[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

llvm-svn: 299041

1 files changed, 53 insertions, 0 deletions

diff --git a/clang/lib/Basic/XRayLists.cpp b/clang/lib/Basic/XRayLists.cpp
new file mode 100644
index 00000000000..dccf3baa75e
--- /dev/null
+++ b/clang/lib/Basic/XRayLists.cpp
@@ -0,0 +1,53 @@
+//===--- XRayFunctionFilter.cpp - XRay automatic-attribution --------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// User-provided filters for always/never XRay instrumenting certain functions.
+//
+//===----------------------------------------------------------------------===//
+#include "clang/Basic/XRayLists.h"
+
+using namespace clang;
+
+XRayFunctionFilter::XRayFunctionFilter(
+    ArrayRef<std::string> AlwaysInstrumentPaths,
+    ArrayRef<std::string> NeverInstrumentPaths, SourceManager &SM)
+    : AlwaysInstrument(
+          llvm::SpecialCaseList::createOrDie(AlwaysInstrumentPaths)),
+      NeverInstrument(llvm::SpecialCaseList::createOrDie(NeverInstrumentPaths)),
+      SM(SM) {}
+
+XRayFunctionFilter::ImbueAttribute
+XRayFunctionFilter::shouldImbueFunction(StringRef FunctionName) const {
+  // First apply the always instrument list, than if it isn't an "always" see
+  // whether it's treated as a "never" instrument function.
+  if (AlwaysInstrument->inSection("fun", FunctionName))
+    return ImbueAttribute::ALWAYS;
+  if (NeverInstrument->inSection("fun", FunctionName))
+    return ImbueAttribute::NEVER;
+  return ImbueAttribute::NONE;
+}
+
+XRayFunctionFilter::ImbueAttribute
+XRayFunctionFilter::shouldImbueFunctionsInFile(StringRef Filename,
+                                               StringRef Category) const {
+  if (AlwaysInstrument->inSection("src", Filename, Category))
+    return ImbueAttribute::ALWAYS;
+  if (NeverInstrument->inSection("src", Filename, Category))
+    return ImbueAttribute::NEVER;
+  return ImbueAttribute::NONE;
+}
+
+XRayFunctionFilter::ImbueAttribute
+XRayFunctionFilter::shouldImbueLocation(SourceLocation Loc,
+                                        StringRef Category) const {
+  if (!Loc.isValid())
+    return ImbueAttribute::NONE;
+  return this->shouldImbueFunctionsInFile(SM.getFilename(SM.getFileLoc(Loc)),
+                                          Category);
+}