https://gcc.gnu.org/bugzilla/show_bug.cgi?id=127303
Bug ID: 127303
Summary: Bounds checking inhibits vectorization in DO loop
although checks could removed
Product: gcc
Version: 17.0
Status: UNCONFIRMED
Severity: enhancement
Priority: P3
Component: fortran
Assignee: unassigned at gcc dot gnu.org
Reporter: tkoenig at gcc dot gnu.org
Target Milestone: ---
On x86_64.
subroutine foo(a,b,c,n)
integer, intent(in) :: n
real, dimension(n), intent(in) :: a,b
real, dimension(n), intent(out) :: c
integer :: i
do i=1,n
c(i) = a(i) + b(i)
end do
end subroutine foo
the inner loop is, with a recent trunk and -O3 -fcheck=bounds,
.L4:
cmpq %rcx, %rdx
je .L10
movss -4(%rdi,%rdx,4), %xmm0
addss -4(%rsi,%rdx,4), %xmm0
movss %xmm0, -4(%r8,%rdx,4)
addq $1, %rdx
cmpl %edx, %eax
jge .L4
(.L10 branches to runtime error). The cmpq instruction is a check against
INT_MAX.
This does not happen for KIND=8 i and n, by the way.
