[cfe-commits] r161703 - in /cfe/trunk: include/clang/AST/Stmt.h lib/AST/Stmt.cpp

[Abramo Bagnara]

Il 14/08/2012 20:19, Richard Smith ha scritto:
> 
> On 13 Aug 2012 23:12, "Abramo Bagnara" <abramo.bagnara at gmail.com
> <mailto:abramo.bagnara at gmail.com>> wrote:
>>
>> Il 13/08/2012 23:54, Eli Friedman ha scritto:
>> > On Mon, Aug 13, 2012 at 2:01 PM, Richard Smith
> <richard at metafoo.co.uk <mailto:richard at metafoo.co.uk>> wrote:
>> >> According to the documentation I can find[1], multiple __asm
> constructs are
>> >> separate statements. In particular, the documentation suggests that
> here:
>> >>
>> >> void f() {
>> >>   if (false)
>> >>     __asm mov eax, ebx
>> >>   __asm mov ebx, eax
>> >> }
>> >>
>> >> the second __asm statement is not controlled by the 'if'. If the
>> >> documentation is correct, we currently misparse this.
>> >>
>> >> [1] http://msdn.microsoft.com/en-us/library/45yd4tzz(v=vs.110).aspx
>> >
>> > I think clang's interpretation is actually right here, but someone
>> > should actually try that on MSVC.
>>
>> void f(int x) {
>>         if (x)
>>                 __asm out dx, ax
>>         __asm out dx, ax
> 
> What about these:
> 
>     if (x)
>        __asm out dx, ax  __asm out dx, ax
>     if (x)
>        __asm out dx, ax ; __asm out dx, ax
>     if (x)
>         __asm out dx, ax ; out dx, ax
> 
> To my reading, the first two are two statements and the third is one
> statement.

Unfortunately not: in the first there is one statement formed by two
"out dx, ax", in the second and the third the text after semicolon is
ignored.

So I'd say that the rules outside {} are:

1) a semicolon in the same line of an __asm is assumed to begin a
comment ending at end of line
2) a newline ends an asm statement
3) an __asm begins a new asm instruction

Inside {} are:

1) a semicolon is assumed to begin a comment ending at end of line (this
means it can eat also a '}')
2) a newline ends an asm instruction
3) an __asm begins a new asm instruction