Gregory's Server@chandlerc One important factor in the slow march to bounds check optimization is that LLVM traditionally lagged behind both GCC and research papers in optimizations based on integer range information. I'm not even sure when/how this got better, since it was after I was following LLVM closely.
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@pervognsen @zwarich @chandlerc there must be a lot of low hanging fruit if gcc is the benchmark :x SBCL(!) used to be stronger at integer range propagation than gcc for finer than power of 2/word size information. OTOH, I guess using range info to generate simpler div by mul is pretty niche. @zwarich @chandlerc In the early days Chris was very opposed to investment in this area on compile time grounds. |
@zwarich @chandlerc The newer ConstraintElim pass in LLVM made a relatively big difference in generated code quality when it comes to non-trivial bounds check elimination.