Related to some other missed-optimization PRs, but particularly simple.
REAL, allocatable :: ot(:)
integer :: time_steps
call foo (ot) ! OK, no temporary
call foo (ot(0:5:1)) ! Unnecessary temporary
call foo (ot(0:time_steps)) ! Unnecessary temporary
end
Note: ot is contiguous (as it is allocatable), stride = 1, and thus all
arguments are simple contiguous - unless the stride is non-unity or one has,
e.g., "ot( [1,3,5])".
Note 2: If one has an explicit-size array, it works - there is no temporary
for:
REAL :: ot(5)
integer :: time_steps
call foo (ot(1:time_steps))
I think the issue is that one mixes up the (:) of an allocatable array with the
(:) of a non-allocatable, assumed-shape dummy argument or a pointer.
The temporary seems to be generated in trans-arrays.c's
gfc_conv_array_parameter; the issue seems to be that "full_array_var" is false
and then later there is either no_pack or contiguous set to false.
--
Summary: Unnecessary array temporary: Passing contiguous array as
actual argument
Product: gcc
Version: 4.5.0
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=43173
