On 6 December 2012 18:30, Alex Rønne Petersen <a...@lycus.org> wrote:
> On 06-12-2012 19:28, Timo Sintonen wrote:
>>
>> I have some memory mapped hardware in my arm controller.
>> I define struct regs to describe the registers and __gshared regs* p to
>> point to the actual address.
>> I have a loop like: while (p.status==0) {...}
>>
>> The body of the loop does not touch status and so gdc optimizer does not
>> evaluate status again, resulting to an endless loop. Gcc does the same,
>> unless the variable is defined as volatile.
>>
>> This is ok in tls variables, but gshared variables are not thread safe.
>> Actually I can see from assembler code that this occurs in all shared
>> variables, like:
>> __gshared int a=0;
>> while (a==0) {}
>> with nothing in the body generates just a jump to itself and the program
>> stops.
>>
>> Another thread, interrupt or hardware can change a __gshared variable
>> any time, so I think that the evalution should not be optimized away.
>
>
> Yes, the compiler *must* assume that anything __gshared is implicitly
> volatile in the C sense.
>Is this going off your word or mine.... I know as a fact gdc marks shared decls as volatile, but not __gshared. This was brought into question once when I pointed it out to you, are you now in agreement? Regards, -- Iain Buclaw *(p < e ? p++ : p) = (c & 0x0f) + '0';
