[clang] [CIR] Add framework for CIR to LLVM IR lowering (PR #124650)

[Aaron Ballman via cfe-commits]

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@@ -55,6 +56,13 @@ class EmitCIRAction : public CIRGenAction {
   EmitCIRAction(mlir::MLIRContext *MLIRCtx = nullptr);
 };
 
+class EmitLLVMAction : public CIRGenAction {
+  virtual void anchor();
+
+public:
+  EmitLLVMAction(mlir::MLIRContext *MLIRCtx = nullptr);
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AaronBallman wrote:

Under what circumstances does it make sense to pass a null MLIR context? (Mostly wondering why the pattern is to use a default parameter here rather than make the caller pass it explicitly.)

https://github.com/llvm/llvm-project/pull/124650