[clang] [clang-repl] Expose RuntimeInterfaceBuilder to allow customization (PR #83126)

[Stefan Gränitz via cfe-commits]

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@@ -741,9 +775,8 @@ Expr *Interpreter::SynthesizeExpr(Expr *E) {
   auto *OutValue = CStyleCastPtrExpr(S, Ctx.VoidPtrTy, (uintptr_t)&LastValue);
 
   // Build `__clang_Interpreter_SetValue*` call.
-  RuntimeInterfaceBuilder Builder(*this, Ctx, S, E, {ThisInterp, OutValue});
+  ExprResult Result = Builder->getCall(E, {ThisInterp, OutValue});
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weliveindetail wrote:

FindRuntimeInterface() and getCall() are virtual functions now, which introduces a tiny runtime overhead for each synthesized expression. It should be negligible compared to the effort for parsing and compilation, but if it's an issue, I am happy to change it to a call to function pointer.

https://github.com/llvm/llvm-project/pull/83126