[LLVMdev] -fPIC warning on every compile on Cygwin

Nick Lewycky
Thu, 19 Feb 2009 18:55:53 -0000

Aaron Gray wrote:
> On Thu, Feb 19, 2009 at 5:52 PM, Nick Lewycky <nicholas at mxc.ca
> <mailto:nicholas at mxc.ca>> wrote:
>
>     Aaron Gray wrote:
>      > Hi,
>      >
>      > I partly built LLVM on Cygwin yesterday and it was fine as far as
it
>      > went. But after doing a svn update today I am getting the
following
>      > warning on every compile :-
>      >
>      >
>      >     llvm[3]: Compiling LowerAllocations.cpp for Debug build
>      >     /usr/src/llvm/lib/Transforms/Utils/LowerAllocations.cpp:1:
>     warning:
>      >     -fPIC ignored for target (all code is position independent)
>      >
>      >
>      > This maybe happening on other targets too.
>
>     Thanks for the report. This is certainly due to my change last night to
>     make LLVM build as PIC by default.
>
> I was a little perplex at the warning as I could not ascertain where
> thery were coming from and could see no obvious commit  !:)
>
> Out of interest, could you point me to the patch or commit, please.

r65019 / r65020:
http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20090216/073983.html
http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20090216/073984.html

(note: links will change)

Nick

>
>
>
>     Part of the fix is going to be splitting apart whether we're
building
>     PIC and whether we pass in the -fPIC flag. We want to know whether the
>     build is PIC in order to control whether libLTO should be built. On
your
>     platform we'll still want to build libLTO but don't want to
pass the
>     -fPIC flag.
>
> Nice
>
>  >The other part of the fix I'm not so sure about. How should the
build
>  >system detect that we're building PIC without the -fPIC flag on
this
>  >platform?
>
> Looks like configure/autoconf territory. 'configure' flashes up
that
> Cygwin supports PIC. See attached config.out file.
>
>
> Aaron
>
>
>
>     Nick
>
>      > Aaron
>      >
>      >
>      >
>      >
>      >
>
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