Commercial compilers provide a way to tell the compiler invariants that are known to always hold, e.g. MSVC provides __assume(x). LLVM eliminates such assumptions prematurely according to this link:

https://github.com/preames/llvm-assume-hack

Does this also affect:

http://llvm.org/docs/LangRef.html#llvm-assume-intrinsic

?

Does LDC provide some means for providing assumptions to the compiler, for library authors? One use case is to provide assumptions about alignment of void pointers and similar constrains that are known to hold for library ADTs.

On 20 Feb 2015, at 10:33, via digitalmars-d-ldc wrote:
> Does LDC provide some means for providing assumptions to the compiler, for library authors? One use case is to provide assumptions about alignment of void pointers and similar constrains that are known to hold for library ADTs.

Not yet. I wondered how to best implement this a while back, but decided that I needed to have a more in-depth look at the related parts of the LLVM infrastructure to be able to decide on the best design. I didn't quite get around to that since.

It seems like Rust chose a very simple implementation (https://github.com/rust-lang/rust/issues/18051), which would be trivial to add to LDC's druntime. Pull requests are very welcome, as always.

Cheers,
David

On 20 Feb 2015, at 10:33, via digitalmars-d-ldc wrote:
> Does LDC provide some means for providing assumptions to the compiler, for library authors? One use case is to provide assumptions about alignment of void pointers and similar constrains that are known to hold for library ADTs.

Not yet. I wondered how to best implement this a while back, but decided that I needed to have a more in-depth look at the related parts of the LLVM infrastructure to be able to decide on the best design. I didn't quite get around to that since.

It seems like Rust chose a very simple implementation (https://github.com/rust-lang/rust/issues/18051), which would be trivial to add to LDC's druntime. Pull requests are very welcome, as always.

Cheers,
David

On Saturday, 21 February 2015 at 17:34:32 UTC, David Nadlinger wrote:
> It seems like Rust chose a very simple implementation
> (https://github.com/rust-lang/rust/issues/18051), which would be trivial
> to add to LDC's druntime. Pull requests are very welcome, as always.

Hm... yes... the argument might be reduced to "true", but maybe that is ok.