1//===- Interpreter.cpp - Top-Level LLVM Interpreter Implementation --------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file implements the top-level functionality for the LLVM interpreter.
10// This interpreter is designed to be a very simple, portable, inefficient
11// interpreter.
12//
13//===----------------------------------------------------------------------===//
14
15#include "Interpreter.h"
16#include "llvm/CodeGen/IntrinsicLowering.h"
17#include "llvm/IR/DerivedTypes.h"
18#include "llvm/IR/Module.h"
19#include <cstring>
20using namespace llvm;
21
22namespace {
23
24static struct RegisterInterp {
25  RegisterInterp() { Interpreter::Register(); }
26} InterpRegistrator;
27
28}
29
30extern "C" void LLVMLinkInInterpreter() { }
31
32/// Create a new interpreter object.
33///
34ExecutionEngine *Interpreter::create(std::unique_ptr<Module> M,
35                                     std::string *ErrStr) {
36  // Tell this Module to materialize everything and release the GVMaterializer.
37  if (Error Err = M->materializeAll()) {
38    std::string Msg;
39    handleAllErrors(std::move(Err), [&](ErrorInfoBase &EIB) {
40      Msg = EIB.message();
41    });
42    if (ErrStr)
43      *ErrStr = Msg;
44    // We got an error, just return 0
45    return nullptr;
46  }
47
48  return new Interpreter(std::move(M));
49}
50
51//===----------------------------------------------------------------------===//
52// Interpreter ctor - Initialize stuff
53//
54Interpreter::Interpreter(std::unique_ptr<Module> M)
55    : ExecutionEngine(std::move(M)) {
56
57  memset(&ExitValue.Untyped, 0, sizeof(ExitValue.Untyped));
58  // Initialize the "backend"
59  initializeExecutionEngine();
60  initializeExternalFunctions();
61  emitGlobals();
62
63  IL = new IntrinsicLowering(getDataLayout());
64}
65
66Interpreter::~Interpreter() {
67  delete IL;
68}
69
70void Interpreter::runAtExitHandlers () {
71  while (!AtExitHandlers.empty()) {
72    callFunction(AtExitHandlers.back(), None);
73    AtExitHandlers.pop_back();
74    run();
75  }
76}
77
78/// run - Start execution with the specified function and arguments.
79///
80GenericValue Interpreter::runFunction(Function *F,
81                                      ArrayRef<GenericValue> ArgValues) {
82  assert (F && "Function *F was null at entry to run()");
83
84  // Try extra hard not to pass extra args to a function that isn't
85  // expecting them.  C programmers frequently bend the rules and
86  // declare main() with fewer parameters than it actually gets
87  // passed, and the interpreter barfs if you pass a function more
88  // parameters than it is declared to take. This does not attempt to
89  // take into account gratuitous differences in declared types,
90  // though.
91  const size_t ArgCount = F->getFunctionType()->getNumParams();
92  ArrayRef<GenericValue> ActualArgs =
93      ArgValues.slice(0, std::min(ArgValues.size(), ArgCount));
94
95  // Set up the function call.
96  callFunction(F, ActualArgs);
97
98  // Start executing the function.
99  run();
100
101  return ExitValue;
102}
103