On Wed, Nov 18, 2009 at 06:34:00PM +0100, Martin Schwidefsky wrote:
> used for parameter passing. 64 bit values are passed as registers pairs
> with the first register an even numbered register. The effect of that
> rule is that parameter registers may be skipped or that the whole 64 bit
> value is passed on the stack. Examples:
Erm, did I miss something? The 32 bit ABI doesn't say anything about
even/odd register pairs for 64 bit values. Also gcc doesn't generate
such code:
> fn(int a, long long b, int c)
> a is passed in %r2, b is passed in %r4/%r5, c is passed in %r6, %r3 is
> skipped.
extern void fn(int a, long long b, int c);
void bla(void)
{
fn(0, 1, 2);
}
00000000 <bla>:
0: 90 ef f0 38 stm %r14,%r15,56(%r15)
4: a7 fa ff a0 ahi %r15,-96
8: a7 28 00 00 lhi %r2,0
c: a7 38 00 00 lhi %r3,0
10: a7 48 00 01 lhi %r4,1
14: a7 58 00 02 lhi %r5,2
18: c0 e5 00 00 00 00 brasl %r14,18 <bla+0x18>
1e: 98 ef f0 98 lm %r14,%r15,152(%r15)
22: 07 fe br %r14
Not that it really matters, since other archs enforce the rule anyway.
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