https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66522
Bug ID: 66522
Summary: handle casts in nr of iterations in
try_transform_to_exit_first_loop_alt
Product: gcc
Version: 6.0
Status: UNCONFIRMED
Severity: enhancement
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: vries at gcc dot gnu.org
Target Milestone: ---
There's a todo in try_transform_to_exit_first_loop_alt:
...
/* There is a number of test-cases for which we don't get an alt_bound
here: they're listed here, with the lhs of the last stmt as the nit:
libgomp.graphite/force-parallel-1.c:
_21 = (signed long) N_6(D);
_19 = _21 + -1;
_7 = (unsigned long) _19;
libgomp.graphite/force-parallel-2.c:
_33 = (signed long) N_9(D);
_16 = _33 + -1;
_37 = (unsigned long) _16;
libgomp.graphite/force-parallel-5.c:
<bb 6>:
# graphite_IV.5_46 = PHI <0(5), graphite_IV.5_47(11)>
<bb 7>:
_33 = (unsigned long) graphite_IV.5_46;
g++.dg/tree-ssa/pr34355.C:
_2 = (unsigned int) i_9;
_3 = 4 - _2;
gcc.dg/pr53849.c:
_5 = d.0_11 + -2;
_18 = (unsigned int) _5;
We will be able to handle some of these cases, if we can determine
when
it's safe to look past casts. */
...
I'm running into this todo for a trivial fortran test-case
gcc/testsuite/gfortran.dg/parloops-exit-first-loop-alt.f95:
...
! { dg-additional-options "-O2" }
! { dg-require-effective-target pthread }
! { dg-additional-options "-ftree-parallelize-loops=2" }
! { dg-additional-options "-fdump-tree-parloops" }
! Variable bound, vector addition.
subroutine foo(nr)
integer, intent(in) :: nr
integer, parameter :: n = 1000
integer, dimension (0:n-1) :: a, b, c
common a, b, c
integer :: ii
do ii = 0, nr - 1
c(ii) = a(ii) + b(ii) + 25
end do
end subroutine foo
! Three times 'plus 25'
! - one in f._loopfn.0
! - one in the parallel
! - one in the low iteration count loop
! Crucially, none for a peeled off last iteration following the parallel.
! { dg-final { scan-tree-dump-times "(?n) \\+ 25;" 3 "parloops" } }
...
The scan-tree-dump-times currently fails, so
try_transform_to_exit_first_loop_alt is failing.
