DDX/DDY could cause miscompilation, but I think that only happens if LLVM clones or causes some paths to net execute them.
Someone proposed some time ago on llvmdev to add a flag to tell llvm to never duplicate an intrinsic, not sure if that went through (iirc, it was for a barrier instruction that relied on the instruction pointer). Alternatively, it should be possible to just disable any passes that clone basic blocks if those instructions are present. The non-execution problem should be fixable by declaring DDX/DDY to have global-write-like side effects (this will prevent dead code elimination of them if they are totally unused, but hopefully shaders are not written so badly they need that). ------------------------------------------------------------------------------ Download Intel® Parallel Studio Eval Try the new software tools for yourself. Speed compiling, find bugs proactively, and fine-tune applications for parallel performance. See why Intel Parallel Studio got high marks during beta. http://p.sf.net/sfu/intel-sw-dev _______________________________________________ Mesa3d-dev mailing list Mesa3d-dev@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/mesa3d-dev
