https://llvm.org/bugs/show_bug.cgi?id=31118
Bug ID: 31118
Summary: AVX512: inefficient code generation
Product: libraries
Version: trunk
Hardware: PC
OS: Linux
Status: NEW
Severity: normal
Priority: P
Component: Backend: X86
Assignee: unassignedb...@nondot.org
Reporter: roland.sch...@intel.com
CC: llvm-bugs@lists.llvm.org
Classification: Unclassified
Compared to ICC 17u1 on KNL, clang produces inefficient code for intrinsic code
Steps to reproduce:
git clone -b clang https://github.com/rolandschulz/gromacs.git
cd gromacs
mkdir clang
cd clang
CC=clang CXX=clang++ cmake -DGMX_MPI=on -DGMX_SIMD=AVX_512_KNL
-DGMX_BUILD_HELP=OFF -DBUILD_SHARED_LIBS=no -DGMX_CYCLE_SUBCOUNTERS=yes ..
make
cd ..
mkdir icc
cd icc
CC=icc CXX=icpc cmake .. -DGMX_FFT_LIBRARY=mkl -DGMX_SIMD=AVX_512_KNL
-DGMX_MPI=on -DGMX_BUILD_HELP=OFF -DBUILD_SHARED_LIBS=no
-DGMX_CYCLE_SUBCOUNTERS=yes
On KNL (7250) for both binaries (clang/bin and icc/bin)
OMP_WAIT_POLICY=active mpirun -n 34 numactl -m 1 gmx_mpi mdrun -ntomp 4 -nsteps
8000 -resetstep 4000 -noconfout -nstlist 35 -npme 7 -notunepme -pin on
My results (values in second for function which is the most important compute
kernel and mostly intrinsics):
awk /Nonb/'{print $6}' md.log
ICC: 4.921
Clang: 5.349
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