[Bug target/88013] can't vectorize rgb to grayscale conversion code

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88013 Andrew Pinski changed: What|Removed |Added Severity|normal |enhancement

[Bug target/88013] can't vectorize rgb to grayscale conversion code

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88013 --- Comment #9 from krux --- (In reply to ktkachov from comment #7) > I tried current trunk (future GCC 9) > GCC 9 learned to avoid excessive widening during vectorisation, which is > what accounts for the large number of instructions you see.

[Bug target/88013] can't vectorize rgb to grayscale conversion code

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88013 Ramana Radhakrishnan changed: What|Removed |Added Status|UNCONFIRMED |NEW Last reconfirmed|

[Bug target/88013] can't vectorize rgb to grayscale conversion code

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88013 --- Comment #7 from ktkachov at gcc dot gnu.org --- I tried current trunk (future GCC 9) GCC 9 learned to avoid excessive widening during vectorisation, which is what accounts for the large number of instructions you see.

[Bug target/88013] can't vectorize rgb to grayscale conversion code

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88013 --- Comment #6 from krux --- -mfloat-abi=hard was missing indeed. It's a pity there's no warning like when trying to use the intrinsics. Still I see a lot more instructions, maybe that got fixed after v7.2? https://godbolt.org/z/OWzgXi

[Bug target/88013] can't vectorize rgb to grayscale conversion code

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88013 ktkachov at gcc dot gnu.org changed: What|Removed |Added CC||ktkachov at gcc dot gnu.org

[Bug target/88013] can't vectorize rgb to grayscale conversion code

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88013 --- Comment #4 from krux --- On x64 indeed both compilers generate a huge amount of code. https://godbolt.org/z/TH7mqn

[Bug target/88013] can't vectorize rgb to grayscale conversion code

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88013 --- Comment #3 from krux --- A few NEON instructions are sufficient: https://web.archive.org/web/20170227190422/http://hilbert-space.de/?p=22 clang seems to generate similar code, see the godbolt links.

[Bug target/88013] can't vectorize rgb to grayscale conversion code

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88013 Richard Biener changed: What|Removed |Added Keywords||missed-optimization

[Bug target/88013] can't vectorize rgb to grayscale conversion code

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88013 --- Comment #1 from krux --- Something like -march=armv8-a -mfpu=neon-fp-armv8 does not work either. https://godbolt.org/z/MpBQ0I