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+//===--- ByteCodeEmitter.h - Instruction emitter for the VM ---------*- 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
+//
+//===----------------------------------------------------------------------===//
+//
+// Defines the instruction emitters.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_AST_INTERP_LINKEMITTER_H
+#define LLVM_CLANG_AST_INTERP_LINKEMITTER_H
+
+#include "ByteCodeGenError.h"
+#include "Context.h"
+#include "InterpStack.h"
+#include "InterpState.h"
+#include "PrimType.h"
+#include "Program.h"
+#include "Source.h"
+#include "llvm/Support/Error.h"
+
+namespace clang {
+namespace interp {
+class Context;
+class SourceInfo;
+enum Opcode : uint32_t;
+
+/// An emitter which links the program to bytecode for later use.
+class ByteCodeEmitter {
+protected:
+ using LabelTy = uint32_t;
+ using AddrTy = uintptr_t;
+ using Local = Scope::Local;
+
+public:
+ /// Compiles the function into the module.
+ llvm::Expected<Function *> compileFunc(const FunctionDecl *F);
+
+protected:
+ ByteCodeEmitter(Context &Ctx, Program &P) : Ctx(Ctx), P(P) {}
+
+ virtual ~ByteCodeEmitter() {}
+
+ /// Define a label.
+ void emitLabel(LabelTy Label);
+ /// Create a label.
+ LabelTy getLabel() { return ++NextLabel; }
+
+ /// Methods implemented by the compiler.
+ virtual bool visitFunc(const FunctionDecl *E) = 0;
+ virtual bool visitExpr(const Expr *E) = 0;
+ virtual bool visitDecl(const VarDecl *E) = 0;
+
+ /// Bails out if a given node cannot be compiled.
+ bool bail(const Stmt *S) { return bail(S->getBeginLoc()); }
+ bool bail(const Decl *D) { return bail(D->getBeginLoc()); }
+ bool bail(const SourceLocation &Loc);
+
+ /// Emits jumps.
+ bool jumpTrue(const LabelTy &Label);
+ bool jumpFalse(const LabelTy &Label);
+ bool jump(const LabelTy &Label);
+ bool fallthrough(const LabelTy &Label);
+
+ /// Callback for local registration.
+ Local createLocal(Descriptor *D);
+
+ /// Parameter indices.
+ llvm::DenseMap<const ParmVarDecl *, unsigned> Params;
+ /// Local descriptors.
+ llvm::SmallVector<SmallVector<Local, 8>, 2> Descriptors;
+
+private:
+ /// Current compilation context.
+ Context &Ctx;
+ /// Program to link to.
+ Program &P;
+ /// Index of the next available label.
+ LabelTy NextLabel = 0;
+ /// Offset of the next local variable.
+ unsigned NextLocalOffset = 0;
+ /// Location of a failure.
+ llvm::Optional<SourceLocation> BailLocation;
+ /// Label information for linker.
+ llvm::DenseMap<LabelTy, unsigned> LabelOffsets;
+ /// Location of label relocations.
+ llvm::DenseMap<LabelTy, llvm::SmallVector<unsigned, 5>> LabelRelocs;
+ /// Program code.
+ std::vector<char> Code;
+ /// Opcode to expression mapping.
+ SourceMap SrcMap;
+
+ /// Returns the offset for a jump or records a relocation.
+ int32_t getOffset(LabelTy Label);
+
+ /// Emits an opcode.
+ template <typename... Tys>
+ bool emitOp(Opcode Op, const Tys &... Args, const SourceInfo &L);
+
+protected:
+#define GET_LINK_PROTO
+#include "Opcodes.inc"
+#undef GET_LINK_PROTO
+};
+
+} // namespace interp
+} // namespace clang
+
+#endif