* Over optimisation
@ 1999-09-23 7:26 Andrew Davies
1999-09-23 7:43 ` Jeffrey A Law
` (4 more replies)
0 siblings, 5 replies; 11+ messages in thread
From: Andrew Davies @ 1999-09-23 7:26 UTC (permalink / raw)
To: help-gcc
Hi,
I have a problem with the optimiser. When I compile the following test
loop:
do {
test = regbase->utx & 0x8000;
}while(test == 0x0000);
It produces the following code:
send_byte:
link.w %a6,#0
move.w 16775430,%d0
and.w #32768,%d0
.even
.L9:
tst.w %d0
jbeq .L9
I think the optimiser is assuming the line inside the do while loop is
static and therefore removes it from the loop. As a result it gets stuck.
Anyone know how to solve this without turning the optimiser off?
Thanks
^ permalink raw reply [flat|nested] 11+ messages in thread* Re: Over optimisation
1999-09-23 7:26 Over optimisation Andrew Davies
@ 1999-09-23 7:43 ` Jeffrey A Law
1999-09-30 23:56 ` Jeffrey A Law
1999-10-01 0:00 ` Jeffrey A Law
1999-09-23 8:13 ` Michel Decima
` (3 subsequent siblings)
4 siblings, 2 replies; 11+ messages in thread
From: Jeffrey A Law @ 1999-09-23 7:43 UTC (permalink / raw)
To: Andrew Davies; +Cc: help-gcc
In message < 01bf05ce$5ca544c0$4f7fa890@us1.lincoln.msl.mitel.com >you write:
> Hi,
> I have a problem with the optimiser. When I compile the following test
> loop:
>
> do {
> test = regbase->utx & 0x8000;
> }while(test == 0x0000);
>
>
> It produces the following code:
>
>
> send_byte:
> link.w %a6,#0
> move.w 16775430,%d0
> and.w #32768,%d0
> .even
> .L9:
> tst.w %d0
> jbeq .L9
>
> I think the optimiser is assuming the line inside the do while loop is
> static and therefore removes it from the loop. As a result it gets stuck.
> Anyone know how to solve this without turning the optimiser off?
There's no way to tell without a complete bug report. Please read the FAQ to
learn how to properly send bug reports.
jeff
^ permalink raw reply [flat|nested] 11+ messages in thread* Re: Over optimisation
1999-09-23 7:43 ` Jeffrey A Law
@ 1999-09-30 23:56 ` Jeffrey A Law
1999-10-01 0:00 ` Jeffrey A Law
1 sibling, 0 replies; 11+ messages in thread
From: Jeffrey A Law @ 1999-09-30 23:56 UTC (permalink / raw)
To: Andrew Davies; +Cc: help-gcc
In message < 01bf05ce$5ca544c0$4f7fa890@us1.lincoln.msl.mitel.com >you write:
> Hi,
> I have a problem with the optimiser. When I compile the following test
> loop:
>
> do {
> test = regbase->utx & 0x8000;
> }while(test == 0x0000);
>
>
> It produces the following code:
>
>
> send_byte:
> link.w %a6,#0
> move.w 16775430,%d0
> and.w #32768,%d0
> .even
> .L9:
> tst.w %d0
> jbeq .L9
>
> I think the optimiser is assuming the line inside the do while loop is
> static and therefore removes it from the loop. As a result it gets stuck.
> Anyone know how to solve this without turning the optimiser off?
There's no way to tell without a complete bug report. Please read the FAQ to
learn how to properly send bug reports.
jeff
^ permalink raw reply [flat|nested] 11+ messages in thread* Re: Over optimisation
1999-09-23 7:43 ` Jeffrey A Law
1999-09-30 23:56 ` Jeffrey A Law
@ 1999-10-01 0:00 ` Jeffrey A Law
1 sibling, 0 replies; 11+ messages in thread
From: Jeffrey A Law @ 1999-10-01 0:00 UTC (permalink / raw)
To: Andrew Davies; +Cc: help-gcc
In message < 01bf05ce$5ca544c0$4f7fa890@us1.lincoln.msl.mitel.com >you write:
> Hi,
> I have a problem with the optimiser. When I compile the following test
> loop:
>
> do {
> test = regbase->utx & 0x8000;
> }while(test == 0x0000);
>
>
> It produces the following code:
>
>
> send_byte:
> link.w %a6,#0
> move.w 16775430,%d0
> and.w #32768,%d0
> .even
> .L9:
> tst.w %d0
> jbeq .L9
>
> I think the optimiser is assuming the line inside the do while loop is
> static and therefore removes it from the loop. As a result it gets stuck.
> Anyone know how to solve this without turning the optimiser off?
There's no way to tell without a complete bug report. Please read the FAQ to
learn how to properly send bug reports.
jeff
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: Over optimisation
1999-09-23 7:26 Over optimisation Andrew Davies
1999-09-23 7:43 ` Jeffrey A Law
@ 1999-09-23 8:13 ` Michel Decima
1999-09-30 23:56 ` Michel Decima
1999-10-01 0:00 ` Michel Decima
1999-09-30 23:56 ` Andrew Davies
` (2 subsequent siblings)
4 siblings, 2 replies; 11+ messages in thread
From: Michel Decima @ 1999-09-23 8:13 UTC (permalink / raw)
To: help-gcc
Andrew Davies wrote:
> I think the optimiser is assuming the line inside the do while loop is
> static and therefore removes it from the loop. As a result it gets stuck.
> Anyone know how to solve this without turning the optimiser off?
volatile int test;
HTH
--
mailto:michel.decima@cnet.francetelecom.fr
^ permalink raw reply [flat|nested] 11+ messages in thread* Over optimisation
1999-09-23 7:26 Over optimisation Andrew Davies
1999-09-23 7:43 ` Jeffrey A Law
1999-09-23 8:13 ` Michel Decima
@ 1999-09-30 23:56 ` Andrew Davies
1999-10-01 0:00 ` Andrew Davies
1999-10-03 9:55 ` Veksler Michael
4 siblings, 0 replies; 11+ messages in thread
From: Andrew Davies @ 1999-09-30 23:56 UTC (permalink / raw)
To: help-gcc
Hi,
I have a problem with the optimiser. When I compile the following test
loop:
do {
test = regbase->utx & 0x8000;
}while(test == 0x0000);
It produces the following code:
send_byte:
link.w %a6,#0
move.w 16775430,%d0
and.w #32768,%d0
.even
.L9:
tst.w %d0
jbeq .L9
I think the optimiser is assuming the line inside the do while loop is
static and therefore removes it from the loop. As a result it gets stuck.
Anyone know how to solve this without turning the optimiser off?
Thanks
^ permalink raw reply [flat|nested] 11+ messages in thread* Over optimisation
1999-09-23 7:26 Over optimisation Andrew Davies
` (2 preceding siblings ...)
1999-09-30 23:56 ` Andrew Davies
@ 1999-10-01 0:00 ` Andrew Davies
1999-10-03 9:55 ` Veksler Michael
4 siblings, 0 replies; 11+ messages in thread
From: Andrew Davies @ 1999-10-01 0:00 UTC (permalink / raw)
To: help-gcc
Hi,
I have a problem with the optimiser. When I compile the following test
loop:
do {
test = regbase->utx & 0x8000;
}while(test == 0x0000);
It produces the following code:
send_byte:
link.w %a6,#0
move.w 16775430,%d0
and.w #32768,%d0
.even
.L9:
tst.w %d0
jbeq .L9
I think the optimiser is assuming the line inside the do while loop is
static and therefore removes it from the loop. As a result it gets stuck.
Anyone know how to solve this without turning the optimiser off?
Thanks
^ permalink raw reply [flat|nested] 11+ messages in thread* Re: Over optimisation
1999-09-23 7:26 Over optimisation Andrew Davies
` (3 preceding siblings ...)
1999-10-01 0:00 ` Andrew Davies
@ 1999-10-03 9:55 ` Veksler Michael
1999-10-31 13:57 ` Veksler Michael
4 siblings, 1 reply; 11+ messages in thread
From: Veksler Michael @ 1999-10-03 9:55 UTC (permalink / raw)
To: help-gcc
Andrew Davies <Andrew_Davies@Xmitel.com> wrote:
> Hi,
> I have a problem with the optimiser. When I compile the following test
> loop:
>
> do {
> test = regbase->utx & 0x8000;
> }while(test == 0x0000);
[snip]
> I think the optimiser is assuming the line inside the do while loop is
> static and therefore removes it from the loop. As a result it gets stuck.
> Anyone know how to solve this without turning the optimiser off?
The optimizer is right, unless you declare regbase volatile. Otherwise,
the compiler has a right to assume that no one is modifying 'regbase'.
Michael
^ permalink raw reply [flat|nested] 11+ messages in thread* Re: Over optimisation
1999-10-03 9:55 ` Veksler Michael
@ 1999-10-31 13:57 ` Veksler Michael
0 siblings, 0 replies; 11+ messages in thread
From: Veksler Michael @ 1999-10-31 13:57 UTC (permalink / raw)
To: help-gcc
Andrew Davies <Andrew_Davies@Xmitel.com> wrote:
> Hi,
> I have a problem with the optimiser. When I compile the following test
> loop:
>
> do {
> test = regbase->utx & 0x8000;
> }while(test == 0x0000);
[snip]
> I think the optimiser is assuming the line inside the do while loop is
> static and therefore removes it from the loop. As a result it gets stuck.
> Anyone know how to solve this without turning the optimiser off?
The optimizer is right, unless you declare regbase volatile. Otherwise,
the compiler has a right to assume that no one is modifying 'regbase'.
Michael
^ permalink raw reply [flat|nested] 11+ messages in thread
end of thread, other threads:[~1999-10-31 13:57 UTC | newest]
Thread overview: 11+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
1999-09-23 7:26 Over optimisation Andrew Davies
1999-09-23 7:43 ` Jeffrey A Law
1999-09-30 23:56 ` Jeffrey A Law
1999-10-01 0:00 ` Jeffrey A Law
1999-09-23 8:13 ` Michel Decima
1999-09-30 23:56 ` Michel Decima
1999-10-01 0:00 ` Michel Decima
1999-09-30 23:56 ` Andrew Davies
1999-10-01 0:00 ` Andrew Davies
1999-10-03 9:55 ` Veksler Michael
1999-10-31 13:57 ` Veksler Michael
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