* movsi on a 16 bit machine
@ 2009-07-20 13:33 Florent Defay
2009-07-20 18:37 ` Ian Lance Taylor
0 siblings, 1 reply; 3+ messages in thread
From: Florent Defay @ 2009-07-20 13:33 UTC (permalink / raw)
To: gcc-help
Hello,
I am working on a new port for a 16-bit machine.
I have trouble with movsi.
As the machine is 16-bit, movsi cannot be done in one shot. So I split
it into two movhi:
(define_insn_and_split "movsi"
[(set (match_operand:SI 0 "nonimmediate_operand" "=r,m")
(match_operand:SI 1 "general_operand" "rim,r"))]
""
"#"
"reload_completed"
[(set (match_dup 2)
(match_dup 3))
(set (match_dup 4)
(match_dup 5))]
{
operands[2] = simplify_gen_subreg(HImode,operands[0],SImode,0);
operands[4] = simplify_gen_subreg(HImode,operands[0],SImode,2);
operands[3] = simplify_gen_subreg(HImode,operands[1],SImode,0);
operands[5] = simplify_gen_subreg(HImode,operands[1],SImode,2);
}
)
But there is a problem (rare) when the following case is encountered:
move 4(R0),R0
move 6(R0),R1
Here, the operands considered are:
operand0: R0:R1 (16 bits + 16 bits)
operand1: 4(R0):6(R0) (16 bits + 16 bits)
this should be moving operand1 into operand0 but operand1 is addressed
by R0 and R0 is modified at first line, so second line is false.
I would like to modify the implementation to fix it but I do not know how.
Please help.
Regards,
Florent.
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: movsi on a 16 bit machine
2009-07-20 13:33 movsi on a 16 bit machine Florent Defay
@ 2009-07-20 18:37 ` Ian Lance Taylor
2009-07-24 9:16 ` Florent Defay
0 siblings, 1 reply; 3+ messages in thread
From: Ian Lance Taylor @ 2009-07-20 18:37 UTC (permalink / raw)
To: Florent Defay; +Cc: gcc-help
Florent Defay <spira.inhabitant@gmail.com> writes:
> I have trouble with movsi.
>
> As the machine is 16-bit, movsi cannot be done in one shot. So I split
> it into two movhi:
>
> (define_insn_and_split "movsi"
> [(set (match_operand:SI 0 "nonimmediate_operand" "=r,m")
> (match_operand:SI 1 "general_operand" "rim,r"))]
> ""
> "#"
> "reload_completed"
> [(set (match_dup 2)
> (match_dup 3))
> (set (match_dup 4)
> (match_dup 5))]
> {
> operands[2] = simplify_gen_subreg(HImode,operands[0],SImode,0);
> operands[4] = simplify_gen_subreg(HImode,operands[0],SImode,2);
> operands[3] = simplify_gen_subreg(HImode,operands[1],SImode,0);
> operands[5] = simplify_gen_subreg(HImode,operands[1],SImode,2);
> }
> )
>
> But there is a problem (rare) when the following case is encountered:
>
> move 4(R0),R0
> move 6(R0),R1
>
> Here, the operands considered are:
> operand0: R0:R1 (16 bits + 16 bits)
> operand1: 4(R0):6(R0) (16 bits + 16 bits)
>
> this should be moving operand1 into operand0 but operand1 is addressed
> by R0 and R0 is modified at first line, so second line is false.
You need to make your split a little more complicated so that when the
registers overlap, it generates
move 6(R0),R1
move 4(R0),R0
A define_insn_and_split is permitted to generate the actual instructions
to use followed by DONE, just as in define_expand.
Ian
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: movsi on a 16 bit machine
2009-07-20 18:37 ` Ian Lance Taylor
@ 2009-07-24 9:16 ` Florent Defay
0 siblings, 0 replies; 3+ messages in thread
From: Florent Defay @ 2009-07-24 9:16 UTC (permalink / raw)
To: Ian Lance Taylor; +Cc: gcc-help
>
> You need to make your split a little more complicated so that when the
> registers overlap, it generates
> move 6(R0),R1
> move 4(R0),R0
> A define_insn_and_split is permitted to generate the actual instructions
> to use followed by DONE, just as in define_expand.
>
Alright. I did it. It works.
Thank you.
Florent
^ permalink raw reply [flat|nested] 3+ messages in thread
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