https://bugs.llvm.org/show_bug.cgi?id=44115
Bug ID: 44115
Summary: Benchmark partialsums - worse perf with -march=haswell
Product: libraries
Version: trunk
Hardware: PC
OS: Linux
Status: NEW
Severity: enhancement
Priority: P
Component: Backend: X86
Assignee: unassignedb...@nondot.org
Reporter: david.bolvan...@gmail.com
CC: craig.top...@gmail.com, llvm-bugs@lists.llvm.org,
llvm-...@redking.me.uk, spatel+l...@rotateright.com
Benchmark source:
https://github.com/llvm/llvm-test-suite/blob/master/SingleSource/Benchmarks/BenchmarkGame/partialsums.c
clang cc.c -Ofast -lm
0m0,133s
clang cc.c -Ofast -march=haswell -lm
0m0,146s
Codegen: https://godbolt.org/z/sZpeCQ
clang cc.c -Ofast -fno-unroll-loops -lm
0m0,129s
So, there is codegen and loop unrolling issue here..
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