Re: [9fans] debugging help asked for

[Charles Forsyth <forsyth@terzarima.net>]

> I compiled successfully a code ported from gcc/linux that runs OK there. However, I'm getting stack underflow error when running it under Plan 9.

that often happens when a function that returns double has no external declaration in scope where it's used,
and it gets the default type of int, so the result on the floating-point stack is not popped at the point of call.
that applies even when it's called for side-effect.

double	f(int);

void
g(void)
{
	f(3);
}

h% 8c -S db.c
	TEXT	g+0(SB),0,$8
	MOVL	$3,AX
	MOVL	AX,(SP)
	CALL	,f+0(SB)
	FMOVDP	F0,F0
	RET	,
	END	,

note the P (pop) suffix on FMOVDP

of course, the compiler will have complained about the missing
declaration unless you've told it otherwise.