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Intel SPMD Program Compiler
C++ LLVM Python Cuda C Makefile Other

Merge pull request #1027 from dbabokin/osxsave

Adding check for OSXSAVE before checking xgetbv in cpu detection code.
latest commit 1328efd027
@dbabokin dbabokin authored
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builtins Adding check for OSXSAVE before checking xgetbv in cpu detection code.
contrib Vim syntax support for operators
docs Copyright refresh
examples Copyright refresh
llvm_patches Update 3_5_win_coff_debug_info.patch
ptxtools Copyright refresh
tests Added structure alignment in headers; extended the test system to sup…
tests_errors Choose type for integer literals to match the target mask size (if po…
.gitignore Windows support
LICENSE.txt 3.7-related copyright update
Makefile Typo fix in Makefile
README.rst Include AVX2 in supported ISAs allow x86_64 in (run_tests has no problems with it)
ast.cpp Copyright refresh
ast.h correction of --instrument option support
buildall.bat Fix various warnings / build issues on Windows
buildispc.bat Adding new line to error/warning message on Windows and fixing some t…
builtins.cpp LLVM debug info fix, again
builtins.h Copyright refresh
cbackend.cpp Fix for trunk revision #232397 small corrections of test system
check_isa.cpp Adding check for OSXSAVE before checking xgetbv in cpu detection code. removed some dead code
ctx.cpp Fix typos in the previous LLVM debug info commit
ctx.h LLVM debug info fix, again
decl.cpp added #ifdef ISPC_NVPTX_ENALED ... #endif guards
decl.h Copyright update
doxygen.cfg Bumping version to 1.8.2dev
expr.cpp Adding missing AddressOfExpr::GetLValueType()
expr.h Adding missing AddressOfExpr::GetLValueType()
fail_db.txt fixed ptr-22.ispc on knl
func.cpp Merge pull request #1024 from Vsevolod-Livinskij/multitarget
func.h Copyright update
ispc.cpp Adding check for OSXSAVE before checking xgetbv in cpu detection code.
ispc.h Merge pull request #1024 from Vsevolod-Livinskij/multitarget
ispc.sln Windows build fix
ispc.vcxproj Windows build fix
lex.ll changed notation, task[Index,Count]_[x,y,z] -> task[Index,Count][1,2,…
llvmutil.cpp wiped out all LLVM 3.1 support
llvmutil.h Copyright refresh
main.cpp Change opt help message to be more clear.
module.cpp Merge pull request #1024 from Vsevolod-Livinskij/multitarget
module.h LLVM debug info fix, again
opt.cpp Added explicit types for llvm::GetElementPtrInst::Create()
opt.h Copyright update
parse.yy wiped out all LLVM 3.1 support
perf.ini changing of examples set 3.4 version of LLVM to, correction fixed knc target
simple.vcxproj Windows: fix some compiler warnings during build
stdlib.ispc Merge branch 'master' into nvptx_clean_master Python build compatible on both python 2 and 3
stmt.cpp Merge branch 'master' into nvptx_clean_master
stmt.h Copyright update
sym.cpp Copyright update
sym.h Copyright update
test_static.cpp Copyright refresh
test_static_cuda.cpp Whitespace and copyright fixes in test_static*.cpp
test_static_nvptx.cpp Whitespace and copyright fixes in test_static*.cpp import bux fixed
type.cpp Fix typos in the previous LLVM debug info commit
type.h LLVM debug info fix, again
util.cpp wiped out all LLVM 3.1 support
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.

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