Hi,
I am working on gcc 4.1.1 and Itanium architecture. I want to modify
the machine description of ia64.md to add some checks before each ld
instruction. the
following is the original define_insn:
(define_insn "*movqi_internal"
[(set (match_operand:QI 0 "destination_operand" "=r,r,r, m, r,*f,*f")
(match_operand:QI 1 "move_operand" "rO,J,m,rO,*f,rO,*f"))]
"ia64_move_ok (operands[0], operands[1])"
"@
mov %0 = %r1
addl %0 = %1, r0
ld1%O1 %0 = %1%P1
st1%Q0 %0 = %r1%P0
getf.sig %0 = %1
setf.sig %0 = %r1
mov %0 = %1"
[(set_attr "itanium_class" "ialu,ialu,ld,st,frfr,tofr,fmisc")])
I observe that there is a ld instruction in 3rd alternative, so I add
a new define_insn before it in the hope that it will be matched
firstly.
(define_insn "*ld_movqi_internal"
[(set (match_operand:QI 0 "destination_operand" "=r")
(match_operand:QI 1 "move_operand" "m"))]
"ia64_move_ok (operands[0], operands[1])
&& flag_check_ld"
{
printf("define_insn ld_movqi_internal\n");
return "ld1%O1 %0 = %1%P1";
}
[(set_attr "itanium_class" "ld")]
I keep every thing the same as 3rd alternative in original define_insn
except using C statement to return the desired output template.
However, when I use the newly builded gcc to compile the following
program, it crashes.
#include <stdio.h>
char characters[8192]={'a',};
int main()
{
char c = characters[0];
printf("Hello World! c:%c\n", c);
}
the error reported is:
hi.c:9: error: unable to generate reloads for:
(insn 10 9 12 1 (set (mem/c/i:QI (reg/f:DI 111 loc79) [0 c+0 S1 A128])
(reg:QI 14 r14 [orig:342 characters ] [342])) 3
{*gift_movqi_internal_ld} (nil)
(expr_list:REG_DEAD (reg:QI 14 r14 [orig:342 characters ] [342])
(nil)))
hi.c:9: internal compiler error: in find_reloads, at reload.c:3738
In IA64, the first pesudo register number is 334, thus register 111
and register 14 are both hardware registers.
I looked at find_reloads at reload.c and find the following code
fragement and comment:
/* The operands don't meet the constraints.
goal_alternative describes the alternative
that we could reach by reloading the fewest operands.
Reload so as to fit it. */
if (best == MAX_RECOG_OPERANDS * 2 + 600)
{
/* No alternative works with reloads?? */
if (insn_code_number >= 0)
fatal_insn ("unable to generate reloads for:", insn);
...
So, what is going on here? Especially, what is find_reloads going to
finish and why it is going wrong here...
I would appreciate any help on this question, thx!
Best Regards
--andy.wu
