[LLVMdev] General strategy to optimize LLVM IR

St├ęphane Letz letz at grame.fr
Tue Jul 16 08:16:41 PDT 2013


Our DSL emit sub-optimal LLVM IR that we optimize later on (LLVM IR ==> LLVM IR) before dynamically compiling it with the JIT. We would like to simply follow what clang/clang++ does when compiling with -O1/-O2/-O3 options. Our strategy up to now what to look at the opt.cpp code and take part of it in order to implement our optimization code.

It appears to be rather difficult to follow evolution of the LLVM IR optimization strategies. With LLVM 3.3 our optimization code does not produce code as fast as the one produced with clang -03 anymore. Moreover the new vectorizations passes are still not working.

It there a recommended way to add -O1/-O2/-O3 kind of optimizations on LLVM IR code? Any code to look at beside the opt.cpp tool?


St├ęphane Letz

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