Add -finstrument-function-entry-bare flag

This is an instrumentation flag that's similar to
-finstrument-functions, but it only inserts calls on function entry, the
calls are inserted post-inlining, and they don't take any arugments.

This is intended for users who want to instrument function entry with
minimal overhead.

(-pg would be another alternative, but forces frame pointer emission and
affects link flags, so is probably best left alone to be used for
generating gcov data.)

Differential revision: https://reviews.llvm.org/D40276

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@318785 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 15 insertions, 9 deletions

diff --git a/lib/CodeGen/CodeGenFunction.cpp b/lib/CodeGen/CodeGenFunction.cpp
index 8544da3da7..6b8359141b 100644
--- a/lib/CodeGen/CodeGenFunction.cpp
+++ b/lib/CodeGen/CodeGenFunction.cpp
@@ -355,10 +355,11 @@ void CodeGenFunction::FinishFunction(SourceLocation EndLoc) {
   llvm::DebugLoc Loc = EmitReturnBlock();
 
   if (ShouldInstrumentFunction()) {
-    CurFn->addFnAttr(!CGM.getCodeGenOpts().InstrumentFunctionsAfterInlining
-                         ? "instrument-function-exit"
-                         : "instrument-function-exit-inlined",
-                     "__cyg_profile_func_exit");
+    if (CGM.getCodeGenOpts().InstrumentFunctions)
+      CurFn->addFnAttr("instrument-function-exit", "__cyg_profile_func_exit");
+    if (CGM.getCodeGenOpts().InstrumentFunctionsAfterInlining)
+      CurFn->addFnAttr("instrument-function-exit-inlined",
+                       "__cyg_profile_func_exit");
   }
 
   // Emit debug descriptor for function end.
@@ -443,7 +444,8 @@ void CodeGenFunction::FinishFunction(SourceLocation EndLoc) {
 /// instrumented with __cyg_profile_func_* calls
 bool CodeGenFunction::ShouldInstrumentFunction() {
   if (!CGM.getCodeGenOpts().InstrumentFunctions &&
-      !CGM.getCodeGenOpts().InstrumentFunctionsAfterInlining)
+      !CGM.getCodeGenOpts().InstrumentFunctionsAfterInlining &&
+      !CGM.getCodeGenOpts().InstrumentFunctionEntryBare)
     return false;
   if (!CurFuncDecl || CurFuncDecl->hasAttr<NoInstrumentFunctionAttr>())
     return false;
@@ -982,10 +984,14 @@ void CodeGenFunction::StartFunction(GlobalDecl GD,
   }
 
   if (ShouldInstrumentFunction()) {
-    Fn->addFnAttr(!CGM.getCodeGenOpts().InstrumentFunctionsAfterInlining
-                      ? "instrument-function-entry"
-                      : "instrument-function-entry-inlined",
-                  "__cyg_profile_func_enter");
+    if (CGM.getCodeGenOpts().InstrumentFunctions)
+      CurFn->addFnAttr("instrument-function-entry", "__cyg_profile_func_enter");
+    if (CGM.getCodeGenOpts().InstrumentFunctionsAfterInlining)
+      CurFn->addFnAttr("instrument-function-entry-inlined",
+                       "__cyg_profile_func_enter");
+    if (CGM.getCodeGenOpts().InstrumentFunctionEntryBare)
+      CurFn->addFnAttr("instrument-function-entry-inlined",
+                       "__cyg_profile_func_enter_bare");
   }
 
   // Since emitting the mcount call here impacts optimizations such as function