Hi Hal, Thanks, the patches are committed in r244523 and r244526.
There are two possibilities to give the user control over pointer checking. We could add a loop hint option like vectorize(check_safety) that would be a safe version of ‘assume_safety’ or we could simply make it always emit the necessary pointer checks, no matter how many of them there are, when the loop hint vectorize(enable) is specified? What do you think? Tyler > On Aug 9, 2015, at 9:41 PM, Hal Finkel <hfin...@anl.gov> wrote: > > Hi Tyler, > > This looks very useful. > > Please don't mention '-mllvm -runtime-memory-check-threshold=' in the error > message. We should add some clause to #pragma clang loop to control this > feature with some associated metadata. '-mllvm' things should not be part of > the advertised interface to end users (but that should be a separate set of > patches regardless). > > Otherwise, LGTM. > > Thanks again, > Hal > > ----- Original Message ----- >> From: "Tyler Nowicki" <tnowi...@apple.com <mailto:tnowi...@apple.com>> >> To: "Hal J. Finkel" <hfin...@anl.gov <mailto:hfin...@anl.gov>>, "Commit >> Messages and Patches for LLVM" <llvm-comm...@lists.llvm.org >> <mailto:llvm-comm...@lists.llvm.org>>, "llvm >> cfe" <cfe-commits@lists.llvm.org <mailto:cfe-commits@lists.llvm.org>> >> Cc: "Gerolf Hoflehner" <ghofleh...@apple.com <mailto:ghofleh...@apple.com>> >> Sent: Thursday, August 6, 2015 3:25:26 PM >> Subject: [Patch][LoopVectorize] Late evaluate of runtime pointer check's >> threshold >> >> >> Hi, >> >> >> This patch extends the patches in ' Late evaluation of vectorization >> requirements’ (still in review). This makes the num runtime pointer >> checks test into a late diagnostic so we can give the user a better >> diagnostic message. Clang appends the diagnostic with options for >> getting the loop vectorized. Here is an example of the diagnostic >> the user will see: >> >> >> "remark: loop not vectorized: cannot prove pointers refer to >> independent arrays in memory. The loop requires 9 runtime >> independence checks to safely vectorize the loop, but that would >> exceed the limit of 8 checks; increase the number of runtime pointer >> checks with the compiler option ‘-mllvm >> -runtime-memory-check-threshold=’. To avoid runtime pointer checking >> when you know the arrays will always be independent specify ‘#pragma >> clang loop vectorize(assume_safety)’ before the loop or specify >> ‘restrict’ on the array arguments. Erroneous results will occur if >> these options are incorrectly applied." >> >> >> The diagnostic is produced when the command line option >> -Rpass-analysis=loop-vectorize is provided. >> >> >> Reviews/comments are much appreciated! >> >> >> Tyler >> >> >> >> >> >> >> > > -- > Hal Finkel > Assistant Computational Scientist > Leadership Computing Facility > Argonne National Laboratory
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