[Bug fortran/38199] [4.4 regression] I/O performance
manfred99 at gmx dot ch
gcc-bugzilla@gcc.gnu.org
Thu Nov 20 16:11:00 GMT 2008
------- Comment #4 from manfred99 at gmx dot ch 2008-11-20 16:09 -------
Consider
!234567
program internalread3
implicit none
character value*100000
integer i,j
DO j=1,9999
write(value,'(i4)') j
write(*,*) value(1:4)
read(value(1:LEN_TRIM(value)),*) i
write(*,*) i
ENDDO
end program internalread3
gfortran4.4 (20081120, 64bit): 1.079s
i.e. speedup by factor 23 ...
but there are cases where the user can't solve the issue like this.
And such basic optimizations are more efficiently done
by the compiler.
Besides this: This is an internal read, so the compiler has full
control over the contents of this string variable. It can e.g.
null terminate the string or similar, or it can carry on an index
of the last character in string (set on assignment), or ...
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38199
More information about the Gcc-bugs
mailing list