[tree-ssa] Out of SSA status and issues

[Geoff Keating]

kenner@vlsi1.ultra.nyu.edu (Richard Kenner) writes:

>     Consider instead that '*p' is just the name given a register's
>     contents.  Neither 'i' nor '9' are processor internal.  Both are
>     external to the cpu.  The memory reference for 'i' is source code
>     implicit, the memory reference for '*p' is source code explicit.  
> 
> True, but given caching effects, it's hard to see how *p could be less
> expensive than 'i'.

Given the code

i = *p;
// operations that don't use 'i' or change '*p'
foo(i);

and this is the only use of 'i', surely this is always as fast or faster than

foo(*p);

due to reducing register pressure.

-- 
- Geoffrey Keating <geoffk@geoffk.org>