Some documentation about debugging the swift compiler: https://github.com/apple/swift/blob/master/docs/DebuggingTheCompiler.rst <https://github.com/apple/swift/blob/master/docs/DebuggingTheCompiler.rst>
Possibly, not all flags are documented: https://github.com/apple/swift/blob/master/lib/SILOptimizer/PassManager/PassManager.cpp <https://github.com/apple/swift/blob/master/lib/SILOptimizer/PassManager/PassManager.cpp> To your specific question: We run several stages of the PerformanceInliner (https://github.com/apple/swift/blob/master/lib/SILOptimizer/Transforms/PerformanceInliner.cpp#L866 <https://github.com/apple/swift/blob/master/lib/SILOptimizer/Transforms/PerformanceInliner.cpp#L866>) during our PassPipeline (https://github.com/apple/swift/blob/master/lib/SILOptimizer/PassManager/PassPipeline.cpp#L221 <https://github.com/apple/swift/blob/master/lib/SILOptimizer/PassManager/PassPipeline.cpp#L221>) . One stage — “the high-level stage” — inlines everything up to “@_semantics” functions. The next stage also inlines those. - Run PerformanceInliner without-semantic-inlining (https://github.com/apple/swift/blob/master/lib/SILOptimizer/PassManager/PassPipeline.cpp#L445 <https://github.com/apple/swift/blob/master/lib/SILOptimizer/PassManager/PassPipeline.cpp#L445>) - Run Optimizations that rely on seeing @semantics calls - … - Run PerformanceInline with-semantic-inlining (https://github.com/apple/swift/blob/master/lib/SILOptimizer/PassManager/PassPipeline.cpp#L449 <https://github.com/apple/swift/blob/master/lib/SILOptimizer/PassManager/PassPipeline.cpp#L449>) - … If you mark a function like append with @_semantics which internally has calls to @_semantics functions you prevent the optimizations that rely on having those calls exposed/inlined from working since those calls are now hidden behind an @_semantics function that did not get inlined. The file https://github.com/apple/swift/blob/master/lib/SILOptimizer/PassManager/PassPipeline.cpp <https://github.com/apple/swift/blob/master/lib/SILOptimizer/PassManager/PassPipeline.cpp> contains the code that sets up the pass pipeline. You can see which optimizations are scheduled in which order. If you want to see a list of passes being run dynamically "-Xllvm -sil-print-pass-name" would be the flag to add, I think. > On Mar 3, 2017, at 9:58 AM, Ben Ng via swift-dev <swift-dev@swift.org> wrote: > > I noticed that adding any semantic attribute to the two Array.append > functions causes performance regressions in the Array benchmark. I think that > it’s because the delayed inlining is blocking some array optimizations from > happening. > > What are some tips for debugging this sort of issue? There are a whole bunch > of passes, and it’s difficult to figure out how they all interact. Reading > the SIL generated after all optimizations have been run is pretty tedious, > and I’m hoping that there’s a smarter way to go about this > . > > Can I get debug output that tells me what optimizations happened, and then > diff the two outputs to find out what changed? > > I also see a “Pass Pipeline” utility that looks useful, but it’s not obvious > to me how to use it.
_______________________________________________ swift-dev mailing list swift-dev@swift.org https://lists.swift.org/mailman/listinfo/swift-dev
