Add -fobjc-trace to emit a call before and after each Objective-C message send
for hooking in code flow visualisation applications.  



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@154321 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/clang/Driver/CC1Options.td b/include/clang/Driver/CC1Options.td
index 3ab8f83..e212cb2 100644
--- a/include/clang/Driver/CC1Options.td
+++ b/include/clang/Driver/CC1Options.td
@@ -619,6 +619,8 @@
   HelpText<"Enable Objective-C Ivar layout bitmap print trace">;
 def fobjc_fragile_abi : Flag<"-fobjc-fragile-abi">,
   HelpText<"Use Objective-C's fragile ABI">;
+def fobjc_trace : Flag<"-fobjc-trace">,
+  HelpText<"Enable tracing of Objective-C message sends">;
 def fno_objc_infer_related_result_type : Flag<
     "-fno-objc-infer-related-result-type">,
   HelpText<
diff --git a/include/clang/Driver/Options.td b/include/clang/Driver/Options.td
index 1b6b20c..3db345b 100644
--- a/include/clang/Driver/Options.td
+++ b/include/clang/Driver/Options.td
@@ -476,6 +476,9 @@
   "-fno-objc-infer-related-result-type">, Group<f_Group>;
 def fobjc_link_runtime: Flag<"-fobjc-link-runtime">, Group<f_Group>;
 
+def fobjc_trace: Flag<"-fobjc-trace">, Group<f_Group>;
+def fno_objc_trace: Flag<"-fno-objc-trace">, Group<f_Group>;
+
 // Objective-C ABI options.
 def fobjc_abi_version_EQ : Joined<"-fobjc-abi-version=">, Group<f_Group>;
 def fobjc_nonfragile_abi_version_EQ : Joined<"-fobjc-nonfragile-abi-version=">, Group<f_Group>;
diff --git a/include/clang/Frontend/CodeGenOptions.h b/include/clang/Frontend/CodeGenOptions.h
index e844f88..ec18684 100644
--- a/include/clang/Frontend/CodeGenOptions.h
+++ b/include/clang/Frontend/CodeGenOptions.h
@@ -82,6 +82,8 @@
                                   /// use of the inline keyword.
   unsigned NoNaNsFPMath      : 1; /// Assume FP arguments, results not NaN.
   unsigned NoZeroInitializedInBSS : 1; /// -fno-zero-initialized-in-bss
+  unsigned ObjCTrace          : 1; /// Emit tracing calls for visualising code
+                                   /// flow in Objective-C programs
   unsigned ObjCDispatchMethod : 2; /// Method of Objective-C dispatch to use.
   unsigned ObjCRuntimeHasARC : 1; /// The target runtime supports ARC natively
   unsigned ObjCRuntimeHasTerminate : 1; /// The ObjC runtime has objc_terminate
diff --git a/lib/CodeGen/CGObjCGNU.cpp b/lib/CodeGen/CGObjCGNU.cpp
index db0bd95..6cf370f 100644
--- a/lib/CodeGen/CGObjCGNU.cpp
+++ b/lib/CodeGen/CGObjCGNU.cpp
@@ -322,6 +322,11 @@
   /// Function used for non-object declared property setters.
   LazyRuntimeFunction SetStructPropertyFn;
 
+  /// Function called before message sends, when tracing
+  LazyRuntimeFunction TraceEnterFn;
+  /// Function called after  message sends, when tracing
+  LazyRuntimeFunction TraceExitFn;
+
   /// The version of the runtime that this class targets.  Must match the
   /// version in the runtime.
   int RuntimeVersion;
@@ -768,6 +773,9 @@
   SetStructPropertyFn.init(&CGM, "objc_setPropertyStruct", VoidTy, PtrTy, PtrTy, 
       PtrDiffTy, BoolTy, BoolTy, NULL);
 
+  TraceEnterFn.init(&CGM, "objc_trace_enter", VoidTy, IdTy, SelectorTy, NULL);
+  TraceExitFn.init(&CGM, "objc_trace_exit", VoidTy, IdTy, SelectorTy, NULL);
+
   // IMP type
   llvm::Type *IMPArgs[] = { IdTy, SelectorTy };
   IMPTy = llvm::PointerType::getUnqual(llvm::FunctionType::get(IdTy, IMPArgs,
@@ -1212,12 +1220,19 @@
   ActualArgs[0] = CallArg(RValue::get(Receiver), ASTIdTy, false);
 
   imp = EnforceType(Builder, imp, MSI.MessengerType);
+  if (CGM.getCodeGenOpts().ObjCTrace) {
+    Builder.CreateCall2(TraceEnterFn, Receiver, cmd);
+  }
 
   llvm::Instruction *call;
   RValue msgRet = CGF.EmitCall(MSI.CallInfo, imp, Return, ActualArgs,
       0, &call);
   call->setMetadata(msgSendMDKind, node);
 
+  if (CGM.getCodeGenOpts().ObjCTrace) {
+    Builder.CreateCall2(TraceExitFn, Receiver, cmd);
+  }
+
 
   if (!isPointerSizedReturn) {
     messageBB = CGF.Builder.GetInsertBlock();
diff --git a/lib/Driver/Tools.cpp b/lib/Driver/Tools.cpp
index 8093d2f..3bb6818 100644
--- a/lib/Driver/Tools.cpp
+++ b/lib/Driver/Tools.cpp
@@ -2400,6 +2400,10 @@
     CmdArgs.push_back("-fobjc-default-synthesize-properties");
   }
 
+  if (Args.hasFlag(options::OPT_fobjc_trace, options::OPT_fno_objc_trace,
+                   false))
+    CmdArgs.push_back("-fobjc-trace");
+
   // Allow -fno-objc-arr to trump -fobjc-arr/-fobjc-arc.
   // NOTE: This logic is duplicated in ToolChains.cpp.
   bool ARC = isObjCAutoRefCount(Args);
diff --git a/lib/Frontend/CompilerInvocation.cpp b/lib/Frontend/CompilerInvocation.cpp
index 02947c7..aae0b48 100644
--- a/lib/Frontend/CompilerInvocation.cpp
+++ b/lib/Frontend/CompilerInvocation.cpp
@@ -249,6 +249,8 @@
     Res.push_back("-mconstructor-aliases");
   if (Opts.ObjCAutoRefCountExceptions)
     Res.push_back("-fobjc-arc-eh");
+  if (Opts.ObjCTrace)
+    Res.push_back("-fobjc-trace");
   if (!Opts.DebugPass.empty()) {
     Res.push_back("-mdebug-pass", Opts.DebugPass);
   }
@@ -1109,6 +1111,7 @@
 
   Opts.AsmVerbose = Args.hasArg(OPT_masm_verbose);
   Opts.ObjCAutoRefCountExceptions = Args.hasArg(OPT_fobjc_arc_exceptions);
+  Opts.ObjCTrace = Args.hasArg(OPT_fobjc_trace);
   Opts.ObjCRuntimeHasARC = Args.hasArg(OPT_fobjc_runtime_has_arc);
   Opts.ObjCRuntimeHasTerminate = Args.hasArg(OPT_fobjc_runtime_has_terminate);
   Opts.CUDAIsDevice = Args.hasArg(OPT_fcuda_is_device);
diff --git a/test/CodeGenObjC/trace.m b/test/CodeGenObjC/trace.m
new file mode 100644
index 0000000..a67903a
--- /dev/null
+++ b/test/CodeGenObjC/trace.m
@@ -0,0 +1,13 @@
+///RUN: %clang_cc1 -triple x86_64-unknown-freebsd9.0 -fobjc-trace -fgnu-runtime -fobjc-dispatch-method=non-legacy -emit-llvm -o - %s | FileCheck %s
+
+
+@interface A
++ (id)msg;
+@end
+
+void f(void) {
+  [A msg];
+  // CHECK: call void @objc_trace_enter(
+  // CHECK: @objc_msgSend
+  // CHECK: call void @objc_trace_exit(
+}