Sunday, 26 August 2012

The More I See

It is possible to use printf inside an OpenCL CPU kernel on OSX; however, remember to cast the string literal operand to (char const*) pointer to get it to compile.

Further, when running an OpenCL using program it is possible to force error logging to stdout (e.g. for .cl compile errors) via 

    CL_LOG_ERRORS=stdout program Args 

Wednesday, 22 August 2012


There is an offline compiler for OpenCL included in OSX 10.7, at /System/Library/Frameworks/OpenCL.framework/Versions/A/Libraries/openclc 

This is pretty much a standard clang executable, and accepts common clang options. Sample arguments of interest, 

    -O3  -x cl -triple i386-applecl-darwin -S <

Shows the assembly code for an OpenCL kernel.

    -x cl -triple i386-applecl-darwin -emit-llvm <

Shows the LLVM textual-IR for a kernel.

The official documentation and example of this suggest the use of generating LLVM bit code offline, for 32 and 64 bit CPU and 32 bit GPU. More useful advice included in the OpenCL Mac programming guide.