[Bug fortran/31593] Invariant DO loop variables and subroutines
tkoenig at gcc dot gnu.org
Sun Jul 19 17:29:43 GMT 2020
--- Comment #50 from Thomas Koenig <tkoenig at gcc dot gnu.org> ---
(In reply to Thomas Koenig from comment #49)
> The second loop:
> leaq 8(%rsp), %rdi
> call intent_in_
> movl %ebx, 8(%rsp)
> addl $1, %ebx
> cmpl $12, %ebx
> jne .L3
> No reload from the stack, but not quite ideal yet. That
> movl %ebx, 8(%rsp) would have been unneeded had one of the
> callee-saved registers been used.
Actually, that comment is not correct - we need to store the
value of the argument so the subroutine an access it.
So, we're just seeing the inevitable overhead of passing
by reference here.
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