digitalmars.D - Clarification on testsuite 'runnable/testmath.d'
- Daniel Green <venix1 gmail.com> Jan 13 2012
- Walter Bright <newshound2 digitalmars.com> Jan 14 2012
- Daniel Green <venix1 gmail.com> Jan 14 2012
- Daniel Green <venix1 gmail.com> Jan 14 2012
- Iain Buclaw <ibuclaw ubuntu.com> Jan 14 2012
- Iain Buclaw <ibuclaw ubuntu.com> Jan 14 2012
I've been working on fixing GDC/MinGW's runtime support. I ran across
the following and was hoping to get a clarification on what DMD does
differently than GDC.
void testexp()
{
printf("exp(3.0) = %Lg, %Lg\n", exp(3.0), E * E * E);
assert(equals(exp(3.0), E * E * E, 16));
}
Of interest is exp(3.0). GDC matches exp(3.0) to double exp(double).
This causes problems with printf due to %Lg wanting a real but only
receiving a double.
Looking at the D specification for overloading functions.
1. no match
2. match with implicit conversions
3. match with conversion to const
4. exact match
The specification doesn't indicate what levels are better. I would
guess 4 is the best since an exact match should take precedence.
However, that results in GDC matching exp(3.0) to double exp(double).
How does DMD match exp(3.0)?
Could it possibly be a typo? For 32-bit this test passes because the
printf doesn't segfault, it's only noticeable with 64-bit since it
segfaults.
Jan 13 2012
On 1/13/2012 10:51 PM, Daniel Green wrote:Could it possibly be a typo? For 32-bit this test passes because the printf doesn't segfault, it's only noticeable with 64-bit since it segfaults.
3.0 should match double, when there is both double and real.
Jan 14 2012
On 1/14/2012 3:29 AM, Walter Bright wrote:On 1/13/2012 10:51 PM, Daniel Green wrote:Could it possibly be a typo? For 32-bit this test passes because the printf doesn't segfault, it's only noticeable with 64-bit since it segfaults.
3.0 should match double, when there is both double and real.
On 1/14/2012 3:29 AM, Walter Bright wrote:On 1/13/2012 10:51 PM, Daniel Green wrote:Could it possibly be a typo? For 32-bit this test passes because the printf doesn't segfault, it's only noticeable with 64-bit since it segfaults.
3.0 should match double, when there is both double and real.
When I run the following through DMD r is type real. For GDC r is type double. The matched function would be double exp(double x) safe pure nothrow { return exp(cast(real)x); }. Is it expected that DMD promotes a double to real? // GDC: r is type double // DMD: r is type real import std.stdio; import std.math; void main() { auto r = exp(3.0); writefln("%s", typeof(r).stringof); }
Jan 14 2012
Daniel Green <venix1 gmail.com> On 1/14/2012 10:34 AM, Iain Buclaw wrote:Strange, I get 'double' for both DMD and GDC... is this maybe a Windows thing?
Just ran it with linux and got 'double' as well. So it appears to be a Windows thing.
Jan 14 2012
On 14 January 2012 15:20, Daniel Green <venix1 gmail.com> wrote:On 1/14/2012 3:29 AM, Walter Bright wrote:On 1/13/2012 10:51 PM, Daniel Green wrote:Could it possibly be a typo? For 32-bit this test passes because the printf doesn't segfault, it's only noticeable with 64-bit since it segfaults.
3.0 should match double, when there is both double and real.
On 1/14/2012 3:29 AM, Walter Bright wrote:On 1/13/2012 10:51 PM, Daniel Green wrote:Could it possibly be a typo? For 32-bit this test passes because the printf doesn't segfault, it's only noticeable with 64-bit since it segfaults.
3.0 should match double, when there is both double and real.
When I run the following through DMD r is type real. =A0For GDC r is type double. The matched function would be =A0 double exp(double x) safe pure nothrow =A0{ return exp(cast(real)x);=
Is it expected that DMD promotes a double to real? // GDC: r is type double // DMD: r is type real import std.stdio; import std.math; void main() { =A0 =A0auto r =3D exp(3.0); =A0 =A0writefln("%s", typeof(r).stringof); }
Strange, I get 'double' for both DMD and GDC... is this maybe a Windows thi= ng? --=20 Iain Buclaw *(p < e ? p++ : p) =3D (c & 0x0f) + '0';
Jan 14 2012
--f46d0418264216e06304b679480e Content-Type: text/plain; charset=ISO-8859-1 I think the only difference may be that gdc possibly folds the call to exp(). Check the difference between what code gdc generates compared to how gcc processed it: -fdump-tree-original -fdump-tree-optimized ---- Iain Buclaw *(p < e ? p++ : p) = (c & 0x0f) + '0'; On 14 Jan 2012 06:56, "Daniel Green" <venix1 gmail.com> wrote:I've been working on fixing GDC/MinGW's runtime support. I ran across
differently than GDC.void testexp() { printf("exp(3.0) = %Lg, %Lg\n", exp(3.0), E * E * E); assert(equals(exp(3.0), E * E * E, 16)); } Of interest is exp(3.0). GDC matches exp(3.0) to double exp(double).
receiving a double.Looking at the D specification for overloading functions. 1. no match 2. match with implicit conversions 3. match with conversion to const 4. exact match The specification doesn't indicate what levels are better. I would guess
However, that results in GDC matching exp(3.0) to double exp(double). How does DMD match exp(3.0)? Could it possibly be a typo? For 32-bit this test passes because the
segfaults. --f46d0418264216e06304b679480e Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable <p>I think the only difference may be that gdc possibly folds the call to e= xp().</p> <p>Check the difference between what code gdc generates compared to how gcc= processed it:=A0 -fdump-tree-original=A0 -fdump-tree-optimized</p> <p>----<br> Iain Buclaw</p> <p>*(p < e ? p++ : p) =3D (c & 0x0f) + '0';</p> <p>On 14 Jan 2012 06:56, "Daniel Green" <<a href=3D"mailto:ven= ix1 gmail.com">venix1 gmail.com</a>> wrote:<br> ><br> > I've been working on fixing GDC/MinGW's runtime support. =A0I = ran across the following and was hoping to get a clarification on what DMD = does differently than GDC.<br> ><br> > void testexp()<br> > {<br> > =A0 =A0printf("exp(3.0) =3D %Lg, %Lg\n", exp(3.0), E * E * E= );<br> > =A0 =A0assert(equals(exp(3.0), E * E * E, 16));<br> > }<br> ><br> > Of interest is exp(3.0). =A0GDC matches exp(3.0) to double exp(double)= . This causes problems with printf due to %Lg wanting a real but only recei= ving a double.<br> ><br> > Looking at the D specification for overloading functions.<br> > =A0 =A01. no match<br> > =A0 =A02. match with implicit conversions<br> > =A0 =A03. match with conversion to const<br> > =A0 =A04. exact match<br> ><br> ><br> > The specification doesn't indicate what levels are better. =A0I wo= uld guess 4 is the best since an exact match should take precedence.<br> > However, that results in GDC matching exp(3.0) to double exp(double).<= br> ><br> > How does DMD match exp(3.0)?<br> ><br> > Could it possibly be a typo? =A0For 32-bit this test passes because th= e printf doesn't segfault, it's only =A0noticeable with 64-bit sinc= e it segfaults.<br> </p> --f46d0418264216e06304b679480e--
Jan 14 2012