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Re: GCC floating point usage
- From: Mike Stump <mrs at apple dot com>
- To: Geoff Keating <geoffk at geoffk dot org>
- Cc: mark at codesourcery dot com, steby at enea dot se, gcc at gcc dot gnu dot org
- Date: Tue, 15 Oct 2002 17:20:07 -0700
- Subject: Re: GCC floating point usage
On Tuesday, October 15, 2002, at 04:37 PM, Geoff Keating wrote:
OK, that's a good description. It's clear, easily understood, and has
a bunch of consequences I bet you haven't thought of yet :-).
For instance, consider a program that uses setjmp in one file, which
contains no use of FP but uses routines from another file that call
longjmp and do use FP.
I believe that case has been thought of. The thing that is marked as
FP or not, is a task. A task that is not marked as FP cannot by
definition call a routine that is in a task that does use FP. No
problem here.
A routine that is compiled with no-implicit-fp is valid to use in a
no-FP task, provided there is no explicit fp in it. A routine that
isn't compiled with this flag isn't valid to use in a non-FP task.
Note that this doesn't apply to "most code"; assuming vxworks defaults
to -msoft-float,
It does not. It multilibs softfloat. On softfloat system, the entire
implicit-fp issue it a non-issue, so we don't care about those. The
only case we care about is by definition on hardfloat systems, when the
context switcher may, or may not save/restore the FP regs.