Follow up to http://gcc.gnu.org/ml/fortran/2008-02/msg00157.html
Contrary to C, Fortran allows a lot of reassociations (-fassociative-math is
enabled by default in Fortran. THE GCC MANPAGE NEEDS TO BE UPDATED!).
Contrary to C with -fassociative-math, parentheses are still honoured, i.e. "(x
+ 2**52) - 2**52)" remains such while "x + 2**52 - 2**52" can be optimized to
"x".
In C the "= x" happens for both versions using -ffast-math. However, in Fortran
it never is done. We should add an option to do so optionally. One could argue
that option should be enabled by default for -ffast-math.
--
Summary: PAREN_EXPR: Option to allow for reassociation
Product: gcc
Version: 4.3.0
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: normal
Priority: P3
Component: fortran
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: burnus at gcc dot gnu dot org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35259
