[PATCH] D25456: [InstrProf] Add support for dead_strip+live_support functionality

[Vedant Kumar via llvm-commits]

vsk created this revision.
vsk added reviewers: davidxl, mehdi_amini.
vsk added a subscriber: llvm-commits.

On Darwin, marking a section as "regular,live_support" means that a
symbol in the section should only be kept live if it has a reference to
something that is live. Otherwise, the linker is free to dead-strip it.

Turn this functionality on for the __llvm_prf_data section.

This means that counters, names, and data associated with dead functions
will be removed from dead-stripped binaries. This will result in smaller
profiles and binaries, and should speed up profile collection.

Tested with check-profile, llvm-lit test/tools/llvm-{cov,profdata}, and
check-llvm.


https://reviews.llvm.org/D25456

Files:
  include/llvm/ProfileData/InstrProf.h
  test/Instrumentation/InstrProfiling/PR23499.ll
  test/Instrumentation/InstrProfiling/platform.ll
  test/Instrumentation/InstrProfiling/profiling.ll


Index: test/Instrumentation/InstrProfiling/profiling.ll
===================================================================
--- test/Instrumentation/InstrProfiling/profiling.ll
+++ test/Instrumentation/InstrProfiling/profiling.ll
@@ -11,21 +11,21 @@
 ; CHECK: @__profn_baz = private constant [3 x i8] c"baz"
 
 ; CHECK: @__profc_foo = hidden global [1 x i64] zeroinitializer, section "__DATA,__llvm_prf_cnts", align 8
-; CHECK: @__profd_foo = hidden {{.*}}, section "__DATA,__llvm_prf_data", align 8
+; CHECK: @__profd_foo = hidden {{.*}}, section "__DATA,__llvm_prf_data,regular,live_support", align 8
 define void @foo() {
   call void @llvm.instrprof.increment(i8* getelementptr inbounds ([3 x i8], [3 x i8]* @__profn_foo, i32 0, i32 0), i64 0, i32 1, i32 0)
   ret void
 }
 
 ; CHECK: @__profc_bar = hidden global [1 x i64] zeroinitializer, section "__DATA,__llvm_prf_cnts", align 8
-; CHECK: @__profd_bar = hidden {{.*}}, section "__DATA,__llvm_prf_data", align 8
+; CHECK: @__profd_bar = hidden {{.*}}, section "__DATA,__llvm_prf_data,regular,live_support", align 8
 define void @bar() {
   call void @llvm.instrprof.increment(i8* getelementptr inbounds ([4 x i8], [4 x i8]* @__profn_bar, i32 0, i32 0), i64 0, i32 1, i32 0)
   ret void
 }
 
 ; CHECK: @__profc_baz = hidden global [3 x i64] zeroinitializer, section "__DATA,__llvm_prf_cnts", align 8
-; CHECK: @__profd_baz = hidden {{.*}}, section "__DATA,__llvm_prf_data", align 8
+; CHECK: @__profd_baz = hidden {{.*}}, section "__DATA,__llvm_prf_data,regular,live_support", align 8
 define void @baz() {
   call void @llvm.instrprof.increment(i8* getelementptr inbounds ([3 x i8], [3 x i8]* @__profn_baz, i32 0, i32 0), i64 0, i32 3, i32 0)
   call void @llvm.instrprof.increment(i8* getelementptr inbounds ([3 x i8], [3 x i8]* @__profn_baz, i32 0, i32 0), i64 0, i32 3, i32 1)
Index: test/Instrumentation/InstrProfiling/platform.ll
===================================================================
--- test/Instrumentation/InstrProfiling/platform.ll
+++ test/Instrumentation/InstrProfiling/platform.ll
@@ -18,7 +18,7 @@
 ; MACHO: @__profc_foo = hidden global [1 x i64] zeroinitializer, section "__DATA,__llvm_prf_cnts", align 8
 ; ELF: @__profc_foo = hidden global [1 x i64] zeroinitializer, section "__llvm_prf_cnts", align 8
 
-; MACHO: @__profd_foo = hidden {{.*}}, section "__DATA,__llvm_prf_data", align 8
+; MACHO: @__profd_foo = hidden {{.*}}, section "__DATA,__llvm_prf_data,regular,live_support", align 8
 ; LINUX: @__profd_foo = hidden {{.*}}, section "__llvm_prf_data", align 8
 ; FREEBSD: @__profd_foo = hidden {{.*}}, section "__llvm_prf_data", align 8
 ; PS4: @__profd_foo = hidden {{.*}}, section "__llvm_prf_data", align 8
Index: test/Instrumentation/InstrProfiling/PR23499.ll
===================================================================
--- test/Instrumentation/InstrProfiling/PR23499.ll
+++ test/Instrumentation/InstrProfiling/PR23499.ll
@@ -15,13 +15,13 @@
 
 ; CHECK: @__profn__Z3barIvEvv = private constant [11 x i8] c"_Z3barIvEvv", align 1
 ; CHECK: @__profc__Z3barIvEvv = linkonce_odr hidden global [1 x i64] zeroinitializer, section "{{.*}}__llvm_prf_cnts", comdat($__profv__Z3barIvEvv), align 8
-; CHECK: @__profd__Z3barIvEvv = linkonce_odr hidden global { i64, i64, i64*, i8*, i8*, i32, [1 x i16] } { i64 4947693190065689389, i64 0, i64* getelementptr inbounds ([1 x i64], [1 x i64]* @__profc__Z3barIvEvv, i32 0, i32 0), i8*{{.*}}, i8* null, i32 1, [1 x i16] zeroinitializer }, section "{{.*}}__llvm_prf_data", comdat($__profv__Z3barIvEvv), align 8
+; CHECK: @__profd__Z3barIvEvv = linkonce_odr hidden global { i64, i64, i64*, i8*, i8*, i32, [1 x i16] } { i64 4947693190065689389, i64 0, i64* getelementptr inbounds ([1 x i64], [1 x i64]* @__profc__Z3barIvEvv, i32 0, i32 0), i8*{{.*}}, i8* null, i32 1, [1 x i16] zeroinitializer }, section "{{.*}}__llvm_prf_data{{.*}}", comdat($__profv__Z3barIvEvv), align 8
 ; CHECK: @__llvm_prf_nm = private constant [{{.*}} x i8] c"{{.*}}", section "{{.*}}__llvm_prf_names"
 
 
 ; COFF: @__profn__Z3barIvEvv = private constant [11 x i8] c"_Z3barIvEvv", align 1
 ; COFF: @__profc__Z3barIvEvv = linkonce_odr hidden global [1 x i64] zeroinitializer, section "{{.*}}__llvm_prf_cnts", comdat, align 8
-; COFF: @__profd__Z3barIvEvv = linkonce_odr hidden global { i64, i64, i64*, i8*, i8*, i32, [1 x i16] } { i64 4947693190065689389, i64 0, i64* getelementptr inbounds ([1 x i64], [1 x i64]* @__profc__Z3barIvEvv, i32 0, i32 0), i8*{{.*}}, i8* null, i32 1, [1 x i16] zeroinitializer }, section "{{.*}}__llvm_prf_data", comdat($__profc__Z3barIvEvv), align 8
+; COFF: @__profd__Z3barIvEvv = linkonce_odr hidden global { i64, i64, i64*, i8*, i8*, i32, [1 x i16] } { i64 4947693190065689389, i64 0, i64* getelementptr inbounds ([1 x i64], [1 x i64]* @__profc__Z3barIvEvv, i32 0, i32 0), i8*{{.*}}, i8* null, i32 1, [1 x i16] zeroinitializer }, section "{{.*}}__llvm_prf_data{{.*}}", comdat($__profc__Z3barIvEvv), align 8
 
 
 declare void @llvm.instrprof.increment(i8*, i64, i32, i32) #1
Index: include/llvm/ProfileData/InstrProf.h
===================================================================
--- include/llvm/ProfileData/InstrProf.h
+++ include/llvm/ProfileData/InstrProf.h
@@ -55,6 +55,7 @@
 /// data.
 inline StringRef getInstrProfDataSectionName(bool AddSegment) {
   return AddSegment ? "__DATA," INSTR_PROF_DATA_SECT_NAME_STR
+                      ",regular,live_support"
                     : INSTR_PROF_DATA_SECT_NAME_STR;
 }
 


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