[XRay] Add -fxray-{always,never}-instrument= flags to clang

Summary:
The -fxray-always-instrument= and -fxray-never-instrument= flags take
filenames that are used to imbue the XRay instrumentation attributes
using a whitelist mechanism (similar to the sanitizer special cases
list). We use the same syntax and semantics as the sanitizer blacklists
files in the implementation.

As implemented, we respect the attributes that are already defined in
the source file (i.e. those that have the
[[clang::xray_{always,never}_instrument]] attributes) before applying
the always/never instrument lists.

Reviewers: rsmith, chandlerc

Subscribers: jfb, mgorny, cfe-commits

Differential Revision: https://reviews.llvm.org/D30388

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@299041 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 113 insertions, 0 deletions

diff --git a/lib/Driver/XRayArgs.cpp b/lib/Driver/XRayArgs.cpp
new file mode 100644
index 0000000000..59a35f1115
--- /dev/null
+++ b/lib/Driver/XRayArgs.cpp
@@ -0,0 +1,113 @@
+//===--- XRayArgs.cpp - Arguments for XRay --------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+#include "clang/Driver/XRayArgs.h"
+#include "ToolChains/CommonArgs.h"
+#include "clang/Driver/Driver.h"
+#include "clang/Driver/DriverDiagnostic.h"
+#include "clang/Driver/Options.h"
+#include "clang/Driver/ToolChain.h"
+#include "llvm/ADT/StringExtras.h"
+#include "llvm/ADT/StringSwitch.h"
+#include "llvm/Support/FileSystem.h"
+#include "llvm/Support/Path.h"
+#include "llvm/Support/SpecialCaseList.h"
+
+using namespace clang;
+using namespace clang::driver;
+using namespace llvm::opt;
+
+namespace {
+constexpr char XRayInstrumentOption[] = "-fxray-instrument";
+constexpr char XRayInstructionThresholdOption[] =
+    "-fxray-instruction-threshold=";
+constexpr char XRayAlwaysInstrumentOption[] = "-fxray-always-instrument=";
+constexpr char XRayNeverInstrumentOption[] = "-fxray-never-instrument=";
+} // namespace
+
+XRayArgs::XRayArgs(const ToolChain &TC, const ArgList &Args) {
+  const Driver &D = TC.getDriver();
+  const llvm::Triple &Triple = TC.getTriple();
+  if (Args.hasFlag(options::OPT_fxray_instrument,
+                   options::OPT_fnoxray_instrument, false)) {
+    if (Triple.getOS() == llvm::Triple::Linux)
+      switch (Triple.getArch()) {
+      case llvm::Triple::x86_64:
+      case llvm::Triple::arm:
+      case llvm::Triple::aarch64:
+      case llvm::Triple::ppc64le:
+      case llvm::Triple::mips:
+      case llvm::Triple::mipsel:
+      case llvm::Triple::mips64:
+      case llvm::Triple::mips64el:
+        break;
+      default:
+        D.Diag(diag::err_drv_clang_unsupported)
+            << (std::string(XRayInstrumentOption) + " on " + Triple.str());
+      }
+    else
+      D.Diag(diag::err_drv_clang_unsupported)
+          << (std::string(XRayInstrumentOption) + " on non-Linux target OS");
+    XRayInstrument = true;
+    if (const Arg *A =
+            Args.getLastArg(options::OPT_fxray_instruction_threshold_,
+                            options::OPT_fxray_instruction_threshold_EQ)) {
+      StringRef S = A->getValue();
+      if (S.getAsInteger(0, InstructionThreshold) || InstructionThreshold < 0)
+        D.Diag(clang::diag::err_drv_invalid_value) << A->getAsString(Args) << S;
+    }
+
+    // Validate the always/never attribute files. We also make sure that they
+    // are treated as actual dependencies.
+    for (const auto &Filename :
+         Args.getAllArgValues(options::OPT_fxray_always_instrument)) {
+      if (llvm::sys::fs::exists(Filename)) {
+        AlwaysInstrumentFiles.push_back(Filename);
+        ExtraDeps.push_back(Filename);
+      } else
+        D.Diag(clang::diag::err_drv_no_such_file) << Filename;
+    }
+
+    for (const auto &Filename :
+         Args.getAllArgValues(options::OPT_fxray_never_instrument)) {
+      if (llvm::sys::fs::exists(Filename)) {
+        NeverInstrumentFiles.push_back(Filename);
+        ExtraDeps.push_back(Filename);
+      } else
+        D.Diag(clang::diag::err_drv_no_such_file) << Filename;
+    }
+  }
+}
+
+void XRayArgs::addArgs(const ToolChain &TC, const ArgList &Args,
+                       ArgStringList &CmdArgs, types::ID InputType) const {
+  if (!XRayInstrument)
+    return;
+
+  CmdArgs.push_back(XRayInstrumentOption);
+  CmdArgs.push_back(Args.MakeArgString(XRayInstructionThresholdOption +
+                                       std::to_string(InstructionThreshold)));
+
+  for (const auto &Always : AlwaysInstrumentFiles) {
+    SmallString<64> AlwaysInstrumentOpt(XRayAlwaysInstrumentOption);
+    AlwaysInstrumentOpt += Always;
+    CmdArgs.push_back(Args.MakeArgString(AlwaysInstrumentOpt));
+  }
+
+  for (const auto &Never : NeverInstrumentFiles) {
+    SmallString<64> NeverInstrumentOpt(XRayNeverInstrumentOption);
+    NeverInstrumentOpt += Never;
+    CmdArgs.push_back(Args.MakeArgString(NeverInstrumentOpt));
+  }
+
+  for (const auto &Dep : ExtraDeps) {
+    SmallString<64> ExtraDepOpt("-fdepfile-entry=");
+    ExtraDepOpt += Dep;
+    CmdArgs.push_back(Args.MakeArgString(ExtraDepOpt));
+  }
+}