> Google is your friend...
Thanks Jack. As you can see in comment #46 of pr40106, I have found
my own way. In my previous attempts I have made two mistakes:
(1) I tried to use the search engine of the gcc mailing lists that
kept parsing optimize_insn_for_speed_p as if the _ were spaces.
(2) I did
On 2010-03-18 15:49:05 +, Joseph S. Myers wrote:
> And the same rule on pow(-0, y) is present in 754-2008 (I don't know
> whether this was deliberately following the C definition, or deciding
> independently that this was the right definition, but you may know as a
> listed member of the bal
On Thu, 18 Mar 2010, Vincent Lefevre wrote:
> On 2010-03-18 15:32:04 +0100, Michael Matz wrote:
> > > So, pow(-0.0, 0.5) should return +0. But sqrt(-0.0) should return -0
> > > according to the IEEE 754 standard (and F.9.4.5 from ISO C99).
> >
> > Yes, and I don't know why they specified it like
On Thu, Mar 18, 2010 at 04:34:56PM +0100, Vincent Lefevre wrote:
> On 2010-03-18 15:32:04 +0100, Michael Matz wrote:
> > But unfortunately you are right, this expansion can only be done for
> > -fno-signed-zeros. (FWIW the general expandsion of pow(x,N/2) where
> > N!=1 is already guarded by unsafe
On 2010-03-18 15:32:04 +0100, Michael Matz wrote:
> > So, pow(-0.0, 0.5) should return +0. But sqrt(-0.0) should return -0
> > according to the IEEE 754 standard (and F.9.4.5 from ISO C99).
>
> Yes, and I don't know why they specified it like that. After all
> (-0)*(-0)==+0 (not ==-0), so the ab
On Thu, Mar 18, 2010 at 04:07:28PM +0100, Dominique Dhumieres wrote:
> May I remind my original question:
>
> > In the block "Handle constant exponents." in gcc/builtins.c, the condition
> > !optimize_size has been replaced with optimize_insn_for_speed_p () between
> > gcc 4.3 and 4.4, but I have
May I remind my original question:
> In the block "Handle constant exponents." in gcc/builtins.c, the condition
> !optimize_size has been replaced with optimize_insn_for_speed_p () between
> gcc 4.3 and 4.4, but I have not been able to find when and why.
> Does anybody remembers the when and why?
Hi,
On Thu, 18 Mar 2010, Vincent Lefevre wrote:
> On 2010-03-16 16:18:17 +0100, Richard Guenther wrote:
> > pow (a, 0.5) is always expanded to sqrt(a).
>
> This violates the ISO C99 standard for -0.0.
>
> According to N1256, F.9.4.4:
>
> pow(±0, y) returns +0 for y > 0 and not an odd integer
On 2010-03-18 14:43:39 +0100, Vincent Lefevre wrote:
> This violates the ISO C99 standard for -0.0.
>
> According to N1256, F.9.4.4:
>
> pow(±0, y) returns +0 for y > 0 and not an odd integer.
>
> So, pow(-0.0, 0.5) should return +0. But sqrt(-0.0) should return -0
> according to the IEEE 754
On 2010-03-16 16:18:17 +0100, Richard Guenther wrote:
> pow (a, 0.5) is always expanded to sqrt(a).
This violates the ISO C99 standard for -0.0.
According to N1256, F.9.4.4:
pow(±0, y) returns +0 for y > 0 and not an odd integer.
So, pow(-0.0, 0.5) should return +0. But sqrt(-0.0) should retu
On Tue, Mar 16, 2010 at 4:11 PM, Dominique Dhumieres wrote:
> In the block "Handle constant exponents." in gcc/builtins.c, the condition
> !optimize_size has been replaced with optimize_insn_for_speed_p () between
> gcc 4.3 and 4.4, but I have not been able to find when and why.
> Does anybody rem
In the block "Handle constant exponents." in gcc/builtins.c, the condition
!optimize_size has been replaced with optimize_insn_for_speed_p () between
gcc 4.3 and 4.4, but I have not been able to find when and why.
Does anybody remembers the when and why?
This change make the optimization sensitive
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