cc1_main.cpp revision 360784 
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/Process.h"
40#include "llvm/Support/Signals.h"
41#include "llvm/Support/TargetRegistry.h"
42#include "llvm/Support/TargetSelect.h"
43#include "llvm/Support/TimeProfiler.h"
44#include "llvm/Support/Timer.h"
45#include "llvm/Support/raw_ostream.h"
46#include "llvm/Target/TargetMachine.h"
47#include <cstdio>
48
49#ifdef CLANG_HAVE_RLIMITS
50#include <sys/resource.h>
51#endif
52
53using namespace clang;
54using namespace llvm::opt;
55
56//===----------------------------------------------------------------------===//
57// Main driver
58//===----------------------------------------------------------------------===//
59
60static void LLVMErrorHandler(void *UserData, const std::string &Message,
61                             bool GenCrashDiag) {
62  DiagnosticsEngine &Diags = *static_cast<DiagnosticsEngine*>(UserData);
63
64  Diags.Report(diag::err_fe_error_backend) << Message;
65
66  // Run the interrupt handlers to make sure any special cleanups get done, in
67  // particular that we remove files registered with RemoveFileOnSignal.
68  llvm::sys::RunInterruptHandlers();
69
70  // We cannot recover from llvm errors.  When reporting a fatal error, exit
71  // with status 70 to generate crash diagnostics.  For BSD systems this is
72  // defined as an internal software error.  Otherwise, exit with status 1.
73  llvm::sys::Process::Exit(GenCrashDiag ? 70 : 1);
74}
75
76#ifdef CLANG_HAVE_RLIMITS
77#if defined(__linux__) && defined(__PIE__)
78static 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
113LLVM_ATTRIBUTE_NOINLINE
114static 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
132static void ensureStackAddressSpace() {}
133#endif
134
135/// Attempt to ensure that we have at least 8MiB of usable stack space.
136static 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
164static void ensureSufficientStack() {}
165#endif
166
167/// Print supported cpus of the given target.
168static int PrintSupportedCPUs(std::string TargetStr) {
169  std::string Error;
170  const llvm::Target *TheTarget =
171      llvm::TargetRegistry::lookupTarget(TargetStr, Error);
172  if (!TheTarget) {
173    llvm::errs() << Error;
174    return 1;
175  }
176
177  // the target machine will handle the mcpu printing
178  llvm::TargetOptions Options;
179  std::unique_ptr<llvm::TargetMachine> TheTargetMachine(
180      TheTarget->createTargetMachine(TargetStr, "", "+cpuHelp", Options, None));
181  return 0;
182}
183
184int cc1_main(ArrayRef<const char *> Argv, const char *Argv0, void *MainAddr) {
185  ensureSufficientStack();
186
187  std::unique_ptr<CompilerInstance> Clang(new CompilerInstance());
188  IntrusiveRefCntPtr<DiagnosticIDs> DiagID(new DiagnosticIDs());
189
190  // Register the support for object-file-wrapped Clang modules.
191  auto PCHOps = Clang->getPCHContainerOperations();
192  PCHOps->registerWriter(std::make_unique<ObjectFilePCHContainerWriter>());
193  PCHOps->registerReader(std::make_unique<ObjectFilePCHContainerReader>());
194
195  // Initialize targets first, so that --version shows registered targets.
196  llvm::InitializeAllTargets();
197  llvm::InitializeAllTargetMCs();
198  llvm::InitializeAllAsmPrinters();
199  llvm::InitializeAllAsmParsers();
200
201  // Buffer diagnostics from argument parsing so that we can output them using a
202  // well formed diagnostic object.
203  IntrusiveRefCntPtr<DiagnosticOptions> DiagOpts = new DiagnosticOptions();
204  TextDiagnosticBuffer *DiagsBuffer = new TextDiagnosticBuffer;
205  DiagnosticsEngine Diags(DiagID, &*DiagOpts, DiagsBuffer);
206  bool Success =
207      CompilerInvocation::CreateFromArgs(Clang->getInvocation(), Argv, Diags);
208
209  if (Clang->getFrontendOpts().TimeTrace) {
210    llvm::timeTraceProfilerInitialize(
211        Clang->getFrontendOpts().TimeTraceGranularity, Argv0);
212  }
213  // --print-supported-cpus takes priority over the actual compilation.
214  if (Clang->getFrontendOpts().PrintSupportedCPUs)
215    return PrintSupportedCPUs(Clang->getTargetOpts().Triple);
216
217  // Infer the builtin include path if unspecified.
218  if (Clang->getHeaderSearchOpts().UseBuiltinIncludes &&
219      Clang->getHeaderSearchOpts().ResourceDir.empty())
220    Clang->getHeaderSearchOpts().ResourceDir =
221      CompilerInvocation::GetResourcesPath(Argv0, MainAddr);
222
223  // Create the actual diagnostics engine.
224  Clang->createDiagnostics();
225  if (!Clang->hasDiagnostics())
226    return 1;
227
228  // Set an error handler, so that any LLVM backend diagnostics go through our
229  // error handler.
230  llvm::install_fatal_error_handler(LLVMErrorHandler,
231                                  static_cast<void*>(&Clang->getDiagnostics()));
232
233  DiagsBuffer->FlushDiagnostics(Clang->getDiagnostics());
234  if (!Success)
235    return 1;
236
237  // Execute the frontend actions.
238  {
239    llvm::TimeTraceScope TimeScope("ExecuteCompiler");
240    Success = ExecuteCompilerInvocation(Clang.get());
241  }
242
243  // If any timers were active but haven't been destroyed yet, print their
244  // results now.  This happens in -disable-free mode.
245  llvm::TimerGroup::printAll(llvm::errs());
246  llvm::TimerGroup::clearAll();
247
248  if (llvm::timeTraceProfilerEnabled()) {
249    SmallString<128> Path(Clang->getFrontendOpts().OutputFile);
250    llvm::sys::path::replace_extension(Path, "json");
251    if (auto profilerOutput =
252            Clang->createOutputFile(Path.str(),
253                                    /*Binary=*/false,
254                                    /*RemoveFileOnSignal=*/false, "",
255                                    /*Extension=*/"json",
256                                    /*useTemporary=*/false)) {
257
258      llvm::timeTraceProfilerWrite(*profilerOutput);
259      // FIXME(ibiryukov): make profilerOutput flush in destructor instead.
260      profilerOutput->flush();
261      llvm::timeTraceProfilerCleanup();
262    }
263  }
264
265  // Our error handler depends on the Diagnostics object, which we're
266  // potentially about to delete. Uninstall the handler now so that any
267  // later errors use the default handling behavior instead.
268  llvm::remove_fatal_error_handler();
269
270  // When running with -disable-free, don't do any destruction or shutdown.
271  if (Clang->getFrontendOpts().DisableFree) {
272    llvm::BuryPointer(std::move(Clang));
273    return !Success;
274  }
275
276  return !Success;
277}
278