pardo@JUNE.CS.WASHINGTON.EDU (07/15/89)
MACHINE: i386 Sequent.
GCC: v 1.34, configured using the standard configuration script.
The following appears to be a bug. `gcc' recognizes operand
specifiers of the form `*&structname.member' and `structname', but
does not recognize oeprand specifiers of the form `structname.member'.
;-D on ( I want a port-a-bull! ) Pardo
* test.c: --------------------------------------------------------------
typedef struct buf_list_t {
struct buf_t *tail;
char lock;
} buf_list_t;
buf_list_t freelist;
int
zork (struct buf_t *buf)
{
asm ( "movl %2,%%ecx\n\txchgl %%ecx,%0\n\tmovl %2,(%%ecx)"
: "=m" (*&freelist.tail)
: "0" (*&freelist.tail)
, "mr" (buf)
: "cx"
);
return (0);
}
* compile: --------
gcc -Wall -S -c test.c
* test.s: --------
.file "test.c"
gcc_compiled.:
.text
.align 2
.globl _zork
_zork:
pushl %ebp
movl %esp,%ebp
/APP
movl 8(%ebp),%ecx
xchgl %ecx,_freelist
movl 8(%ebp),(%ecx)
/NO_APP
xorl %eax,%eax
jmp L1
L1:
leave
ret
.comm _freelist,8
* Change "*&" to "" --------
* compile: --------
gcc -Wall -S -c test.c
test.c: In function zork:
test.c:16: inconsistent operand constraints in an `asm'
*** Error code 1
`all' not remade because of errors
* Change "freelist.tail" to "freelist" --------
* compile: --------
gcc -Wall -S -c test.c
* test.s: --------
<<the same as *&freelist.tail>>
I sent this sample to wilson@ucbarpa.berkeley.edu who writes back with
a quick patch that will stop the error message but does not solve the
problem. His message follows:
Date: Fri, 14 Jul 89 13:41:43 -0700
From: wilson@ucbarpa.Berkeley.EDU (James E. Wilson)
Message-Id: <8907142041.AA01281@ucbarpa.Berkeley.EDU>
To: pardo@june.cs.washington.edu
Subject: Re: More `asm' questions...
[...] The following patch will get rid of the error message, but it
is not complete, and possibly not even correct. Bit-fields will still
generate an error, and I didn't even bother to test unions.
It looks like the real bug is buried somewhere deep inside of the reload
code (which I am not very familiar with).
[...]
*** stmt.c.old Fri Jul 14 12:48:52 1989
--- stmt.c Fri Jul 14 12:49:01 1989
***************
*** 783,789 ****
if (TREE_CODE (val) != VAR_DECL
&& TREE_CODE (val) != PARM_DECL
! && TREE_CODE (val) != INDIRECT_REF)
{
rtx reg = gen_reg_rtx (TYPE_MODE (TREE_TYPE (val)));
/* `build' isn't safe; it really expects args to be trees. */
--- 783,790 ----
if (TREE_CODE (val) != VAR_DECL
&& TREE_CODE (val) != PARM_DECL
! && TREE_CODE (val) != INDIRECT_REF
! && TREE_CODE (val) != COMPONENT_REF)
{
rtx reg = gen_reg_rtx (TYPE_MODE (TREE_TYPE (val)));
/* `build' isn't safe; it really expects args to be trees. */