[llvm-commits] [LLVM, SwitchInst, case ranges] Auxiliary patch #1
Stepan Dyatkovskiy
STPWORLD at narod.ru
Tue Jan 10 09:59:56 PST 2012
Ping.
-Stepan.
09.01.2012, 12:40, "Stepan Dyatkovskiy" <STPWORLD at narod.ru>:
> ping.
> -Stepan.
>
> 06.01.2012, 13:02, "Stepan Dyatkovskiy" <STPWORLD at narod.ru>:
>
>>> My half-baked thought was that we could store 1, 4...7, 12 as [1, <4, 7>, 12], just to distinguish ranges from pairs of scalar values.
>> May be ConstantStruct? Something like this:
>>
>> struct { // 0-level struct represents set of values and ranges.
>> unsigned v1 = 1;
>> struct { // 1-level struct represents ranges, and must have two fields only: "low" and "high".
>> unsigned low = 4;
>> unsigned high = 7;
>> } v2;
>> unsigned v3 = 12;
>> }
>>>> CaseValue = SI->getOperand(SomeIndex); // We use User methods keeping SwitchInst format in mind.
>>>> CaseSuccessor = SI->getSuccessor(SomeIndex2); // We use TerminatorInst methods keeping what each successor means in mind.
>>>> with
>>>> CaseValue = SI->getCaseValue(SomeCaseValueIndex);
>>>> Successor = SI->getCaseSuccessor(SomeSuccessorIndex);
>>> I may not be understanding what you mean, but I think that getting rid of getOperand() (hiding it in SwitchInst) makes sense. getSuccessor() still needs to exist though.
>> Now 0-case value is not a case value instead. It is a Condition. The same with successors. Zero-indexed successor is default destination (not a case successor). We store items with different types and roles in single collection.
>> I propose totally separate this terms on SwitchInst level: to use getCondition() if you need condition, use getDefaultDest() for default destination. Use getCaseValue only for resolving some case value. So getCaseValue(0) means that I need first case value (not condition) and getCaseSuccessor(0) means that I need successors for first case value (not default dest). Ideally, developer that uses SwitchInst should know nothing about internal operators format.
>>
>> -Stepan.
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