search for: pr22346

Hi all, The DAGCombiner pass actually runs even if the optimize level is set to None. This can result in incorrect debug information or unexpected stepping/debugging experience. Not to mention that having good stepping/debugging experience is the major reason to compile at /O0. I recently suggested a patch to disable one specific DAG combine at /O0 that broke stepping on a particular case

...ers, -Quentin > On May 13, 2016, at 12:51 PM, Robinson, Paul via llvm-dev <llvm-dev at lists.llvm.org> wrote: > > (Remembering to re-add llvm-dev again…) > Yes, this would be too aggressive. DAG combiner does more than just optimization (which I discovered as part of D7181, see PR22346). > Internally we've thrown around other ideas, for example inside the worklist loop, skip loads and stores at O0, but haven't done any actual experiments. There are probably other bits of the combiner that could be turned off at O0, but I think they'd have to be considered individu...