[LLVMdev] JumpThreading and @llvm.dbg.declare()

[Hans Wennborg]

On Thu, Feb 5, 2015 at 4:49 AM, Karl-Johan Karlsson
<karl-johan.karlsson at ericsson.com> wrote:
> I have a small issue with the JumpThreading pass (in opt). As described in
> the code (JumpThreading.cpp), the pass may if certain criteria are fulfilled
> duplicate the content of a block. If the duplicated block contain a call to
> @llvm.dbg.declare() you will end up with invalid code as the intrinsic
> @llvm.dbg.declare() only should occur once for each variable.
>
> I think the JumpThreading pass should lower all llvm.dbg.declare() into
> llvm.dbg.value() the same way as the instcombine pass do (see
> InstructionCombining.cpp):
>
>   // Lower dbg.declare intrinsics otherwise their value may be clobbered
>   // by instcombiner.
>   bool DbgDeclaresChanged = LowerDbgDeclare(F);
>
> Do you agree? Ok to commit?

Did you forget to attach a patch? A patch with a test case showing the
problem you're describing would be great.

Also, patches should generally be sent to the llvm-commits list, not llvmdev.

Thanks,
Hans