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 "clang/Basic/Stack.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/Signals.h"
39 #include "llvm/Support/TargetSelect.h"
40 #include "llvm/Support/Timer.h"
41 #include "llvm/Support/raw_ostream.h"
42 #include <cstdio>
43 
44 #ifdef CLANG_HAVE_RLIMITS
45 #include <sys/resource.h>
46 #endif
47 
48 using namespace clang;
49 using namespace llvm::opt;
50 
51 //===----------------------------------------------------------------------===//
52 // Main driver
53 //===----------------------------------------------------------------------===//
54 
55 static void LLVMErrorHandler(void *UserData, const std::string &Message,
56                              bool GenCrashDiag) {
57   DiagnosticsEngine &Diags = *static_cast<DiagnosticsEngine*>(UserData);
58 
59   Diags.Report(diag::err_fe_error_backend) << Message;
60 
61   // Run the interrupt handlers to make sure any special cleanups get done, in
62   // particular that we remove files registered with RemoveFileOnSignal.
63   llvm::sys::RunInterruptHandlers();
64 
65   // We cannot recover from llvm errors.  When reporting a fatal error, exit
66   // with status 70 to generate crash diagnostics.  For BSD systems this is
67   // defined as an internal software error.  Otherwise, exit with status 1.
68   exit(GenCrashDiag ? 70 : 1);
69 }
70 
71 #ifdef LINK_POLLY_INTO_TOOLS
72 namespace polly {
73 void initializePollyPasses(llvm::PassRegistry &Registry);
74 }
75 #endif
76 
77 #ifdef CLANG_HAVE_RLIMITS
78 #if defined(__linux__) && defined(__PIE__)
79 static size_t getCurrentStackAllocation() {
80   // If we can't compute the current stack usage, allow for 512K of command
81   // line arguments and environment.
82   size_t Usage = 512 * 1024;
83   if (FILE *StatFile = fopen("/proc/self/stat", "r")) {
84     // We assume that the stack extends from its current address to the end of
85     // the environment space. In reality, there is another string literal (the
86     // program name) after the environment, but this is close enough (we only
87     // need to be within 100K or so).
88     unsigned long StackPtr, EnvEnd;
89     // Disable silly GCC -Wformat warning that complains about length
90     // modifiers on ignored format specifiers. We want to retain these
91     // for documentation purposes even though they have no effect.
92 #if defined(__GNUC__) && !defined(__clang__)
93 #pragma GCC diagnostic push
94 #pragma GCC diagnostic ignored "-Wformat"
95 #endif
96     if (fscanf(StatFile,
97                "%*d %*s %*c %*d %*d %*d %*d %*d %*u %*lu %*lu %*lu %*lu %*lu "
98                "%*lu %*ld %*ld %*ld %*ld %*ld %*ld %*llu %*lu %*ld %*lu %*lu "
99                "%*lu %*lu %lu %*lu %*lu %*lu %*lu %*lu %*llu %*lu %*lu %*d %*d "
100                "%*u %*u %*llu %*lu %*ld %*lu %*lu %*lu %*lu %*lu %*lu %lu %*d",
101                &StackPtr, &EnvEnd) == 2) {
102 #if defined(__GNUC__) && !defined(__clang__)
103 #pragma GCC diagnostic pop
104 #endif
105       Usage = StackPtr < EnvEnd ? EnvEnd - StackPtr : StackPtr - EnvEnd;
106     }
107     fclose(StatFile);
108   }
109   return Usage;
110 }
111 
112 #include <alloca.h>
113 
114 LLVM_ATTRIBUTE_NOINLINE
115 static void ensureStackAddressSpace() {
116   // Linux kernels prior to 4.1 will sometimes locate the heap of a PIE binary
117   // relatively close to the stack (they are only guaranteed to be 128MiB
118   // apart). This results in crashes if we happen to heap-allocate more than
119   // 128MiB before we reach our stack high-water mark.
120   //
121   // To avoid these crashes, ensure that we have sufficient virtual memory
122   // pages allocated before we start running.
123   size_t Curr = getCurrentStackAllocation();
124   const int kTargetStack = DesiredStackSize - 256 * 1024;
125   if (Curr < kTargetStack) {
126     volatile char *volatile Alloc =
127         static_cast<volatile char *>(alloca(kTargetStack - Curr));
128     Alloc[0] = 0;
129     Alloc[kTargetStack - Curr - 1] = 0;
130   }
131 }
132 #else
133 static void ensureStackAddressSpace() {}
134 #endif
135 
136 /// Attempt to ensure that we have at least 8MiB of usable stack space.
137 static void ensureSufficientStack() {
138   struct rlimit rlim;
139   if (getrlimit(RLIMIT_STACK, &rlim) != 0)
140     return;
141 
142   // Increase the soft stack limit to our desired level, if necessary and
143   // possible.
144   if (rlim.rlim_cur != RLIM_INFINITY &&
145       rlim.rlim_cur < rlim_t(DesiredStackSize)) {
146     // Try to allocate sufficient stack.
147     if (rlim.rlim_max == RLIM_INFINITY ||
148         rlim.rlim_max >= rlim_t(DesiredStackSize))
149       rlim.rlim_cur = DesiredStackSize;
150     else if (rlim.rlim_cur == rlim.rlim_max)
151       return;
152     else
153       rlim.rlim_cur = rlim.rlim_max;
154 
155     if (setrlimit(RLIMIT_STACK, &rlim) != 0 ||
156         rlim.rlim_cur != DesiredStackSize)
157       return;
158   }
159 
160   // We should now have a stack of size at least DesiredStackSize. Ensure
161   // that we can actually use that much, if necessary.
162   ensureStackAddressSpace();
163 }
164 #else
165 static void ensureSufficientStack() {}
166 #endif
167 
168 int cc1_main(ArrayRef<const char *> Argv, const char *Argv0, void *MainAddr) {
169   ensureSufficientStack();
170 
171   std::unique_ptr<CompilerInstance> Clang(new CompilerInstance());
172   IntrusiveRefCntPtr<DiagnosticIDs> DiagID(new DiagnosticIDs());
173 
174   // Register the support for object-file-wrapped Clang modules.
175   auto PCHOps = Clang->getPCHContainerOperations();
176   PCHOps->registerWriter(llvm::make_unique<ObjectFilePCHContainerWriter>());
177   PCHOps->registerReader(llvm::make_unique<ObjectFilePCHContainerReader>());
178 
179   // Initialize targets first, so that --version shows registered targets.
180   llvm::InitializeAllTargets();
181   llvm::InitializeAllTargetMCs();
182   llvm::InitializeAllAsmPrinters();
183   llvm::InitializeAllAsmParsers();
184 
185 #ifdef LINK_POLLY_INTO_TOOLS
186   llvm::PassRegistry &Registry = *llvm::PassRegistry::getPassRegistry();
187   polly::initializePollyPasses(Registry);
188 #endif
189 
190   // Buffer diagnostics from argument parsing so that we can output them using a
191   // well formed diagnostic object.
192   IntrusiveRefCntPtr<DiagnosticOptions> DiagOpts = new DiagnosticOptions();
193   TextDiagnosticBuffer *DiagsBuffer = new TextDiagnosticBuffer;
194   DiagnosticsEngine Diags(DiagID, &*DiagOpts, DiagsBuffer);
195   bool Success = CompilerInvocation::CreateFromArgs(
196       Clang->getInvocation(), Argv.begin(), Argv.end(), Diags);
197 
198   // Infer the builtin include path if unspecified.
199   if (Clang->getHeaderSearchOpts().UseBuiltinIncludes &&
200       Clang->getHeaderSearchOpts().ResourceDir.empty())
201     Clang->getHeaderSearchOpts().ResourceDir =
202       CompilerInvocation::GetResourcesPath(Argv0, MainAddr);
203 
204   // Create the actual diagnostics engine.
205   Clang->createDiagnostics();
206   if (!Clang->hasDiagnostics())
207     return 1;
208 
209   // Set an error handler, so that any LLVM backend diagnostics go through our
210   // error handler.
211   llvm::install_fatal_error_handler(LLVMErrorHandler,
212                                   static_cast<void*>(&Clang->getDiagnostics()));
213 
214   DiagsBuffer->FlushDiagnostics(Clang->getDiagnostics());
215   if (!Success)
216     return 1;
217 
218   // Execute the frontend actions.
219   Success = ExecuteCompilerInvocation(Clang.get());
220 
221   // If any timers were active but haven't been destroyed yet, print their
222   // results now.  This happens in -disable-free mode.
223   llvm::TimerGroup::printAll(llvm::errs());
224 
225   // Our error handler depends on the Diagnostics object, which we're
226   // potentially about to delete. Uninstall the handler now so that any
227   // later errors use the default handling behavior instead.
228   llvm::remove_fatal_error_handler();
229 
230   // When running with -disable-free, don't do any destruction or shutdown.
231   if (Clang->getFrontendOpts().DisableFree) {
232     llvm::BuryPointer(std::move(Clang));
233     return !Success;
234   }
235 
236   return !Success;
237 }
238