[LLVMdev] Trying to use patchpoint in MCJIT

[Will Dietz]

On Tue, Dec 17, 2013 at 4:42 PM, Gaël Thomas <gael.thomas00 at gmail.com> wrote:
> %5 = call i64 (i64, i32, i8*, i32, ...)* @llvm.experimental.patchpoint.i64(
>   i64 42, ;; patch point id is 42
>   i32 0,   ;; 0 bytes for the padding
>   i8* bitcast (i32 (i32)* @f to i8*), ;; my function f
>   i32 1,   ;; 1 argument
>   i32 0)   ;; the argument

It appears patchpoint doesn't yet support function symbols as the target:

SelectionDAGBuilder.cpp:6949:
-----------------------------------
  // Assume that the Callee is a constant address.
  // FIXME: handle function symbols in the future.
  Ops.push_back(
    DAG.getIntPtrConstant(cast<ConstantSDNode>(Callee)->getZExtValue(),
                          /*isTarget=*/true));
-----------------------------------

Which is hit when I attempt to run something similar to your example
through llc.  The assertion doesn't fail when I replace the @f bitcast
with "i8* null".

Hope this helps, attached is sample bitcode demonstrating the issue.

~Will
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