[LLVMdev] Why variables get "optimized away" after the last use in unoptimized code?

[Eric Christopher]

This means that debug info would change code generation in order to
artificially lengthen the lifetimes of variables and is something that
is generally verboten when compiling for debug.

-eric

On Sun, Feb 2, 2014 at 1:57 AM, Yuri <yuri at rawbw.com> wrote:
> On 02/02/2014 01:48, David Chisnall wrote:
>>
>> In most calling conventions, this is a callee-save register.  After its
>> last use, the register allocator may reuse that register. On x86 and ARM,
>> the register that contains this is also (usually) the register used for
>
>
> But the rule "after the last use, the register allocator may reuse it" is
> also introduced by llvm, since register allocator is also llvm. So this
> means that the rule "preserve any values while in scope as much as possible"
> is probably a better one for debugging.
>
> Yuri
>
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