cc1_main.cpp revision 355940 
1//===-- cc1_main.cpp - Clang CC1 Compiler Frontend ------------------------===//
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 is the entry point to the clang -cc1 functionality, which implements the
10// core compiler functionality along with a number of additional tools for
11// demonstration and testing purposes.
12//
13//===----------------------------------------------------------------------===//
14
15#include "clang/Basic/Stack.h"
16#include "clang/Basic/TargetOptions.h"
17#include "clang/CodeGen/ObjectFilePCHContainerOperations.h"
18#include "clang/Config/config.h"
19#include "clang/Driver/DriverDiagnostic.h"
20#include "clang/Driver/Options.h"
21#include "clang/Frontend/CompilerInstance.h"
22#include "clang/Frontend/CompilerInvocation.h"
23#include "clang/Frontend/FrontendDiagnostic.h"
24#include "clang/Frontend/TextDiagnosticBuffer.h"
25#include "clang/Frontend/TextDiagnosticPrinter.h"
26#include "clang/Frontend/Utils.h"
27#include "clang/FrontendTool/Utils.h"
28#include "llvm/ADT/Statistic.h"
29#include "llvm/Config/llvm-config.h"
30#include "llvm/LinkAllPasses.h"
31#include "llvm/Option/Arg.h"
32#include "llvm/Option/ArgList.h"
33#include "llvm/Option/OptTable.h"
34#include "llvm/Support/BuryPointer.h"
35#include "llvm/Support/Compiler.h"
36#include "llvm/Support/ErrorHandling.h"
37#include "llvm/Support/ManagedStatic.h"
38#include "llvm/Support/Path.h"
39#include "llvm/Support/Signals.h"
40#include "llvm/Support/TargetRegistry.h"
41#include "llvm/Support/TargetSelect.h"
42#include "llvm/Support/TimeProfiler.h"
43#include "llvm/Support/Timer.h"
44#include "llvm/Support/raw_ostream.h"
45#include "llvm/Target/TargetMachine.h"
46#include <cstdio>
47
48#ifdef CLANG_HAVE_RLIMITS
49#include <sys/resource.h>
50#endif
51
52using namespace clang;
53using namespace llvm::opt;
54
55//===----------------------------------------------------------------------===//
56// Main driver
57//===----------------------------------------------------------------------===//
58
59static void LLVMErrorHandler(void *UserData, const std::string &Message,
60                             bool GenCrashDiag) {
61  DiagnosticsEngine &Diags = *static_cast<DiagnosticsEngine*>(UserData);
62
63  Diags.Report(diag::err_fe_error_backend) << Message;
64
65  // Run the interrupt handlers to make sure any special cleanups get done, in
66  // particular that we remove files registered with RemoveFileOnSignal.
67  llvm::sys::RunInterruptHandlers();
68
69  // We cannot recover from llvm errors.  When reporting a fatal error, exit
70  // with status 70 to generate crash diagnostics.  For BSD systems this is
71  // defined as an internal software error.  Otherwise, exit with status 1.
72  exit(GenCrashDiag ? 70 : 1);
73}
74
75#ifdef LINK_POLLY_INTO_TOOLS
76namespace polly {
77void initializePollyPasses(llvm::PassRegistry &Registry);
78}
79#endif
80
81#ifdef CLANG_HAVE_RLIMITS
82#if defined(__linux__) && defined(__PIE__)
83static size_t getCurrentStackAllocation() {
84  // If we can't compute the current stack usage, allow for 512K of command
85  // line arguments and environment.
86  size_t Usage = 512 * 1024;
87  if (FILE *StatFile = fopen("/proc/self/stat", "r")) {
88    // We assume that the stack extends from its current address to the end of
89    // the environment space. In reality, there is another string literal (the
90    // program name) after the environment, but this is close enough (we only
91    // need to be within 100K or so).
92    unsigned long StackPtr, EnvEnd;
93    // Disable silly GCC -Wformat warning that complains about length
94    // modifiers on ignored format specifiers. We want to retain these
95    // for documentation purposes even though they have no effect.
96#if defined(__GNUC__) && !defined(__clang__)
97#pragma GCC diagnostic push
98#pragma GCC diagnostic ignored "-Wformat"
99#endif
100    if (fscanf(StatFile,
101               "%*d %*s %*c %*d %*d %*d %*d %*d %*u %*lu %*lu %*lu %*lu %*lu "
102               "%*lu %*ld %*ld %*ld %*ld %*ld %*ld %*llu %*lu %*ld %*lu %*lu "
103               "%*lu %*lu %lu %*lu %*lu %*lu %*lu %*lu %*llu %*lu %*lu %*d %*d "
104               "%*u %*u %*llu %*lu %*ld %*lu %*lu %*lu %*lu %*lu %*lu %lu %*d",
105               &StackPtr, &EnvEnd) == 2) {
106#if defined(__GNUC__) && !defined(__clang__)
107#pragma GCC diagnostic pop
108#endif
109      Usage = StackPtr < EnvEnd ? EnvEnd - StackPtr : StackPtr - EnvEnd;
110    }
111    fclose(StatFile);
112  }
113  return Usage;
114}
115
116#include <alloca.h>
117
118LLVM_ATTRIBUTE_NOINLINE
119static void ensureStackAddressSpace() {
120  // Linux kernels prior to 4.1 will sometimes locate the heap of a PIE binary
121  // relatively close to the stack (they are only guaranteed to be 128MiB
122  // apart). This results in crashes if we happen to heap-allocate more than
123  // 128MiB before we reach our stack high-water mark.
124  //
125  // To avoid these crashes, ensure that we have sufficient virtual memory
126  // pages allocated before we start running.
127  size_t Curr = getCurrentStackAllocation();
128  const int kTargetStack = DesiredStackSize - 256 * 1024;
129  if (Curr < kTargetStack) {
130    volatile char *volatile Alloc =
131        static_cast<volatile char *>(alloca(kTargetStack - Curr));
132    Alloc[0] = 0;
133    Alloc[kTargetStack - Curr - 1] = 0;
134  }
135}
136#else
137static void ensureStackAddressSpace() {}
138#endif
139
140/// Attempt to ensure that we have at least 8MiB of usable stack space.
141static void ensureSufficientStack() {
142  struct rlimit rlim;
143  if (getrlimit(RLIMIT_STACK, &rlim) != 0)
144    return;
145
146  // Increase the soft stack limit to our desired level, if necessary and
147  // possible.
148  if (rlim.rlim_cur != RLIM_INFINITY &&
149      rlim.rlim_cur < rlim_t(DesiredStackSize)) {
150    // Try to allocate sufficient stack.
151    if (rlim.rlim_max == RLIM_INFINITY ||
152        rlim.rlim_max >= rlim_t(DesiredStackSize))
153      rlim.rlim_cur = DesiredStackSize;
154    else if (rlim.rlim_cur == rlim.rlim_max)
155      return;
156    else
157      rlim.rlim_cur = rlim.rlim_max;
158
159    if (setrlimit(RLIMIT_STACK, &rlim) != 0 ||
160        rlim.rlim_cur != DesiredStackSize)
161      return;
162  }
163
164  // We should now have a stack of size at least DesiredStackSize. Ensure
165  // that we can actually use that much, if necessary.
166  ensureStackAddressSpace();
167}
168#else
169static void ensureSufficientStack() {}
170#endif
171
172/// Print supported cpus of the given target.
173static int PrintSupportedCPUs(std::string TargetStr) {
174  std::string Error;
175  const llvm::Target *TheTarget =
176      llvm::TargetRegistry::lookupTarget(TargetStr, Error);
177  if (!TheTarget) {
178    llvm::errs() << Error;
179    return 1;
180  }
181
182  // the target machine will handle the mcpu printing
183  llvm::TargetOptions Options;
184  std::unique_ptr<llvm::TargetMachine> TheTargetMachine(
185      TheTarget->createTargetMachine(TargetStr, "", "+cpuHelp", Options, None));
186  return 0;
187}
188
189int cc1_main(ArrayRef<const char *> Argv, const char *Argv0, void *MainAddr) {
190  ensureSufficientStack();
191
192  std::unique_ptr<CompilerInstance> Clang(new CompilerInstance());
193  IntrusiveRefCntPtr<DiagnosticIDs> DiagID(new DiagnosticIDs());
194
195  // Register the support for object-file-wrapped Clang modules.
196  auto PCHOps = Clang->getPCHContainerOperations();
197  PCHOps->registerWriter(llvm::make_unique<ObjectFilePCHContainerWriter>());
198  PCHOps->registerReader(llvm::make_unique<ObjectFilePCHContainerReader>());
199
200  // Initialize targets first, so that --version shows registered targets.
201  llvm::InitializeAllTargets();
202  llvm::InitializeAllTargetMCs();
203  llvm::InitializeAllAsmPrinters();
204  llvm::InitializeAllAsmParsers();
205
206#ifdef LINK_POLLY_INTO_TOOLS
207  llvm::PassRegistry &Registry = *llvm::PassRegistry::getPassRegistry();
208  polly::initializePollyPasses(Registry);
209#endif
210
211  // Buffer diagnostics from argument parsing so that we can output them using a
212  // well formed diagnostic object.
213  IntrusiveRefCntPtr<DiagnosticOptions> DiagOpts = new DiagnosticOptions();
214  TextDiagnosticBuffer *DiagsBuffer = new TextDiagnosticBuffer;
215  DiagnosticsEngine Diags(DiagID, &*DiagOpts, DiagsBuffer);
216  bool Success = CompilerInvocation::CreateFromArgs(
217      Clang->getInvocation(), Argv.begin(), Argv.end(), Diags);
218
219  if (Clang->getFrontendOpts().TimeTrace)
220    llvm::timeTraceProfilerInitialize();
221
222  // --print-supported-cpus takes priority over the actual compilation.
223  if (Clang->getFrontendOpts().PrintSupportedCPUs)
224    return PrintSupportedCPUs(Clang->getTargetOpts().Triple);
225
226  // Infer the builtin include path if unspecified.
227  if (Clang->getHeaderSearchOpts().UseBuiltinIncludes &&
228      Clang->getHeaderSearchOpts().ResourceDir.empty())
229    Clang->getHeaderSearchOpts().ResourceDir =
230      CompilerInvocation::GetResourcesPath(Argv0, MainAddr);
231
232  // Create the actual diagnostics engine.
233  Clang->createDiagnostics();
234  if (!Clang->hasDiagnostics())
235    return 1;
236
237  // Set an error handler, so that any LLVM backend diagnostics go through our
238  // error handler.
239  llvm::install_fatal_error_handler(LLVMErrorHandler,
240                                  static_cast<void*>(&Clang->getDiagnostics()));
241
242  DiagsBuffer->FlushDiagnostics(Clang->getDiagnostics());
243  if (!Success)
244    return 1;
245
246  // Execute the frontend actions.
247  {
248    llvm::TimeTraceScope TimeScope("ExecuteCompiler", StringRef(""));
249    Success = ExecuteCompilerInvocation(Clang.get());
250  }
251
252  // If any timers were active but haven't been destroyed yet, print their
253  // results now.  This happens in -disable-free mode.
254  llvm::TimerGroup::printAll(llvm::errs());
255
256  if (llvm::timeTraceProfilerEnabled()) {
257    SmallString<128> Path(Clang->getFrontendOpts().OutputFile);
258    llvm::sys::path::replace_extension(Path, "json");
259    auto profilerOutput =
260        Clang->createOutputFile(Path.str(),
261                                /*Binary=*/false,
262                                /*RemoveFileOnSignal=*/false, "",
263                                /*Extension=*/"json",
264                                /*useTemporary=*/false);
265
266    llvm::timeTraceProfilerWrite(*profilerOutput);
267    // FIXME(ibiryukov): make profilerOutput flush in destructor instead.
268    profilerOutput->flush();
269    llvm::timeTraceProfilerCleanup();
270
271    llvm::errs() << "Time trace json-file dumped to " << Path.str() << "\n";
272    llvm::errs()
273        << "Use chrome://tracing or Speedscope App "
274           "(https://www.speedscope.app) for flamegraph visualization\n";
275  }
276
277  // Our error handler depends on the Diagnostics object, which we're
278  // potentially about to delete. Uninstall the handler now so that any
279  // later errors use the default handling behavior instead.
280  llvm::remove_fatal_error_handler();
281
282  // When running with -disable-free, don't do any destruction or shutdown.
283  if (Clang->getFrontendOpts().DisableFree) {
284    llvm::BuryPointer(std::move(Clang));
285    return !Success;
286  }
287
288  return !Success;
289}
290