[llvm-dev] New intrinsic property IntrOnlyWrite

[Nicolai Hähnle via llvm-dev]

Hi,

I'd like to draw your attention to http://reviews.llvm.org/D18291, in 
which I propose a new intrinsic property for intrinsics that are lowered 
to instructions that mayStore, but are neither mayLoad nor hasSideEffects.

This is relevant for AMDGPU, where we have store instructions that don't 
operate on pointers. The codegen backend understands these perfectly 
well as stores, and so we can enable better scheduling decisions than if 
we forced these instruction to hasSideEffects.

In a perfect world, we'd be able to model the behavior of these load and 
store intrinsics via ReadWriteArgMem, but that would require massive 
changes in how LLVM thinks about memory locations and how to describe them.

This comparatively minor addition allows us to move forward with decent 
scheduling in codegen for the time being.

Cheers,
Nicolai