Open Bug 810604 Opened 9 years ago Updated 7 years ago

vertical white lines in downscaled images when building with --enable-optimize=-O3

Categories

(Core :: ImageLib, defect)

x86_64
Linux
defect
Not set
normal

Tracking

()

People

(Reporter: dbaron, Unassigned)

References

Details

Attachments

(2 files)

So ever since bug 486918 landed (but not during the period when it was backed out) I've been seeing vertical white lines in a lot of downscaled images; for images that load incrementally they don't show up until the image is done loading.

However, I only see these lines in builds I build myself, but I don't see them in official Firefox nightlies.  However, I've just verified that the determining factor there is the toolchain or mozconfig rather than my local patches; I still see the white lines with a clean tree.

I haven't yet figured out which parts of my build configuration are the problem, though, but I wanted to get a bug on file in case anyone else is seeing the same thing.
Blocks: 486918
Attached image screenshot
This is one of the worse examples.
Attached file my about:buildconfig
The crucial bit turns out to be:
  --enable-optimize="-O3 -march=corei7 -mtune=corei7"

If I switch to just --enable-optimize (which, on Linux, means -Os) by taking the is_windows path in https://hg.mozilla.org/users/dbaron_mozilla.com/mozconfigs/raw-file/f173758c559e/common-opt , then the problem goes away.
Summary: vertical white lines in downscaled images (some build configurations or toolchains only) → vertical white lines in downscaled images when building with --enable-optimize='-O3 -march=corei7 -mtune=corei7'
Interestingly:
  --enable-optimize="-Os -march=corei7 -mtune=corei7"
works fine.  (And I was getting ready to start poking around in gfx/skia/src/opts/.)
And with just:
  --enable-optimize="-O3"
I still see the bug.
Summary: vertical white lines in downscaled images when building with --enable-optimize='-O3 -march=corei7 -mtune=corei7' → vertical white lines in downscaled images when building with --enable-optimize=-O3
I'm seeing this with march=core-avx-i but on OS, O2 and O3 on gentoo using the last several firefox versions up to the current: GCC 4.8.2, firefox 27.0.1, mesa 9.2.5-r1, xf86-video-intel 2.99.910.
Seeing the same with GCC 4.9 + FF v29, lines go away if I revert to bog-standard CFLAGS on Gentoo with no "custom-optimization custom-cflags", but it's there with OS/O2/etc, so march=native? It's obviously slower with my larger tabsets...
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