[PATCH] D34484: DAG: Provide access to Pass instance from SelectionDAG

[Justin Bogner via llvm-commits]

Matt Arsenault via Phabricator <reviews at reviews.llvm.org> writes:
> arsenm created this revision.
> Herald added a subscriber: wdng.
>
> This allows accessing an analysis pass during lowering.
>
> As asked about here:
> http://lists.llvm.org/pipermail/llvm-dev/2017-June/114067.html

So this feels like an awkward break in abstraction and my gut instincts
don't like it. That said, this has actually come up a little bit before
(in the context of getting at ORE, which you can see is passed in
directly today), so I guess it's obvious that we need to do something
here.

If you don't mind, could you let me think about this a little bit? I'll
reply to the llvm-dev thread with my thoughts sometime in the next week
or so.

> https://reviews.llvm.org/D34484
>
> Files:
>   include/llvm/CodeGen/SelectionDAG.h
>   lib/CodeGen/SelectionDAG/SelectionDAG.cpp
>   lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
>
> Index: lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
> ===================================================================
> --- lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
> +++ lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
> @@ -414,7 +414,7 @@
>  
>    SplitCriticalSideEffectEdges(const_cast<Function &>(Fn), DT, LI);
>  
> -  CurDAG->init(*MF, *ORE);
> +  CurDAG->init(*MF, *ORE, this);
>    FuncInfo->set(Fn, *MF, CurDAG);
>  
>    // Now get the optional analyzes if we want to.
> Index: lib/CodeGen/SelectionDAG/SelectionDAG.cpp
> ===================================================================
> --- lib/CodeGen/SelectionDAG/SelectionDAG.cpp
> +++ lib/CodeGen/SelectionDAG/SelectionDAG.cpp
> @@ -891,8 +891,10 @@
>  }
>  
>  void SelectionDAG::init(MachineFunction &NewMF,
> -                        OptimizationRemarkEmitter &NewORE) {
> +                        OptimizationRemarkEmitter &NewORE,
> +                        Pass *PassPtr) {
>    MF = &NewMF;
> +  SDAGISelPass = PassPtr;
>    ORE = &NewORE;
>    TLI = getSubtarget().getTargetLowering();
>    TSI = getSubtarget().getSelectionDAGInfo();
> Index: include/llvm/CodeGen/SelectionDAG.h
> ===================================================================
> --- include/llvm/CodeGen/SelectionDAG.h
> +++ include/llvm/CodeGen/SelectionDAG.h
> @@ -211,6 +211,7 @@
>    const SelectionDAGTargetInfo *TSI = nullptr;
>    const TargetLowering *TLI = nullptr;
>    MachineFunction *MF;
> +  Pass *SDAGISelPass = nullptr;
>    LLVMContext *Context;
>    CodeGenOpt::Level OptLevel;
>  
> @@ -366,13 +367,16 @@
>    ~SelectionDAG();
>  
>    /// Prepare this SelectionDAG to process code in the given MachineFunction.
> -  void init(MachineFunction &NewMF, OptimizationRemarkEmitter &NewORE);
> +  void init(MachineFunction &NewMF, OptimizationRemarkEmitter &NewORE,
> +            Pass *PassPtr);
>  
>    /// Clear state and free memory necessary to make this
>    /// SelectionDAG ready to process a new block.
>    void clear();
>  
>    MachineFunction &getMachineFunction() const { return *MF; }
> +  const Pass *getPass() const { return SDAGISelPass; }
> +
>    const DataLayout &getDataLayout() const { return MF->getDataLayout(); }
>    const TargetMachine &getTarget() const { return TM; }
>    const TargetSubtargetInfo &getSubtarget() const { return MF->getSubtarget(); }
>