1 //===-- cc1_main.cpp - Clang CC1 Compiler Frontend ------------------------===//
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 is the entry point to the clang -cc1 functionality, which implements the
11 // core compiler functionality along with a number of additional tools for
12 // demonstration and testing purposes.
13 //
14 //===----------------------------------------------------------------------===//
15 
16 #include "llvm/Option/Arg.h"
17 #include "clang/CodeGen/ObjectFilePCHContainerOperations.h"
18 #include "clang/Config/config.h"
19 #include "clang/Basic/Stack.h"
20 #include "clang/Driver/DriverDiagnostic.h"
21 #include "clang/Driver/Options.h"
22 #include "clang/Frontend/CompilerInstance.h"
23 #include "clang/Frontend/CompilerInvocation.h"
24 #include "clang/Frontend/FrontendDiagnostic.h"
25 #include "clang/Frontend/TextDiagnosticBuffer.h"
26 #include "clang/Frontend/TextDiagnosticPrinter.h"
27 #include "clang/Frontend/Utils.h"
28 #include "clang/FrontendTool/Utils.h"
29 #include "llvm/ADT/Statistic.h"
30 #include "llvm/Config/llvm-config.h"
31 #include "llvm/LinkAllPasses.h"
32 #include "llvm/Option/ArgList.h"
33 #include "llvm/Option/OptTable.h"
34 #include "llvm/Support/Compiler.h"
35 #include "llvm/Support/ErrorHandling.h"
36 #include "llvm/Support/ManagedStatic.h"
37 #include "llvm/Support/Signals.h"
38 #include "llvm/Support/TargetSelect.h"
39 #include "llvm/Support/Timer.h"
40 #include "llvm/Support/raw_ostream.h"
41 #include <cstdio>
42 
43 #ifdef CLANG_HAVE_RLIMITS
44 #include <sys/resource.h>
45 #endif
46 
47 using namespace clang;
48 using namespace llvm::opt;
49 
50 //===----------------------------------------------------------------------===//
51 // Main driver
52 //===----------------------------------------------------------------------===//
53 
54 static void LLVMErrorHandler(void *UserData, const std::string &Message,
55                              bool GenCrashDiag) {
56   DiagnosticsEngine &Diags = *static_cast<DiagnosticsEngine*>(UserData);
57 
58   Diags.Report(diag::err_fe_error_backend) << Message;
59 
60   // Run the interrupt handlers to make sure any special cleanups get done, in
61   // particular that we remove files registered with RemoveFileOnSignal.
62   llvm::sys::RunInterruptHandlers();
63 
64   // We cannot recover from llvm errors.  When reporting a fatal error, exit
65   // with status 70 to generate crash diagnostics.  For BSD systems this is
66   // defined as an internal software error.  Otherwise, exit with status 1.
67   exit(GenCrashDiag ? 70 : 1);
68 }
69 
70 #ifdef LINK_POLLY_INTO_TOOLS
71 namespace polly {
72 void initializePollyPasses(llvm::PassRegistry &Registry);
73 }
74 #endif
75 
76 #ifdef CLANG_HAVE_RLIMITS
77 #if defined(__linux__) && defined(__PIE__)
78 static size_t getCurrentStackAllocation() {
79   // If we can't compute the current stack usage, allow for 512K of command
80   // line arguments and environment.
81   size_t Usage = 512 * 1024;
82   if (FILE *StatFile = fopen("/proc/self/stat", "r")) {
83     // We assume that the stack extends from its current address to the end of
84     // the environment space. In reality, there is another string literal (the
85     // program name) after the environment, but this is close enough (we only
86     // need to be within 100K or so).
87     unsigned long StackPtr, EnvEnd;
88     // Disable silly GCC -Wformat warning that complains about length
89     // modifiers on ignored format specifiers. We want to retain these
90     // for documentation purposes even though they have no effect.
91 #if defined(__GNUC__) && !defined(__clang__)
92 #pragma GCC diagnostic push
93 #pragma GCC diagnostic ignored "-Wformat"
94 #endif
95     if (fscanf(StatFile,
96                "%*d %*s %*c %*d %*d %*d %*d %*d %*u %*lu %*lu %*lu %*lu %*lu "
97                "%*lu %*ld %*ld %*ld %*ld %*ld %*ld %*llu %*lu %*ld %*lu %*lu "
98                "%*lu %*lu %lu %*lu %*lu %*lu %*lu %*lu %*llu %*lu %*lu %*d %*d "
99                "%*u %*u %*llu %*lu %*ld %*lu %*lu %*lu %*lu %*lu %*lu %lu %*d",
100                &StackPtr, &EnvEnd) == 2) {
101 #if defined(__GNUC__) && !defined(__clang__)
102 #pragma GCC diagnostic pop
103 #endif
104       Usage = StackPtr < EnvEnd ? EnvEnd - StackPtr : StackPtr - EnvEnd;
105     }
106     fclose(StatFile);
107   }
108   return Usage;
109 }
110 
111 #include <alloca.h>
112 
113 LLVM_ATTRIBUTE_NOINLINE
114 static void ensureStackAddressSpace() {
115   // Linux kernels prior to 4.1 will sometimes locate the heap of a PIE binary
116   // relatively close to the stack (they are only guaranteed to be 128MiB
117   // apart). This results in crashes if we happen to heap-allocate more than
118   // 128MiB before we reach our stack high-water mark.
119   //
120   // To avoid these crashes, ensure that we have sufficient virtual memory
121   // pages allocated before we start running.
122   size_t Curr = getCurrentStackAllocation();
123   const int kTargetStack = DesiredStackSize - 256 * 1024;
124   if (Curr < kTargetStack) {
125     volatile char *volatile Alloc =
126         static_cast<volatile char *>(alloca(kTargetStack - Curr));
127     Alloc[0] = 0;
128     Alloc[kTargetStack - Curr - 1] = 0;
129   }
130 }
131 #else
132 static void ensureStackAddressSpace() {}
133 #endif
134 
135 /// Attempt to ensure that we have at least 8MiB of usable stack space.
136 static void ensureSufficientStack() {
137   struct rlimit rlim;
138   if (getrlimit(RLIMIT_STACK, &rlim) != 0)
139     return;
140 
141   // Increase the soft stack limit to our desired level, if necessary and
142   // possible.
143   if (rlim.rlim_cur != RLIM_INFINITY &&
144       rlim.rlim_cur < rlim_t(DesiredStackSize)) {
145     // Try to allocate sufficient stack.
146     if (rlim.rlim_max == RLIM_INFINITY ||
147         rlim.rlim_max >= rlim_t(DesiredStackSize))
148       rlim.rlim_cur = DesiredStackSize;
149     else if (rlim.rlim_cur == rlim.rlim_max)
150       return;
151     else
152       rlim.rlim_cur = rlim.rlim_max;
153 
154     if (setrlimit(RLIMIT_STACK, &rlim) != 0 ||
155         rlim.rlim_cur != DesiredStackSize)
156       return;
157   }
158 
159   // We should now have a stack of size at least DesiredStackSize. Ensure
160   // that we can actually use that much, if necessary.
161   ensureStackAddressSpace();
162 }
163 #else
164 static void ensureSufficientStack() {}
165 #endif
166 
167 int cc1_main(ArrayRef<const char *> Argv, const char *Argv0, void *MainAddr) {
168   ensureSufficientStack();
169 
170   std::unique_ptr<CompilerInstance> Clang(new CompilerInstance());
171   IntrusiveRefCntPtr<DiagnosticIDs> DiagID(new DiagnosticIDs());
172 
173   // Register the support for object-file-wrapped Clang modules.
174   auto PCHOps = Clang->getPCHContainerOperations();
175   PCHOps->registerWriter(llvm::make_unique<ObjectFilePCHContainerWriter>());
176   PCHOps->registerReader(llvm::make_unique<ObjectFilePCHContainerReader>());
177 
178   // Initialize targets first, so that --version shows registered targets.
179   llvm::InitializeAllTargets();
180   llvm::InitializeAllTargetMCs();
181   llvm::InitializeAllAsmPrinters();
182   llvm::InitializeAllAsmParsers();
183 
184 #ifdef LINK_POLLY_INTO_TOOLS
185   llvm::PassRegistry &Registry = *llvm::PassRegistry::getPassRegistry();
186   polly::initializePollyPasses(Registry);
187 #endif
188 
189   // Buffer diagnostics from argument parsing so that we can output them using a
190   // well formed diagnostic object.
191   IntrusiveRefCntPtr<DiagnosticOptions> DiagOpts = new DiagnosticOptions();
192   TextDiagnosticBuffer *DiagsBuffer = new TextDiagnosticBuffer;
193   DiagnosticsEngine Diags(DiagID, &*DiagOpts, DiagsBuffer);
194   bool Success = CompilerInvocation::CreateFromArgs(
195       Clang->getInvocation(), Argv.begin(), Argv.end(), Diags);
196 
197   // Infer the builtin include path if unspecified.
198   if (Clang->getHeaderSearchOpts().UseBuiltinIncludes &&
199       Clang->getHeaderSearchOpts().ResourceDir.empty())
200     Clang->getHeaderSearchOpts().ResourceDir =
201       CompilerInvocation::GetResourcesPath(Argv0, MainAddr);
202 
203   // Create the actual diagnostics engine.
204   Clang->createDiagnostics();
205   if (!Clang->hasDiagnostics())
206     return 1;
207 
208   // Set an error handler, so that any LLVM backend diagnostics go through our
209   // error handler.
210   llvm::install_fatal_error_handler(LLVMErrorHandler,
211                                   static_cast<void*>(&Clang->getDiagnostics()));
212 
213   DiagsBuffer->FlushDiagnostics(Clang->getDiagnostics());
214   if (!Success)
215     return 1;
216 
217   // Execute the frontend actions.
218   Success = ExecuteCompilerInvocation(Clang.get());
219 
220   // If any timers were active but haven't been destroyed yet, print their
221   // results now.  This happens in -disable-free mode.
222   llvm::TimerGroup::printAll(llvm::errs());
223 
224   // Our error handler depends on the Diagnostics object, which we're
225   // potentially about to delete. Uninstall the handler now so that any
226   // later errors use the default handling behavior instead.
227   llvm::remove_fatal_error_handler();
228 
229   // When running with -disable-free, don't do any destruction or shutdown.
230   if (Clang->getFrontendOpts().DisableFree) {
231     BuryPointer(std::move(Clang));
232     return !Success;
233   }
234 
235   return !Success;
236 }
237