#6063: GHC's build-time ld-flag checks are problematic
---------------------------------+------------------------------------------
Reporter: parcs | Owner: thoughtpolice
Type: bug | Status: new
Priority: high | Milestone: 7.8.1
Component: Compiler | Version: 7.4.1
Keywords: | Os: Linux
Architecture: Unknown/Multiple | Failure: GHC doesn't work at all
Difficulty: Unknown | Testcase:
Blockedby: | Blocking:
Related: #4862 |
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Comment(by thoughtpolice):
I have a patch for this now. I decided to generalize it a little and added
functionality to generally detect linker information at runtime, and
distinguish between several cases. I have verified it works and am
validating on my Mac OS X machine and my other Linux machines. I will set
up a Windows machine as well.
I'd like some code review before I push this patch to the tree directly.
If Ian or anyone else would like to give feedback, please do so. If there
aren't any complaints I'll push this myself.
@nh2 - no, this was not fixed in that work. The issue is a little more
complicated. Please see my commit message and patch which details the
issue fairly clearly.
{{{
commit e1825358b318f847aca19a230fb0a4377830d767
Author: Austin Seipp <
[hidden email]>
Date: Sat May 4 16:07:22 2013 -0500
Detect linker information at runtime. Fixes Trac #6063
Previously, we did ./configure time checks to see if 'GNU ld'
supported
certain options. If it does, we bake those options into the link step.
See Trac #5240. Ergo, this is a build-time configuration.
Unfortunately, the linker we use at runtime can change for several
reasons. One is that the user specifies -pgml 'foo'. The other is if
/usr/bin/ld or whatnot literally *changes* from when GHC was built.
Obviously, not every linker supports these options, like GNU gold,
and that would lead to linking failure. This is Trac #6063.
What this ultimately means is that we need to check at runtime what
linker we're using. Always. This is actually a little bit complicated
because we normally use the C compiler as our linker. Also, OS X does
not support gold OR ld, Windows only has GNU ld, etc.
Finally, this patch also unconditionally gives '--hash-size=31' and
'--reduce-memory-overheads' to the system linker if it's GNU ld. These
options have been supported for 8+ years from what I can see, and
there
are probably a lot of *other* reasons why GHC would not work with such
an ancient binutils, all things considered.
See Note [Run-time linker info] in SysTools for more details. There
are plenty of comments as well in the surrounding code.
Signed-off-by: Austin Seipp <
[hidden email]>
}}}
--
Ticket URL: <
http://hackage.haskell.org/trac/ghc/ticket/6063#comment:12>
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http://www.haskell.org/ghc/>
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