• Vladimir Panteleev (21/21) Mar 11 2016 Hi,
• Iain Buclaw (4/15) Mar 11 2016 https://github.com/D-Programming-Language/dmd/blob/master/src/root/rmem....
• Vladimir Panteleev (3/24) Mar 11 2016 Thanks :) After changing that to version(all), LDC is faster now.
• Edwin van Leeuwen (3/5) Mar 11 2016 How much faster is LDC?
• Vladimir Panteleev (2/7) Mar 11 2016 About 10%, but I didn't measure rigorously.
• Iain Buclaw (6/13) Mar 11 2016 Yes, I know. And if I were to say which behaviour is desired.
• Johan Engelen (5/7) Mar 11 2016 I can't judge what is best here, but LDC does not always mark
• David Nadlinger (9/13) Mar 11 2016 I distinctly remember Daniel and me having to remove those

Vladimir Panteleev <thecybershadow.lists gmail.com> writes:

Hi,

In the process of setting up a new development environment, I 
noticed that DMD's codegen seems to outperform GDC's or LDC's 
when building DMD itself.

I wrote a test script to measure the time it takes for DMD (built 
with different compilers) to build Phobos:

http://dump.thecybershadow.net/9e42ff2858d1419cf41108cc50b0a83a/bench.sh

My results are:

dmd: 11.26
ldc: 15.35
gdc: 14.80

Compiler versions:

LDC - the LLVM D compiler (0.17.0):
   based on DMD v2.068.2 and LLVM 3.7.1
gdc (GCC) 5.3.0

GDC/LDC binaries are the ones packaged in Arch Linux. Host DMD is 
the one installed and chosen by AUTO_BOOTSTRAP (2.068.2). Target 
DMD/Phobos is from git master and built with ENABLE_RELEASE=1.

To me this seems surprising, especially considering that on 
Windows I used to get a significant speed increase when building 
DMD with MSVC instead of DMC.

Iain Buclaw <ibuclaw gdcproject.org> writes:

On Friday, 11 March 2016 at 13:39:04 UTC, Vladimir Panteleev 
wrote:
 Hi,

 In the process of setting up a new development environment, I 
 noticed that DMD's codegen seems to outperform GDC's or LDC's 
 when building DMD itself.

 I wrote a test script to measure the time it takes for DMD 
 (built with different compilers) to build Phobos:

 http://dump.thecybershadow.net/9e42ff2858d1419cf41108cc50b0a83a/bench.sh

 My results are:

 dmd: 11.26
 ldc: 15.35
 gdc: 14.80


https://github.com/D-Programming-Language/dmd/blob/master/src/root/rmem.d#L166-L193

How memory is allocated makes a huge difference.

Vladimir Panteleev <thecybershadow.lists gmail.com> writes:

On Friday, 11 March 2016 at 14:32:26 UTC, Iain Buclaw wrote:
 On Friday, 11 March 2016 at 13:39:04 UTC, Vladimir Panteleev 
 wrote:
 Hi,

 In the process of setting up a new development environment, I 
 noticed that DMD's codegen seems to outperform GDC's or LDC's 
 when building DMD itself.

 I wrote a test script to measure the time it takes for DMD 
 (built with different compilers) to build Phobos:

 http://dump.thecybershadow.net/9e42ff2858d1419cf41108cc50b0a83a/bench.sh

 My results are:

 dmd: 11.26
 ldc: 15.35
 gdc: 14.80


 https://github.com/D-Programming-Language/dmd/blob/master/src/root/rmem.d#L166-L193

 How memory is allocated makes a huge difference.

Thanks :) After changing that to version(all), LDC is faster now. 
Doesn't build with GDC though (multiple definitions)...

Edwin van Leeuwen <edder tkwsping.nl> writes:

On Friday, 11 March 2016 at 14:46:59 UTC, Vladimir Panteleev 
wrote:
 Thanks :) After changing that to version(all), LDC is faster 
 now. Doesn't build with GDC though (multiple definitions)...

How much faster is LDC?

Vladimir Panteleev <thecybershadow.lists gmail.com> writes:

On Friday, 11 March 2016 at 15:04:44 UTC, Edwin van Leeuwen wrote:
 On Friday, 11 March 2016 at 14:46:59 UTC, Vladimir Panteleev 
 wrote:
 Thanks :) After changing that to version(all), LDC is faster 
 now. Doesn't build with GDC though (multiple definitions)...

 How much faster is LDC?

About 10%, but I didn't measure rigorously.

Iain Buclaw <ibuclaw gdcproject.org> writes:

On Friday, 11 March 2016 at 14:46:59 UTC, Vladimir Panteleev 
wrote:
 On Friday, 11 March 2016 at 14:32:26 UTC, Iain Buclaw wrote:
 https://github.com/D-Programming-Language/dmd/blob/master/src/root/rmem.d#L166-L193

 How memory is allocated makes a huge difference.

 Thanks :) After changing that to version(all), LDC is faster 
 now. Doesn't build with GDC though (multiple definitions)...

Yes, I know.  And if I were to say which behaviour is desired.  
I'd say GDC is doing the right thing.

Marking all functions as 'weak' is a terrible idea on both DMD's 
and LDC's part.

Johan Engelen <j j.nl> writes:

On Friday, 11 March 2016 at 15:09:26 UTC, Iain Buclaw wrote:
 Marking all functions as 'weak' is a terrible idea on both 
 DMD's and LDC's part.

I can't judge what is best here, but LDC does not always mark 
functions as weak. After the DDMD switch, we have multiple def. 
problems on Windows when bootstrapping using LDC 0.17: 
https://github.com/ldc-developers/ldc/issues/1310

David Nadlinger <code klickverbot.at> writes:

On Friday, 11 March 2016 at 15:09:26 UTC, Iain Buclaw wrote:
 Yes, I know.  And if I were to say which behaviour is desired.  
 I'd say GDC is doing the right thing.

 Marking all functions as 'weak' is a terrible idea on both 
 DMD's and LDC's part.

I distinctly remember Daniel and me having to remove those 
functions from DDMD when we first got it to build with LDC 
during/after DConf 2015.

LDC definitely does not mark symbols as weak/comdat/etc. by 
default. However, the linker might not pull in an object file 
from a static library if the respective symbols have already been 
resolved using other files.

  — David