yes I think you are right, it is same with msvc v6.
I don't know well the tcc code, but I don't think it inline functions
(like a macro, should be complicated to do).
So defining inline (alone) as static maybe a good idea ?
int tccgen.c line 3042
change:
case TOK_INLINE1:
case TOK_INLINE2:
case TOK_INLINE3:
t |= VT_INLINE;
next();
break;
to
case TOK_INLINE1:
case TOK_INLINE2:
case TOK_INLINE3:
if (!(t & VT_EXTERN)) // if extern
defined ignore 'inline'
t |= VT_INLINE | VT_STATIC; // if not extern, set
static as default
next();
break;
and line 3030
change
case TOK_EXTERN:
t |= VT_EXTERN;
to
case TOK_EXTERN:
{
t |= VT_EXTERN;
t &= ~VT_INLINE; // remove
'inline'
}
I don't know if some more changes are required ?
Pierre
Le 11/12/2013 23:22, Rob a écrit :
'inline' alone should not generate code, I'm pretty certain.
It's an
inline-only definition. If it can't be inlined, you get a
linker error.
For example:
inline int f()
{
return 3;
}
int main()
{
return f();
}
A standalone function named 'f' will never appear in the
generated code.
If the compiler inlines 'f' into main, the program will link.
If the
compiler doesn't or can't inline 'f', you'll get a linker error.
So we get a linker error with 'gcc -std=c99 -O0', but the
program links
fine with 'gcc -std=c99 -O1', as f isn't referenced (since it's
inlined by an optimiser).
Also, I checked - gcc defaults to -std=gnu89, which means gnu89
inline
semantics, so when testing, make sure you give it '-std=c99'.
Clang exhibits the same behaviour w.r.t. inline, so I'm pretty
sure I've
interpreted the standard correctly. Note that clang defaults to
C99.
Thanks,
Rob
On Wed, 11 Dec 2013, Pierre wrote:
So inline alone should export nothing if not refferenced
(with code or forward declared), and at most, create a static
function if cannot be inlined ?
And an 'extern inline ' simply ignore 'inline' ?
Le 11/12/2013 22:33, Rob a écrit :
On Wed, 11 Dec 2013, Thomas Preud'homme wrote:
Le mercredi 11 décembre 2013, 09:28:07
Christian JULLIEN a écrit :
I knew about the fact that it is a hint and I
knew even when inlined, the
function still needs to be output in case its
address is used. However I
forgot about the other details. I stand
corrected, thanks.
I remembered extern and inline has a special
meaning as well but I forgot so I
checked online and I think the documentation
of gcc [0] explains pretty well
how inline behave. I'm a bit surprised though
because I thought the special
meaning of extern inline was not in the
standard but something gcc specific.
Again, I stand corrected.
[0]
http://gcc.gnu.org/onlinedocs/gcc/Inline.html
If you want to avoid problems when you
define an inlined function in a .h is
to declare this function static. This
way, if compiler is not able to
inline function, the two or more
translation units using it will have their
own static copy that will make linker
happy.
Or extern inline which has a slightly
different meaning. With static inline you
need to provide two implementation of the
function, one with static inline in
the header, and one normal implementation
somewhere else in case there is a
call that cannot be inlined or if the address
of the function is used. With
extern inline you make it clear that you want
the function inlined no matter
what. At least that is my understanding after
a quick read but again, I might
have read too quickly.
There are very subtle differences and with gcc I'm
pretty sure you have
to specify -std=c99 otherwise it defaults to gnu89
which has different,
GNU inline semantics.
'inline', unfortunately is not just a hint to the
compiler. There are a
few checks compilers have to perform too.
So we have three forms of inline:
extern inline void func() { ... } // 1
static inline void func() { ... } // 2
inline void func() { ... } // 3
The first form, 'extern inline', will always cause a
standalone/non-inlined function to be emitted, just
as if 'inline'
wasn't present. The inline modifier here simply
acts as a hint that this
function may be inlined.
The second form, 'static inline', will cause
function code to be
emitted, but the compiler may omit this if it knows
the function is
never used (since it's static, it's not called from
another translation
unit). Again, 'inline' acts only as a hint.
The final form, 'inline' without a storage class is
where we have
special handling. In this case, standalone function
code is never
emitted, this version is _only_ to be used for
inline substitution.
For the final form to take affect, none of the
declarations of `func'
must mention extern, for example:
inline f();
inline f();
extern inline f(); // this causes `f' to be in form 2
inline f() { ... }
At least, that's what I've gathered from the
standard and various
searches.
Thanks, Rob
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