llvm dev - Apr 2013 - [LLVMdev] Getting the position of a BasicBlock that doesn't exist anymore in the backend

Hello,

In our LLVM backend we needto  output certain labels in the AsmPrinter 
in order to access certain data through those labels. These labels are 
related to BlockAddress objects (that come from above) and they should 
be put into a position that is related to the BasicBlock pointed by that 
BlockAddress.

The problem I'm hitting is that if the BasicBlock that the BlockAddress 
points to is optimized away by the LLVM optimizer the BlockAddress 
becomes unreliable and the BasicBlock it points to is not anymore in the 
Function it was supposed to be. Because of this I'm not able to actually 
decide the position where to output the label anymore (because I rely on 
the position of the BasicBlock in the Function to decide the position of 
the label).

The most desirable situation would be to be able to know which is the 
BasicBlock that is immediately after in the stream and point to that, 
but I don't know if there is a reliable way to do that ( I tried to use 
the ->getPrevNode() ->getNextNode() on the BasicBlock object pointed by 
the BlockAddress, but I get unreliable results). Any idea?

Cheers,
Marcello

-- 
Marcello Maggioni
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