[flang] call memset to initialise when the value to be filled is zero

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[flang] call memset to initialise when the value to be filled is zero #65194

Open vfdff opened 1 year ago

vfdff commented 1 year ago

test: https://gcc.godbolt.org/z/Te3c73K9h


subroutine cloud_0(nlay, a, c, cond)
integer, intent(in) :: nlay
logical,  dimension(nlay), intent(in) :: cond
real(kind=8), intent(out) :: a(:)
integer :: i

do i = 1,nlay
   a(i) = 0.
enddo

end subroutine cloud_0



* call memset to initialise usually benefit to the performance because the library is optimized manually.
  now the **classic-flang(old flang)** call memset when the value to be filled is zero.

llvmbot commented 1 year ago

@llvm/issue-subscribers-flang-ir

vfdff commented 3 months ago

the issue still exist, both gfortran and F18 don't optimatize them into memset if the dest value is not zero, https://gcc.godbolt.org/z/jGsz1zzaE