[ubsan] Add -fsanitize-undefined-strip-path-components=N

Summary:
This option allows the user to control how much of the file name is
emitted by UBSan. Tuning this option allows one to save space in the
resulting binary, which is helpful for restricted execution
environments.

With a positive N, UBSan skips the first N path components.
With a negative N, UBSan only keeps the last N path components.

Reviewers: rsmith

Subscribers: cfe-commits

Differential Revision: http://reviews.llvm.org/D19666

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@269309 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/docs/UndefinedBehaviorSanitizer.rst b/docs/UndefinedBehaviorSanitizer.rst
index db1325cc022e2b7e9be21687fc316cf5db81cd9a..7babb96a65a14c8330e4c64477f9d466433f17f2 100644 (file)
--- a/docs/UndefinedBehaviorSanitizer.rst
+++ b/docs/UndefinedBehaviorSanitizer.rst
@@ -228,6 +228,26 @@ UndefinedBehaviorSanitizer is available on selected platforms starting from LLVM
 3.3. The test suite is integrated into the CMake build and can be run with
 ``check-ubsan`` command.
 
+Additional Configuration
+========================
+
+UndefinedBehaviorSanitizer adds static check data for each check unless it is
+in trap mode. This check data includes the full file name. The option
+``-fsanitize-undefined-strip-path-components=N`` can be used to trim this
+information. If ``N`` is positive, file information emitted by
+UndefinedBehaviorSanitizer will drop the first ``N`` components from the file
+path. If ``N`` is negative, the last ``N`` components will be kept.
+
+Example
+-------
+
+For a file called ``/code/library/file.cpp``, here is what would be emitted:
+* Default (No flag, or ``-fsanitize-undefined-strip-path-components=0``): ``/code/library/file.cpp``
+* ``-fsanitize-undefined-strip-path-components=1``: ``code/library/file.cpp``
+* ``-fsanitize-undefined-strip-path-components=2``: ``library/file.cpp``
+* ``-fsanitize-undefined-strip-path-components=-1``: ``file.cpp``
+* ``-fsanitize-undefined-strip-path-components=-2``: ``library/file.cpp``
+
 More Information
 ================
 

diff --git a/include/clang/Driver/Options.td b/include/clang/Driver/Options.td
index 602e8fa7de7d00826a5c1ee66b089aba8dd3df3f..4dd092599a589d7edec244920189809ae37795a9 100644 (file)
--- a/include/clang/Driver/Options.td
+++ b/include/clang/Driver/Options.td
@@ -677,6 +677,10 @@ def fsanitize_stats : Flag<["-"], "fsanitize-stats">,
 def fno_sanitize_stats : Flag<["-"], "fno-sanitize-stats">,
                                  Group<f_clang_Group>, Flags<[CC1Option]>,
                                  HelpText<"Disable sanitizer statistics gathering.">;
+def fsanitize_undefined_strip_path_components_EQ : Joined<["-"], "fsanitize-undefined-strip-path-components=">,
+  Group<f_clang_Group>, Flags<[CC1Option]>, MetaVarName<"<number>">,
+  HelpText<"Strip (or keep only, if negative) a given number of path components "
+           "when emitting check metadata.">;
 def funsafe_math_optimizations : Flag<["-"], "funsafe-math-optimizations">,
   Group<f_Group>;
 def fno_unsafe_math_optimizations : Flag<["-"], "fno-unsafe-math-optimizations">,

diff --git a/include/clang/Frontend/CodeGenOptions.def b/include/clang/Frontend/CodeGenOptions.def
index d0d4f7a69399922184de2caed83dd4768ee96383..2e2344a8e4a487eca22401edc69fff8773ac4f47 100644 (file)
--- a/include/clang/Frontend/CodeGenOptions.def
+++ b/include/clang/Frontend/CodeGenOptions.def
@@ -225,6 +225,10 @@ ENUM_CODEGENOPT(VecLib, VectorLibrary, 1, NoLibrary)
 /// The default TLS model to use.
 ENUM_CODEGENOPT(DefaultTLSModel, TLSModel, 2, GeneralDynamicTLSModel)
 
+/// Number of path components to strip when emitting checks. (0 == full
+/// filename)
+VALUE_CODEGENOPT(EmitCheckPathComponentsToStrip, 32, 0)
+
 #undef CODEGENOPT
 #undef ENUM_CODEGENOPT
 #undef VALUE_CODEGENOPT

diff --git a/lib/CodeGen/CGExpr.cpp b/lib/CodeGen/CGExpr.cpp
index 3ecd8e3f0f6c1d7437824400e67106e5ef39e8a1..8896eb4db123d09e79d0eef40cb83267e91f2940 100644 (file)
--- a/lib/CodeGen/CGExpr.cpp
+++ b/lib/CodeGen/CGExpr.cpp
@@ -32,6 +32,7 @@
 #include "llvm/IR/MDBuilder.h"
 #include "llvm/Support/ConvertUTF.h"
 #include "llvm/Support/MathExtras.h"
+#include "llvm/Support/Path.h"
 #include "llvm/Transforms/Utils/SanitizerStats.h"
 
 using namespace clang;
@@ -2367,7 +2368,33 @@ llvm::Constant *CodeGenFunction::EmitCheckSourceLocation(SourceLocation Loc) {
 
   PresumedLoc PLoc = getContext().getSourceManager().getPresumedLoc(Loc);
   if (PLoc.isValid()) {
-    auto FilenameGV = CGM.GetAddrOfConstantCString(PLoc.getFilename(), ".src");
+    StringRef FilenameString = PLoc.getFilename();
+
+    int PathComponentsToStrip =
+        CGM.getCodeGenOpts().EmitCheckPathComponentsToStrip;
+    if (PathComponentsToStrip < 0) {
+      assert(PathComponentsToStrip != INT_MIN);
+      int PathComponentsToKeep = -PathComponentsToStrip;
+      auto I = llvm::sys::path::rbegin(FilenameString);
+      auto E = llvm::sys::path::rend(FilenameString);
+      while (I != E && --PathComponentsToKeep)
+        ++I;
+
+      FilenameString = FilenameString.substr(I - E);
+    } else if (PathComponentsToStrip > 0) {
+      auto I = llvm::sys::path::begin(FilenameString);
+      auto E = llvm::sys::path::end(FilenameString);
+      while (I != E && PathComponentsToStrip--)
+        ++I;
+
+      if (I != E)
+        FilenameString =
+            FilenameString.substr(I - llvm::sys::path::begin(FilenameString));
+      else
+        FilenameString = llvm::sys::path::filename(FilenameString);
+    }
+
+    auto FilenameGV = CGM.GetAddrOfConstantCString(FilenameString, ".src");
     CGM.getSanitizerMetadata()->disableSanitizerForGlobal(
                           cast<llvm::GlobalVariable>(FilenameGV.getPointer()));
     Filename = FilenameGV.getPointer();

diff --git a/lib/Driver/Tools.cpp b/lib/Driver/Tools.cpp
index 98c0d1deebcdc464f4f935eb699479f793b25099..5da1fd6c969c7d9b80a851f8a9f79f12853c66a5 100644 (file)
--- a/lib/Driver/Tools.cpp
+++ b/lib/Driver/Tools.cpp
@@ -5607,6 +5607,10 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
   if (Arg *A = Args.getLastArg(options::OPT_fshow_overloads_EQ))
     A->render(Args, CmdArgs);
 
+  if (Arg *A = Args.getLastArg(
+          options::OPT_fsanitize_undefined_strip_path_components_EQ))
+    A->render(Args, CmdArgs);
+
   // -fdollars-in-identifiers default varies depending on platform and
   // language; only pass if specified.
   if (Arg *A = Args.getLastArg(options::OPT_fdollars_in_identifiers,

diff --git a/lib/Frontend/CompilerInvocation.cpp b/lib/Frontend/CompilerInvocation.cpp
index f11188d0ff95af8d306a82d8e1f38f42400e0ea2..8e93ff1a4b4ef415ac856814ec21834f33fb67dc 100644 (file)
--- a/lib/Frontend/CompilerInvocation.cpp
+++ b/lib/Frontend/CompilerInvocation.cpp
@@ -823,6 +823,9 @@ static bool ParseCodeGenArgs(CodeGenOptions &Opts, ArgList &Args, InputKind IK,
 
   Opts.Backchain = Args.hasArg(OPT_mbackchain);
 
+  Opts.EmitCheckPathComponentsToStrip = getLastArgIntValue(
+      Args, OPT_fsanitize_undefined_strip_path_components_EQ, 0, Diags);
+
   return Success;
 }
 

diff --git a/test/CodeGen/ubsan-strip-path-components.cpp b/test/CodeGen/ubsan-strip-path-components.cpp
new file mode 100644 (file)
index 0000000..7a95324
--- /dev/null
+++ b/test/CodeGen/ubsan-strip-path-components.cpp
@@ -0,0 +1,29 @@
+// RUN: %clang_cc1 %s -triple=x86_64-linux-gnu -emit-llvm -fsanitize=unreachable -o - | FileCheck %s -check-prefix=REGULAR -check-prefix=CHECK
+// RUN: %clang_cc1 %s -triple=x86_64-linux-gnu -emit-llvm -fsanitize=unreachable -o - -fsanitize-undefined-strip-path-components=0 | FileCheck %s -check-prefix=REGULAR -check-prefix=CHECK
+// RUN: %clang_cc1 %s -triple=x86_64-linux-gnu -emit-llvm -fsanitize=unreachable -o - -fsanitize-undefined-strip-path-components=2 | FileCheck %s -check-prefix=REMOVE-FIRST-TWO -check-prefix=CHECK
+
+// Try to strip too much:
+// RUN: %clang_cc1 %s -triple=x86_64-linux-gnu -emit-llvm -fsanitize=unreachable -o - -fsanitize-undefined-strip-path-components=-99999 | FileCheck %s -check-prefix=REGULAR
+// RUN: %clang_cc1 %s -triple=x86_64-linux-gnu -emit-llvm -fsanitize=unreachable -o - -fsanitize-undefined-strip-path-components=99999 | FileCheck %s -check-prefix=LAST-ONLY
+
+// Check stripping from the file name
+// RUN: %clang_cc1 %s -triple=x86_64-linux-gnu -emit-llvm -fsanitize=unreachable -o - -fsanitize-undefined-strip-path-components=-2 | FileCheck %s -check-prefix=LAST-TWO
+// RUN: %clang_cc1 %s -triple=x86_64-linux-gnu -emit-llvm -fsanitize=unreachable -o - -fsanitize-undefined-strip-path-components=-1 | FileCheck %s -check-prefix=LAST-ONLY
+
+// REGULAR: @[[SRC:[0-9.a-zA-Z_]+]] =      private unnamed_addr constant [{{.*}} x i8] c"{{.*test(.|\\5C)CodeGen(.|\\5C)ubsan-strip-path-components\.cpp}}\00", align 1
+
+// First path component: "/" or "$drive_letter:", then a name, or '\5C' on Windows
+// REMOVE-FIRST-TWO: @[[STR:[0-9.a-zA-Z_]+]] = private unnamed_addr constant [{{.*}} x i8] c"{{(.:|/)([^\\/]*(/|\\5C))}}[[REST:.*ubsan-strip-path-components\.cpp]]\00", align 1
+// REMOVE-FIRST-TWO: @[[SRC:[0-9.a-zA-Z_]+]] = private unnamed_addr constant [{{.*}} x i8] c"[[REST]]\00", align 1
+
+// LAST-TWO: @[[SRC:[0-9.a-zA-Z_]+]] =     private unnamed_addr constant [{{.*}} x i8] c"CodeGen{{/|\\5C}}ubsan-strip-path-components.cpp\00", align 1
+// LAST-ONLY: @[[SRC:[0-9.a-zA-Z_]+]] =    private unnamed_addr constant [{{.*}} x i8] c"ubsan-strip-path-components.cpp\00", align 1
+
+// CHECK: @[[STATIC_DATA:[0-9.a-zA-Z_]+]] = private unnamed_addr global { { [{{.*}} x i8]*, i32, i32 } } { { [{{.*}} x i8]*, i32, i32 } { [{{.*}} x i8]* @[[SRC]], i32 [[@LINE+6]], i32 3 } }
+void g(const char *);
+void f() {
+  // CHECK-LABEL: @_Z1fv(
+  g(__FILE__);
+  // CHECK: call void @__ubsan_handle_builtin_unreachable(i8* bitcast ({ { [{{.*}} x i8]*, i32, i32 } }* @[[STATIC_DATA]] to i8*)) {{.*}}, !nosanitize
+  __builtin_unreachable();
+}

diff --git a/test/Driver/fubsan-strip-path-components.cpp b/test/Driver/fubsan-strip-path-components.cpp
new file mode 100644 (file)
index 0000000..1300241
--- /dev/null
+++ b/test/Driver/fubsan-strip-path-components.cpp
@@ -0,0 +1,2 @@
+// RUN: %clang %s -### -o %t.o -fsanitize-undefined-strip-path-components=42 2>&1 | FileCheck %s
+// CHECK: "-fsanitize-undefined-strip-path-components=42"