Bug 53620 – GCC compiler on ARM issues bogus warnings and fails to compile.

• Component: New Bugs
• Status: RESOLVED FIXED

[Dimitri Glazkov (Google)]

GCC compiler on ARM issues bogus warnings and fails to compile.

[Dimitri Glazkov (Google)]

Created attachment 80955 [details]
Patch

[Dimitri Glazkov (Google)]

Here's an example from http://build.chromium.org/p/chromium/builders/Arm/builds/4693/steps/compile/logs/stdio:


cc1plus: warnings being treated as errors
third_party/WebKit/Source/WebCore/css/CSSPrimitiveValue.cpp: In static member function 'static WTF::PassRefPtr<WebCore::CSSPrimitiveValue> WebCore::CSSPrimitiveValue::createColor(unsigned int)':
third_party/WebKit/Source/WebCore/css/CSSPrimitiveValue.cpp:130: error: 'colorTransparent.unstatic.4909' may be used uninitialized in this function

[Eric Seidel (no email)]

Comment on attachment 80955 [details]
Patch

Please link to the GCC bug url both in the ChangeLog and the actual code change.  The ChangeLog should give an example of the warning and explain better what we're doing here.

[Eric Seidel (no email)]

Is it possible to also just disable that warning on the arm build?  The code change is an OK approach, but I wonder if there is a nicer hack for ARM?

We could also encase the added code in an ARM #ifdef?

[Eric Seidel (no email)]

My main goal here is to make the code you're adding easily self-documenting as to when it can be removed. Currently what you're adding can never be removed for fear of breaking some obscure compiler that I don't have access to.  You should better document (ideally through #ifdefs and bug links) when it can be removed.

[Dimitri Glazkov (Google)]

Compiler: gcc (Ubuntu 4.4.3-4ubuntu5) 4.4.3

[Dimitri Glazkov (Google)]

(In reply to comment #5)
> My main goal here is to make the code you're adding easily self-documenting as to when it can be removed. Currently what you're adding can never be removed for fear of breaking some obscure compiler that I don't have access to.  You should better document (ideally through #ifdefs and bug links) when it can be removed.

I like the idea of the ifdefs. I'll ask nsylvain to try it on the device.

[Dimitri Glazkov (Google)]

(In reply to comment #4)
> Is it possible to also just disable that warning on the arm build?  The code change is an OK approach, but I wonder if there is a nicer hack for ARM?
> 
> We could also encase the added code in an ARM #ifdef?

The warning is explicitly disabled. I double-checked. Here's the spew from make V=1 for the CSSPrimitiveValue. If you search for it, the -Wno-uninitialized is there:

  /usr/local/crosstool-trusted/arm-2009q3/bin/arm-none-linux-gnueabi-g++ -B/usr/local/tot-binutils/arm-none-linux-gnueabi/bin '-DNO_TCMALLOC' '-DNO_HEAPCHECKER' '-DDISABLE_NACL' '-DCHROMIUM_BUILD' '-DTOOLKIT_VIEWS=1' '-DOS_CHROMEOS=1' '-DENABLE_REMOTING=1' '-DENABLE_FLAPPER_HACKS=1' '-DENABLE_GPU=1' '-DWEBCORE_NAVIGATOR_VENDOR="Google Inc."' '-DENABLE_3D_CANVAS=1' '-DENABLE_3D_PLUGIN=1' '-DENABLE_BLOB=1' '-DENABLE_BLOB_SLICE=1' '-DENABLE_CHANNEL_MESSAGING=1' '-DENABLE_CLIENT_BASED_GEOLOCATION=1' '-DENABLE_DASHBOARD_SUPPORT=0' '-DENABLE_DATABASE=1' '-DENABLE_DATAGRID=0' '-DENABLE_DEVICE_ORIENTATION=1' '-DENABLE_DIRECTORY_UPLOAD=1' '-DENABLE_DOM_STORAGE=1' '-DENABLE_EVENTSOURCE=1' '-DENABLE_FILE_SYSTEM=1' '-DENABLE_FILTERS=1' '-DENABLE_GEOLOCATION=1' '-DENABLE_ICONDATABASE=0' '-DENABLE_INDEXED_DATABASE=1' '-DENABLE_INPUT_SPEECH=1' '-DENABLE_JAVASCRIPT_DEBUGGER=1' '-DENABLE_JSC_MULTIPLE_THREADS=0' '-DENABLE_LINK_PREFETCH=1' '-DENABLE_METER_TAG=1' '-DENABLE_NOTIFICATIONS=1' '-DENABLE_OFFLINE_WEB_APPLICATIONS=1' '-DENABLE_OPENTYPE_SANITIZER=1' '-DENABLE_ORIENTATION_EVENTS=0' '-DENABLE_PROGRESS_TAG=1' '-DENABLE_REQUEST_ANIMATION_FRAME=1' '-DENABLE_RUBY=1' '-DENABLE_SANDBOX=1' '-DENABLE_SHARED_WORKERS=1' '-DENABLE_SVG=1' '-DENABLE_SVG_ANIMATION=1' '-DENABLE_SVG_AS_IMAGE=1' '-DENABLE_SVG_FONTS=1' '-DENABLE_SVG_FOREIGN_OBJECT=1' '-DENABLE_SVG_USE=1' '-DENABLE_TOUCH_EVENTS=1' '-DENABLE_V8_SCRIPT_DEBUG_SERVER=1' '-DENABLE_VIDEO=1' '-DENABLE_WEB_SOCKETS=1' '-DENABLE_WEB_TIMING=1' '-DENABLE_WEBGL=1' '-DENABLE_WORKERS=1' '-DENABLE_XHR_RESPONSE_BLOB=1' '-DENABLE_XPATH=1' '-DENABLE_XSLT=1' '-DWTF_USE_WEBP=1' '-DWTF_USE_WEBKIT_IMAGE_DECODERS=1' '-DWTF_USE_ACCELERATED_COMPOSITING=1' '-DENABLE_3D_RENDERING=1' '-DENABLE_ACCELERATED_2D_CANVAS=1' '-DBUILDING_CHROMIUM__=1' '-DUSE_SYSTEM_MALLOC=1' '-DWTF_USE_PTHREADS=1' '-DU_STATIC_IMPLEMENTATION' '-DSK_BUILD_NO_IMAGE_ENCODE' '-DGR_GL_CUSTOM_SETUP_HEADER="GrGLConfig_chrome.h"' '-DGR_SKIP_2POINTRADIAL_PROGRAMS' '-DUSE_SYSTEM_LIBPNG' '-DLIBXML_STATIC' '-DLIBXSLT_STATIC' '-DUSE_SYSTEM_LIBJPEG' '-D__STDC_FORMAT_MACROS' '-DNDEBUG' '-DNVALGRIND' '-DDYNAMIC_ANNOTATIONS_ENABLED=0' -Ithird_party/icu/public/common -Ithird_party/icu/public/i18n -Igpu -Iout/Release/obj.target/geni -Ithird_party/WebKit/Source/WebCore -Ithird_party/WebKit/Source/WebCore/accessibility -Ithird_party/WebKit/Source/WebCore/accessibility/chromium -Ithird_party/WebKit/Source/WebCore/bindings -Ithird_party/WebKit/Source/WebCore/bindings/generic -Ithird_party/WebKit/Source/WebCore/bindings/v8 -Ithird_party/WebKit/Source/WebCore/bindings/v8/custom -Ithird_party/WebKit/Source/WebCore/bindings/v8/specialization -Ithird_party/WebKit/Source/WebCore/css -Ithird_party/WebKit/Source/WebCore/dom -Ithird_party/WebKit/Source/WebCore/dom/default -Ithird_party/WebKit/Source/WebCore/editing -Ithird_party/WebKit/Source/WebCore/fileapi -Ithird_party/WebKit/Source/WebCore/history -Ithird_party/WebKit/Source/WebCore/html -Ithird_party/WebKit/Source/WebCore/html/canvas -Ithird_party/WebKit/Source/WebCore/html/parser -Ithird_party/WebKit/Source/WebCore/html/shadow -Ithird_party/WebKit/Source/WebCore/inspector -Ithird_party/WebKit/Source/WebCore/loader -Ithird_party/WebKit/Source/WebCore/loader/appcache -Ithird_party/WebKit/Source/WebCore/loader/archive -Ithird_party/WebKit/Source/WebCore/loader/cache -Ithird_party/WebKit/Source/WebCore/loader/icon -Ithird_party/WebKit/Source/WebCore/mathml -Ithird_party/WebKit/Source/WebCore/notifications -Ithird_party/WebKit/Source/WebCore/page -Ithird_party/WebKit/Source/WebCore/page/animation -Ithird_party/WebKit/Source/WebCore/page/chromium -Ithird_party/WebKit/Source/WebCore/platform -Ithird_party/WebKit/Source/WebCore/platform/animation -Ithird_party/WebKit/Source/WebCore/platform/audio -Ithird_party/WebKit/Source/WebCore/platform/audio/chromium -Ithird_party/WebKit/Source/WebCore/platform/chromium -Ithird_party/WebKit/Source/WebCore/platform/graphics -Ithird_party/WebKit/Source/WebCore/platform/graphics/chromium -Ithird_party/WebKit/Source/WebCore/platform/graphics/filters -Ithird_party/WebKit/Source/WebCore/platform/graphics/gpu -Ithird_party/WebKit/Source/WebCore/platform/graphics/opentype -Ithird_party/WebKit/Source/WebCore/platform/graphics/skia -Ithird_party/WebKit/Source/WebCore/platform/graphics/transforms -Ithird_party/WebKit/Source/WebCore/platform/image-decoders -Ithird_party/WebKit/Source/WebCore/platform/image-decoders/bmp -Ithird_party/WebKit/Source/WebCore/platform/image-decoders/gif -Ithird_party/WebKit/Source/WebCore/platform/image-decoders/ico -Ithird_party/WebKit/Source/WebCore/platform/image-decoders/jpeg -Ithird_party/WebKit/Source/WebCore/platform/image-decoders/png -Ithird_party/WebKit/Source/WebCore/platform/image-decoders/skia -Ithird_party/WebKit/Source/WebCore/platform/image-decoders/xbm -Ithird_party/WebKit/Source/WebCore/platform/image-decoders/webp -Ithird_party/WebKit/Source/WebCore/platform/image-encoders/skia -Ithird_party/WebKit/Source/WebCore/platform/mock -Ithird_party/WebKit/Source/WebCore/platform/network -Ithird_party/WebKit/Source/WebCore/platform/network/chromium -Ithird_party/WebKit/Source/WebCore/platform/sql -Ithird_party/WebKit/Source/WebCore/platform/text -Ithird_party/WebKit/Source/WebCore/platform/text/transcoder -Ithird_party/WebKit/Source/WebCore/plugins -Ithird_party/WebKit/Source/WebCore/plugins/chromium -Ithird_party/WebKit/Source/WebCore/rendering -Ithird_party/WebKit/Source/WebCore/rendering/style -Ithird_party/WebKit/Source/WebCore/rendering/svg -Ithird_party/WebKit/Source/WebCore/storage -Ithird_party/WebKit/Source/WebCore/storage/chromium -Ithird_party/WebKit/Source/WebCore/svg -Ithird_party/WebKit/Source/WebCore/svg/animation -Ithird_party/WebKit/Source/WebCore/svg/graphics -Ithird_party/WebKit/Source/WebCore/svg/graphics/filters -Ithird_party/WebKit/Source/WebCore/svg/properties -Ithird_party/WebKit/Source/WebCore/thirdparty/glu -Ithird_party/WebKit/Source/WebCore/webaudio -Ithird_party/WebKit/Source/WebCore/websockets -Ithird_party/WebKit/Source/WebCore/workers -Ithird_party/WebKit/Source/WebCore/xml -Ithird_party/angle/include/GLSLANG -Iout/Release/obj/gen/webkit -Iout/Release/obj/gen/webkit/bindings -Ithird_party/WebKit/Source/JavaScriptCore -Ithird_party/WebKit/Source/JavaScriptCore/wtf -I. -Iskia/config -Ithird_party/skia/include/config -Ithird_party/skia/include/core -Ithird_party/skia/include/effects -Ithird_party/skia/include/gpu -Ithird_party/skia/gpu/include -Iskia/ext -Ithird_party/iccjpeg -Ithird_party/libwebp -Ithird_party/libwebp/webp -Ithird_party/libxml/linux/include -Ithird_party/libxml/src/include -Ithird_party/libxslt -Ithird_party/npapi -Ithird_party/npapi/bindings -Ithird_party/ots/include -Ithird_party/sqlite -Iv8/include -Wno-uninitialized -Werror -pthread -fno-exceptions -Wall -Wno-unused-parameter -Wno-missing-field-initializers -D_FILE_OFFSET_BITS=64 -fvisibility=hidden -pipe -fPIC -fno-strict-aliasing -I/usr/local/arm-rootfs/usr/include/libpng12 -I/usr/local/arm-rootfs/usr/include -pthread -I/usr/local/arm-rootfs/usr/include/gtk-2.0 -I/usr/local/arm-rootfs/usr/lib/gtk-2.0/include -I/usr/local/arm-rootfs/usr/include/atk-1.0 -I/usr/local/arm-rootfs/usr/include/cairo -I/usr/local/arm-rootfs/usr/include/pango-1.0 -I/usr/local/arm-rootfs/usr/include/glib-2.0 -I/usr/local/arm-rootfs/usr/lib/glib-2.0/include -I/usr/local/arm-rootfs/usr/include/pixman-1 -I/usr/local/arm-rootfs/usr/include/freetype2 -I/usr/local/arm-rootfs/usr/include -I/usr/local/arm-rootfs/usr/include/libpng12 -mthumb -Wa,-mimplicit-it=thumb -march=armv7-a -mtune=cortex-a8 -mfloat-abi=softfp -mfpu=vfpv3-d16 --sysroot=/usr/local/arm-rootfs -O2 -fno-ident -fdata-sections -ffunction-sections -fno-rtti -fno-threadsafe-statics -fvisibility-inlines-hidden -Wno-abi -MMD -MF out/Release/.deps/out/Release/obj.target/webcore_remaining/third_party/WebKit/Source/WebCore/css/CSSPrimitiveValue.o.d.raw  -c -o out/Release/obj.target/webcore_remaining/third_party/WebKit/Source/WebCore/css/CSSPrimitiveValue.o third_party/WebKit/Source/WebCore/css/CSSPrimitiveValue.cpp

[Dimitri Glazkov (Google)]

Created attachment 80991 [details]
Prettier words.

[WebKit Review Bot]

Attachment 80991 [details] did not build on chromium:
Build output: http://queues.webkit.org/results/7687694

[Dimitri Glazkov (Google)]

Comment on attachment 80991 [details]
Prettier words.

i suck.

[Eric Seidel (no email)]

Comment on attachment 80991 [details]
Prettier words.

Definitely better.  do we not have any information about the compiler bug itself?  gcc has a bugzilla instance. :)  We don't know what versions this affects?  It's stil impossible to ever remove this code as written...

[Dimitri Glazkov (Google)]

Created attachment 80998 [details]
Fixed my mistakes.

[Dimitri Glazkov (Google)]

(In reply to comment #12)
> (From update of attachment 80991 [details])
> Definitely better.  do we not have any information about the compiler bug itself?  gcc has a bugzilla instance. :)  We don't know what versions this affects?  It's stil impossible to ever remove this code as written...

I scanned gcc.gnu.org, but couldn't find anything interesting. Lots of bugs related to the warning, all in different states. I mentioned the version in the ChangeLog.

This would be a much more doable task if I actually had access to an ARM device. Right now, it takes me asking nsylvain to patch the bot (!!!!) and see of the patch actually works -- for each iteration.

[Build Bot]

Attachment 80991 [details] did not build on win:
Build output: http://queues.webkit.org/results/7690236

[David Levin]

Comment on attachment 80998 [details]
Fixed my mistakes.

ok.

[Dimitri Glazkov (Google)]

Comment on attachment 80998 [details]
Fixed my mistakes.

Yaaay!

[WebKit Commit Bot]

Comment on attachment 80998 [details]
Fixed my mistakes.

Clearing flags on attachment: 80998

Committed r77464: <http://trac.webkit.org/changeset/77464>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.

[Darin Adler]

Comment on attachment 80998 [details]
Fixed my mistakes.

View in context: https://bugs.webkit.org/attachment.cgi?id=80998&action=review

> Source/WebCore/css/CSSPrimitiveValue.cpp:130
> +#if CPU(ARM) && OS(LINUX)

I’d rather see a condition that more directly targets the buggy compiler. For example, this expression doesn’t even include COMPILER(GCC)!

> Source/WebCore/css/CSSPrimitiveValue.cpp:131
> +         // A workaround for gcc bug on ARM.

It would be so much better if this had specifics about the bug.

[David Levin]

(In reply to comment #20)
> (From update of attachment 80998 [details])
> View in context: https://bugs.webkit.org/attachment.cgi?id=80998&action=review
> 
> > Source/WebCore/css/CSSPrimitiveValue.cpp:130
> > +#if CPU(ARM) && OS(LINUX)
> 
> I’d rather see a condition that more directly targets the buggy compiler. For example, this expression doesn’t even include COMPILER(GCC)!
> 
> > Source/WebCore/css/CSSPrimitiveValue.cpp:131
> > +         // A workaround for gcc bug on ARM.
> 
> It would be so much better if this had specifics about the bug.

Filed bug 53808.