[OpenJDK 2D-Dev] [PATCH FOR REVIEW] Building ExtensionSubtables.cpp should use -fno-strict-aliasing
ahughes at redhat.com
Wed May 23 16:32:10 UTC 2012
----- Original Message -----
> I suppose the problem that some new version of GCC enables this
> by default and
> we could run into a problem at run time if we don't disable it ?
Yes, 4.4 to be precise. It's not particularly new; it came out on
April 21st, 2009.
> But this patch would appear to disable it for the whole ICU library
> and any other C++ code in the .so
> which I would have to suppose impacts the compiler's ability to
> the code, in order to
> eliminate a single warning.
> Can you devise a more targeted fix ?
Yes, I thought the same. But I don't see how you can direct flags to
one specific file in the Makefiles. Any ideas?
Alternatively, is this READ_LONG macro even necessary? I'm not surprised
gcc balks at it to be honest.
> On 5/23/2012 5:59 AM, Andrew Hughes wrote:
> > At present, the building of ExtensionSubtables.cpp produces a
> > warning:
> > ../../../src/share/native/sun/font/layout/ExtensionSubtables.cpp:57:31:
> > warning: dereferencing type-punned pointer will break
> > strict-aliasing rules [-Wstrict-aliasing]
> > due to this code:
> > // read a 32-bit value that might only be 16-bit-aligned in memory
> > #define READ_LONG(code) (le_uint32)((SWAPW(*(le_uint16*)&code)<<
> > 16) + SWAPW(*(((le_uint16*)&code) + 1)))
> > where code is a le_uint32.
> > This can be avoided by setting -fno-strict-aliasing, as done in
> > this webrev:
> > http://cr.openjdk.java.net/~andrew/no-strict-aliasing/
> > making the code safer in the process.
> > Ok for jdk8? If so, can I have a bug ID for this please?
> > Thanks,
Free Java Software Engineer
Red Hat, Inc. (http://www.redhat.com)
PGP Key: 248BDC07 (https://keys.indymedia.org/)
Fingerprint = EC5A 1F5E C0AD 1D15 8F1F 8F91 3B96 A578 248B DC07
More information about the 2d-dev