821.gcc_s
SPEC CPU®2026 Benchmark Description

Benchmark Name

821.gcc_s

Benchmark Program General Category

C Language optimizing compiler

Benchmark Authors

Richard Stallman and a large cast of contributors.
For a full list, see http://gcc.gnu.org/onlinedocs/gcc/Contributors.html.

Benchmark Description

The benchmark is based on GCC Version 11.2.0. It generates code for an x86_64 processor. The benchmark runs as a compiler with many of its optimization flags enabled.

The benchmark has altered inlining heuristics, so as to inline more code than may be typical of Unix systems as of the time that the porting work was done for the benchmark. This was first done in CPU 2017 502.gcc_r so that it would spend more time analyzing its source code inputs, which consumes more memory.

Input Description

The inputs to the SPECrate® benchmark 721.gcc_r are C source code files coming from SPEC CPU 2017 502.gcc. The large files for the ref workloads are GCC itself, after preprocessing. The presentation of the entire (preprocessed) source set at one time reduces I/O and allows the benchmark compiler a wide scope as it considers optimizations. There are several optimizations used, which can be found in the file control in each of the input directories. For example, the brief 'test' workload uses -O3 -finline-limit=50000 to simply compile "hello world".

The SPECspeed® benchmark 821.gcc_s runs a multi-tasking batch flow, mimicking a "make -j" scenario. The input consists of 2800 pre-processed C files that are run using "nthreads" worker jobs simultaneously. The 2800 inputs come from other SPEC CPU benchmark sources, along with some other inputs offered by the University of Alberta's workloads analysis on 502.gcc and Stephen McCaman's single compilation-unit programs. These are pre-processed source files from RocksDB, 505.mcf, 777.zstd, gcc, 735.gem5, 709.cactus, oggenc, bzip2, and 519.lbm.

New inputs can be generated by writing C source code and preprocessing it.

Output Description

The 721.gcc_r (SPECrate) output files are x86_64 assembly code files. These are validated in total without any tolerance.

The 821.gcc_s (SPECspeed) output files are also x86_64 assembly code files; however in order to save time the validation does not occur on the full output of the files, but rather the sha256sum of each file is printed out into a file which is alphabetically sorted when all tasks are complete. This accomodates out-of-order completion of each task, as well as quick validation of 2800 output files.

Programming Language

C / C++

Threading Model

The SPECrate version is single-threaded. The SPECspeed version runs several processes with different inputs concurrently.

Known Portability Issues

None

Sources and Licensing

721.gcc_r and 821.gcc_s are based on the GNU C compiler version 11.2.

The directories src/libcpp and src/libdecnumber are part of GCC. They are released under GPL Version 3.
The directory src/libiberty is distributed under GPL Version 2 and includes modules that are copyrighted by the Regents of the University of California and distributed under the BSD License.
The directory src/libbacktrace is distributed with Copyright (C) Free Software Foundation, Inc. copyright under the BSD license
The directories src/mpfr, src/mpc, src/gmp are distributed with Copyright (C) Free Software Foundation, Inc. under GNU Lesser General Public License Version 3
The directory src/zlib is copyrighted by Jean-loup Gailly and Mark Adler and distributed with a permissive software license: LICENSE.zlib.txt

The input data for gcc uses a variety of applications which are licensed separately from the gcc sources, as detailed below:

GCC 4.5 distributed under GPL Version 3
Scilab distributed under GPL Version 2
libbacktrace distributed under BSD license
Cactus source files are distributed under the GNU Library GPL-v2.0. The original sources for Cactus may be found on the SPEC CPU ISO image in the directory called redistributable_sources/original/709.cactus_r.
GCC source files are distributed under the GNU GPL-v3.0. The original sources for GCC may be found on the SPEC CPU ISO image in the directory called redistributable_sources/original/721.gcc_r.
Gem5 source files are distributed under the BSD-3 license. The original sources for Gem5 may be found on the SPEC CPU ISO image in the directory called redistributable_sources/original/735.gem5_r.
RocksDB source files are used under the Apache License v2.0.
Zstd source files are distributed under the BSD-3 license. The original sources for Zstd may be found on the SPEC CPU ISO image in the directory called redistributable_sources/original/777.zstd_r.
oggenc source files are distributed under the GNU Library GPL-v2.0.
MCF is licensed directly to SPEC by Dr. Andreas Löbel. Konrad-Zuse-Zentrum Berlin (ZIB).
LBM is licensed directly to SPEC by Thomas Pohl.

References

GCC 11.2.0 (latest on GCC git)
José Nelson Amaral et al., The Alberta Workloads for the SPEC CPU 2017 Benchmark Suite, 2018 IEEE International Symposium on Performance Analysis of Systems and Software (ISPASS), Belfast, UK, 2018, pp. 159-168, doi: 10.1109/ISPASS.2018.00029.
Scilab

821.gcc_s SPEC CPU®2026 Benchmark Description