[LLVMdev] Indirect branch instruction

[Nicolas Geoffray]

Chris Lattner wrote:
>> Yes, that was the original question. But actually, for my purpose, 
>> Chris' solution is functional enough. However, I looked into llvm-gcc 
>> code and the switch instruction switches for all possible labels defined 
>> in the method. Does LLVM is smart enough to realize that it switches on 
>> the address of a label, therefore only has to generate a jmp in x86 or a 
>> {mtctr, bctr} couple in powerpc?
>>     
>
> I'm not sure what you mean.  We do reasonable optimization of switch 
> statements, but I'm sure there are cases we miss.  If so, please let us 
> know, so we can add them to lib/Target/README.txt
>
>   
Two jumps are executed when using a switch statement for indirect branch:
the first jump goes to the right switch case, the second jumps to the 
corresponding
label. However, indirect branches need only one jump: jumping to the 
value contained
in a register for example (which contains the address of a label).

Nicolas