[m-rev.] diff: fix datestamp file bug for --target asm

[Fergus Henderson]

On 27-Jul-2001, Fergus Henderson <fjh at cs.mu.oz.au> wrote:
> On 27-Jul-2001, Simon Taylor <stayl at cs.mu.OZ.AU> wrote:
> > On 27-Jul-2001, Fergus Henderson <fjh at cs.mu.OZ.AU> wrote:
> > > Estimated hours taken: 0.5
> > > Branches: main
> > > 
> > > compiler/mercury_compile.m:
> > > 	Fix a bug in stayl's recent change to add *_date files:
> > > 	the option for PIC in the --target asm back-end is `--pic',
> > > 	not `--pic-reg'.
> > 
> > Why do we need two different options for position independent code?
> 
> `--pic-reg' affects link compatibility, whereas `--pic' doesn't.
> `--pic-reg' is needed when generating executables with `--shared',
> whereas `--pic' isn't.
> 
> `--pic-reg' can be (and is) used in MCFLAGS/MGNUCFLAGS, whereas `--pic'
> can't, because `--pic' changes the name of the generated file, rather
> than just changing the generated code.

That explanation was a bit low-level.  A higher-level way of saying it is that
the "--pic" option gives you position-independent code, whereas the "--pic-reg"
options gives you code that is *compatible* with position-independent code,
but isn't necessarily position-independent itself.

-- 
Fergus Henderson <fjh at cs.mu.oz.au>  |  "I have always known that the pursuit
The University of Melbourne         |  of excellence is a lethal habit"
WWW: <http://www.cs.mu.oz.au/~fjh>  |     -- the last words of T. S. Garp.
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