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/MC/TargetRegistry.h"
32 #include "llvm/Option/Arg.h"
33 #include "llvm/Option/ArgList.h"
34 #include "llvm/Option/OptTable.h"
35 #include "llvm/Support/BuryPointer.h"
36 #include "llvm/Support/Compiler.h"
37 #include "llvm/Support/ErrorHandling.h"
38 #include "llvm/Support/ManagedStatic.h"
39 #include "llvm/Support/Path.h"
40 #include "llvm/Support/Process.h"
41 #include "llvm/Support/Signals.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
53 using namespace clang;
54 using namespace llvm::opt;
55
56 //===----------------------------------------------------------------------===//
57 // Main driver
58 //===----------------------------------------------------------------------===//
59
LLVMErrorHandler(void * UserData,const char * Message,bool GenCrashDiag)60 static void LLVMErrorHandler(void *UserData, const char *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__)
getCurrentStackAllocation()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
ensureStackAddressSpace()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
ensureStackAddressSpace()132 static void ensureStackAddressSpace() {}
133 #endif
134
135 /// Attempt to ensure that we have at least 8MiB of usable stack space.
ensureSufficientStack()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
ensureSufficientStack()164 static void ensureSufficientStack() {}
165 #endif
166
167 /// Print supported cpus of the given target.
PrintSupportedCPUs(std::string TargetStr)168 static 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,
181 std::nullopt));
182 return 0;
183 }
184
cc1_main(ArrayRef<const char * > Argv,const char * Argv0,void * MainAddr)185 int cc1_main(ArrayRef<const char *> Argv, const char *Argv0, void *MainAddr) {
186 ensureSufficientStack();
187
188 std::unique_ptr<CompilerInstance> Clang(new CompilerInstance());
189 IntrusiveRefCntPtr<DiagnosticIDs> DiagID(new DiagnosticIDs());
190
191 // Register the support for object-file-wrapped Clang modules.
192 auto PCHOps = Clang->getPCHContainerOperations();
193 PCHOps->registerWriter(std::make_unique<ObjectFilePCHContainerWriter>());
194 PCHOps->registerReader(std::make_unique<ObjectFilePCHContainerReader>());
195
196 // Initialize targets first, so that --version shows registered targets.
197 llvm::InitializeAllTargets();
198 llvm::InitializeAllTargetMCs();
199 llvm::InitializeAllAsmPrinters();
200 llvm::InitializeAllAsmParsers();
201
202 // Buffer diagnostics from argument parsing so that we can output them using a
203 // well formed diagnostic object.
204 IntrusiveRefCntPtr<DiagnosticOptions> DiagOpts = new DiagnosticOptions();
205 TextDiagnosticBuffer *DiagsBuffer = new TextDiagnosticBuffer;
206 DiagnosticsEngine Diags(DiagID, &*DiagOpts, DiagsBuffer);
207
208 // Setup round-trip remarks for the DiagnosticsEngine used in CreateFromArgs.
209 if (find(Argv, StringRef("-Rround-trip-cc1-args")) != Argv.end())
210 Diags.setSeverity(diag::remark_cc1_round_trip_generated,
211 diag::Severity::Remark, {});
212
213 bool Success = CompilerInvocation::CreateFromArgs(Clang->getInvocation(),
214 Argv, Diags, Argv0);
215
216 if (Clang->getFrontendOpts().TimeTrace ||
217 !Clang->getFrontendOpts().TimeTracePath.empty()) {
218 Clang->getFrontendOpts().TimeTrace = 1;
219 llvm::timeTraceProfilerInitialize(
220 Clang->getFrontendOpts().TimeTraceGranularity, Argv0);
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 Clang->getDiagnosticClient().finish();
245 return 1;
246 }
247
248 // Execute the frontend actions.
249 {
250 llvm::TimeTraceScope TimeScope("ExecuteCompiler");
251 Success = ExecuteCompilerInvocation(Clang.get());
252 }
253
254 // If any timers were active but haven't been destroyed yet, print their
255 // results now. This happens in -disable-free mode.
256 llvm::TimerGroup::printAll(llvm::errs());
257 llvm::TimerGroup::clearAll();
258
259 if (llvm::timeTraceProfilerEnabled()) {
260 SmallString<128> Path(Clang->getFrontendOpts().OutputFile);
261 llvm::sys::path::replace_extension(Path, "json");
262 if (!Clang->getFrontendOpts().TimeTracePath.empty()) {
263 // replace the suffix to '.json' directly
264 SmallString<128> TracePath(Clang->getFrontendOpts().TimeTracePath);
265 if (llvm::sys::fs::is_directory(TracePath))
266 llvm::sys::path::append(TracePath, llvm::sys::path::filename(Path));
267 Path.assign(TracePath);
268 }
269 if (auto profilerOutput = Clang->createOutputFile(
270 Path.str(), /*Binary=*/false, /*RemoveFileOnSignal=*/false,
271 /*useTemporary=*/false)) {
272 llvm::timeTraceProfilerWrite(*profilerOutput);
273 profilerOutput.reset();
274 llvm::timeTraceProfilerCleanup();
275 Clang->clearOutputFiles(false);
276 }
277 }
278
279 // Our error handler depends on the Diagnostics object, which we're
280 // potentially about to delete. Uninstall the handler now so that any
281 // later errors use the default handling behavior instead.
282 llvm::remove_fatal_error_handler();
283
284 // When running with -disable-free, don't do any destruction or shutdown.
285 if (Clang->getFrontendOpts().DisableFree) {
286 llvm::BuryPointer(std::move(Clang));
287 return !Success;
288 }
289
290 return !Success;
291 }
292