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| author | Roman Lebedev <lebedev.ri@gmail.com> | 2020-01-03 19:53:29 +0300 |
|---|---|---|
| committer | Roman Lebedev <lebedev.ri@gmail.com> | 2020-01-03 20:27:29 +0300 |
| commit | cc0216bedb85642e085a53bf046966fc87dd8afc (patch) | |
| tree | 15a7f59e9cc18c585d41fb8a205fda97454a6a3e /llvm/lib/DebugInfo/DWARF/DWARFDebugLine.cpp | |
| parent | b87a351182cd7883080fe0e82c803db71ff2ba91 (diff) | |
| download | bcm5719-llvm-cc0216bedb85642e085a53bf046966fc87dd8afc.tar.gz bcm5719-llvm-cc0216bedb85642e085a53bf046966fc87dd8afc.zip | |
[NFC][InstCombine] '(X & (- Y)) - X' -> '- (X & (Y - 1))' fold (PR44448)
Name: (X & (- Y)) - X -> - (X & (Y - 1)) (PR44448)
%negy = sub i8 0, %y
%unbiasedx = and i8 %negy, %x
%r = sub i8 %unbiasedx, %x
=>
%ymask = add i8 %y, -1
%xmasked = and i8 %ymask, %x
%r = sub i8 0, %xmasked
https://rise4fun.com/Alive/OIpla
This decreases use count of %x, may allow us to
later hoist said negation even further,
and results in marginally nicer X86 codegen.
See
https://bugs.llvm.org/show_bug.cgi?id=44448
https://reviews.llvm.org/D71499
Diffstat (limited to 'llvm/lib/DebugInfo/DWARF/DWARFDebugLine.cpp')
0 files changed, 0 insertions, 0 deletions
