RFR 8022183: GCC 4.56 changes default setting for omit-frame-pointer which breaks hotspot stack walking

[harold seigel]

Hi David,

Thanks for your comments.  I was hoping to limit the impact of my 
change.  So, I only modified i486.make.  I'll look into moving the 
change to gcc.make and see if it impacts clang.

Thanks, Harold

On 8/21/2013 11:19 PM, David Holmes wrote:
> Hi Harold,
>
> I know you modelled this on the code in amd64.make but it really seems 
> to me that this belongs in gcc.make. Note that gcc.make already 
> contains related flags for clang:
>
> ifeq ($(USE_CLANG), true)
>   # Before Clang 3.1, we had to pass the stack alignment specification 
> directly to llvm with the help of '-mllvm'
>   # Starting with version 3.1, Clang understands the 
> '-mstack-alignment' (and rejects '-mllvm -stack-alignment')
>   ifneq "$(shell expr \( $(CC_VER_MAJOR) \> 3 \) \| \( \( 
> $(CC_VER_MAJOR) = 3 \) \& \( $(CC_VER_MINOR) \>= 1 \) \))" "0"
>     STACK_ALIGNMENT_OPT = -mno-omit-leaf-frame-pointer 
> -mstack-alignment=16
>   else
>     STACK_ALIGNMENT_OPT = -mno-omit-leaf-frame-pointer -mllvm 
> -stack-alignment=16
>   endif
> endif
>
> If placed in gcc.make the code in amd64.make could be removed.
>
> Hmmm, it also seems to me that this change will also add the flag for 
> clang (as does the existing amd5=64 code). I'm unsure if that is good 
> or bad? Maybe one of our clang experts could chime in if they are on 
> this list.
>
> Thanks,
> David
>
> On 22/08/2013 7:19 AM, harold seigel wrote:
>> Hi,
>>
>> Please review this small fix for bug 8022183.  This fix is needed in
>> order to build hotspot on 32-bit Linux with newer versions of gcc. The
>> fix explicitly specifies "-fno-omit-frame-pointer" in the makefile for
>> 32-bit Linux.
>>
>> The fix was tested using NMT with -version and with GCBasher.
>>
>> Open webrev at: http://cr.openjdk.java.net/~hseigel/bug_8022183/
>> <http://cr.openjdk.java.net/%7Ehseigel/bug_8022183/>
>>
>> bug: http://bugs.sun.com/view_bug.do?bug_id=8022183
>>
>> JBS bug: https://jbs.oracle.com/bugs/browse/JDK-8022183
>>
>> Thanks, Harold