1 //===-- MCJIT.h - MC-Based Just-In-Time Execution Engine --------*- C++ -*-===//
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 forces the MCJIT to link in on certain operating systems.
10 // (Windows).
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #ifndef LLVM_EXECUTIONENGINE_MCJIT_H
15 #define LLVM_EXECUTIONENGINE_MCJIT_H
16 
17 #include "llvm/ExecutionEngine/ExecutionEngine.h"
18 #include <cstdlib>
19 
20 extern "C" void LLVMLinkInMCJIT();
21 
22 namespace {
23   struct ForceMCJITLinking {
ForceMCJITLinkingForceMCJITLinking24     ForceMCJITLinking() {
25       // We must reference MCJIT in such a way that compilers will not
26       // delete it all as dead code, even with whole program optimization,
27       // yet is effectively a NO-OP. As the compiler isn't smart enough
28       // to know that getenv() never returns -1, this will do the job.
29       // This is so that globals in the translation units where these functions
30       // are defined are forced to be initialized, populating various
31       // registries.
32       if (std::getenv("bar") != (char*) -1)
33         return;
34 
35       LLVMLinkInMCJIT();
36     }
37   } ForceMCJITLinking;
38 }
39 
40 #endif
41