[PATCH] D14033: [PGO] Eliminate emission of runtime hook user (Linux)

[Justin Bogner via llvm-commits]

David Li <davidxl at google.com> writes:
> davidxl created this revision.
> davidxl added a reviewer: bogner.
> davidxl added a subscriber: llvm-commits.
>
> This is patch part-2 following: http://reviews.llvm.org/D14030
>
> http://reviews.llvm.org/D14033
>
> Files:
>   lib/Transforms/Instrumentation/InstrProfiling.cpp
>   test/Instrumentation/InstrProfiling/linkage.ll
>
> Index: test/Instrumentation/InstrProfiling/linkage.ll
> ===================================================================
> --- test/Instrumentation/InstrProfiling/linkage.ll
> +++ test/Instrumentation/InstrProfiling/linkage.ll
> @@ -1,7 +1,7 @@
>  ;; Check that runtime symbols get appropriate linkage.
>  
>  ; RUN: opt < %s -mtriple=x86_64-apple-macosx10.10.0 -instrprof -S | FileCheck %s
> -; RUN: opt < %s -mtriple=x86_64-unknown-linux -instrprof -S | FileCheck %s
> +; RUN: opt < %s -mtriple=x86_64-unknown-linux -instrprof -S | FileCheck %s --check-prefix=LINUX
>  
>  @__llvm_profile_name_foo = hidden constant [3 x i8] c"foo"
>  @__llvm_profile_name_foo_weak = weak hidden constant [8 x i8] c"foo_weak"
> @@ -10,6 +10,8 @@
>  
>  ; CHECK: @__llvm_profile_counters_foo = hidden global
>  ; CHECK: @__llvm_profile_data_foo = hidden constant
> +; LINUX: @__llvm_profile_counters_foo = hidden global
> +; LINUX: @__llvm_profile_data_foo = hidden constant

You can simplify the checks a bit by using multiple prefices - FileCheck
will check all of them. So you'd change these to "COMMON:" or something
and then have specific ones for emitting and skipping the runtime hook
definition below.

>  define void @foo() {
>    call void @llvm.instrprof.increment(i8* getelementptr inbounds ([3 x i8], [3 x i8]* @__llvm_profile_name_foo, i32 0, i32 0), i64 0, i32 1, i32 0)
>    ret void
> @@ -17,6 +19,8 @@
>  
>  ; CHECK: @__llvm_profile_counters_foo_weak = weak hidden global
>  ; CHECK: @__llvm_profile_data_foo_weak = weak hidden constant
> +; LINUX: @__llvm_profile_counters_foo_weak = weak hidden global
> +; LINUX: @__llvm_profile_data_foo_weak = weak hidden constant
>  define weak void @foo_weak() {
>    call void @llvm.instrprof.increment(i8* getelementptr inbounds ([8 x i8], [8 x i8]* @__llvm_profile_name_foo_weak, i32 0, i32 0), i64 0, i32 1, i32 0)
>    ret void
> @@ -24,6 +28,8 @@
>  
>  ; CHECK: @"__llvm_profile_counters_linkage.ll:foo_internal" = internal global
>  ; CHECK: @"__llvm_profile_data_linkage.ll:foo_internal" = internal constant
> +; LINUX: @"__llvm_profile_counters_linkage.ll:foo_internal" = internal global
> +; LINUX: @"__llvm_profile_data_linkage.ll:foo_internal" = internal constant
>  define internal void @foo_internal() {
>    call void @llvm.instrprof.increment(i8* getelementptr inbounds ([23 x i8], [23 x i8]* @"__llvm_profile_name_linkage.ll:foo_internal", i32 0, i32 0), i64 0, i32 1, i32 0)
>    ret void
> @@ -31,6 +37,8 @@
>  
>  ; CHECK: @__llvm_profile_counters_foo_inline = linkonce_odr hidden global
>  ; CHECK: @__llvm_profile_data_foo_inline = linkonce_odr hidden constant
> +; LINUX: @__llvm_profile_counters_foo_inline = linkonce_odr hidden global
> +; LINUX: @__llvm_profile_data_foo_inline = linkonce_odr hidden constant
>  define linkonce_odr void @foo_inline() {
>    call void @llvm.instrprof.increment(i8* getelementptr inbounds ([10 x i8], [10 x i8]* @__llvm_profile_name_foo_inline, i32 0, i32 0), i64 0, i32 1, i32 0)
>    ret void
> @@ -39,8 +47,11 @@
>  declare void @llvm.instrprof.increment(i8*, i64, i32, i32)
>  
>  ; CHECK: @__llvm_profile_runtime = external global i32
> +; LINUX-NOT: @__llvm_profile_runtime = external global i32
>  
>  ; CHECK: define linkonce_odr hidden i32 @__llvm_profile_runtime_user() {{.*}} {
>  ; CHECK:   %[[REG:.*]] = load i32, i32* @__llvm_profile_runtime
>  ; CHECK:   ret i32 %[[REG]]
>  ; CHECK: }
> +; LINUX-NOT: define linkonce_odr hidden i32 @__llvm_profile_runtime_user() {{.*}} {
> +; LINUX-NOT:   %[[REG:.*]] = load i32, i32* @__llvm_profile_runtime
> Index: lib/Transforms/Instrumentation/InstrProfiling.cpp
> ===================================================================
> --- lib/Transforms/Instrumentation/InstrProfiling.cpp
> +++ lib/Transforms/Instrumentation/InstrProfiling.cpp
> @@ -288,6 +288,8 @@
>  
>  void InstrProfiling::emitRuntimeHook() {
>  
> +  if (Triple(M->getTargetTriple()).isOSLinux()) return;
> +

This could use a comment. Also, despite the formatting on the line
below, the style is to put the return on a new line. clang-format will
do that for you.

>    // If the module's provided its own runtime, we don't need to do anything.
>    if (M->getGlobalVariable(getInstrProfRuntimeHookVarName())) return;