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
207 // Setup round-trip remarks for the DiagnosticsEngine used in CreateFromArgs.
208 if (find(Argv, StringRef("-Rround-trip-cc1-args")) != Argv.end())
209 Diags.setSeverity(diag::remark_cc1_round_trip_generated,
210 diag::Severity::Remark, {});
211
212 bool Success = CompilerInvocation::CreateFromArgs(Clang->getInvocation(),
213 Argv, Diags, Argv0);
214
215 if (Clang->getFrontendOpts().TimeTrace) {
216 llvm::timeTraceProfilerInitialize(
217 Clang->getFrontendOpts().TimeTraceGranularity, Argv0);
218 }
219 // --print-supported-cpus takes priority over the actual compilation.
220 if (Clang->getFrontendOpts().PrintSupportedCPUs)
221 return PrintSupportedCPUs(Clang->getTargetOpts().Triple);
222
223 // Infer the builtin include path if unspecified.
224 if (Clang->getHeaderSearchOpts().UseBuiltinIncludes &&
225 Clang->getHeaderSearchOpts().ResourceDir.empty())
226 Clang->getHeaderSearchOpts().ResourceDir =
227 CompilerInvocation::GetResourcesPath(Argv0, MainAddr);
228
229 // Create the actual diagnostics engine.
230 Clang->createDiagnostics();
231 if (!Clang->hasDiagnostics())
232 return 1;
233
234 // Set an error handler, so that any LLVM backend diagnostics go through our
235 // error handler.
236 llvm::install_fatal_error_handler(LLVMErrorHandler,
237 static_cast<void*>(&Clang->getDiagnostics()));
238
239 DiagsBuffer->FlushDiagnostics(Clang->getDiagnostics());
240 if (!Success)
241 return 1;
242
243 // Execute the frontend actions.
244 {
245 llvm::TimeTraceScope TimeScope("ExecuteCompiler");
246 Success = ExecuteCompilerInvocation(Clang.get());
247 }
248
249 // If any timers were active but haven't been destroyed yet, print their
250 // results now. This happens in -disable-free mode.
251 llvm::TimerGroup::printAll(llvm::errs());
252 llvm::TimerGroup::clearAll();
253
254 if (llvm::timeTraceProfilerEnabled()) {
255 SmallString<128> Path(Clang->getFrontendOpts().OutputFile);
256 llvm::sys::path::replace_extension(Path, "json");
257 if (auto profilerOutput = Clang->createOutputFile(
258 Path.str(), /*Binary=*/false, /*RemoveFileOnSignal=*/false,
259 /*useTemporary=*/false)) {
260 llvm::timeTraceProfilerWrite(*profilerOutput);
261 // FIXME(ibiryukov): make profilerOutput flush in destructor instead.
262 profilerOutput->flush();
263 llvm::timeTraceProfilerCleanup();
264 Clang->clearOutputFiles(false);
265 }
266 }
267
268 // Our error handler depends on the Diagnostics object, which we're
269 // potentially about to delete. Uninstall the handler now so that any
270 // later errors use the default handling behavior instead.
271 llvm::remove_fatal_error_handler();
272
273 // When running with -disable-free, don't do any destruction or shutdown.
274 if (Clang->getFrontendOpts().DisableFree) {
275 llvm::BuryPointer(std::move(Clang));
276 return !Success;
277 }
278
279 return !Success;
280}
281