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In `PPCGCodeGeneration`, we try to take the references of every `Value` that is used within a Scop to offload to the kernel. This occurs in `GPUNodeBuilder::createLaunchParameters`. This breaks if one of the values is a function pointer, since one of these cases will trigger: 1. We try to to take the references of an intrinsic function, and this breaks at `verifyModule`, since it is illegal to take the reference of an intrinsic. 2. We manage to take the reference to a function, but this fails at `verifyModule` since the function will not be present in the module that is created in the kernel. 3. Even if `verifyModule` succeeds (which should not occur), we would then try to call a *host function* from the *device*, which is illegal runtime behaviour. So, we disable this entire range of possibilities by simply not allowing function references within a `Scop` which corresponds to a kernel. However, note that this is too conservative. We *can* allow intrinsics within kernels if the backend can lower the intrinsic correctly. For example, an intrinsic like `llvm.powi.*` can actually be lowered by the `NVPTX` backend. We will now gradually whitelist intrinsics which are known to be safe. Differential Revision: https://reviews.llvm.org/D33414 llvm-svn: 305185
Polly - Polyhedral optimizations for LLVM ----------------------------------------- http://polly.llvm.org/ Polly uses a mathematical representation, the polyhedral model, to represent and transform loops and other control flow structures. Using an abstract representation it is possible to reason about transformations in a more general way and to use highly optimized linear programming libraries to figure out the optimal loop structure. These transformations can be used to do constant propagation through arrays, remove dead loop iterations, optimize loops for cache locality, optimize arrays, apply advanced automatic parallelization, drive vectorization, or they can be used to do software pipelining.