Use SILPrinter callback mechanism to annotate the printed SIL code

[mhong]

4e27ff2 added code for annotating SIL code with TFPartition markings.

One follow-up suggestion from clattner is to use sil printer callback before printing each instruction (SILPrinter.cpp:634):

    for (const SILInstruction &I : *BB) {
      Ctx.printInstructionCallBack(&I);
      if (SILPrintGenericSpecializationInfo) {
        if (auto AI = ApplySite::isa(const_cast<SILInstruction *>(&I)))
          if (AI.getSpecializationInfo() && AI.getCalleeFunction())
            printGenericSpecializationInfo(
                PrintState.OS, "call-site", AI.getCalleeFunction()->getName(),
                AI.getSpecializationInfo(), AI.getSubstitutions());
      }
      print(&I);
    }

So we can derive a struct from SILPrintContext, and implement [move] kind of annotations by overriding Ctx.printInstructionCallBack. This way we hopefully just need to call “print” on the function with the right printer context defined.

Example code:

/// A print context which records the line numbers where instructions are
/// printed.
struct AnalysisPrintContext : public SILPrintContext {
  AnalysisPrintContext(llvm::raw_ostream &OS) : SILPrintContext(OS) {}

  ~AnalysisPrintContext() override {}

  void printInstructionCallBack(const SILInstruction *I) override {
    OutStream << "XXXX ";
    I->print(OutStream);
  }
};

Call site:

  if (auto *outs = getTFDumpIntermediateStream()) {
    AnalysisPrintContext ctx(*outs);
    fn.print(ctx);
  }

One challenge is that in addition to annotating instructions, we also want to annotate BB args (code here). So the current callback mechanism on inst level is not sufficient. One option is to extend the SILPrinter callback infra to support annotating BB args.

[lattner]

Makes sense. It would be great to upstream such an extension, I suspect that the swift.org folks would take such a patch with no concern.

[rxwei]

Moved to SR-7669.