--gc-sections and GDC
Mike via D.gnu
d.gnu at puremagic.com
Wed Jul 16 06:52:56 PDT 2014
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
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