Version Tracking

This page documents the exact version identifiers embedded in the cicc v13.0 binary and the version relationships between its components. Every version listed here was recovered from string constants, constructor initializations, or binary header fields in the stripped ELF binary. This is the single source of truth for version-related questions across the wiki.

Version Summary

LLVM Version: The Dual Identity

CICC has two LLVM version identities. Internally, it is an LLVM 20.0.0 fork -- all modern instruction opcodes, metadata formats, type encodings, and pass infrastructure from LLVM 20 are present. Externally, the bitcode it emits identifies itself as "LLVM7.0.1" in the producer field.

The reason is historical: NVVM IR 2.0 was defined against LLVM 7.0.1. The entire NVVM toolchain ecosystem (libNVVM, nvcc's device pipeline, nvdisasm, third-party NVVM IR consumers) standardized on "LLVM7.0.1" as the format identifier. Changing the producer string would require a coordinated update across the entire CUDA toolkit and all downstream consumers.

Binary evidence:

• ctor_036 at 0x48CC90: reads LLVM_OVERRIDE_PRODUCER environment variable, falls back to "20.0.0" (the true version).
• ctor_154 at 0x4CE640: reads LLVM_OVERRIDE_PRODUCER, falls back to "7.0.1" (the compatibility marker). This is the constructor that runs for the bitcode writer path.
• sub_E7A190: contains the string "llvm-mc (based on LLVM 20.0.0)".
• sub_1538EC0 (writeModule): emits "LLVM" + "7.0.1" = "LLVM7.0.1" as the IDENTIFICATION_BLOCK producer.

Both constructors accept the LLVM_OVERRIDE_PRODUCER environment variable to override the default. Setting it changes the embedded producer string in output bitcode.

See Bitcode Reader/Writer for the full dual-producer mechanism.

EDG 6.6 Frontend

The EDG (Edison Design Group) frontend is a licensed commercial C/C++ frontend. Version 6.6 occupies 3.2 MB of code at 0x5D0000--0x8F0000. The version string is embedded literally as "Based on Edison Design Group C/C++ Front End, version 6.6" and is accessible via the --version flag.

EDG 6.6 in cicc is configured to emulate GCC 8.1 (DEFAULT_GNU_VERSION = 80100) and Clang 9.1 (DEFAULT_CLANG_VERSION = 90100). It supports C++23 as the newest C++ standard and C23 as the newest C standard, with C++17 as the default mode.

See EDG 6.6 Frontend for the full frontend documentation.

NVVM IR Version

The NVVM IR version is a metadata tuple (major, minor) embedded in every NVVM bitcode module via the !nvvmir.version named metadata node. CICC v13.0 has two distinct version contexts:

User code: the IR generation phase (sub_9151E0) emits !nvvmir.version with the current version tuple. The version checker at sub_157E370 enforces major == 3 and minor <= 2, making 3.2 the current maximum accepted version. Modules with major != 3 or minor > 2 are rejected with "Broken module found, compilation aborted!".

Libdevice: the embedded libdevice.10.bc carries !nvvmir.version = !{i32 2, i32 0}. The version (2, 0) is hard-coded in the version checker (sub_12BDA30) as an always-compatible sentinel -- it passes the check regardless of the current NVVM IR version. This ensures the embedded math library is compatible with any user module.

Container format: the NVVM container binary header stores version fields separately at offsets 0x06--0x07 (nvvm_ir_major, nvvm_ir_minor). These track the container-level IR spec version and may differ from the bitcode-level metadata tuple.

Bypass: setting NVVM_IR_VER_CHK=0 in the environment disables version validation entirely, allowing any version tuple to pass.

See Bitcode Reader/Writer for the version gate implementation and NVVM Container for the container-level version fields.

Embedded Libdevice

The embedded libdevice is libdevice.10.bc, a 455,876-byte LLVM bitcode library containing 352 GPU-optimized math functions. Two identical copies are statically embedded in the binary:

Key properties:

• Target triple: nvptx64-nvidia-gpulibs
• Function count: 352 (all alwaysinline nounwind)
• NVVM IR version: (2, 0) -- always-compatible sentinel
• Producer: "clang version 3.8.0 (tags/RELEASE_380/final)" -- the Clang version that originally compiled libdevice (not indicative of cicc's own compiler version)
• NVVMReflect calls: uses __nvvm_reflect("__CUDA_FTZ"), __nvvm_reflect("__CUDA_ARCH"), and __nvvm_reflect("__CUDA_PREC_SQRT") for runtime specialization

The libdevice.10.bc naming convention carries forward from the CUDA 5.0 era. The 10 in the filename originally indicated "compute capability 1.0 and above" (i.e., universal), not a version number.

See Libdevice Linking for the linking algorithm, version validation, and NVVMReflect interaction.

NVVM Container Format Version

The NVVM container binary envelope uses its own versioning scheme, independent of the NVVM IR version:

The container's LLVM version encoding stores the combined value 20 * 100 + 0 = 2000, confirming the internal LLVM 20.0.0 base.

See NVVM Container for the full binary format specification.

Version Cross-Reference Matrix

How versions flow through the pipeline:

                    EDG 6.6 Frontend
                         |
                         v
                    NVVM IR Generation
                    (emits nvvmir.version = {3, 2})
                         |
                    +----+----+
                    |         |
              libdevice    user IR
           (version 2,0) (version 3,2)
                    |         |
                    +----+----+
                         |
                    NVVM IR Version Check
                    (gate: major==3, minor<=2)
                    (sentinel: 2,0 always passes)
                         |
                    LLVM 20.0.0 Optimizer
                         |
                    Bitcode Writer
                    (producer: "LLVM7.0.1")
                         |
                    NVVM Container Serializer
                    (container version 1.x, LLVM encoded as 2000)
                         |
                         v
                    .ptx / .optixir output

Future Updates

This wiki documents cicc v13.0 from CUDA 12.8. When a new CUDA toolkit release ships a newer cicc binary, the following version fields are the most likely to change:

• LLVM base version: NVIDIA periodically rebases on newer LLVM releases. A jump from 20.0.0 to a later version would change the internal string, the container LLVM encoding, and potentially add new passes, opcodes, and metadata formats.
• EDG version: EDG releases track independently of LLVM. A bump from 6.6 to a later version would affect C++ standard support, keyword handling, and the frontend error catalog.
• NVVM IR version minor: the minor field (currently 2 in the major == 3 series) may increment to accommodate new metadata kinds or intrinsic conventions without breaking the major version.
• PTX ISA version: new SM targets require new PTX versions. sm_100 Blackwell already uses a higher PTX version than sm_90 Hopper.
• SM target range: new GPU architectures add new SM numbers. The sm_75--sm_121 range in v13.0 will expand in future releases.

The bitcode producer string ("LLVM7.0.1") is unlikely to change in the near term -- doing so would break backward compatibility with the entire NVVM IR ecosystem. The libdevice version sentinel (2, 0) is similarly stable because the version checker special-cases it.

To update this wiki for a new cicc version:

1. Extract the build string (search for cuda_XX.Y.rXX.Y/compiler.).
2. Check ctor_036 for the LLVM version fallback string.
3. Check the EDG version string at sub_617BD0.
4. Check the NVVM IR version gate constants at the version checker function.
5. Measure the embedded libdevice size and function count.
6. Verify the NVVM container header version fields.

Cross-References

• Bitcode Reader/Writer -- producer string mechanism, version gate implementation
• NVVM Container -- container binary format with version header fields
• Libdevice Linking -- embedded math library, version sentinel
• EDG 6.6 Frontend -- frontend version, GCC/Clang emulation modes
• Binary Layout -- build ID string, ELF properties
• Entry Point & CLI -- dual-path dispatch, version string arguments
• Environment Variables -- LLVM_OVERRIDE_PRODUCER, NVVM_IR_VER_CHK
• Debug Info Verification -- debug version field (3.2)