Hi Liliana,

Liliana Marie Prikler <liliana.prikler@ist.tugraz.at> writes:

> Am Donnerstag, den 04.11.2021, 19:15 -0400 schrieb Mark H Weaver:
[...]
>> A more conservative approach would be to apply a patch to
>> trunk/Source/WTF/wtf/CheckedArithmetic.h analogous to the one in the
>> second link I cited above, namely this one:
>> 
>>   https://trac.webkit.org/changeset/272140/webkit
>> 
>> However, it would need to be changed slightly.  The patch above
>> arranges to avoid using __builtin_mul_overflow on 32-bit ARM
>> systems.  We would need to do the same for 32-bit x86 as well.  So,
>> where the patch above has this:
>> 
>> --8<---------------cut here---------------start------------->8---
>> /* On Linux with clang, libgcc is usually used instead of compiler-
>> rt, and it does    
>>  * not provide the __mulodi4 symbol used by clang for
>> __builtin_mul_overflow    
>>  */    
>> #if COMPILER(GCC) || (COMPILER(CLANG) && !(CPU(ARM) &&
>> OS(LINUX)))    
>> #define USE_MUL_OVERFLOW 1    
>> #endif    
>> --8<---------------cut here---------------end--------------->8---
>> 
>> We would need to change "CPU(ARM)" to "(CPU(ARM) || CPU(XXX))", where
>> XXX is the appropriate symbol for 32-bit x86.  Or maybe there's
>> another solution.
>> 
>> I won't be able to look at this in the next couple of days, so
>> hopefully someone else can pick this up.
> The #else case doesn't look so bad on this, so we could for the time
> being just do #if COMPILER(GCC) or even #if 0.

I just noticed that the aforementioned patch is already applied to
upstream WebKitGTK-2.34.1, so all we would need to do is change "1" to
"0" in the following line on i686-linux systems:

  #define USE_MUL_OVERFLOW 1

I pushed the following (untested) commit to 'gnuzilla-updates' that does
exactly this, and does so in such a way that rebuilds will not be needed
on other systems.  Hopefully I didn't make a mistake.

     Regards,
       Mark