Add XRay flags to Clang. We implement two flags to control the XRay behaviour:

-fxray-instrument: enables XRay annotation of IR
-fxray-instruction-threshold: configures the threshold for function size (looking at IR instructions), and allow LLVM to decide whether to add the nop sleds later on in the process.

Also implements the related xray_always_instrument and xray_never_instrument function attributes.

Patch by Dean Michael Berris.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@275330 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/clang/Basic/Attr.td b/include/clang/Basic/Attr.td
index 51903cbf921dff121c158819cee577e815032d05..7305c746ce77584391f4e9ed5be0c66faf5475b8 100644 (file)
--- a/include/clang/Basic/Attr.td
+++ b/include/clang/Basic/Attr.td
@@ -428,6 +428,22 @@ def AlwaysInline : InheritableAttr {
   let Documentation = [Undocumented];
 }
 
+def XRayInstrument : InheritableAttr {
+  let Spellings = [GNU<"xray_always_instrument">,
+                   CXX11<"clang", "xray_always_instrument">,
+                   GNU<"xray_never_instrument">,
+                   CXX11<"clang", "xray_never_instrument">];
+  let Subjects = SubjectList<[CXXMethod, ObjCMethod, Function], WarnDiag,
+                              "ExpectedFunctionOrMethod">;
+  let Accessors = [Accessor<"alwaysXRayInstrument",
+                     [GNU<"xray_always_instrument">,
+                      CXX11<"clang", "xray_always_instrument">]>,
+                   Accessor<"neverXRayInstrument",
+                     [GNU<"xray_never_instrument">,
+                      CXX11<"clang", "xray_never_instrument">]>];
+  let Documentation = [XRayDocs];
+}
+
 def TLSModel : InheritableAttr {
   let Spellings = [GCC<"tls_model">];
   let Subjects = SubjectList<[TLSVar], ErrorDiag, "ExpectedTLSVar">;

diff --git a/include/clang/Basic/AttrDocs.td b/include/clang/Basic/AttrDocs.td
index 6ed1f298eb0bcf1eaa2e756b0a23f6da2ba96efd..cb65a445e8aa8870afa7160d869e7f16da1c9196 100644 (file)
--- a/include/clang/Basic/AttrDocs.td
+++ b/include/clang/Basic/AttrDocs.td
@@ -2450,3 +2450,14 @@ See the RenderScript_ documentation for more information.
 .. _RenderScript: https://developer.android.com/guide/topics/renderscript/compute.html
   }];
 }
+
+def XRayDocs : Documentation {
+  let Category = DocCatFunction;
+  let Content = [{
+``__attribute__((xray_always_instrument))`` or ``[[clang:xray_always_instrument]]`` is used to mark member functions (in C++), methods (in Objective C), and free functions (in C, C++, and Objective C) to be instrumented with XRay. This will cause the function to always have space at the beginning and exit points to allow for runtime patching.
+
+Conversely, ``__attribute__((xray_never_instrument))`` or ``[[clang:xray_never_instrument]]`` will inhibit the insertion of these instrumentation points.
+
+If a function has neither of these attributes, they become subject to the XRay heuristics used to determine whether a function should be instrumented or otherwise.
+  }];
+}

diff --git a/include/clang/Driver/Options.td b/include/clang/Driver/Options.td
index 06c5739cac914feebbb31757815277650ca6a20f..2bc64c6681cf51867b0c94fee640c4ebae3ac3f6 100644 (file)
--- a/include/clang/Driver/Options.td
+++ b/include/clang/Driver/Options.td
@@ -781,6 +781,21 @@ def finput_charset_EQ : Joined<["-"], "finput-charset=">, Group<f_Group>;
 def fexec_charset_EQ : Joined<["-"], "fexec-charset=">, Group<f_Group>;
 def finstrument_functions : Flag<["-"], "finstrument-functions">, Group<f_Group>, Flags<[CC1Option]>,
   HelpText<"Generate calls to instrument function entry and exit">;
+
+def fxray_instrument : Flag<["-"], "fxray-instrument">, Group<f_Group>,
+  Flags<[CC1Option]>,
+  HelpText<"Generate XRay instrumentation sleds on function entry and exit">;
+def fnoxray_instrument : Flag<["-"], "fno-xray-instrument">, Group<f_Group>,
+  Flags<[CC1Option]>;
+
+def fxray_instruction_threshold_EQ :
+  JoinedOrSeparate<["-"], "fxray-instruction-threshold=">,
+  Group<f_Group>, Flags<[CC1Option]>,
+  HelpText<"Sets the minimum function size to instrument with XRay">;
+def fxray_instruction_threshold_ :
+  JoinedOrSeparate<["-"], "fxray-instruction-threshold">,
+  Group<f_Group>, Flags<[CC1Option]>;
+
 def flat__namespace : Flag<["-"], "flat_namespace">;
 def flax_vector_conversions : Flag<["-"], "flax-vector-conversions">, Group<f_Group>;
 def flimited_precision_EQ : Joined<["-"], "flimited-precision=">, Group<f_Group>;

diff --git a/include/clang/Frontend/CodeGenOptions.def b/include/clang/Frontend/CodeGenOptions.def
index 85f7c90dcd9f1d6c9f090f6f529a73ccc320d65b..6a4474cfe75f8e4362374720ef26451b6bc89030 100644 (file)
--- a/include/clang/Frontend/CodeGenOptions.def
+++ b/include/clang/Frontend/CodeGenOptions.def
@@ -74,6 +74,14 @@ CODEGENOPT(ForbidGuardVariables , 1, 0) ///< Issue errors if C++ guard variables
 CODEGENOPT(FunctionSections  , 1, 0) ///< Set when -ffunction-sections is enabled.
 CODEGENOPT(InstrumentFunctions , 1, 0) ///< Set when -finstrument-functions is
                                        ///< enabled.
+
+CODEGENOPT(XRayInstrumentFunctions , 1, 0) ///< Set when -fxray-instrument is
+                                           ///< enabled.
+
+///< Set the minimum number of instructions in a function to determine selective
+///< XRay instrumentation.
+VALUE_CODEGENOPT(XRayInstructionThreshold , 32, 200)
+
 CODEGENOPT(InstrumentForProfiling , 1, 0) ///< Set when -pg is enabled.
 CODEGENOPT(LessPreciseFPMAD  , 1, 0) ///< Enable less precise MAD instructions to
                                      ///< be generated.

diff --git a/lib/CodeGen/CodeGenFunction.cpp b/lib/CodeGen/CodeGenFunction.cpp
index 755881fb1480f67a9b1695e2f231250a31551a44..183ee12ea2321b37d02d6ebc653bf23f566ff3fd 100644 (file)
--- a/lib/CodeGen/CodeGenFunction.cpp
+++ b/lib/CodeGen/CodeGenFunction.cpp
@@ -397,6 +397,12 @@ bool CodeGenFunction::ShouldInstrumentFunction() {
   return true;
 }
 
+/// ShouldXRayInstrument - Return true if the current function should be
+/// instrumented with XRay nop sleds.
+bool CodeGenFunction::ShouldXRayInstrumentFunction() const {
+  return CGM.getCodeGenOpts().XRayInstrumentFunctions;
+}
+
 /// EmitFunctionInstrumentation - Emit LLVM code to call the specified
 /// instrumentation function with the current function and the call site, if
 /// function instrumentation is enabled.
@@ -686,6 +692,20 @@ void CodeGenFunction::StartFunction(GlobalDecl GD,
   if (SanOpts.has(SanitizerKind::SafeStack))
     Fn->addFnAttr(llvm::Attribute::SafeStack);
 
+  // Apply xray attributes to the function (as a string, for now)
+  if (D && ShouldXRayInstrumentFunction()) {
+    if (const auto *XRayAttr = D->getAttr<XRayInstrumentAttr>()) {
+      if (XRayAttr->alwaysXRayInstrument())
+        Fn->addFnAttr("function-instrument", "xray-always");
+      if (XRayAttr->neverXRayInstrument())
+        Fn->addFnAttr("function-instrument", "xray-never");
+    } else {
+      Fn->addFnAttr(
+          "xray-instruction-threshold",
+          llvm::itostr(CGM.getCodeGenOpts().XRayInstructionThreshold));
+    }
+  }
+
   // Pass inline keyword to optimizer if it appears explicitly on any
   // declaration. Also, in the case of -fno-inline attach NoInline
   // attribute to all functions that are not marked AlwaysInline, or

diff --git a/lib/CodeGen/CodeGenFunction.h b/lib/CodeGen/CodeGenFunction.h
index fff7a05b107f672f4305e627f2f56f51f0ee6150..08a3b307a4c0e0277487e41ac4fd349b0b72a0eb 100644 (file)
--- a/lib/CodeGen/CodeGenFunction.h
+++ b/lib/CodeGen/CodeGenFunction.h
@@ -1521,6 +1521,10 @@ public:
   /// instrumented with __cyg_profile_func_* calls
   bool ShouldInstrumentFunction();
 
+  /// ShouldXRayInstrument - Return true if the current function should be
+  /// instrumented with XRay nop sleds.
+  bool ShouldXRayInstrumentFunction() const;
+
   /// EmitFunctionInstrumentation - Emit LLVM code to call the specified
   /// instrumentation function with the current function and the call site, if
   /// function instrumentation is enabled.

diff --git a/lib/Driver/Tools.cpp b/lib/Driver/Tools.cpp
index d3844dd912e837a192601a4541318912ad672dbf..e4dd0c6f6c03125dcb02089be411034edbbc5e03 100644 (file)
--- a/lib/Driver/Tools.cpp
+++ b/lib/Driver/Tools.cpp
@@ -3181,6 +3181,28 @@ static bool addSanitizerRuntimes(const ToolChain &TC, const ArgList &Args,
   return !StaticRuntimes.empty();
 }
 
+static bool addXRayRuntime(const ToolChain &TC, const ArgList &Args,
+                           ArgStringList &CmdArgs) {
+  if (Args.hasFlag(options::OPT_fxray_instrument,
+                   options::OPT_fnoxray_instrument, false)) {
+    CmdArgs.push_back("-whole-archive");
+    CmdArgs.push_back(TC.getCompilerRTArgString(Args, "xray", false));
+    CmdArgs.push_back("-no-whole-archive");
+    return true;
+  }
+  return false;
+}
+
+static void linkXRayRuntimeDeps(const ToolChain &TC, ArgStringList &CmdArgs) {
+  CmdArgs.push_back("--no-as-needed");
+  CmdArgs.push_back("-lpthread");
+  CmdArgs.push_back("-lrt");
+  CmdArgs.push_back("-lm");
+  CmdArgs.push_back("-latomic");
+  if (TC.getTriple().getOS() != llvm::Triple::FreeBSD)
+    CmdArgs.push_back("-ldl");
+}
+
 static bool areOptimizationsEnabled(const ArgList &Args) {
   // Find the last -O arg and see if it is non-zero.
   if (Arg *A = Args.getLastArg(options::OPT_O_Group))
@@ -4582,6 +4604,17 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
 
   Args.AddAllArgs(CmdArgs, options::OPT_finstrument_functions);
 
+  if (Args.hasFlag(options::OPT_fxray_instrument,
+                   options::OPT_fnoxray_instrument, false)) {
+    CmdArgs.push_back("-fxray-instrument");
+    if (const Arg *A =
+            Args.getLastArg(options::OPT_fxray_instruction_threshold_,
+                            options::OPT_fxray_instruction_threshold_EQ)) {
+      CmdArgs.push_back("-fxray-instruction-threshold");
+      CmdArgs.push_back(A->getValue());
+    }
+  }
+
   addPGOAndCoverageFlags(C, D, Output, Args, CmdArgs);
 
   // Add runtime flag for PS4 when PGO or Coverage are enabled.
@@ -9390,6 +9423,7 @@ void gnutools::Linker::ConstructJob(Compilation &C, const JobAction &JA,
     CmdArgs.push_back("--no-demangle");
 
   bool NeedsSanitizerDeps = addSanitizerRuntimes(ToolChain, Args, CmdArgs);
+  bool NeedsXRayDeps = addXRayRuntime(ToolChain, Args, CmdArgs);
   AddLinkerInputs(ToolChain, Inputs, Args, CmdArgs);
   // The profile runtime also needs access to system libraries.
   getToolChain().addProfileRTLibs(Args, CmdArgs);
@@ -9416,6 +9450,9 @@ void gnutools::Linker::ConstructJob(Compilation &C, const JobAction &JA,
       if (NeedsSanitizerDeps)
         linkSanitizerRuntimeDeps(ToolChain, CmdArgs);
 
+      if (NeedsXRayDeps)
+        linkXRayRuntimeDeps(ToolChain, CmdArgs);
+
       bool WantPthread = Args.hasArg(options::OPT_pthread) ||
                          Args.hasArg(options::OPT_pthreads);
 

diff --git a/lib/Frontend/CompilerInvocation.cpp b/lib/Frontend/CompilerInvocation.cpp
index 5910664e6a6cfe651272b31fadb10ec8a992c2d5..c6948ebfc4b4ef140fbbeff7a7c9a7a9fcff3aef 100644 (file)
--- a/lib/Frontend/CompilerInvocation.cpp
+++ b/lib/Frontend/CompilerInvocation.cpp
@@ -687,6 +687,9 @@ static bool ParseCodeGenArgs(CodeGenOptions &Opts, ArgList &Args, InputKind IK,
   }
 
   Opts.InstrumentFunctions = Args.hasArg(OPT_finstrument_functions);
+  Opts.XRayInstrumentFunctions = Args.hasArg(OPT_fxray_instrument);
+  Opts.XRayInstructionThreshold =
+      getLastArgIntValue(Args, OPT_fxray_instruction_threshold_, 200, Diags);
   Opts.InstrumentForProfiling = Args.hasArg(OPT_pg);
   Opts.EmitOpenCLArgMetadata = Args.hasArg(OPT_cl_kernel_arg_info);
   Opts.CompressDebugSections = Args.hasArg(OPT_compress_debug_sections);

diff --git a/lib/Sema/SemaDeclAttr.cpp b/lib/Sema/SemaDeclAttr.cpp
index 4c36ab05d14fa14d04aba3d0d1668ee59d2370ce..a5780a7d71fb0ad0ccb5253b9c8a4add5ad3c289 100644 (file)
--- a/lib/Sema/SemaDeclAttr.cpp
+++ b/lib/Sema/SemaDeclAttr.cpp
@@ -5909,10 +5909,13 @@ static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
   case AttributeList::AT_TypeTagForDatatype:
     handleTypeTagForDatatypeAttr(S, D, Attr);
     break;
-
   case AttributeList::AT_RenderScriptKernel:
     handleSimpleAttribute<RenderScriptKernelAttr>(S, D, Attr);
     break;
+  // XRay attributes.
+  case AttributeList::AT_XRayInstrument:
+    handleSimpleAttribute<XRayInstrumentAttr>(S, D, Attr);
+    break;
   }
 }
 

diff --git a/test/CodeGen/xray-attributes-supported.cpp b/test/CodeGen/xray-attributes-supported.cpp
new file mode 100644 (file)
index 0000000..d70b3aa
--- /dev/null
+++ b/test/CodeGen/xray-attributes-supported.cpp
@@ -0,0 +1,13 @@
+// RUN: %clang_cc1 %s -fxray-instrument -std=c++11 -x c++ -emit-llvm -o - -triple x86_64-unknown-linux-gnu | FileCheck %s
+
+// Make sure that the LLVM attribute for XRay-annotated functions do show up.
+[[clang::xray_always_instrument]] void foo() {
+// CHECK: define void @_Z3foov() #0
+};
+
+[[clang::xray_never_instrument]] void bar() {
+// CHECK: define void @_Z3barv() #1
+};
+
+// CHECK: #0 = {{.*}}"function-instrument"="xray-always"
+// CHECK: #1 = {{.*}}"function-instrument"="xray-never"

diff --git a/test/Sema/xray-always-instrument-attr.c b/test/Sema/xray-always-instrument-attr.c
new file mode 100644 (file)
index 0000000..3c063e2
--- /dev/null
+++ b/test/Sema/xray-always-instrument-attr.c
@@ -0,0 +1,6 @@
+// RUN: %clang_cc1 %s -verify -fsyntax-only -std=c11
+void foo() __attribute__((xray_always_instrument));
+
+struct __attribute__((xray_always_instrument)) a { int x; }; // expected-warning {{'xray_always_instrument' attribute only applies to functions and methods}}
+
+void bar() __attribute__((xray_always_instrument("not-supported"))); // expected-error {{'xray_always_instrument' attribute takes no arguments}}

diff --git a/test/Sema/xray-always-instrument-attr.cpp b/test/Sema/xray-always-instrument-attr.cpp
new file mode 100644 (file)
index 0000000..8d42837
--- /dev/null
+++ b/test/Sema/xray-always-instrument-attr.cpp
@@ -0,0 +1,10 @@
+// RUN: %clang_cc1 %s -verify -fsyntax-only -std=c++11 -x c++
+void foo [[clang::xray_always_instrument]] ();
+
+struct [[clang::xray_always_instrument]] a { int x; }; // expected-warning {{'xray_always_instrument' attribute only applies to functions and methods}}
+
+class b {
+ void c [[clang::xray_always_instrument]] ();
+};
+
+void baz [[clang::xray_always_instrument("not-supported")]] (); // expected-error {{'xray_always_instrument' attribute takes no arguments}}