Skip to content
This repository

Intel SPMD Program Compiler

Merge pull request #781 from dbabokin/master

Revert trigonometry to stdlib implementation on MIC
latest commit 94467fdb70
Dmitry Babokin dbabokin authored
Octocat-spinner-32 builtins Copyright update
Octocat-spinner-32 contrib Vim syntax support for operators
Octocat-spinner-32 docs Changing overload rules to match C++ behavior: Emit a warning when th…
Octocat-spinner-32 examples 2014.
Octocat-spinner-32 llvm_patches adding patch for LLVM 3.4 for bug #712
Octocat-spinner-32 tests Changing overload rules to match C++ behavior: Emit a warning when th…
Octocat-spinner-32 tests_errors Choose type for integer literals to match the target mask size (if po…
Octocat-spinner-32 .gitignore Windows support
Octocat-spinner-32 LICENSE.txt License update (just dates)
Octocat-spinner-32 Makefile support LLVM trunk after r204934 and zlib commits
Octocat-spinner-32 README.rst Include AVX2 in supported ISAs
Octocat-spinner-32 removing winstuff
Octocat-spinner-32 ast.cpp Copyright update
Octocat-spinner-32 ast.h Copyright update
Octocat-spinner-32 correction of --instrument option support
Octocat-spinner-32 buildall.bat Fix various warnings / build issues on Windows
Octocat-spinner-32 buildispc.bat Adding new line to error/warning message on Windows and fixing some t…
Octocat-spinner-32 builtins.cpp Copyright update
Octocat-spinner-32 builtins.h Copyright update
Octocat-spinner-32 cbackend.cpp support LLVM trunk after r204934 and zlib commits
Octocat-spinner-32 small corrections of test system
Octocat-spinner-32 check_isa.cpp Typo fix
Octocat-spinner-32 correction of checking tools in testing environment
Octocat-spinner-32 ctx.cpp adding const to Atomic::Void type
Octocat-spinner-32 ctx.h Copyright update
Octocat-spinner-32 decl.cpp adding const to Atomic::Void type
Octocat-spinner-32 decl.h Copyright update
Octocat-spinner-32 doxygen.cfg Bumping ISPC version to 1.6.1dev
Octocat-spinner-32 expr.cpp Changing overload rules to match C++ behavior: Emit a warning when th…
Octocat-spinner-32 expr.h Changing overload rules to match C++ behavior: Emit a warning when th…
Octocat-spinner-32 fail_db.txt fail_db.txt update on Linux
Octocat-spinner-32 func.cpp adding const to Atomic::Void type
Octocat-spinner-32 func.h Copyright update
Octocat-spinner-32 ispc.cpp Revert trigonometry to stdlib implementation on MIC
Octocat-spinner-32 ispc.h Copyright update
Octocat-spinner-32 ispc.sln Migrating to VS solution files to VS2012
Octocat-spinner-32 ispc.vcxproj removing winstuff
Octocat-spinner-32 lex.ll changed notation, task[Index,Count]_[x,y,z] -> task[Index,Count][1,2,…
Octocat-spinner-32 llvmutil.cpp included suggested changes, ./tests/launch-*.ispc still fails. someth…
Octocat-spinner-32 llvmutil.h Revert "Remove support for building with LLVM 3.1"
Octocat-spinner-32 main.cpp support of LLVM 3.5
Octocat-spinner-32 module.cpp Merge pull request #773 from ifilippov/alias_new
Octocat-spinner-32 module.h Copyright update
Octocat-spinner-32 opt.cpp Copyright update
Octocat-spinner-32 opt.h Copyright update
Octocat-spinner-32 parse.yy adding const to Atomic::Void type
Octocat-spinner-32 perf.ini changing of examples
Octocat-spinner-32 set 3.4 version of LLVM to, correction
Octocat-spinner-32 removing winstuff
Octocat-spinner-32 simple.vcxproj Windows: fix some compiler warnings during build
Octocat-spinner-32 stdlib.ispc Removing trailing spaces in stdlib.ispc
Octocat-spinner-32 Python build compatible on both python 2 and 3
Octocat-spinner-32 stmt.cpp Copyright update
Octocat-spinner-32 stmt.h Copyright update
Octocat-spinner-32 sym.cpp Copyright update
Octocat-spinner-32 sym.h Copyright update
Octocat-spinner-32 test_static.cpp Copyright update
Octocat-spinner-32 type.cpp These changes fix problem with debug info in LLVM 3.4 with structs an…
Octocat-spinner-32 type.h Merge pull request #767 from jbrodman/nomosoa2
Octocat-spinner-32 util.cpp Copyright update
Octocat-spinner-32 util.h Copyright update

Intel(r) SPMD Program Compiler

ispc is a compiler for a variant of the C programming language, with extensions for single program, multiple data programming. Under the SPMD model, the programmer writes a program that generally appears to be a regular serial program, though the execution model is actually that a number of program instances execute in parallel on the hardware.


ispc compiles a C-based SPMD programming language to run on the SIMD units of CPUs; it frequently provides a 3x or more speedup on CPUs with 4-wide vector SSE units and 5x-6x on CPUs with 8-wide AVX vector units, without any of the difficulty of writing intrinsics code. Parallelization across multiple cores is also supported by ispc, making it possible to write programs that achieve performance improvement that scales by both number of cores and vector unit size.

There are a few key principles in the design of ispc:

  • To build a small set of extensions to the C language that would deliver excellent performance to performance-oriented programmers who want to run SPMD programs on the CPU.
  • To provide a thin abstraction layer between the programmer and the hardware--in particular, to have an execution and data model where the programmer can cleanly reason about the mapping of their source program to compiled assembly language and the underlying hardware.
  • To make it possible to harness the computational power of SIMD vector units without the extremely low-programmer-productivity activity of directly writing intrinsics.
  • To explore opportunities from close coupling between C/C++ application code and SPMD ispc code running on the same processor--to have lightweight function calls between the two languages and to share data directly via pointers without copying or reformatting.

ispc is an open source compiler with the BSD license. It uses the remarkable LLVM Compiler Infrastructure for back-end code generation and optimization and is hosted on github. It supports Windows, Mac, and Linux, with both x86 and x86-64 targets. It currently supports the SSE2, SSE4, AVX1, and AVX2 instruction sets.


ispc provides a number of key features to developers:

  • Familiarity as an extension of the C programming language: ispc supports familiar C syntax and programming idioms, while adding the ability to write SPMD programs.
  • High-quality SIMD code generation: the performance of code generated by ispc is often close to that of hand-written intrinsics code.
  • Ease of adoption with existing software systems: functions written in ispc directly interoperate with application functions written in C/C++ and with application data structures.
  • Portability across over a decade of CPU generations: ispc has targets for SSE2, SSE4, AVX (and soon, AVX2).
  • Portability across operating systems: Microsoft Windows, Mac OS X, and Linux are all supported by ispc.
  • Debugging with standard tools: ispc programs can be debugged with standard debuggers (OS X and Linux only).

Additional Resources

Prebuilt ispc binaries for Windows, OS X and Linux can be downloaded from the ispc downloads page. See also additional documentation and additional performance information.

Something went wrong with that request. Please try again.