llvm dev - Jan 2018 - Splitting BB pre SelectionDAG

Hi everyone,
I'm faily new to LLVM, I'm working on a new backend.

In my backend, one of the requirements is to split a BB on every call, I
considered putting some kind of pseudo instruction using the
TargetLowering::LowerCall function.

Before going said path, I was wondering if there is some way to split the
BB before the SelectionDAG is generated, this way the call instruction
would be last in the SelectionDAG would be last and won't get deleted
during the combining stage.

Thanks in advance, Liad.
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> On Jan 21, 2018, at 11:33, Liad Mordekoviz via llvm-dev <llvm-dev at
lists.llvm.org> wrote:
> 
> Before going said path, I was wondering if there is some way to split the
BB before the SelectionDAG is generated, this way the call instruction would be
last in the SelectionDAG would be last and won't get deleted during the
combining stage.
> 
You can’t/shouldn’t do this before SelectionDAG, since an operation could be
legalized using a call when there was no call present in the original IR.
Additionally, you would still need to separate the code you emit for the call
setup sequence.

-Matt