[Dwarf-Discuss] PROPOSAL: Constant expressions in location lists

Chris Lattner sabre@nondot.org
Mon Jan 7 02:23:54 GMT 2008

On Jan 6, 2008, at 5:26 PM, Jim Blandy wrote:

> At first blush, this might seem like a horrible bloat of the DWARF
> spec: would the spec have to describe (say) C's integral type
> promotion rules for binary operators, the proper handling of 0 when it
> appears as the second or third operand of a ?: expression, and so on?

Why would you want to encode it at the source level?  You just need  
the ability for the compiler to express how to compute it, which  
doesn't require source-level rules.  For example, instead of  
expressing all the semantics of C casts, you could have explicit sign  
extend, truncate, zero extend, etc operations, and have the compiler  
emit those instead.

In fact, this would be a better parity match with most compiler  
backends anyway.


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