[libspirv] Replace libclc-remangler with SYCLRemangleLibspirvPass

[wenju-he]

Remove libclc-remangler tool and replace it with SYCLRemangleLibspirvPass
that remangles OpenCL C mangling in libspirv to match with SYCL mangling.
The pass ports the functionalities in the tool into compile pipeline.

Motivation:

• libclc-remangler executable doesn't fit in runtime build.
• libclc-remangler can't justify as a standalone tool in llvm/tools.

Functional changes:

• Add SYCLRemangleLibspirvPass. It uses Itanium demangler and adapts SPIR type system and SPIR mangler from SPIRV-LLVM-Translator.
• The pass runs at the end of compile pipeline for each .cl file.
  libspirv variants are created without separate remangling step.
• Drop libclc-remangler tool.

llvm-diff changes to remangled libspirv:

• _clc functions from CLC library are now not remangled because we use
  a single clc library that defaults to OpenCL C mangling.
• Some _clc functions from CLC library are no longer inlined for NVPTX.
  Previously, these were called only once and inlined before remangling.
  Now, because remangling can generate two caller variants, the _clc
  function is called twice, causing the inliner to skip them.
• Changes in _CLC_DEFINE_MIPMAP_BINDLESS_READS_BUILTIN also exposed a bug in libclc-remangler which would remangle Z30__spirv_ImageSampleExplicitLodImDv4_cDv3_fET0_T_T1_iS4_S4 (correct) to Z30__spirv_ImageSampleExplicitLodImDv4_aDv3_fET0_T_T1_iS1_S1
  This bug was hidden since correct symbol was hardcoded in the source.
• Fixed 4 __spirv_ImageArrayWrite builtins in nvptx l64.signed_char, e.g.
  _Z23__spirv_ImageArrayWriteIyiiEvT_T0_T1_i -> Z23__spirv_ImageArrayWriteIyiiEvT_T0_iT1;
  _Z23__spirv_ImageArrayWriteImiiEvT_T0_T1_i -> Z23__spirv_ImageArrayWriteImiiEvT_T0_iT1.

[Maetveis]

libclc changes LGTM. I didn't check the new pass or any of the other changes.

[Maetveis]

I'm wondering could we make clang emit calls to these functions using the correct name mangling from the start instead of re-mangling as a pass?
I was thinking a function attribute that allows to switch the name mangling to be OpenCL compatible could theoretically work for this. We would need something similar if we wanted to author libclc sources in C++.

[wenju-he]

I'm wondering could we make clang emit calls to these functions using the correct name mangling from the start instead of re-mangling as a pass?

This is interesting idea, but I don't know about how to implement the automatic mapping.

We would need something similar if we wanted to author libclc sources in C++.

Implement libspirv in C++ and compile in sycl device mode like libdevice does can indeed avoid the remangling issue. However, one problem is that it will be very difficult to share implementation between libclc OpenCL and libspirv builtin wrappers, since eventually the sharing requires a stable interface which SPV-IR intends to be.

[elizabethandrews]

FE changes just add a pass. FE changes LGTM. I have not reviewed the functionality of the pass.

[YuriPlyakhin]

4 comments left to address for files owned by me.

[YuriPlyakhin]

one comment needs to be addressed. #21588 (comment)

[YuriPlyakhin]

dpcpp-tools owned files LGTM

[wenju-he]

@intel/dpcpp-clang-driver-reviewers @intel/dpcpp-nativecpu-reviewers please review, thanks

[Copilot]

Pull request overview

This PR removes the standalone libclc-remangler tool and replaces its functionality with a new LLVM pass (SYCLRemangleLibspirvPass) that remangles libspirv builtins within the compile pipeline, while updating build logic and tests to consume the new libspirv variant naming.

Changes:

• Introduces SYCLRemangleLibspirvPass plus new SPIR mangling utilities to implement remangling inside LLVM.
• Updates libclc build to generate libspirv.l{32,64}.{signed,unsigned}_char.bc variants via the new pass and removes the libclc-remangler tool and related CMake/test wiring.
• Updates SYCL/Clang driver logic, docs, and tests to reference the new libspirv variant filenames and ensure the pass can be enabled in the pipeline.

Reviewed changes

Copilot reviewed 42 out of 46 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
sycl/test/check_device_code/native_cpu/sycl-native-cpu-libclc-windows.cpp	Updates FileCheck expectations to the new libspirv variant filename for Windows.
sycl/test/check_device_code/native_cpu/sycl-native-cpu-libclc-linux.cpp	Updates FileCheck expectations to the new libspirv variant filename for Linux.
sycl/doc/design/CompilerAndRuntimeDesign.md	Renames documented libspirv remangled artifacts to the new naming scheme.
sycl-jit/jit-compiler/lib/rtc/DeviceCompilation.cpp	Switches JIT-side libspirv variant selection to new filenames.
llvm/test/SYCLLowerIR/SYCLRemangleLibspirv/template-types.ll	Adds coverage for template-arg remangling behavior.
llvm/test/SYCLLowerIR/SYCLRemangleLibspirv/qualifiers-and-structs.ll	Adds coverage for qualifier preservation and struct-like names.
llvm/test/SYCLLowerIR/SYCLRemangleLibspirv/pointer-addrspace.ll	Adds coverage for pointer address space remangling behavior.
llvm/test/SYCLLowerIR/SYCLRemangleLibspirv/long-types.ll	Adds coverage for long/ulong remangling across width modes.
llvm/test/SYCLLowerIR/SYCLRemangleLibspirv/float16-types.ll	Adds coverage for half/_Float16 remangling.
llvm/test/SYCLLowerIR/SYCLRemangleLibspirv/filter-non-spirv.ll	Adds coverage ensuring non-__spirv_ functions are not remangled.
llvm/test/SYCLLowerIR/SYCLRemangleLibspirv/char-unsigned.ll	Adds coverage for char remangling when target char is unsigned.
llvm/test/SYCLLowerIR/SYCLRemangleLibspirv/char-signed.ll	Adds coverage for char remangling when target char is signed.
llvm/test/SYCLLowerIR/SYCLRemangleLibspirv/bidirectional-collision.ll	Adds coverage for rename/clone collision handling (.tmp resolution).
llvm/lib/SYCLLowerIR/SYCLRemangleLibspirv.cpp	Implements the new LLVM module pass with remangling + cloning logic.
llvm/lib/SYCLLowerIR/MangleUtils.cpp	Adds SPIR mangling utilities used by the pass.
llvm/lib/SYCLLowerIR/CMakeLists.txt	Registers new sources in the SYCLLowerIR LLVM component.
llvm/lib/Passes/PassRegistry.def	Registers the new pass name for the new pass manager.
llvm/lib/Passes/PassBuilder.cpp	Adds include hook for building pipelines that reference the pass.
llvm/include/llvm/SYCLLowerIR/SYCLRemangleLibspirv.h	Adds the public pass header.
llvm/include/llvm/SYCLLowerIR/MangleUtils.h	Adds SPIR type system declarations used by the mangler.
libclc/utils/libclc-remangler/LibclcRemangler.cpp	Deletes the standalone remangler tool implementation.
libclc/utils/libclc-remangler/CMakeLists.txt	Removes build definition for the deleted remangler tool.
libclc/utils/CMakeLists.txt	Removes subdirectory that built the remangler tool.
libclc/test/CMakeLists.txt	Removes remangler-test target plumbing.
libclc/libspirv/lib/ptx-nvidiacl/images/image.cl	Adjusts builtin macro arguments to avoid prior remangler bug exposure.
libclc/cmake/modules/AddLibclc.cmake	Removes remangle option/logic and moves per-arch objdir creation into function.
libclc/CMakeLists.txt	Generates libspirv variants via new pass; removes remangler tool integration and option.
clang/test/Driver/sycl-oneapi-gpu-nvidia.cpp	Updates driver tests to use new libspirv variant path.
clang/test/Driver/sycl-offload-static-lib-2-old-model.cpp	Updates driver tests to use new libspirv variant path.
clang/test/Driver/sycl-offload-old-model.cpp	Updates driver tests to use new libspirv variant path.
clang/test/Driver/sycl-offload-nvptx.cpp	Updates driver tests to rely on resource-dir and expect new libspirv variant selection.
clang/test/Driver/sycl-nvptx-link.cpp	Updates link-stage checks to match new libspirv variant filename.
clang/test/Driver/sycl-libspirv-toolchain.cpp	Updates toolchain discovery tests + error messages for new libspirv filenames.
clang/test/Driver/sycl-libspirv-invalid.cpp	Updates invalid-path error expectations to new libspirv filenames.
clang/test/Driver/sycl-device-obj-asm.cpp	Updates explicit libspirv input path used in warning tests.
clang/test/Driver/sycl-cuda-rdc.cpp	Updates CUDA RDC driver test to use new libspirv variant filename.
clang/test/CodeGen/sycl-remangle-libspirv-pipeline.cl	Adds a pipeline-print test ensuring the clang flag enables the pass.
clang/lib/Driver/ToolChains/SYCL.cpp	Updates default libspirv basename selection to new naming scheme.
clang/lib/CodeGen/BackendUtil.cpp	Wires CodeGen option to add the pass at optimizer-last EP callback.
clang/include/clang/Options/Options.td	Adds -fsycl-remangle-libspirv CC1 option to enable the pass.
clang/include/clang/Basic/CodeGenOptions.def	Adds SYCLRemangleLibspirv codegen option flag.
buildbot/configure.py	Removes obsolete LIBCLC_GENERATE_REMANGLED_VARIANTS buildbot plumbing.

Comments suppressed due to low confidence (2)

llvm/test/SYCLLowerIR/SYCLRemangleLibspirv/char-signed.ll:1

• This RUN line doesn't actually run the new pass, so the test won't validate remangling behavior (and may fail due to unused/unknown options depending on how opt is built). Update the invocation to include the pass pipeline (e.g., -passes=sycl-remangle-libspirv) consistent with the other tests in this directory.
  llvm/lib/SYCLLowerIR/SYCLRemangleLibspirv.cpp:1
• The remangled-name validity check is enforced only via assert, meaning release builds won't guard against producing malformed names if an unexpected demangler/mangler edge case occurs. Consider turning this into a runtime check (e.g., return false when isValidRemangledBuiltinName fails) so the pass remains safe in non-assert builds.

[wenju-he]

@bratpiorka @intel/dpcpp-nativecpu-reviewers please review, thanks

[wenju-he]

@intel/llvm-gatekeepers please merge, thanks