Reland "[HIPSPV] Add in-tree SPIR-V backend support for chipStar" by pvelesko · Pull Request #213052 · llvm/llvm-project

pvelesko · 2026-07-30T15:44:26Z

Relands #206910 (reverted in #213088) with the fix for the breakage.

IsIntegratedBackendDefault() was tied to whether the SPIR-V backend is
registered, but it also controls whether clang collapses the compile and backend
jobs, so builds without the SPIR-V target split every HIPSPV RDC device compile
and failed hipspv-toolchain-rdc.hip. The default is back to the base class value
and the translator fallback is decided in constructLinkAndEmitSpirvCommand.
Third commit adds a test not guarded by spirv-registered-target.

Validated in X86;SPIRV and X86 only builds: driver tests pass in both, and
non-RDC plus RDC (new driver) flows run for real emit spirv-val clean modules
via the backend and via llvm-spirv respectively.

llvmorg-github-actions · 2026-07-30T15:45:11Z

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

@llvm/pr-subscribers-clang

Author: Paulius Velesko (pvelesko)

Changes

Fixes the buildbot breakage from #206910 on builders that do not build the SPIR-V target (e.g. llvm-clang-x86_64-sie-ubuntu-fast).

IsIntegratedBackendDefault() was made to depend on whether the in-tree SPIR-V backend is registered. That default also controls whether clang collapses the compile and backend jobs into a single -cc1 invocation, so without the SPIR-V target every HIPSPV RDC device compile was split into an -emit-llvm-bc job plus a separate -emit-obj job, failing Clang :: Driver/hipspv-toolchain-rdc.hip.

This keeps the base class default and decides the llvm-spirv translator fallback in HIPSPV::Linker::constructLinkAndEmitSpirvCommand. IsIntegratedBackendSupported() still reports whether the backend is built, so -fintegrated-objemitter is still diagnosed when it is not, and -fno-integrated-objemitter still selects the translator.

Verified both ways: with the SPIR-V target built, and with backend availability forced off to emulate the bot, where hipspv-toolchain-rdc.hip now passes.

Full diff: https://github.com/llvm/llvm-project/pull/213052.diff

2 Files Affected:

(modified) clang/lib/Driver/ToolChains/HIPSPV.cpp (+11-10)
(modified) clang/lib/Driver/ToolChains/HIPSPV.h (+6-1)

diff --git a/clang/lib/Driver/ToolChains/HIPSPV.cpp b/clang/lib/Driver/ToolChains/HIPSPV.cpp
index e67b1541ef51b..6c99ff54adcb7 100644
--- a/clang/lib/Driver/ToolChains/HIPSPV.cpp
+++ b/clang/lib/Driver/ToolChains/HIPSPV.cpp
@@ -49,6 +49,12 @@ static std::string findPassPlugin(const Driver &D,
   return std::string();
 }
 
+// Is the in-tree SPIR-V backend built into this clang?
+static bool isSPIRVBackendAvailable(const llvm::Triple &T) {
+  std::string IgnoredError;
+  return llvm::TargetRegistry::lookupTarget(T, IgnoredError);
+}
+
 // Runs the HipSpvPasses plugin via `opt` on TempFile when the plugin is found.
 // Returns the lowered bitcode path, or TempFile unchanged if no plugin exists.
 static const char *runHipSpvPasses(Compilation &C, const JobAction &JA,
@@ -108,7 +114,9 @@ void HIPSPV::Linker::constructLinkAndEmitSpirvCommand(
     TempFile = runHipSpvPasses(C, JA, *this, getToolChain(), Inputs, Output,
                                Args, Name, TempFile);
 
-    if (!getToolChain().useIntegratedBackend()) {
+    // Note that useIntegratedBackend() is consulted first so that an explicit
+    // -f(no-)integrated-objemitter still gets diagnosed against this toolchain.
+    if (!getToolChain().useIntegratedBackend() || !isSPIRVBackendAvailable(T)) {
       // External translator path: BC -> SPIR-V via llvm-spirv.
       llvm::opt::ArgStringList TrArgs;
       if (T.getSubArch() == llvm::Triple::NoSubArch)
@@ -254,15 +262,8 @@ HIPSPVToolChain::HIPSPVToolChain(const Driver &D, const llvm::Triple &Triple,
 }
 
 bool HIPSPVToolChain::IsIntegratedBackendSupported() const {
-  // The in-tree SPIR-V backend can only be used when it is built.
-  std::string IgnoredError;
-  return llvm::TargetRegistry::lookupTarget(getTriple(), IgnoredError);
-}
-
-bool HIPSPVToolChain::IsIntegratedBackendDefault() const {
-  // Prefer the in-tree SPIR-V backend; fall back to the external llvm-spirv
-  // translator when the backend is not built.
-  return IsIntegratedBackendSupported();
+  // The in-tree SPIR-V backend can only be requested when it is built.
+  return isSPIRVBackendAvailable(getTriple());
 }
 
 void HIPSPVToolChain::addClangTargetOptions(
diff --git a/clang/lib/Driver/ToolChains/HIPSPV.h b/clang/lib/Driver/ToolChains/HIPSPV.h
index 176ef5ddde8b3..e38a7135a60fd 100644
--- a/clang/lib/Driver/ToolChains/HIPSPV.h
+++ b/clang/lib/Driver/ToolChains/HIPSPV.h
@@ -55,7 +55,12 @@ class LLVM_LIBRARY_VISIBILITY HIPSPVToolChain final : public ToolChain {
     return HostTC ? &HostTC->getTriple() : nullptr;
   }
 
-  bool IsIntegratedBackendDefault() const override;
+  // Keep IsIntegratedBackendDefault() at the base class' "true": it also
+  // decides whether clang's compile and backend jobs are collapsed into a
+  // single -cc1 invocation, so making it depend on whether the SPIR-V backend
+  // was built would change the device compilation job layout of every HIPSPV
+  // compile. The fallback to the external llvm-spirv translator is decided in
+  // HIPSPV::Linker::constructLinkAndEmitSpirvCommand instead.
   bool IsIntegratedBackendSupported() const override;
   bool IsNonIntegratedBackendSupported() const override { return true; }

nico · 2026-07-30T16:48:19Z

Can you either land this or revert your original change, to unbreak HEAD?

pvelesko · 2026-07-30T16:53:00Z

@nico I don't have write access.
@@yxsamliu Please review

yxsamliu · 2026-07-30T22:09:01Z

@pvelesko Since #206910 was reverted, could you update this PR to reland the original change together with this fix?

The normal pre-merge CI does not test a build without the SPIR-V target, and most HIPSPV tests are skipped in that configuration. Please also test both RDC and non-RDC chipStar flows with the SPIR-V target disabled, including actually running the llvm-spirv fallback. I can review the combined change and results.

…vm#206910) This reverts commit 6162922, which reverted llvm#206910. The original change is relanded here unmodified; the buildbot breakage that caused the revert is fixed by the next commit in this PR.

…ckend llvm#206910 made HIPSPVToolChain::IsIntegratedBackendDefault() return false when the in-tree SPIR-V backend is not built. That default does more than select the SPIR-V emitter: it also decides whether clang collapses the compile and backend jobs into one -cc1 invocation. On builds without the SPIR-V target every HIPSPV RDC device compile therefore got split into an -emit-llvm-bc job plus a separate -emit-obj job, which broke Clang :: Driver/hipspv-toolchain-rdc.hip on X86-only bots such as llvm-clang-x86_64-sie-ubuntu-fast. Keep the base class default (integrated) and decide the llvm-spirv translator fallback where it belongs, in HIPSPV::Linker::constructLinkAndEmitSpirvCommand. IsIntegratedBackendSupported() still reports whether the backend is built, so an explicit -fintegrated-objemitter is still diagnosed when it is not, and -fno-integrated-objemitter still selects the translator. The device compilation job layout is now independent of which LLVM targets are built, so hipspv-toolchain-rdc.hip passes in both configurations.

The existing HIPSPV driver tests are guarded by the spirv-registered-target feature, so a builder configured without the SPIR-V target (e.g. an X86-only bot) skips nearly all of them. That is how the job-layout regression fixed in the previous commit reached the buildbots. Add a test that is deliberately not guarded: it pins the RDC device compilation job layout, which is a property of the driver rather than of the registered targets, and checks that -fno-integrated-objemitter selects the external llvm-spirv translator. Both hold in either configuration.

pvelesko · 2026-07-31T12:29:57Z

@yxsamliu Updated: commit 1 relands #206910 unmodified, commit 2 is the fix, commit 3 adds a test not guarded by spirv-registered-target.

Tested in X86;SPIRV and X86 only builds. Driver tests pass in both. Non-RDC and RDC (new driver, cross-TU) flows were run for real: the X86 only build emits through llvm-spirv, the X86;SPIRV build through the in-tree backend, both spirv-val clean.

RDC with the old offload driver fails in both configurations, but reproduces with the pre-#206910 sources on the same LLVM, so it is pre-existing on main.

yxsamliu

LGTM

pvelesko · 2026-07-31T17:07:16Z

@yxsamliu please merge when you can, I have no write access.

pvelesko · 2026-08-03T08:23:02Z

@yxsamliu is it possible to back port this to LLVM 23?

…vm#213052) Relands llvm#206910 (reverted in llvm#213088) with the fix for the breakage. IsIntegratedBackendDefault() was tied to whether the SPIR-V backend is registered, but it also controls whether clang collapses the compile and backend jobs, so builds without the SPIR-V target split every HIPSPV RDC device compile and failed hipspv-toolchain-rdc.hip. The default is back to the base class value and the translator fallback is decided in constructLinkAndEmitSpirvCommand. Third commit adds a test not guarded by spirv-registered-target. Validated in X86;SPIRV and X86 only builds: driver tests pass in both, and non-RDC plus RDC (new driver) flows run for real emit spirv-val clean modules via the backend and via llvm-spirv respectively.

LLVM 23 is pinned to the upstream tag llvmorg-23.1.0-rc2 plus two patches; all four patches were verified to apply with git apply against a pristine rc2 checkout and llvm_release_230, and the patched HIPSPV.cpp and SPIRVSubtarget.cpp compile. 0001 backports llvm/llvm-project#213052 (merged 2026-07-31 as 7ef0ca2b13f9, a reland of #206910), which landed after release/23.x was cut. It makes the HIPSPV toolchain emit device SPIR-V with the in-tree SPIR-V backend by default and fall back to llvm-spirv under -fno-integrated-objemitter or when the SPIR-V target was not built. The upstream commit sits on a main that already had the extension list and the debug-info translator flags; release/23.x has neither, so both are folded in and a patched 23 matches main exactly. 0002 honors -g for device code, but only when the in-tree backend is the effective emitter. The translator encodes DebugTypeComposite with a Parent operand, producing a cyclic forward reference that spirv-val rejects and IGC mis-handles, so -g must keep being stripped there. The remaining llvm-21/llvm-22 patches are unnecessary here: the SPIR-V version and extension selection, static device library unbundling, the data layout and the macOS Mach-O support are all already in 23. Refs: #1004

…vm#213052) Relands llvm#206910 (reverted in llvm#213088) with the fix for the breakage. IsIntegratedBackendDefault() was tied to whether the SPIR-V backend is registered, but it also controls whether clang collapses the compile and backend jobs, so builds without the SPIR-V target split every HIPSPV RDC device compile and failed hipspv-toolchain-rdc.hip. The default is back to the base class value and the translator fallback is decided in constructLinkAndEmitSpirvCommand. Third commit adds a test not guarded by spirv-registered-target. Validated in X86;SPIRV and X86 only builds: driver tests pass in both, and non-RDC plus RDC (new driver) flows run for real emit spirv-val clean modules via the backend and via llvm-spirv respectively.

yxsamliu · 2026-08-06T14:44:55Z

/cherry-pick 7ef0ca2

llvmbot · 2026-08-06T14:52:40Z

Failed to cherry-pick: 7ef0ca2

https://github.com/llvm/llvm-project/actions/runs/31112381662

Please manually backport the fix and push it to your github fork. Once this is done, please create a pull request

yxsamliu · 2026-08-06T18:20:55Z

@pvelesko I opened #214531 to backport this to LLVM 23. I resolved the conflicts and tested both SPIR-V-enabled and X86-only builds. Could you please take a look?

hongtaihu · 2026-08-07T16:21:55Z

This also fixes #208711

…vm#213052) Relands llvm#206910 (reverted in llvm#213088) with the fix for the breakage. IsIntegratedBackendDefault() was tied to whether the SPIR-V backend is registered, but it also controls whether clang collapses the compile and backend jobs, so builds without the SPIR-V target split every HIPSPV RDC device compile and failed hipspv-toolchain-rdc.hip. The default is back to the base class value and the translator fallback is decided in constructLinkAndEmitSpirvCommand. Third commit adds a test not guarded by spirv-registered-target. Validated in X86;SPIRV and X86 only builds: driver tests pass in both, and non-RDC plus RDC (new driver) flows run for real emit spirv-val clean modules via the backend and via llvm-spirv respectively. (cherry picked from commit 7ef0ca2)

llvmorg-github-actions Bot added clang Clang issues not falling into any other category clang:driver 'clang' and 'clang++' user-facing binaries. Not 'clang-cl' labels Jul 30, 2026

Prabhuk mentioned this pull request Jul 30, 2026

[HIPSPV] Add in-tree SPIR-V backend support for chipStar #206910

Merged

pvelesko added 3 commits July 31, 2026 07:35

Reland "[HIPSPV] Add in-tree SPIR-V backend support for chipStar" (ll…

ca93f3d

…vm#206910) This reverts commit 6162922, which reverted llvm#206910. The original change is relanded here unmodified; the buildbot breakage that caused the revert is fixed by the next commit in this PR.

pvelesko force-pushed the hipspv-integrated-backend-default branch from 33e0515 to 3ca7d4f Compare July 31, 2026 05:27

llvmorg-github-actions Bot added the backend:SPIR-V label Jul 31, 2026

pvelesko changed the title ~~[HIPSPV] Don't tie the integrated-objemitter default to the SPIR-V backend~~ Reland "[HIPSPV] Add in-tree SPIR-V backend support for chipStar" Jul 31, 2026

yxsamliu approved these changes Jul 31, 2026

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yxsamliu merged commit 7ef0ca2 into llvm:main Jul 31, 2026
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yxsamliu added this to the LLVM 23.x Release milestone Aug 6, 2026

github-project-automation Bot added this to LLVM Release Status Aug 6, 2026

github-project-automation Bot moved this to Done in LLVM Release Status Aug 6, 2026

llvmbot added the release:cherry-pick-failed label Aug 6, 2026

yxsamliu mentioned this pull request Aug 6, 2026

release/23.x: Reland "[HIPSPV] Add in-tree SPIR-V backend support for chipStar" (#213052) #214531

Open

hongtaihu mentioned this pull request Aug 7, 2026

[clang][driver] clang crash in spirv64v1.3 #208711

Closed

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Reland "[HIPSPV] Add in-tree SPIR-V backend support for chipStar" - #213052

Reland "[HIPSPV] Add in-tree SPIR-V backend support for chipStar"#213052
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