[Frontend] Fix mcount inlining bug

Since some profiling tools, such as gprof, ftrace, and uftrace, use
-pg option to generate a mcount function call at the entry of each
function. Function invocation can be detected by this hook function.

But mcount insertion is done before function inlining phase in clang,
sometime a function that already has a mcount call can be inlined in the
middle of another function.

This patch adds an attribute "counting-function" to each function
rather than emitting the mcount call directly in frontend so that this
attribute can be processed in backend. Then the mcount calls can be
properly inserted in backend after all the other optimizations are
completed.

Link: https://llvm.org/bugs/show_bug.cgi?id=28660
Reviewers: hans, rjmccall, hfinkel, rengolin, compnerd

Subscribers: shenhan, cfe-commits

Differential Revision: https://reviews.llvm.org/D22666

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@280355 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/CodeGenFunction.cpp b/lib/CodeGen/CodeGenFunction.cpp
index 94c9fd7ec6c5f03587529e266b557342dd50a866..1cf068fd38856a22c3256883ffeb6868b6a6e85e 100644 (file)
--- a/lib/CodeGen/CodeGenFunction.cpp
+++ b/lib/CodeGen/CodeGenFunction.cpp
@@ -428,14 +428,6 @@ void CodeGenFunction::EmitFunctionInstrumentation(const char *Fn) {
   EmitNounwindRuntimeCall(F, args);
 }
 
-void CodeGenFunction::EmitMCountInstrumentation() {
-  llvm::FunctionType *FTy = llvm::FunctionType::get(VoidTy, false);
-
-  llvm::Constant *MCountFn =
-    CGM.CreateRuntimeFunction(FTy, getTarget().getMCountName());
-  EmitNounwindRuntimeCall(MCountFn);
-}
-
 // OpenCL v1.2 s5.6.4.6 allows the compiler to store kernel argument
 // information in the program executable. The argument information stored
 // includes the argument name, its type, the address and access qualifiers used.
@@ -794,8 +786,12 @@ void CodeGenFunction::StartFunction(GlobalDecl GD,
   if (ShouldInstrumentFunction())
     EmitFunctionInstrumentation("__cyg_profile_func_enter");
 
+  // 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)
-    EmitMCountInstrumentation();
+    Fn->addFnAttr("counting-function", getTarget().getMCountName());
 
   if (RetTy->isVoidType()) {
     // Void type; nothing to return.

diff --git a/test/CodeGen/mcount.c b/test/CodeGen/mcount.c
index 99dc90795b5e648085ce9b3918cb378b732f36f7..7f915841952eb495d318f28752a964d1fd913fc5 100644 (file)
--- a/test/CodeGen/mcount.c
+++ b/test/CodeGen/mcount.c
@@ -1,4 +1,5 @@
 // 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
@@ -12,7 +13,20 @@
 // 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
-void foo(void) {
-// CHECK: call void @mcount()
-// CHECK-PREFIXED: call void @_mcount()
+// 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) {
+  return foo();
+}
+
+// CHECK: attributes #{{[0-9]+}} = { {{.*}}"counting-function"="mcount"{{.*}} }
+// CHECK-PREFIXED: attributes #{{[0-9]+}} = { {{.*}}"counting-function"="_mcount"{{.*}} }
+// NO-MCOUNT-NOT: attributes #{{[0-9]}} = { {{.*}}"counting-function"={{.*}} }

diff --git a/test/Frontend/gnu-mcount.c b/test/Frontend/gnu-mcount.c
index c279b89ddadf8f807637bf0de1ef88704bc89f22..de07743f3849e6ffef25986e6a6d51de44960f11 100644 (file)
--- a/test/Frontend/gnu-mcount.c
+++ b/test/Frontend/gnu-mcount.c
@@ -44,35 +44,35 @@ int f() {
 }
 
 // CHECK-LABEL: f
-// CHECK-ARM-IOS-NOT: call void @_mcount()
-// CHECK-ARM-IOS-NOT: call void @"\01__gnu_mcount_nc"()
-// CHECK-ARM-EABI: call void @"\01mcount"()
-// CHECK-ARM-EABI-NOT: call void @"\01__gnu_mcount_nc"()
-// CHECK-ARM64-EABI: call void @mcount()
-// CHECK-ARM64-EABI-MEABI-GNU: call void @"\01_mcount"()
-// CHECK-ARM64-EABI-NOT: call void @"\01__gnu_mcount_nc"()
-// CHECK-ARM-EABI-FREEBSD: call void @__mcount()
-// CHECK-ARM-EABI-FREEBSD-NOT: call void @"\01__gnu_mcount_nc"()
-// CHECK-ARM64-EABI-FREEBSD: call void @.mcount()
-// CHECK-ARM64-EABI-FREEBSD-NOT: call void @"\01__gnu_mcount_nc"()
-// CHECK-ARM-EABI-NETBSD: call void @_mcount()
-// CHECK-ARM-EABI-NETBSD-NOT: call void @"\01__gnu_mcount_nc"()
-// CHECK-ARM-EABI-OPENBSD: call void @__mcount()
-// CHECK-ARM-EABI-OPENBSD-NOT: call void @"\01__gnu_mcount_nc"()
-// CHECK-ARM64-EABI-OPENBSD: call void @mcount()
-// CHECK-ARM64-EABI-OPENBSD-NOT: call void @"\01__gnu_mcount_nc"()
-// CHECK-ARM-EABI-MEABI-GNU-NOT: call void @mcount()
-// CHECK-ARM-EABI-MEABI-GNU: call void @"\01__gnu_mcount_nc"()
-// CHECK-ARM-EABI-BITRIG: call void @__mcount()
-// CHECK-ARM-EABI-BITRIG-NOT: call void @"\01__gnu_mcount_nc"()
-// CHECK-ARM54-EABI-BITRIG: call void @mcount()
-// CHECK-ARM54-EABI-BITRIG-NOT: call void @"\01__gnu_mcount_nc"()
-// CHECK-ARM-EABI-RTEMS: call void @mcount()
-// CHECK-ARM-EABI-RTEMS-NOT: call void @"\01__gnu_mcount_nc"()
-// CHECK-ARM64-EABI-RTEMS: call void @mcount()
-// CHECK-ARM64-EABI-RTEMS-NOT: call void @"\01__gnu_mcount_nc"()
-// CHECK-ARM-EABI-CLOUDABI: call void @mcount()
-// CHECK-ARM-EABI-CLOUDABI-NOT: call void @"\01__gnu_mcount_nc"()
-// CHECK-ARM64-EABI-CLOUDABI: call void @mcount()
-// CHECK-ARM64-EABI-CLOUDABI-NOT: call void @"\01__gnu_mcount_nc"()
+// CHECK-ARM-IOS-NOT: attributes #{{[0-9]+}} = { {{.*}}"counting-function"="_mcount"{{.*}} }
+// CHECK-ARM-IOS-NOT: attributes #{{[0-9]+}} = { {{.*}}"counting-function"="\01__gnu_mcount_nc"{{.*}} }
+// CHECK-ARM-EABI: attributes #{{[0-9]+}} = { {{.*}}"counting-function"="\01mcount"{{.*}} }
+// CHECK-ARM-EABI-NOT: attributes #{{[0-9]+}} = { {{.*}}"counting-function"="\01__gnu_mcount_nc"{{.*}} }
+// CHECK-ARM64-EABI: attributes #{{[0-9]+}} = { {{.*}}"counting-function"="mcount"{{.*}} }
+// CHECK-ARM64-EABI-MEABI-GNU: attributes #{{[0-9]+}} = { {{.*}}"counting-function"="\01_mcount"{{.*}} }
+// CHECK-ARM64-EABI-NOT: attributes #{{[0-9]+}} = { {{.*}}"counting-function"="\01__gnu_mcount_nc"{{.*}} }
+// CHECK-ARM-EABI-FREEBSD: attributes #{{[0-9]+}} = { {{.*}}"counting-function"="__mcount"{{.*}} }
+// CHECK-ARM-EABI-FREEBSD-NOT: attributes #{{[0-9]+}} = { {{.*}}"counting-function"="\01__gnu_mcount_nc"{{.*}} }
+// CHECK-ARM64-EABI-FREEBSD: attributes #{{[0-9]+}} = { {{.*}}"counting-function"=".mcount"{{.*}} }
+// CHECK-ARM64-EABI-FREEBSD-NOT: attributes #{{[0-9]+}} = { {{.*}}"counting-function"="\01__gnu_mcount_nc"{{.*}} }
+// CHECK-ARM-EABI-NETBSD: attributes #{{[0-9]+}} = { {{.*}}"counting-function"="_mcount"{{.*}} }
+// CHECK-ARM-EABI-NETBSD-NOT: attributes #{{[0-9]+}} = { {{.*}}"counting-function"="\01__gnu_mcount_nc"{{.*}} }
+// CHECK-ARM-EABI-OPENBSD: attributes #{{[0-9]+}} = { {{.*}}"counting-function"="__mcount"{{.*}} }
+// CHECK-ARM-EABI-OPENBSD-NOT: attributes #{{[0-9]+}} = { {{.*}}"counting-function"="\01__gnu_mcount_nc"{{.*}} }
+// CHECK-ARM64-EABI-OPENBSD: attributes #{{[0-9]+}} = { {{.*}}"counting-function"="mcount"{{.*}} }
+// CHECK-ARM64-EABI-OPENBSD-NOT: attributes #{{[0-9]+}} = { {{.*}}"counting-function"="\01__gnu_mcount_nc"{{.*}} }
+// CHECK-ARM-EABI-MEABI-GNU-NOT: attributes #{{[0-9]+}} = { {{.*}}"counting-function"="mcount"{{.*}} }
+// CHECK-ARM-EABI-MEABI-GNU: attributes #{{[0-9]+}} = { {{.*}}"counting-function"="\01__gnu_mcount_nc"{{.*}} }
+// CHECK-ARM-EABI-BITRIG: attributes #{{[0-9]+}} = { {{.*}}"counting-function"="__mcount"{{.*}} }
+// CHECK-ARM-EABI-BITRIG-NOT: attributes #{{[0-9]+}} = { {{.*}}"counting-function"="\01__gnu_mcount_nc"{{.*}} }
+// CHECK-ARM54-EABI-BITRIG: attributes #{{[0-9]+}} = { {{.*}}"counting-function"="mcount"{{.*}} }
+// CHECK-ARM54-EABI-BITRIG-NOT: attributes #{{[0-9]+}} = { {{.*}}"counting-function"="\01__gnu_mcount_nc"{{.*}} }
+// CHECK-ARM-EABI-RTEMS: attributes #{{[0-9]+}} = { {{.*}}"counting-function"="mcount"{{.*}} }
+// CHECK-ARM-EABI-RTEMS-NOT: attributes #{{[0-9]+}} = { {{.*}}"counting-function"="\01__gnu_mcount_nc"{{.*}} }
+// CHECK-ARM64-EABI-RTEMS: attributes #{{[0-9]+}} = { {{.*}}"counting-function"="mcount"{{.*}} }
+// CHECK-ARM64-EABI-RTEMS-NOT: attributes #{{[0-9]+}} = { {{.*}}"counting-function"="\01__gnu_mcount_nc"{{.*}} }
+// CHECK-ARM-EABI-CLOUDABI: attributes #{{[0-9]+}} = { {{.*}}"counting-function"="mcount"{{.*}} }
+// CHECK-ARM-EABI-CLOUDABI-NOT: attributes #{{[0-9]+}} = { {{.*}}"counting-function"="\01__gnu_mcount_nc"{{.*}} }
+// CHECK-ARM64-EABI-CLOUDABI: attributes #{{[0-9]+}} = { {{.*}}"counting-function"="mcount"{{.*}} }
+// CHECK-ARM64-EABI-CLOUDABI-NOT: attributes #{{[0-9]+}} = { {{.*}}"counting-function"="\01__gnu_mcount_nc"{{.*}} }