Big problem with Small programs

[Sean Kelly]

Sean Kelly wrote:
> Walter Bright wrote:
>> kris wrote:
>>> I have a helloworld.d program. I compile it on both Win32 and on 
>>> linux. On linux, the executable is 72KB whereas on Win32 it is 141KB. 
>>> Why is this?
>>>
>>> Turns out that D programs importing comprehensive Win32 D headers 
>>> will wind up with executable space occupied for *all* constants and 
>>> *all* struct initializers for the darned Win32 decls; where none of 
>>> them are actually used.
>>>
>>> That amounts to ~70KB of junk in the executable -- almost a full 100% 
>>> increase in size beyond what it should be.
>>>
>>> Does OptLink remove this? I've had no success with it. Walter? Can 
>>> you help with this?
>>
>> Try using enums instead of const variables, they don't take up any 
>> space in the object file.
> 
> For reference, the "hello world" app test was compiled with Bud, which 
> basically just recursively compiled all .d files and links the objects 
> together.  However, I just tried creating a library out of the Win32 
> modules and renamed them to .di files to keep Bud from building them, 
> and the resulting app was 90k instead of 144k.  I don't suppose you can 
> explain how linking a lib and linking individual object files can have 
> such glaringly different effects?  I'm going to try a manual build 
> without Bud and see if the app is 144k now too.

I'm beginning to suspect a compiler/linker bug.  Here is my first test 
supplying all modules on one line:

--------------------------------------------------------------------------------

C:\code\src\d\test\appsize>dmd -inline -release -O hello.d 
\code\import\tango\tango\io\Console.d 
\code\import\tango\tango\sys\Common.d 
\code\import\tango\tango\sys\win32\Types.d 
\code\import\tango\tango\sys\win32\Common.d 
\code\import\tango\tango\io\Buffer.d 
\code\import\tango\tango\io\Exception.d 
\code\import\tango\tango\io\model\IBuffer.d 
\code\import\tango\tango\io\model\IConduit.d 
\code\import\tango\tango\io\DeviceConduit.d 
\code\import\tango\tango\io\Conduit.d

c:\bin\dmd\bin\..\..\dm\bin\link.exe 
hello+Console+Common+Types+Common+Buffer+Ex
ception+IBuffer+IConduit+DeviceConduit+Conduit,,,user32+kernel32/noi;

C:\code\src\d\test>dir hello.exe
  Volume in drive C is System
  Volume Serial Number is 58B0-B8C5

  Directory of C:\code\src\d\test\appsize

01/23/2007  12:05 PM           141,852 hello.exe

--------------------------------------------------------------------------------

And my second test compiling all modules separately and then linking 
into an app:

--------------------------------------------------------------------------------

dmd -inline -release -O -c hello.d
dmd -inline -release -O -c \code\import\tango\tango\io\Console.d
dmd -inline -release -O -c \code\import\tango\tango\sys\Common.d
dmd -inline -release -O -c \code\import\tango\tango\sys\win32\Types.d
dmd -inline -release -O -c \code\import\tango\tango\sys\win32\Common.d 
-ofCommonWin32.obj
dmd -inline -release -O -c \code\import\tango\tango\io\Buffer.d
dmd -inline -release -O -c \code\import\tango\tango\io\Exception.d
dmd -inline -release -O -c \code\import\tango\tango\io\model\IBuffer.d
dmd -inline -release -O -c \code\import\tango\tango\io\model\IConduit.d
dmd -inline -release -O -c \code\import\tango\tango\io\DeviceConduit.d
dmd -inline -release -O -c \code\import\tango\tango\io\Conduit.d

C:\code\src\d\test\appsize>dmd hello *.obj
c:\bin\dmd\bin\..\..\dm\bin\link.exe hello+*,,,user32+kernel32/noi;

C:\code\src\d\test\appsize>dir hello.exe
  Volume in drive C is System
  Volume Serial Number is 58B0-B8C5

  Directory of C:\code\src\d\test\appsize

01/23/2007  12:13 PM           141,340 hello.exe

--------------------------------------------------------------------------------

And now my third test where tango/sys/win32/*.* is compiled into a 
library (win32.lib) and the lib is linked instead of the module object 
files:

--------------------------------------------------------------------------------

C:\code\src\d\test\appsize>lib -c -n Win32.lib CommonWin32.obj Types.obj
Digital Mars Librarian Version 8.00n
Copyright (C) Digital Mars 2000-2002 All Rights Reserved www.digitalmars.com
Digital Mars Librarian complete.

C:\code\src\d\test\appsize>del CommonWin32.obj Types.obj

C:\code\src\d\test\appsize>dmd hello *.obj Win32.lib
c:\bin\dmd\bin\..\..\dm\bin\link.exe 
hello+*,,,Win32.lib+user32+kernel32/noi;

C:\code\src\d\test\appsize>dir hello.exe
  Volume in drive C is System
  Volume Serial Number is 58B0-B8C5

  Directory of C:\code\src\d\test\appsize

01/23/2007  12:20 PM            90,140 hello.exe

--------------------------------------------------------------------------------

As you can see, simply putting the Win32 object files into a library 
prior to linking reduced the application size by 51,100 bytes, but 
separate compilation had the same (bad) result as compiling all modules 
on one line.  I grant that 51k may not be a huge issue for the average 
Windows app, but it could be a killer for handheld (WinCE) applications. 
  Could you please explain the size difference if this is indeed not a 
bug?  I don't mind making these files .di files and adding a pragma(lib, 
"Win32.lib"), but this seems like something that must be addressed in a 
more general manner at some point.


Sean