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//===-- cc1_main.cpp - Clang CC1 Compiler Frontend ------------------------===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
// This is the entry point to the clang -cc1 functionality, which implements the
// core compiler functionality along with a number of additional tools for
// demonstration and testing purposes.
#include "clang/Basic/Stack.h"
#include "clang/Basic/TargetOptions.h"
#include "clang/CodeGen/ObjectFilePCHContainerOperations.h"
#include "clang/Config/config.h"
#include "clang/Driver/DriverDiagnostic.h"
#include "clang/Driver/Options.h"
#include "clang/Frontend/CompilerInstance.h"
#include "clang/Frontend/CompilerInvocation.h"
#include "clang/Frontend/FrontendDiagnostic.h"
#include "clang/Frontend/TextDiagnosticBuffer.h"
#include "clang/Frontend/TextDiagnosticPrinter.h"
#include "clang/Frontend/Utils.h"
#include "clang/FrontendTool/Utils.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Config/llvm-config.h"
#include "llvm/LinkAllPasses.h"
#include "llvm/MC/TargetRegistry.h"
#include "llvm/Option/Arg.h"
#include "llvm/Option/ArgList.h"
#include "llvm/Option/OptTable.h"
#include "llvm/Support/BuryPointer.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/ManagedStatic.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/Process.h"
#include "llvm/Support/Signals.h"
#include "llvm/Support/TargetSelect.h"
#include "llvm/Support/TimeProfiler.h"
#include "llvm/Support/Timer.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetMachine.h"
#include <cstdio>
#include <sys/resource.h>
using namespace clang;
using namespace llvm::opt;
// Main driver
static void LLVMErrorHandler(void *UserData, const char *Message,
bool GenCrashDiag) {
DiagnosticsEngine &Diags = *static_cast<DiagnosticsEngine*>(UserData);
Diags.Report(diag::err_fe_error_backend) << Message;
// Run the interrupt handlers to make sure any special cleanups get done, in
// particular that we remove files registered with RemoveFileOnSignal.
// We cannot recover from llvm errors. When reporting a fatal error, exit
// with status 70 to generate crash diagnostics. For BSD systems this is
// defined as an internal software error. Otherwise, exit with status 1.
llvm::sys::Process::Exit(GenCrashDiag ? 70 : 1);
#if defined(__linux__) && defined(__PIE__)
static size_t getCurrentStackAllocation() {
// If we can't compute the current stack usage, allow for 512K of command
// line arguments and environment.
size_t Usage = 512 * 1024;
if (FILE *StatFile = fopen("/proc/self/stat", "r")) {
// We assume that the stack extends from its current address to the end of
// the environment space. In reality, there is another string literal (the
// program name) after the environment, but this is close enough (we only
// need to be within 100K or so).
unsigned long StackPtr, EnvEnd;
// Disable silly GCC -Wformat warning that complains about length
// modifiers on ignored format specifiers. We want to retain these
// for documentation purposes even though they have no effect.
#if defined(__GNUC__) && !defined(__clang__)
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wformat"
if (fscanf(StatFile,
"%*d %*s %*c %*d %*d %*d %*d %*d %*u %*lu %*lu %*lu %*lu %*lu "
"%*lu %*ld %*ld %*ld %*ld %*ld %*ld %*llu %*lu %*ld %*lu %*lu "
"%*lu %*lu %lu %*lu %*lu %*lu %*lu %*lu %*llu %*lu %*lu %*d %*d "
"%*u %*u %*llu %*lu %*ld %*lu %*lu %*lu %*lu %*lu %*lu %lu %*d",
&StackPtr, &EnvEnd) == 2) {
#if defined(__GNUC__) && !defined(__clang__)
#pragma GCC diagnostic pop
Usage = StackPtr < EnvEnd ? EnvEnd - StackPtr : StackPtr - EnvEnd;
return Usage;
#include <alloca.h>
static void ensureStackAddressSpace() {
// Linux kernels prior to 4.1 will sometimes locate the heap of a PIE binary
// relatively close to the stack (they are only guaranteed to be 128MiB
// apart). This results in crashes if we happen to heap-allocate more than
// 128MiB before we reach our stack high-water mark.
// To avoid these crashes, ensure that we have sufficient virtual memory
// pages allocated before we start running.
size_t Curr = getCurrentStackAllocation();
const int kTargetStack = DesiredStackSize - 256 * 1024;
if (Curr < kTargetStack) {
volatile char *volatile Alloc =
static_cast<volatile char *>(alloca(kTargetStack - Curr));
Alloc[0] = 0;
Alloc[kTargetStack - Curr - 1] = 0;
static void ensureStackAddressSpace() {}
/// Attempt to ensure that we have at least 8MiB of usable stack space.
static void ensureSufficientStack() {
struct rlimit rlim;
if (getrlimit(RLIMIT_STACK, &rlim) != 0)
// Increase the soft stack limit to our desired level, if necessary and
// possible.
if (rlim.rlim_cur != RLIM_INFINITY &&
rlim.rlim_cur < rlim_t(DesiredStackSize)) {
// Try to allocate sufficient stack.
if (rlim.rlim_max == RLIM_INFINITY ||
rlim.rlim_max >= rlim_t(DesiredStackSize))
rlim.rlim_cur = DesiredStackSize;
else if (rlim.rlim_cur == rlim.rlim_max)
rlim.rlim_cur = rlim.rlim_max;
if (setrlimit(RLIMIT_STACK, &rlim) != 0 ||
rlim.rlim_cur != DesiredStackSize)
// We should now have a stack of size at least DesiredStackSize. Ensure
// that we can actually use that much, if necessary.
static void ensureSufficientStack() {}
/// Print supported cpus of the given target.
static int PrintSupportedCPUs(std::string TargetStr) {
std::string Error;
const llvm::Target *TheTarget =
llvm::TargetRegistry::lookupTarget(TargetStr, Error);
if (!TheTarget) {
llvm::errs() << Error;
return 1;
// the target machine will handle the mcpu printing
llvm::TargetOptions Options;
std::unique_ptr<llvm::TargetMachine> TheTargetMachine(
TheTarget->createTargetMachine(TargetStr, "", "+cpuhelp", Options, None));
return 0;
int cc1_main(ArrayRef<const char *> Argv, const char *Argv0, void *MainAddr) {
std::unique_ptr<CompilerInstance> Clang(new CompilerInstance());
IntrusiveRefCntPtr<DiagnosticIDs> DiagID(new DiagnosticIDs());
// Register the support for object-file-wrapped Clang modules.
auto PCHOps = Clang->getPCHContainerOperations();
// Initialize targets first, so that --version shows registered targets.
// Buffer diagnostics from argument parsing so that we can output them using a
// well formed diagnostic object.
IntrusiveRefCntPtr<DiagnosticOptions> DiagOpts = new DiagnosticOptions();
TextDiagnosticBuffer *DiagsBuffer = new TextDiagnosticBuffer;
DiagnosticsEngine Diags(DiagID, &*DiagOpts, DiagsBuffer);
// Setup round-trip remarks for the DiagnosticsEngine used in CreateFromArgs.
if (find(Argv, StringRef("-Rround-trip-cc1-args")) != Argv.end())
diag::Severity::Remark, {});
bool Success = CompilerInvocation::CreateFromArgs(Clang->getInvocation(),
Argv, Diags, Argv0);
if (Clang->getFrontendOpts().TimeTrace) {
Clang->getFrontendOpts().TimeTraceGranularity, Argv0);
// --print-supported-cpus takes priority over the actual compilation.
if (Clang->getFrontendOpts().PrintSupportedCPUs)
return PrintSupportedCPUs(Clang->getTargetOpts().Triple);
// Infer the builtin include path if unspecified.
if (Clang->getHeaderSearchOpts().UseBuiltinIncludes &&
Clang->getHeaderSearchOpts().ResourceDir =
CompilerInvocation::GetResourcesPath(Argv0, MainAddr);
// Create the actual diagnostics engine.
if (!Clang->hasDiagnostics())
return 1;
// Set an error handler, so that any LLVM backend diagnostics go through our
// error handler.
if (!Success)
return 1;
// Execute the frontend actions.
llvm::TimeTraceScope TimeScope("ExecuteCompiler");
Success = ExecuteCompilerInvocation(Clang.get());
// If any timers were active but haven't been destroyed yet, print their
// results now. This happens in -disable-free mode.
if (llvm::timeTraceProfilerEnabled()) {
SmallString<128> Path(Clang->getFrontendOpts().OutputFile);
llvm::sys::path::replace_extension(Path, "json");
if (auto profilerOutput = Clang->createOutputFile(
Path.str(), /*Binary=*/false, /*RemoveFileOnSignal=*/false,
/*useTemporary=*/false)) {
// FIXME(ibiryukov): make profilerOutput flush in destructor instead.
// Our error handler depends on the Diagnostics object, which we're
// potentially about to delete. Uninstall the handler now so that any
// later errors use the default handling behavior instead.
// When running with -disable-free, don't do any destruction or shutdown.
if (Clang->getFrontendOpts().DisableFree) {
return !Success;
return !Success;