gcc-bugs: gcc-3.0 pre, problems with _Bool arguments on stack-up

[John David Anglin]

> Dave, I put this in as PR 2782.
> < http://gcc.gnu.org/ml/gcc-bugs/2001-05/msg00230.html >
> Since I still haven't done the work to understand RTL though I think I've
> understood the assembler I was hoping you could have a look. Jeff seems
> to be off the air. 
> Toon Moene in < http://gcc.gnu.org/ml/gcc/2001-05/msg01018.html >
> has put it up to a high priority and at least for Fortran it is a
> regression from 2.95.[23].

As you found, this is a C problem with respect to passing of _Bool
arguments on the stack on the PA.  Although this was all in your
various reports, there was some impression that this was a Fortran
related bug.  Here is a simpler testcase that demonstrates the problem:

#include <stdbool.h>

int f (int a, int b, int c, _Bool d, _Bool e, _Bool f, char g)
{
  if (g != 1 || d != true || e != true || f != true) abort ();
  return a + b + c;
}

main ()
{
  exit (f (1, 2, -3, true, true, true, '\001'));
}

The char argument of f is there for comparison with the _Bool arguments.
Here is the assembler code showing the argument saves to the frame and
the `if':

	stw %r26,-36(%r3)
	stw %r25,-40(%r3)
	stw %r24,-44(%r3)
	stb %r23,-48(%r3)
	ldw -60(%r3),%r19		<== argument `g'
	stb %r19,8(%r3)
	.stabn 68,0,5,L$M2-f
L$M2:
	ldb 8(%r3),%r19
	extrs %r19,31,8,%r19
	comib,<>,n 1,%r19,L$0003
	ldb -48(%r3),%r19
	comib,<>,n 1,%r19,L$0003
	ldb -52(%r3),%r19		<== argument `e'
	comib,<>,n 1,%r19,L$0003	<== branches to abort
	ldb -56(%r3),%r19
	comib,<>,n 1,%r19,L$0003
	b,n L$0002
L$0003
	.CALL 
	bl abort,%r2
	nop
L$0002

The PA defines PROMOTE_PROTOTYPES and PROMOTE_MODE.  The arguments e, f
and g are placed on the stack as words as follows:

	ldi 1,%r19
	stw %r19,-52(%r30)
	stw %r19,-56(%r30)
	stw %r19,-60(%r30)

This seems ok to me.  It looks like _Bool arguments are not being
demoted properly after being passed on the stack.  I believe this is
what you had concluded.

Dave
-- 
J. David Anglin                                  dave.anglin@nrc.ca
National Research Council of Canada              (613) 990-0752 (FAX: 952-6605)