Optimizing Immutable Data?

[Kai Nacke via digitalmars-d-ldc]

On Monday, 6 July 2015 at 18:40:11 UTC, Jack Stouffer wrote:
> At Dconf, one of the speakers made an off-hand comment that LDC 
> could use an LLVM feature to optimize immutable variables by 
> storing them differently than mutable data. The LDC developer 
> that was there made a response, but the mic didn't pick it up.
>
> Is this something that has already been done? Should a bug 
> report be filed so this is tracked?

David was at Dconf. It would be nice if he could repeat his 
answer here. I am currently unsure to which LLVM feature the 
speaker referred.

Suppose in module imm.d:

int x = 6;
immutable(int) y = 42;

This is translated to the following IR:

@_D3imm1xi = thread_local global i32 6
@_D3imm1yyi = constant i32 42

which is already different.

Regards,
Kai