[OpenJDK 2D-Dev] [PATCH FOR REVIEW] Building ExtensionSubtables.cpp should use -fno-strict-aliasing

[Damon Hart-Davis]

That is indeed the sort of horror we used to implement out DontOptimise(something.cpp) and DontOptimiseMuch(somethingelse.cpp) macros at a now-famously-defunct investment bank.  The code outlived the bank...  B^>

Rgds

Damon


On 29 May 2012, at 18:12, Kelly O'Hair wrote:

> 
> You should be able to do something like:
> 
> # Turn off aliasing with GCC for ExtensionSubtables.cpp
> ifeq ($(PLATFORM), linux)
>   CXXFLAGS += $(CXXFLAGS_$(@F))
>   CC_NEWER_THAN_43 := \
>         $(shell $(EXPR) $(CC_MAJORVER) \> 4 \| \
>             \( $(CC_MAJORVER) = 4 \& $(CC_MINORVER) \> 3 \) )
>    ifeq ($(CC_NEWER_THAN_43),1)
>        CXXFLAGS_ExtensionSubtables.o = -fno-strict-aliasing
>    endif
> endif
> 
> -kto
> 
> On May 29, 2012, at 6:50 AM, Phil Race wrote:
> 
>> I have one concern
>> 
>> It sounds like the option is new in gcc 4.4 : http://gcc.gnu.org/gcc-4.4/porting_to.html
>> 
>> I am not sure you can assume that since ..
>> 
>> http://hg.openjdk.java.net/jdk8/jdk8/raw-file/tip/README-builds.html#gcc
>> " The GNU gcc compiler version should be 4.3 or newer."
>> 
>> And I suggest a push to 2d-dev since its in the 2d code we get
>> a warning and the "build" change is in 2D build files, specifically to work
>> around that warning .. its really precious little to do with the build system.
>> 
>> -phil.
>> 
>> On 5/29/12 6:13 AM, Andrew Hughes wrote:
>>> ----- Original Message -----
>>> 
>>>> In anticipation of the updated fix I created
>>>> 7171223 : Building ExtensionSubtables.cpp should use
>>>> -fno-strict-aliasing
>>>> 
>>>> -phil.
>>>> 
>>>> 
>>>>> Ok for jdk8?  If so, can I have a bug ID for this please?
>>>>> 
>>>>> Thanks,
>>>>> 
>>> Thanks for the bug ID, Phil.
>>> 
>>> Here's the revised webrev:
>>> 
>>> 
>>> http://cr.openjdk.java.net/~andrew/no-strict-aliasing/webrev.02/
>>> 
>>> 
>>> Sorry for the delay.  I found when trying to build the build tree
>>> that HotSpot had regressed and become unbuildable:
>>> 
>>> 
>>> http://mail.openjdk.java.net/pipermail/hotspot-dev/2012-May/005945.html
>>> 
>>> 
>>> All patched now.  Is build the preferred tree to push this too,
>>> or would you prefer somewhere else?
>>> 
>>> Thanks,
>>> 
>> 
>