[llvm] e56626e - [PGO] Move __profc_ and __profvp_ from their own comdat groups to __profd_'s comdat group
Fangrui Song via llvm-commits
llvm-commits at lists.llvm.org
Mon Aug 3 20:40:22 PDT 2020
Author: Fangrui Song
Date: 2020-08-03T20:35:50-07:00
New Revision: e56626e43826c9d7c35113635d62b57c905ef3c0
URL: https://github.com/llvm/llvm-project/commit/e56626e43826c9d7c35113635d62b57c905ef3c0
DIFF: https://github.com/llvm/llvm-project/commit/e56626e43826c9d7c35113635d62b57c905ef3c0.diff
LOG: [PGO] Move __profc_ and __profvp_ from their own comdat groups to __profd_'s comdat group
D68041 placed `__profc_`, `__profd_` and (if exists) `__profvp_` in different comdat groups.
There are some issues:
* Cost: one or two additional section headers (`.group` section(s)): 64 or 128 bytes on ELF64.
* `__profc_`, `__profd_` and (if exists) `__profvp_` should be retained or
discarded. Placing them into separate comdat groups is conceptually inferior.
* If the prevailing group does not include `__profvp_` (value profiling not
used) but a non-prevailing group from another translation unit has `__profvp_`
(the function is inlined into another and triggers value profiling), there
will be a stray `__profvp_` if --gc-sections is not enabled.
This has been fixed by 3d6f53018f845e893ad34f64ff2851a2e5c3ba1d.
Actually, we can reuse an existing symbol (we choose `__profd_`) as the group
signature to avoid a string in the string table (the sole reason that D68041
could improve code size is that `__profv_` was an otherwise unused symbol which
wasted string table space). This saves one or two section headers.
For a -DCMAKE_BUILD_TYPE=Release -DLLVM_BUILD_INSTRUMENTED=IR build, `ninja
clang lld`, the patch has saved 10.5MiB (2.2%) for the total .o size.
Reviewed By: davidxl
Differential Revision: https://reviews.llvm.org/D84723
Added:
Modified:
llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp
llvm/test/Instrumentation/InstrProfiling/PR23499.ll
llvm/test/Instrumentation/InstrProfiling/comdat.ll
llvm/test/Instrumentation/InstrProfiling/icall.ll
llvm/test/Instrumentation/InstrProfiling/linkage.ll
llvm/test/Transforms/PGOProfile/comdat_internal.ll
Removed:
################################################################################
diff --git a/llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp b/llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp
index 75988893fdb85..623f463293cd9 100644
--- a/llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp
+++ b/llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp
@@ -882,9 +882,10 @@ InstrProfiling::getOrCreateRegionCounters(InstrProfIncrementInst *Inc) {
Visibility = GlobalValue::HiddenVisibility;
}
}
+ std::string DataVarName = getVarName(Inc, getInstrProfDataVarPrefix());
auto MaybeSetComdat = [=](GlobalVariable *GV) {
if (NeedComdat)
- GV->setComdat(M->getOrInsertComdat(GV->getName()));
+ GV->setComdat(M->getOrInsertComdat(DataVarName));
};
uint64_t NumCounters = Inc->getNumCounters()->getZExtValue();
@@ -949,9 +950,9 @@ InstrProfiling::getOrCreateRegionCounters(InstrProfIncrementInst *Inc) {
#define INSTR_PROF_DATA(Type, LLVMType, Name, Init) Init,
#include "llvm/ProfileData/InstrProfData.inc"
};
- auto *Data = new GlobalVariable(*M, DataTy, false, Linkage,
- ConstantStruct::get(DataTy, DataVals),
- getVarName(Inc, getInstrProfDataVarPrefix()));
+ auto *Data =
+ new GlobalVariable(*M, DataTy, false, Linkage,
+ ConstantStruct::get(DataTy, DataVals), DataVarName);
Data->setVisibility(Visibility);
Data->setSection(getInstrProfSectionName(IPSK_data, TT.getObjectFormat()));
Data->setAlignment(Align(INSTR_PROF_DATA_ALIGNMENT));
diff --git a/llvm/test/Instrumentation/InstrProfiling/PR23499.ll b/llvm/test/Instrumentation/InstrProfiling/PR23499.ll
index 1a4c04947a2b1..098153f39e1db 100644
--- a/llvm/test/Instrumentation/InstrProfiling/PR23499.ll
+++ b/llvm/test/Instrumentation/InstrProfiling/PR23499.ll
@@ -14,13 +14,13 @@ $_Z3barIvEvv = comdat any
@__profn__Z3barIvEvv = linkonce_odr hidden constant [11 x i8] c"_Z3barIvEvv", align 1
; CHECK-NOT: __profn__Z3barIvEvv
-; CHECK: @__profc__Z3barIvEvv = linkonce_odr hidden global [1 x i64] zeroinitializer, section "{{.*}}__llvm_prf_cnts", comdat, align 8
+; CHECK: @__profc__Z3barIvEvv = linkonce_odr hidden global [1 x i64] zeroinitializer, section "{{.*}}__llvm_prf_cnts", comdat($__profd__Z3barIvEvv), align 8
; CHECK: @__profd__Z3barIvEvv = linkonce_odr hidden global { i64, i64, i64*, i8*, i8*, i32, [2 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, [2 x i16] zeroinitializer }, section "{{.*}}__llvm_prf_data{{.*}}", comdat, align 8
; CHECK: @__llvm_prf_nm = private constant [{{.*}} x i8] c"{{.*}}", section "{{.*}}__llvm_prf_names"
; COFF-NOT: __profn__Z3barIvEvv
-; COFF: @__profc__Z3barIvEvv = linkonce_odr hidden global [1 x i64] zeroinitializer, section "{{.*}}prfc$M", comdat, align 8
+; COFF: @__profc__Z3barIvEvv = linkonce_odr hidden global [1 x i64] zeroinitializer, section "{{.*}}prfc$M", comdat($__profd__Z3barIvEvv), align 8
; COFF: @__profd__Z3barIvEvv = linkonce_odr hidden global { i64, i64, i64*, i8*, i8*, i32, [2 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, [2 x i16] zeroinitializer }, section "{{.*}}prfd{{.*}}", comdat, align 8
diff --git a/llvm/test/Instrumentation/InstrProfiling/comdat.ll b/llvm/test/Instrumentation/InstrProfiling/comdat.ll
index 3f169c4b73423..dfcd71fd06291 100644
--- a/llvm/test/Instrumentation/InstrProfiling/comdat.ll
+++ b/llvm/test/Instrumentation/InstrProfiling/comdat.ll
@@ -15,9 +15,9 @@ $foo_inline = comdat any
@__profn_foo_inline = linkonce_odr hidden constant [10 x i8] c"foo_inline"
-; ELF: @__profc_foo_inline = linkonce_odr hidden global{{.*}}, section "__llvm_prf_cnts", comdat, align 8
+; ELF: @__profc_foo_inline = linkonce_odr hidden global{{.*}}, section "__llvm_prf_cnts", comdat($__profd_foo_inline), align 8
; ELF: @__profd_foo_inline = linkonce_odr hidden global{{.*}}, section "__llvm_prf_data", comdat, align 8
-; COFF: @__profc_foo_inline = linkonce_odr hidden global{{.*}}, section ".lprfc$M", comdat, align 8
+; COFF: @__profc_foo_inline = linkonce_odr hidden global{{.*}}, section ".lprfc$M", comdat($__profd_foo_inline), align 8
; COFF: @__profd_foo_inline = linkonce_odr hidden global{{.*}}, section ".lprfd$M", comdat, align 8
define weak_odr void @foo_inline() comdat {
call void @llvm.instrprof.increment(i8* getelementptr inbounds ([10 x i8], [10 x i8]* @__profn_foo_inline, i32 0, i32 0), i64 0, i32 1, i32 0)
@@ -28,9 +28,9 @@ $foo_extern = comdat any
@__profn_foo_extern = linkonce_odr hidden constant [10 x i8] c"foo_extern"
-; ELF: @__profc_foo_extern = linkonce_odr hidden global{{.*}}, section "__llvm_prf_cnts", comdat, align 8
+; ELF: @__profc_foo_extern = linkonce_odr hidden global{{.*}}, section "__llvm_prf_cnts", comdat($__profd_foo_extern), align 8
; ELF: @__profd_foo_extern = linkonce_odr hidden global{{.*}}, section "__llvm_prf_data", comdat, align 8
-; COFF: @__profc_foo_extern = linkonce_odr hidden global{{.*}}, section ".lprfc$M", comdat, align 8
+; COFF: @__profc_foo_extern = linkonce_odr hidden global{{.*}}, section ".lprfc$M", comdat($__profd_foo_extern), align 8
; COFF: @__profd_foo_extern = linkonce_odr hidden global{{.*}}, section ".lprfd$M", comdat, align 8
define available_externally void @foo_extern() {
call void @llvm.instrprof.increment(i8* getelementptr inbounds ([10 x i8], [10 x i8]* @__profn_foo_extern, i32 0, i32 0), i64 0, i32 1, i32 0)
diff --git a/llvm/test/Instrumentation/InstrProfiling/icall.ll b/llvm/test/Instrumentation/InstrProfiling/icall.ll
index d92de47421d40..9d45d7cd56358 100644
--- a/llvm/test/Instrumentation/InstrProfiling/icall.ll
+++ b/llvm/test/Instrumentation/InstrProfiling/icall.ll
@@ -14,6 +14,7 @@
@__profn_foo = private constant [3 x i8] c"foo"
+ at __profn_bar = private constant [3 x i8] c"bar"
define i32 @foo(i32 ()* ) {
call void @llvm.instrprof.increment(i8* getelementptr inbounds ([3 x i8], [3 x i8]* @__profn_foo, i32 0, i32 0), i64 12884901887, i32 1, i32 0)
@@ -23,6 +24,17 @@ define i32 @foo(i32 ()* ) {
ret i32 %3
}
+$bar = comdat any
+
+define i32 @bar(i32 ()* ) comdat {
+entry:
+ call void @llvm.instrprof.increment(i8* getelementptr inbounds ([3 x i8], [3 x i8]* @__profn_bar, i32 0, i32 0), i64 12884901887, i32 1, i32 0)
+ %1 = ptrtoint i32 ()* %0 to i64
+ call void @llvm.instrprof.value.profile(i8* getelementptr inbounds ([3 x i8], [3 x i8]* @__profn_bar, i32 0, i32 0), i64 12884901887, i64 %1, i32 0, i32 0)
+ %2 = tail call i32 %0()
+ ret i32 %2
+}
+
; Function Attrs: nounwind
declare void @llvm.instrprof.increment(i8*, i64, i32, i32) #0
@@ -31,7 +43,8 @@ declare void @llvm.instrprof.value.profile(i8*, i64, i64, i32, i32) #0
attributes #0 = { nounwind }
-; STATIC: @__profvp_foo
+; STATIC: @__profvp_foo = private global [1 x i64] zeroinitializer, section "{{[^"]+}}", align 8
+; STATIC: @__profvp_bar = private global [1 x i64] zeroinitializer, section "{{[^"]+}}", comdat($__profd_bar), align 8
; STATIC: @__llvm_prf_vnodes
; DYN-NOT: @__profvp_foo
diff --git a/llvm/test/Instrumentation/InstrProfiling/linkage.ll b/llvm/test/Instrumentation/InstrProfiling/linkage.ll
index be3af8e51a5f8..5e55ef716820e 100644
--- a/llvm/test/Instrumentation/InstrProfiling/linkage.ll
+++ b/llvm/test/Instrumentation/InstrProfiling/linkage.ll
@@ -55,11 +55,11 @@ define linkonce_odr void @foo_inline() {
ret void
}
-; LINUX: @__profc_foo_extern = linkonce_odr hidden global {{.*}}section "__llvm_prf_cnts", comdat, align 8
+; LINUX: @__profc_foo_extern = linkonce_odr hidden global {{.*}}section "__llvm_prf_cnts", comdat($__profd_foo_extern), align 8
; LINUX: @__profd_foo_extern = linkonce_odr hidden global {{.*}}section "__llvm_prf_data", comdat, align 8
; MACHO: @__profc_foo_extern = linkonce_odr hidden global
; MACHO: @__profd_foo_extern = linkonce_odr hidden global
-; COFF: @__profc_foo_extern = linkonce_odr hidden global {{.*}}section ".lprfc$M", comdat, align 8
+; COFF: @__profc_foo_extern = linkonce_odr hidden global {{.*}}section ".lprfc$M", comdat($__profd_foo_extern), align 8
; COFF: @__profd_foo_extern = linkonce_odr hidden global {{.*}}section ".lprfd$M", comdat, align 8
define available_externally void @foo_extern() {
call void @llvm.instrprof.increment(i8* getelementptr inbounds ([10 x i8], [10 x i8]* @__profn_foo_extern, i32 0, i32 0), i64 0, i32 1, i32 0)
diff --git a/llvm/test/Transforms/PGOProfile/comdat_internal.ll b/llvm/test/Transforms/PGOProfile/comdat_internal.ll
index f0906bf2b3720..e5915d906a086 100644
--- a/llvm/test/Transforms/PGOProfile/comdat_internal.ll
+++ b/llvm/test/Transforms/PGOProfile/comdat_internal.ll
@@ -7,12 +7,13 @@ $foo = comdat any
; CHECK: $foo = comdat any
; CHECK: $__llvm_profile_raw_version = comdat any
+; CHECK: $__profd__stdin__foo.[[FOO_HASH:[0-9]+]] = comdat any
@bar = global i32 ()* @foo, align 8
; CHECK: @__llvm_profile_raw_version = constant i64 {{[0-9]+}}, comdat
; CHECK-NOT: __profn__stdin__foo
-; CHECK: @__profc__stdin__foo.[[FOO_HASH:[0-9]+]] = private global [1 x i64] zeroinitializer, section "__llvm_prf_cnts", comdat, align 8
+; CHECK: @__profc__stdin__foo.[[FOO_HASH]] = private global [1 x i64] zeroinitializer, section "__llvm_prf_cnts", comdat($__profd__stdin__foo.[[FOO_HASH]]), align 8
; CHECK: @__profd__stdin__foo.[[FOO_HASH]] = private global { i64, i64, i64*, i8*, i8*, i32, [2 x i16] } { i64 -5640069336071256030, i64 [[FOO_HASH]], i64* getelementptr inbounds ([1 x i64], [1 x i64]* @__profc__stdin__foo.[[FOO_HASH]], i32 0, i32 0), i8* null
; CHECK-NOT: bitcast (i32 ()* @foo to i8*)
; CHECK-SAME: , i8* null, i32 1, [2 x i16] zeroinitializer }, section "__llvm_prf_data", comdat, align 8
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