[Libre-soc-isa] [Bug 560] big-endian little-endian SV regfile layout idea

[bugzilla-daemon at libre-soc.org]

https://bugs.libre-soc.org/show_bug.cgi?id=560

--- Comment #33 from Jacob Lifshay <programmerjake at gmail.com> ---
Some very approximate statistics on how common bitcasting is in vector code:
jacob at jacob-desktop:~/llvm-project$ find | grep '.*\.ll$' | xargs -d$'\n' grep
'<[0-9]\+ x ' | sed 's/^\([^:]*\):.*/\1/' | uniq | xargs -d$'\n' cat | grep
bitcast | wc
  31146  353435 1776041
jacob at jacob-desktop:~/llvm-project$ find | grep '.*\.ll$' | xargs -d$'\n' grep
'<[0-9]\+ x ' | sed 's/^\([^:]*\):.*/\1/' | uniq | xargs -d$'\n' cat | wc
2090019 14424313 95369527
jacob at jacob-desktop:~/llvm-project$ git status
HEAD detached at llvmorg-11.0.0
nothing to commit, working tree clean

So 31146 bitcast instructions out of 2090019 lines of LLVM IR that mention
vector types somewhere.
31146*100%/2090019=1.49%
Note that this is mostly LLVM's testsuite so likely not as representative of
actual code. Also, this statistic includes comments and blank lines and isn't
representative of the part we care about -- how often bitcasts are executed in
performance-sensitive code.

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