[Bug rtl-optimization/323] optimized code gives strange floating point results
------- Comment #127 from jsm28 at gcc dot gnu dot org 2009-03-30 01:57 -------
Fixed for C (and ObjC) for 4.5 with the new -fexcess-precision=standard
support.
The issue remains for other languages (and maybe for some m68k processors);
I quote from my original message
<http://gcc.gnu.org/ml/gcc-patches/2008-11/msg00105.html>:
It would be possible to implement the option for non-C languages, to
provide whatever predictable semantics are appropriate for those
languages (whether or not described in their standards). Note that
bug 323 was originally reported with a C++ testcase. If implemented
for all languages, the option might supersede -ffloat-store. Right
now, -ffloat-store checks are scattered about the optimizers and it
seems unlikely that -ffloat-store really implements any form of
predictable semantics now; such semantic effect as it was intended to
have could be better represented as an alias for a
-fexcess-precision=standard option supported for all languages. It
would probably be most appropriate not to close bug 323 without having
some form of predictable semantics available for each language.
and:
I have not changed the m68k back end in this patch. Thus the option
may not be fully effective for the affected m68k processors (classic
m68k with 68881, before 68040, only, not ColdFire, not 68040 or
later). If anyone wishes to make it fully effective for such
processors they should copy the testcases to gcc.target/m68k/ and go
through m68k insn patterns appropriately adjusting them.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323
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