On 12/2/2017 4:13 AM, Iain Buclaw wrote:
On 29 November 2017 at 03:18, Walter Bright via Digitalmars-d
<digitalmars-d@puremagic.com> wrote:
On 11/28/2017 9:27 AM, Jacob Carlborg wrote:
Why would druntime be a barrier for you for those projects?
When the C version is 90K and the translated D version is 1200K, it is a
barrier. It's a barrier for others, as well.
Did you add an extra 0 here for the D version?
No. I used the sizes for MicroEmacs in C vs MicroEmacs in D. (I translated the
former into the latter.)
With BetterC, I've been able to create virtually identical binaries for C and D.
Another barrier for me has turned out to be the way assert() works in D. It
just is not lightweight, and it visibly slows down dmd to have assert's
turned on internally. The amount of machinery involved with it in druntime
is way overblown. Hence, asserts in dmd are turned off, and that wound up
causing me a lot of problems recently. There are even initiatives to add
writefln like formatting to asserts. With betterC, asserts became
lightweight and simple again.
I find this assertion hard to believe (pun not intended). Unless you
are omitting some extra check (invariant calls?), whether you are
using D's assert or C's assert, both have the same runtime cost.
asserts are significantly larger in D. One reason is the filename string is
passed as a D string, which is 2 pushes. A C string is one push.
Consider that D asserts throw an exception. Where's the catch going to be, if
you're linking the D code into a C program? And the D personality function,
needed for D exception unwinding, is in druntime.
BetterC is a door-opener for an awful lot of areas D has been excluded from,
and requiring druntime is a barrier for that.
It's not a door opener, and druntime is not a barrier.
If you have a C program, and want to add a D function to it, you really don't
want to add druntime as well. BetterC enables people to provide D addon
libraries for people who have C main programs.
There's a point to making incremental use of D as low cost as possible.
