On Tue, Oct 4, 2011 at 5:46 AM, Pedro Alves <pe...@codesourcery.com> wrote: > On Tuesday 04 October 2011 11:16:30, Gabriel Dos Reis wrote: > >> > Do we need to consider ABIs that have calling conventions that >> > treat unprototyped and varargs functions differently? (is there any?) >> >> Could you elaborate on the equivalence of these declarations? > > I expected that with: > > extern void foo(); > extern void bar(...); > foo (1, 2, 0.3f, NULL, 5); > bar (1, 2, 0.3f, NULL, 5); > > the compiler would emit the same for both of those > calls (calling convention wise). That is, for example, > on x86-64, %rax is set to 1 (number of floating point > parameters passed to the function in SSE registers) in > both cases.
Except that variadics use a different kind of calling convention than the rest. > > But not to be equivalent at the source level, that is: > > extern void foo(); > extern void foo(int a); > extern void bar(...); > extern void bar(int a); > > should be a "conflicting types for ’bar’" error in C. > > -- > Pedro Alves >
