On Wednesday, 16 July 2014 at 13:52:57 UTC, Mike wrote:
I received a question from Dicebot in at the end of my
presentation. He asked about the --gc-sections linker flag
breaking code from GDC.
I recently discovered how one can see why this is occurring,
and I hope this will help identify the problem and lead to a
solution.
Compile any simple hello world program with the following gcc
command:
gcc --verbose -Wl,--verbose test.c.
Part of the output is GCC's internal linker script as shown
below. I believe this is the source of the problem. Here's my
theory.
D is not C, and is likely generating code that the GCC internal
linker script doesn't know about. This code may be incorrectly
identified as dead code because there is no 'link' to it and,
therefore, appears unused. If D or GDC is generating any code
like this, it needs to be marked as KEEP in the linker script.
You can see examples of this in GCC's internal linker script
below.
If my theory is correct, GDC may have to make an internal
linker script specifically for D's code generation that marks
such code as KEEP.
I hope I'm not just blowing smoke.
Mike
And I just checked with GDC...
gdc --verbose -Wl,--verbose test.d
... and the internal linker script is exactly the same as the C
version. That doesn't seem right to me. I would expect them to
be at least a little different.
Mike
