[Bug target/55939] [4.6/4.7/4.8 regression] gcc miscompiles gmp-5.0.5 on m68k-linux

[joseph at codesourcery dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55939

--- Comment #20 from joseph at codesourcery dot com <joseph at codesourcery dot com> 2013-01-30 21:11:31 UTC ---
On Tue, 29 Jan 2013, jakub at gcc dot gnu.org wrote:

> Perhaps -fexcess-precision=standard might fix this too (and be less 
> expensive).

Note that -fexcess-precision=standard is not fully implemented for m68k: 
the back-end patterns claiming to carry out SFmode/DFmode operations, that 
actually do XFmode arithmetic, haven't been disabled for 
-fexcess-precision=standard as I did for x86 (along with some related 
fixes for conversions to SFmode/DFmode).  While the disabling of SFmode / 
DFmode operations is just for safety - if the architecture-independent 
parts of GCC are working correctly, it shouldn't matter whether they are 
enabled or not because there will be no arithmetic in those modes in the 
GIMPLE anyway - I don't know if m68k needs similar fixes to conversion 
operations.