[LLVMdev] Indirect branch instruction

Chris Lattner sabre at nondot.org
Sat Jan 13 13:51:04 CST 2007


On Thu, 11 Jan 2007, Eric van Riet Paap wrote:

>> The switch instruction serves the same functional role.  In llvm- gcc, 
>> the GCC "Address of label" and "indirect goto" extensions are compiled 
>> into a switch instruction.
>
> I think the question is how to branch to a location of which you do not 
> have a label.

I'm not sure what you mean.  The compiler needs to have an accurate CFG to 
be successful with dataflow analysis (i.e. not miscompile your code).

> Presumably to avoid a stack overflow when you know that 
> you only want to return the result of an indirect call.

It sounds like you just want tail call elimination?  Jumping to the 
address of an indirect call is a great way to get a crash, except in the 
most trivial cases.

-Chris

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