[clang] [ORC] Implement basic reoptimization. (PR #67050)

[via cfe-commits]

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+//===- RedirectionManager.h - Redirection manager interface -----*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// Redirection manager interface that redirects a call to symbol to another.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_EXECUTIONENGINE_ORC_REDIRECTIONMANAGER_H
+#define LLVM_EXECUTIONENGINE_ORC_REDIRECTIONMANAGER_H
+
+#include "llvm/ExecutionEngine/Orc/Core.h"
+
+namespace llvm {
+namespace orc {
+
+/// Base class for performing redirection of call to symbol to another symbol in
+/// runtime.
+class RedirectionManager {
+public:
+  /// Symbol name to symbol definition map.
+  using SymbolAddrMap = DenseMap<SymbolStringPtr, ExecutorSymbolDef>;
+
+  virtual ~RedirectionManager() = default;
+  /// Change the redirection destination of given symbols to new destination
+  /// symbols.
+  virtual Error redirect(JITDylib &JD, const SymbolAddrMap &NewDests) = 0;
+
+  /// Change the redirection destination of given symbol to new destination
+  /// symbol.
+  virtual Error redirect(JITDylib &JD, SymbolStringPtr Symbol,
+                         ExecutorSymbolDef NewDest) {
+    return redirect(JD, {{Symbol, NewDest}});
+  }
+
+private:
+  virtual void anchor();
+};
+
+/// Base class for managing redirectable symbols in which a call
+/// gets redirected to another symbol in runtime.
+class RedirectableSymbolManager : public RedirectionManager {
+public:
+  /// Create redirectable symbols with given symbol names and initial
+  /// desitnation symbol addresses.
+  Error createRedirectableSymbols(ResourceTrackerSP RT,
+                                  const SymbolMap &InitialDests);
+
+  /// Create a single redirectable symbol with given symbol name and initial
+  /// desitnation symbol address.
+  Error createRedirectableSymbol(ResourceTrackerSP RT, SymbolStringPtr Symbol,
+                                 ExecutorSymbolDef InitialDest) {
+    return createRedirectableSymbols(RT, {{Symbol, InitialDest}});
+  }
+
+  /// Emit redirectable symbol
+  virtual void
+  emitRedirectableSymbols(std::unique_ptr<MaterializationResponsibility> MR,
+                          const SymbolMap &InitialDests) = 0;
+};
+
+class RedirectableMaterializationUnit : public MaterializationUnit {
+public:
+  RedirectableMaterializationUnit(RedirectableSymbolManager &RM,
+                                  const SymbolMap &InitialDests)
+      : MaterializationUnit(convertToFlags(InitialDests)), RM(RM),
+        InitialDests(InitialDests) {}
+
+  StringRef getName() const override {
+    return "RedirectableSymbolMaterializationUnit";
+  }
+
+  void materialize(std::unique_ptr<MaterializationResponsibility> R) override {
+    RM.emitRedirectableSymbols(std::move(R), std::move(InitialDests));
+  }
+
+  void discard(const JITDylib &JD, const SymbolStringPtr &Name) override {
+    InitialDests.erase(Name);
+  }
+
+private:
+  static MaterializationUnit::Interface
+  convertToFlags(const SymbolMap &InitialDests) {
+    SymbolFlagsMap Flags;
+    for (auto [K, V] : InitialDests) {
+      Flags[K] = V.getFlags();
+    }
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lhames wrote:

No braces needed for single-line loops. :)

https://github.com/llvm/llvm-project/pull/67050