHIP-SPV/chipStar#1219 locally on couple days old LLVM and I haven't seen issues. I'm wondering if it necessary to have this.

[linehill]

I think CPU/GPU model is expected here which is not same thing as what Triple::getArchName() returns. For SPIR-V I think we can set it to "generic" - that's the default model used elsewhere for SPIR-V targets.

[linehill]

Also, is it a problem if the Arch is empty for non-chipStar SPIR-V targets?

[linehill]

IIUC, this function is related to availability of std::aligned_alloc(). I'm wondering what this has to do with HIP. Like does HIP language support std::aligned_alloc() to be called from device code?

[linehill]

This change got introduced in #187655 so a rebase maybe needed before merge.

[linehill]

Using clang driver for emitting SPIR-V (through SPIR-V BE) seems hazarous - it think it's better to use cc1 like HIPAMD does.

[linehill]

This portion is a duplicate from the below - could you refactor the duplication away?

[linehill]

This if fine for now. I just want to comment that I regret making the "ChipStar" an OS component but it doesn't matter unless/until chipStar adds a driver backend that requires Vulkan or other SPIR-V environment. It would have been better if it were a vendor component instead to differentiate the target environment - something like "spirv64-chipstar-vulkan".

[pvelesko]

doesn't matter unless/until chipStar adds a driver backend that requires Vulkan

I have a branch that converts our generated SPIRV from OpenCL to Vulkan SPIRV. This is for simplifying integration with clvk - converting SPIRV to Vulkan SPIRV on our side allows us to bypass the clspv component of clvk.

Not sure if this is something that will ever get merged or how that would affect llvm if so.

@linehill