[LLVMdev] How to know if an instruction is "usable"

[Giacomo Tagliabue]

Thanks,
So, how do I check if a block dominates another one?


On 25 April 2013 11:59, Krzysztof Parzyszek <kparzysz at codeaurora.org> wrote:

> On 4/25/2013 11:52 AM, Giacomo Tagliabue wrote:
>
>> Is there an easy way to know if, at a certain instruction, a certain
>> value is usable or not? i.e., I am sure that if i use that value i don't
>> to get the error "Instruction does not dominate all uses!"
>>
>
> Check if the block containing the definition dominates the block where you
> want to use the value.  If this is the same block, the definition has to
> appear before the use.  This follows directly from the error message, so
> I'm not sure if this answers your question.  Use the dominator tree
> analysis to check the dominance.
>
> -Krzysztof
>
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