[Clang] Handle interaction of -pg and no_instrument_function attribute.

[manojgupta]

Summary

Disable generation of counting-function attribute if no_instrument_function
attribute is present in function.
Interaction between -pg and no_instrument_function is the desired behavior
and matches gcc as well.
This is required for fixing a crash in Linux kernel when function tracing
is enabled.

Fixes PR33515.

[hfinkel]

LGTM

[manojgupta]

Thanks for the quick review.

lib/CodeGen/CodeGenFunction.cpp

void CodeGenFunction::StartFunction(GlobalDecl GD,
 
   // Since emitting the mcount call here impacts optimizations such as function
   // inlining, we just add an attribute to insert a mcount call in backend.
   // 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
+    else {
+      if (!CurFuncDecl || !CurFuncDecl->hasAttr<NoInstrumentFunctionAttr>())
         Fn->addFnAttr("counting-function", getTarget().getMCountName());
     }
+  }
 
   if (RetTy->isVoidType()) {
     // Void type; nothing to return.
     ReturnValue = Address::invalid();
 
     // Count the implicit return.
     if (!endsWithReturn(D))
       ++NumReturnExprs;

test/CodeGen/mcount.c

 // RUN: %clang_cc1 -pg -triple i386-unknown-unknown -emit-llvm -o - %s | FileCheck %s
 // RUN: %clang_cc1 -pg -triple i386-unknown-unknown -emit-llvm -O2 -o - %s | FileCheck %s
-// RUN: %clang_cc1 -pg -triple powerpc-unknown-gnu-linux -emit-llvm -o - %s | FileCheck -check-prefix=CHECK-PREFIXED %s
-// RUN: %clang_cc1 -pg -triple powerpc64-unknown-gnu-linux -emit-llvm -o - %s | FileCheck -check-prefix=CHECK-PREFIXED %s
-// RUN: %clang_cc1 -pg -triple powerpc64le-unknown-gnu-linux -emit-llvm -o - %s | FileCheck -check-prefix=CHECK-PREFIXED %s
-// RUN: %clang_cc1 -pg -triple i386-netbsd -emit-llvm -o - %s | FileCheck -check-prefix=CHECK-PREFIXED %s
-// RUN: %clang_cc1 -pg -triple x86_64-netbsd -emit-llvm -o - %s | FileCheck -check-prefix=CHECK-PREFIXED %s
-// RUN: %clang_cc1 -pg -triple arm-netbsd-eabi -emit-llvm -o - %s | FileCheck -check-prefix=CHECK-PREFIXED %s
-// RUN: %clang_cc1 -pg -triple aarch64-netbsd -emit-llvm -o - %s | FileCheck -check-prefix=CHECK-PREFIXED %s
-// RUN: %clang_cc1 -pg -triple mips-netbsd -emit-llvm -o - %s | FileCheck -check-prefix=CHECK-PREFIXED %s
-// RUN: %clang_cc1 -pg -triple powerpc-netbsd -emit-llvm -o - %s | FileCheck -check-prefix=CHECK-PREFIXED %s
-// RUN: %clang_cc1 -pg -triple powerpc64-netbsd -emit-llvm -o - %s | FileCheck -check-prefix=CHECK-PREFIXED %s
-// RUN: %clang_cc1 -pg -triple powerpc64le-netbsd -emit-llvm -o - %s | FileCheck -check-prefix=CHECK-PREFIXED %s
-// RUN: %clang_cc1 -pg -triple sparc-netbsd -emit-llvm -o - %s | FileCheck -check-prefix=CHECK-PREFIXED %s
-// RUN: %clang_cc1 -pg -triple sparc64-netbsd -emit-llvm -o - %s | FileCheck -check-prefix=CHECK-PREFIXED %s
+// RUN: %clang_cc1 -pg -triple powerpc-unknown-gnu-linux -emit-llvm -o - %s | FileCheck -check-prefixes=CHECK-PREFIXED,NO-MCOUNT1 %s
+// RUN: %clang_cc1 -pg -triple powerpc64-unknown-gnu-linux -emit-llvm -o - %s | FileCheck -check-prefixes=CHECK-PREFIXED,NO-MCOUNT1 %s
+// RUN: %clang_cc1 -pg -triple powerpc64le-unknown-gnu-linux -emit-llvm -o - %s | FileCheck -check-prefixes=CHECK-PREFIXED,NO-MCOUNT1 %s
+// RUN: %clang_cc1 -pg -triple i386-netbsd -emit-llvm -o - %s | FileCheck -check-prefixes=CHECK-PREFIXED,NO-MCOUNT1 %s
+// RUN: %clang_cc1 -pg -triple x86_64-netbsd -emit-llvm -o - %s | FileCheck -check-prefixes=CHECK-PREFIXED,NO-MCOUNT1 %s
+// RUN: %clang_cc1 -pg -triple arm-netbsd-eabi -emit-llvm -o - %s | FileCheck -check-prefixes=CHECK-PREFIXED,NO-MCOUNT1 %s
+// RUN: %clang_cc1 -pg -triple aarch64-netbsd -emit-llvm -o - %s | FileCheck -check-prefixes=CHECK-PREFIXED,NO-MCOUNT1 %s
+// RUN: %clang_cc1 -pg -triple mips-netbsd -emit-llvm -o - %s | FileCheck -check-prefixes=CHECK-PREFIXED,NO-MCOUNT1 %s
+// RUN: %clang_cc1 -pg -triple powerpc-netbsd -emit-llvm -o - %s | FileCheck -check-prefixes=CHECK-PREFIXED,NO-MCOUNT1 %s
+// RUN: %clang_cc1 -pg -triple powerpc64-netbsd -emit-llvm -o - %s | FileCheck -check-prefixes=CHECK-PREFIXED,NO-MCOUNT1 %s
+// RUN: %clang_cc1 -pg -triple powerpc64le-netbsd -emit-llvm -o - %s | FileCheck -check-prefixes=CHECK-PREFIXED,NO-MCOUNT1 %s
+// RUN: %clang_cc1 -pg -triple sparc-netbsd -emit-llvm -o - %s | FileCheck -check-prefixes=CHECK-PREFIXED,NO-MCOUNT1 %s
+// RUN: %clang_cc1 -pg -triple sparc64-netbsd -emit-llvm -o - %s | FileCheck -check-prefixes=CHECK-PREFIXED,NO-MCOUNT1 %s
 // RUN: %clang_cc1 -emit-llvm -o - %s | FileCheck %s -check-prefix=NO-MCOUNT
 
 int bar(void) {
   return 0;
 }
 
 int foo(void) {
   return bar();
 }
 
-int main(void) {
+int __attribute__((no_instrument_function)) no_instrument(void) {
   return foo();
 }
 
-// CHECK: attributes #{{[0-9]+}} = { {{.*}}"counting-function"="mcount"{{.*}} }
-// CHECK-PREFIXED: attributes #{{[0-9]+}} = { {{.*}}"counting-function"="_mcount"{{.*}} }
+int main(void) {
+  return no_instrument();
+}
+
+// CHECK: attributes #0 = { {{.*}}"counting-function"="mcount"{{.*}} }
+// CHECK: attributes #1 = { {{.*}} }
+// CHECK-PREFIXED: attributes #0 = { {{.*}}"counting-function"="_mcount"{{.*}} }
+// CHECK-PREFIXED: attributes #1 = { {{.*}} }
 // NO-MCOUNT-NOT: attributes #{{[0-9]}} = { {{.*}}"counting-function"={{.*}} }
+// NO-MCOUNT1-NOT: attributes #1 = { {{.*}}"counting-function"={{.*}} }