1 //===-- llvm/Support/Threading.cpp- Control multithreading mode --*- C++ -*-==//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file defines helper functions for running LLVM in a multi-threaded
11 // environment.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #include "llvm/Support/Threading.h"
16 #include "llvm/Config/config.h"
17 #include "llvm/Support/Host.h"
18 
19 #include <cassert>
20 #include <errno.h>
21 #include <stdlib.h>
22 #include <string.h>
23 
24 using namespace llvm;
25 
26 //===----------------------------------------------------------------------===//
27 //=== WARNING: Implementation here must contain only TRULY operating system
28 //===          independent code.
29 //===----------------------------------------------------------------------===//
30 
31 bool llvm::llvm_is_multithreaded() {
32 #if LLVM_ENABLE_THREADS != 0
33   return true;
34 #else
35   return false;
36 #endif
37 }
38 
39 #if LLVM_ENABLE_THREADS == 0 ||                                                \
40     (!defined(LLVM_ON_WIN32) && !defined(HAVE_PTHREAD_H))
41 // Support for non-Win32, non-pthread implementation.
42 void llvm::llvm_execute_on_thread(void (*Fn)(void *), void *UserData,
43                                   unsigned RequestedStackSize) {
44   (void)RequestedStackSize;
45   Fn(UserData);
46 }
47 
48 unsigned llvm::heavyweight_hardware_concurrency() { return 1; }
49 
50 uint64_t llvm::get_threadid() { return 0; }
51 
52 uint32_t llvm::get_max_thread_name_length() { return 0; }
53 
54 void llvm::set_thread_name(const Twine &Name) {}
55 
56 void llvm::get_thread_name(SmallVectorImpl<char> &Name) { Name.clear(); }
57 
58 #else
59 
60 #include <thread>
61 unsigned llvm::heavyweight_hardware_concurrency() {
62   // Since we can't get here unless LLVM_ENABLE_THREADS == 1, it is safe to use
63   // `std::thread` directly instead of `llvm::thread` (and indeed, doing so
64   // allows us to not define `thread` in the llvm namespace, which conflicts
65   // with some platforms such as FreeBSD whose headers also define a struct
66   // called `thread` in the global namespace which can cause ambiguity due to
67   // ADL.
68   int NumPhysical = sys::getHostNumPhysicalCores();
69   if (NumPhysical == -1)
70     return std::thread::hardware_concurrency();
71   return NumPhysical;
72 }
73 
74 // Include the platform-specific parts of this class.
75 #ifdef LLVM_ON_UNIX
76 #include "Unix/Threading.inc"
77 #endif
78 #ifdef LLVM_ON_WIN32
79 #include "Windows/Threading.inc"
80 #endif
81 
82 #endif
83