Subj : Re: crash in JS_NewContext
To   : netscape.public.mozilla.jseng
From : Weiyang Zhou
Date : Wed Sep 07 2005 03:48 pm

I have tried to take the BUILD_OPT=1 out and it worked fine.


"Weiyang Zhou" <weiyangzhou@nowhere.com> wrote in message 
news:dfngfe$2ph1@ripley.aoltw.net...
> We are using mips-elf-gcc (GCC) 3.2.
>
> We really don't think it is the compiler's problem because the ALIGN macro 
> is doing the things it suppose to do.  Here are the values from the 
> sprintf statement.:
>
> 807ef884 807ef888 8 8 4
>
> You can see str is shifted to 8 bytes boundary  from the start address of 
> buf.
>
>
>
> "Brendan Eich" <brendan@meer.net> wrote in message 
> news:431F2922.9000009@meer.net...
>> Weiyang Zhou wrote:
>>> Hi,
>>>
>>> We are porting SpiderMonkey to an embedded system running on a RISC 
>>> 32bit microprocessor.
>>
>> What compiler are you using?
>>
>>>     str = ALIGN(buf, JSString);
>>
>> Could you please provide disassembly of the generated code for this line?
>>
>> What you describe, especially the following, sounds like a compiler bug.
>>
>> /be
>>
>>>     {
>>>
>>>         char buffer[256];
>>>
>>>         sprintf(buffer, "%x %x %d %d %d\n", buf, str, 
>>> ALIGNMENT(JSString), sizeof(JSString), (jsuword)(buf) % 
>>> ALIGNMENT(JSString));
>>>
>>>         printf("%s", buffer);
>>>
>>>     }
>>> .....
>>>
>>> Then it won't crash during the initialization. You can see the debug 
>>> code doesn't do anything significant except it uses the stack. But it 
>>> still crashes when I start using JS_CompileScript.
>>>
>>> With the above debug statements, I saw a difference between Windows and 
>>> the target device. In Windows, (jsuword)(buf) % ALIGNMENT(JSString) is 
>>> 0, but on the target device, (jsuword)(buf) % ALIGNMENT(JSString) is 4. 
>>> Will this make the two macros in jsatom.c fail? ALIGNMENT(JSString) and 
>>> sizeof(JSString) are both 8 in the two enviroment.
>>>
>>> #define ALIGNMENT(t)    JS_MAX(JSVAL_ALIGN, sizeof(t))
>>> #define ALIGN(b,t)      ((t*) &(b)[ALIGNMENT(t) - (jsuword)(b) % 
>>> ALIGNMENT(t)])
>>>
>>> Also, can anyone explain the purpose of the ALIGN macro? Any help will 
>>> be appreciated. Thanks a lot.
>>>
>>>
>>>
>

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