Noticed while optimizing crc16 that gcc -O performed much better
than gcc -O2 while doing crc16:
# > gcc -O1 CRC16.c ;./a.out
crc1:f532 crc2:f532
crc16 tv_res:0 :12768
CRC16 tv_res:0 :10795
# > gcc -O2 CRC16.c ;./a.out
crc1:f532 crc2:f532
crc16 tv_res:0 :17092
CRC16 tv_res:0 :11581
#> gcc --ve
Richard Guenther wrote on 2010/02/14 19:05:24:
>
> On Sun, Feb 14, 2010 at 5:51 PM, Joakim Tjernlund
> wrote:
> >
> > Noticed while optimizing crc16 that gcc -O performed much better
> > than gcc -O2 while doing crc16:
>
> Reducing the noise by adding a loop wit
Jakub Jelinek wrote on 2010/02/14 20:21:50:
>
> On Sun, Feb 14, 2010 at 08:06:20PM +0100, Joakim Tjernlund wrote:
> > the warmup isn't really needed after I added memset and inline or not should
> > not matter that much are only used once so I think my
> > conclusi
Noticed that gcc 4.3.4 doesn't optimize "add with carry" properly:
static u32
add32carry(u32 sum, u32 x)
{
u32 z = sum + x;
if (sum + x < x)
z++;
return z;
}
Becomes:
add32carry:
add 3,3,4
subfc 0,4,3
subfe 0,0,0
subfc 0,0,3
mr 3,0
Instead of:
Ian Lance Taylor wrote on 2010/04/25 20:07:03:
> Joakim Tjernlund writes:
>
> > Noticed that gcc 4.3.4 doesn't optimize "add with carry" properly:
>
> Please file a missed-optimization report according to
> http://gcc.gnu.org/bugs/ . Thanks.
I rather not,
Ian Lance Taylor wrote on 2010/04/25 20:07:03:
>
> Joakim Tjernlund writes:
>
> > Noticed that gcc 4.3.4 doesn't optimize "add with carry" properly:
BTW, I can see in gcc src:
(define_insn ""
[(set (match_operand:CC 0 "cc_reg_operand" &qu
Manuel López-Ibáñez wrote on 2010/04/26 13:59:04:
> On 26 April 2010 09:13, Joakim Tjernlund
> wrote:
> > Ian Lance Taylor wrote on 2010/04/25 20:07:03:
> >> Joakim Tjernlund writes:
> >>
> >> > Noticed that gcc 4.3.4 doesn't optimize "add
David Edelsohn wrote on 2010/04/26 14:54:55:
>
> On Mon, Apr 26, 2010 at 8:21 AM, Joakim Tjernlund
> wrote:
> > Manuel López-Ibáñez wrote on 2010/04/26 13:59:04:
> >> On 26 April 2010 09:13, Joakim Tjernlund
> >> wrote:
> >> > Ian Lance Taylor
Manuel López-Ibáñez wrote on 2010/04/26 15:29:54:
>
> On 26 April 2010 15:22, Joakim Tjernlund
> wrote:
> >
> >> feature enhancement. Some of the information can be left blank, but
> >> if we do not have information about the system and an example, we may
>
Is memcpy supposed to work when the src and dest are the same:
memcpy(p, p, 100);
Jocke
Jan-Benedict Glaw wrote on 2010/04/30 16:10:42:
>
> On Fri, 2010-04-30 16:08:15 +0200, Joakim Tjernlund
> wrote:
> > Is memcpy supposed to work when the src and dest are the same:
> > memcpy(p, p, 100);
>
> It may work, but you cannot rely on it. Use memmove() alter
While doing relocation work on u-boot I often whish for strings/const data
to be accessible through %pc relative address rather than and ABS address
or through GOT. Has this feature ever been considered by gcc?
Jocke
Ian Lance Taylor wrote on 2010/10/05 15:47:38:
>
> Joakim Tjernlund writes:
>
> > While doing relocation work on u-boot I often whish for strings/const data
> > to be accessible through %pc relative address rather than and ABS address
> > or through GOT. Has this feat
Richard Henderson wrote on 2010/10/05 20:56:55:
>
> On 10/05/2010 06:54 AM, Joakim Tjernlund wrote:
> > Ian Lance Taylor wrote on 2010/10/05 15:47:38:
> >> Joakim Tjernlund writes:
> >>> While doing relocation work on u-boot I often whish for strings/const da
Richard Henderson wrote on 2010/10/05 23:12:19:
>
> On 10/05/2010 01:55 PM, Joakim Tjernlund wrote:
> > I don't do x86 or alpha so let me ask: If you run the code on an address
> > != link address, will it do the right thing?
>
> Yes of course. It wouldn't be
Alan Modra wrote on 2010/10/06 00:19:26:
>
> On Tue, Oct 05, 2010 at 11:40:11PM +0200, Joakim Tjernlund wrote:
> > yes, but this could be a new PIC mode that uses a new better
> > PIC mode for everything. Especially one that doesn't require each function
> > to cal
Gabriel Paubert wrote on 2010/10/06 10:15:26:
>
> On Tue, Oct 05, 2010 at 10:55:36PM +0200, Joakim Tjernlund wrote:
> > Richard Henderson wrote on 2010/10/05 20:56:55:
> > >
> > > On 10/05/2010 06:54 AM, Joakim Tjernlund wrote:
> > > > Ian
Richard Henderson wrote on 2010/10/06 00:13:22:
>
> On 10/05/2010 02:40 PM, Joakim Tjernlund wrote:
> > Especially one that doesn't require each function
> > to calculate the GOT address in the function prologue(why is that so?)
>
> Because PIC code can be called
Michael Meissner wrote on 2010/10/07 15:00:25:
>
> On Tue, Oct 05, 2010 at 11:56:55AM -0700, Richard Henderson wrote:
> > On 10/05/2010 06:54 AM, Joakim Tjernlund wrote:
> > > Ian Lance Taylor wrote on 2010/10/05 15:47:38:
> > >> Joakim Tjernlund writes:
> &g
Michael Meissner wrote on 2010/10/07 20:21:38:
>
> On Thu, Oct 07, 2010 at 04:50:50PM +0200, Joakim Tjernlund wrote:
> > Why not offer some of this on PowerPC32? mcmodel=small would probably be
> > enough.
>
> Well as they say, contributions are welcome. Note, 32-bit mod
Michael Meissner wrote on 2010/10/07 20:21:38:
>
> On Thu, Oct 07, 2010 at 04:50:50PM +0200, Joakim Tjernlund wrote:
> > Why not offer some of this on PowerPC32? mcmodel=small would probably be
> > enough.
>
> Well as they say, contributions are welcome. Note, 32-bit mo
Alan Modra wrote on 2010/10/06 00:19:26:
>
> On Tue, Oct 05, 2010 at 11:40:11PM +0200, Joakim Tjernlund wrote:
> > yes, but this could be a new PIC mode that uses a new better
> > PIC mode for everything. Especially one that doesn't require each function
> > to cal
Alan Modra wrote on 2010/10/11 14:58:45:
>
> On Sun, Oct 10, 2010 at 11:20:06AM +0200, Joakim Tjernlund wrote:
> > Now I have had a closer look at this and it looks much like -fpic
> > on ppc32, you still use the GOT/TOC to load the address where the data is.
>
> No, wi
Alan Modra wrote on 2010/10/11 14:58:45:
>
> On Sun, Oct 10, 2010 at 11:20:06AM +0200, Joakim Tjernlund wrote:
> > Now I have had a closer look at this and it looks much like -fpic
> > on ppc32, you still use the GOT/TOC to load the address where the data is.
>
> No, wi
Joakim Tjernlund/Transmode wrote on 2010/10/09 18:32:40:
>
> Michael Meissner wrote on 2010/10/07
20:21:38:
> >
> > On Thu, Oct 07, 2010 at 04:50:50PM +0200, Joakim Tjernlund wrote:
> > > Why not offer some of this on PowerPC32? mcmodel=small would
probably be en
Joakim Tjernlund/Transmode wrote on 2010/10/12 11:00:36:
>
> Alan Modra wrote on 2010/10/11 14:58:45:
> >
> > On Sun, Oct 10, 2010 at 11:20:06AM +0200, Joakim Tjernlund wrote:
> > > Now I have had a closer look at this and it looks much like -fpic
> > > on
Joakim Tjernlund/Transmode wrote on 2010/10/14 15:54:32:
>
> Joakim Tjernlund/Transmode wrote on 2010/10/12 11:00:36:
> >
> > Alan Modra wrote on 2010/10/11 14:58:45:
> > >
> > > On Sun, Oct 10, 2010 at 11:20:06AM +0200, Joakim Tjernlund wrote:
> > >
Alan Modra wrote on 2010/10/27 04:01:50:
>
> On Wed, Oct 27, 2010 at 12:53:00AM +0100, Dave Korn wrote:
> > On 26/10/2010 23:37, Joakim Tjernlund wrote:
> >
> > > Everything went dead quiet the minute I stated to send patches, what did
> > > I do wrong?
>
Using gcc 4.4.4 -Os on
loop(long *to, long *from, long len)
{
for (; len; --len)
*++to = *++from;
}
I get
/* gcc 4.4.4 -Os
loop:
addi 5,5,1
li 9,0
mtctr 5
b .L2
.L3:
lwzx 0,4,9
stwx 0,3,9
.L2:
addi 9,9,4
bdnz .
Andrew Pinski wrote on 2010/11/03 17:44:17:
>
> On Wed, Nov 3, 2010 at 9:02 AM, Joakim Tjernlund
> wrote:
> >
> > Using gcc 4.4.4 -Os on
>
> You might want to try 4.5.0 which IIRC has a fix for this issue. The
> issue is IV-OPTs does not take into account load/sto
Dave Korn wrote on 2010/10/27 13:59:00:
>
> On 27/10/2010 07:47, Joakim Tjernlund wrote:
> > Alan Modra wrote on 2010/10/27 04:01:50:
> >> On Wed, Oct 27, 2010 at 12:53:00AM +0100, Dave Korn wrote:
> >>> On 26/10/2010 23:37, Joakim Tjernlund wrote:
> >&
gcc 4.4.5, powerpc32 does not fail
const char wd[6] = "Wednes";
even though wd only has room for 6 chars. Is this intended?
Jocke
Why is not
const char cstr[] = "mystr";
const int myint = 3;
added to a read only section?
Especially since
const int myarr[]={1,2,3};
is placed in .rodata.
hmm, -G 0 does place these in .rodata but why do I have to specify that?
Nathan Froyd wrote on 2010/12/01 18:33:23:
>
> On Tue, Nov 30, 2010 at 08:04:06PM +0100, Joakim Tjernlund wrote:
> > Why is not
> > const char cstr[] = "mystr";
> > const int myint = 3;
> > added to a read only section?
> > Especially since
>
Nathan Froyd wrote on 2010/12/01 18:33:23:
>
> On Tue, Nov 30, 2010 at 08:04:06PM +0100, Joakim Tjernlund wrote:
> > Why is not
> > const char cstr[] = "mystr";
> > const int myint = 3;
> > added to a read only section?
> > Especially since
>
I have noticed gcc 4.4.5 often produces less optimzed code
than the old 3.4.6. Below is the latest example. I am
starting to wonder if I need rebuild gcc 4.4.5 and/or
add new options to gcc when I compile. Any insight?
Jocke
const char *test(int i)
{
const char *p = "abc\0def\0gef";
David Edelsohn wrote on 2010/12/08 17:38:11:
>
> On Wed, Dec 8, 2010 at 4:37 AM, Joakim Tjernlund
> wrote:
> >
> > I have noticed gcc 4.4.5 often produces less optimzed code
> > than the old 3.4.6. Below is the latest example. I am
> > starting to wonder i
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