[LLVMdev] Problem using 'bitcast'

Dave Cope dwcope at gmail.com
Fri Apr 4 10:11:30 PDT 2008

I have been trying to compile some Llvm code that I generate, and I am
running into a problem assembling my ll code.  Here is a snippet of the code
I am trying to compile:
    %loc0 = alloca i32
    call void @llvm.dbg.declare( {  }* bitcast(i32* %loc0 to {  }*), {  }*
bitcast (%llvm.dbg.variable.type* @llvm.dbg.variable1 to {  }*) )

I get an error from the second line of code:
    Invalid reference to global

Just to try to get the code to compile, I replaced the reference to %loc0
with null:
    %loc0 = alloca i32
    call void @llvm.dbg.declare( {  }* bitcast(i32* null to {  }*), {  }*
bitcast (%llvm.dbg.variable.type* @llvm.dbg.variable1 to {  }*) )

This code compiles fine, but obviously will not give the end result I want.

My current solution is to introduce a temporary variable like this:
    %loc0 = alloca i32
    %loc0_void = bitcast i32* %loc0 to {  }*
    call void @llvm.dbg.declare( {  }* %loc0_void, {  }* bitcast
(%llvm.dbg.variable.type* @llvm.dbg.variable1 to {  }*) )

I would prefer to make the first code snippet work (to avoid adding
temporary variables and cluttering up the ll code).  But my workaround is
alright for now.

I am wondering why my first code snippet doesn't compile properly.  Am I
doing something incorrect?  Or is this possibly and LLVM bug of some kind?

Thanks a lot,
Dave Cope
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