Hi, Thank you for investigation.
I have a colleague who is working on the machine pipeliner. I'll ask him. Regards, Takahiro Kawashima, Fujitsu > > It is caused by enabling the slp-vectorizer pass. > > Failing tests are the following. > > > > > > https://github.com/fujitsu/compiler-test-suite/blob/main/Fortran/0105/0105_0223.f90 > > > > https://github.com/fujitsu/compiler-test-suite/blob/main/Fortran/0631/0631_0051.f > > > > https://github.com/fujitsu/compiler-test-suite/blob/main/Fortran/0631/0631_0054.f > > > > Compiler flags are the following. > > > > flang -O3 -mcpu=neoverse-v1 -msve-vector-bits=scalable -mllvm > > -scalable-vectorization=preferred -mllvm > > -treat-scalable-fixed-error-as-warning=false -mllvm > > -aarch64-enable-pipeliner -mllvm -pipeliner-mve-cg -DNDEBUG -fstack-arrays > > > > 0631_0051.f and 0631_0054.f seem to fail by miscompiling. Output of ot test > > execution differs form the expected one. > > > > 0105_0223.f90 fails by an assertion failure in the backend. > > > > flang: llvm/include/llvm/CodeGen/SlotIndexes.h:626: void > > llvm::SlotIndexes::insertMBBInMaps(llvm::MachineBasicBlock*): Assertion > > `unsigned(mbb->getNumber()) == MBBRanges.size() && "Blocks must be added in > > order"' failed. > > Thank you for pointing me in the right direction. I was able to reproduce the > issue in my own > environment as well. It appears that it's the combination of "-mllvm > -aarch64-enable-pipeliner -mllvm -pipeliner-mve-cg" > with "-fslp-vectorize" that is causing problems in this case. Based on my > testing: > > flang -O3 -mcpu=neoverse-v1 -mllvm -aarch64-enable-pipeliner -mllvm > -pipeliner-mve-cg -fslp-vectorize 0105_0223.f90 <- broken > flang -O3 -mcpu=neoverse-v1 -mllvm -aarch64-enable-pipeliner -mllvm > -pipeliner-mve-cg -fno-slp-vectorize 0105_0223.f90 <- working > flang -O3 -mcpu=neoverse-v1 -fslp-vectorize 0105_0223.f90 <- working > flang -O3 -mcpu=neoverse-v1 0105_0223.f90 <- working (same as above, > -fslp-vectorize is enabled by O3) > > I've not had any prior experience with the two machine pipeliner flags in > question, but I'll reach > out to some people who should know more and try to determine where the issue > is coming from. > > Overall I think the consensus in the flang community is that -O3 should > behave the same way it does > in clang, and since clang enables the slp-vectorizer by default then so > should flang. I'm not sure > whether an interaction with llvm backend flags such as this one here is > reason enough to diverge > from that, but I'll start a discussion and get some external opinions on > that. I suppose it depends > on whether the issue actually originates in the slp-vectorizer or in the > pipeliner flags. > > In the meantime, would you be able to determine whether the reasons for those > flags being passed to > your test suite in the first place are already covered by the slp-vectorizer? > As in, does omitting > "-mllvm -aarch64-enable-pipeliner -mllvm -pipeliner-mve-cg" actually achieve > measurably worse > results than leaving those in alongside "-fno-slp-vectorize"? If so then it > will be a very useful > datapoint for determining what the priority here should be. > > Thanks, > Kajetan _______________________________________________ linaro-toolchain mailing list -- linaro-toolchain@lists.linaro.org To unsubscribe send an email to linaro-toolchain-le...@lists.linaro.org
