Do not generate calls to fentry with __attribute__((no_instrument_fun…

…ction))

Summary:
Currently only calls to mcount were suppressed with
no_instrument_function attribute.
Linux kernel requires that calls to fentry should also not be
generated.
This is an extended fix for PR PR33515.

Reviewers: hfinkel, rengolin, srhines, rnk, rsmith, rjmccall, hans

Reviewed By: rjmccall

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D43995

llvm-svn: 326639

clang/lib/CodeGen/CodeGenFunction.cpp

@@ -1016,10 +1016,12 @@ void CodeGenFunction::StartFunction(GlobalDecl GD,
   // The attribute "counting-function" is set to mcount function name which is
   // architecture dependent.
   if (CGM.getCodeGenOpts().InstrumentForProfiling) {
-    if (CGM.getCodeGenOpts().CallFEntry)
-      Fn->addFnAttr("fentry-call", "true");
-    else {
-      if (!CurFuncDecl || !CurFuncDecl->hasAttr<NoInstrumentFunctionAttr>()) {
+    // Calls to fentry/mcount should not be generated if function has
+    // the no_instrument_function attribute.
+    if (!CurFuncDecl || !CurFuncDecl->hasAttr<NoInstrumentFunctionAttr>()) {
+      if (CGM.getCodeGenOpts().CallFEntry)
+        Fn->addFnAttr("fentry-call", "true");
+      else {
         Fn->addFnAttr("instrument-function-entry-inlined",
                       getTarget().getMCountName());
       }

clang/test/CodeGen/fentry.c

@@ -7,5 +7,12 @@ int foo(void) {
   return 0;
 }
 
-//CHECK: attributes #{{[0-9]+}} = { {{.*}}"fentry-call"="true"{{.*}} }
-//NOPG-NOT: attributes #{{[0-9]+}} = { {{.*}}"fentry-call"{{.*}} }
+int __attribute__((no_instrument_function)) no_instrument(void) {
+  return foo();
+}
+
+//CHECK: attributes #0 = { {{.*}}"fentry-call"="true"{{.*}} }
+//CHECK: attributes #1 = { {{.*}} }
+//CHECK-NOT: attributes #1 = { {{.*}}"fentry-call"="true"{{.*}} }
+//NOPG-NOT: attributes #0 = { {{.*}}"fentry-call"{{.*}} }
+//NOPG-NOT: attributes #1 = { {{.*}}"fentry-call"{{.*}} }