[PGO] Turn off comdat renaming in IR PGO by default

Summary:
In IR PGO we append the function hash to comdat functions to avoid the
potential hash mismatch. This turns out not legal in some cases: if the comdat
function is address-taken and used in comparison. Renaming changes the semantic.

This patch turns off comdat renaming by default.

To alleviate the hash mismatch issue, we now rename the profile variable
for comdat functions. Profile allows co-existing multiple versions of profiles
with different hash value. The inlined copy will always has the correct profile
counter. The out-of-line copy might not have the correct count. But we will
not have the bogus mismatch warning.

Reviewers: davidxl

Subscribers: llvm-commits, xur

Differential Revision: https://reviews.llvm.org/D28416

llvm-svn: 291588

5 files changed, 81 insertions, 21 deletions

diff --git a/llvm/test/Transforms/PGOProfile/Inputs/multiple_hash_profile.proftext b/llvm/test/Transforms/PGOProfile/Inputs/multiple_hash_profile.proftext
new file mode 100644
index 00000000000..5bf67fb2bfa
--- /dev/null
+++ b/llvm/test/Transforms/PGOProfile/Inputs/multiple_hash_profile.proftext
@@ -0,0 +1,36 @@
+# IR level Instrumentation Flag
+:ir
+_Z3fooi
+# Func Hash:
+72057606922829823
+# Num Counters:
+2
+# Counter Values:
+18
+12
+
+_Z3fooi
+# Func Hash:
+12884901887
+# Num Counters:
+1
+# Counter Values:
+0
+
+_Z3bari
+# Func Hash:
+72057606922829823
+# Num Counters:
+2
+# Counter Values:
+0
+0
+
+_Z4m2f1v
+# Func Hash:
+12884901887
+# Num Counters:
+1
+# Counter Values:
+1
+
diff --git a/llvm/test/Transforms/PGOProfile/comdat_internal.ll b/llvm/test/Transforms/PGOProfile/comdat_internal.ll
index 25dafbea103..7df6f91fe72 100644
--- a/llvm/test/Transforms/PGOProfile/comdat_internal.ll
+++ b/llvm/test/Transforms/PGOProfile/comdat_internal.ll
@@ -4,17 +4,17 @@ target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"
 
 $foo = comdat any
-; CHECK: $foo.[[FOO_HASH:[0-9]+]] = comdat any
+; CHECK: $foo = comdat any
 
 ; CHECK: $__llvm_profile_raw_version = comdat any
-; CHECK: $__profv__stdin__foo.[[FOO_HASH]] = comdat any
+; CHECK: $__profv__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: @__profn__stdin__foo.[[FOO_HASH]] = private constant [23 x i8] c"<stdin>:foo.[[FOO_HASH]]"
+; CHECK: @__profn__stdin__foo = private constant [11 x i8] c"<stdin>:foo"
 ; CHECK: @__profc__stdin__foo.[[FOO_HASH]] = private global [1 x i64] zeroinitializer, section "__llvm_prf_cnts", comdat($__profv__stdin__foo.[[FOO_HASH]]), align 8
-; CHECK: @__profd__stdin__foo.[[FOO_HASH]] = private global { i64, i64, i64*, i8*, i8*, i32, [1 x i16] } { i64 6965568665848889497, i64 [[FOO_HASH]], i64* getelementptr inbounds ([1 x i64], [1 x i64]* @__profc__stdin__foo.[[FOO_HASH]], i32 0, i32 0), i8* null
+; CHECK: @__profd__stdin__foo.[[FOO_HASH]] = private global { i64, i64, i64*, i8*, i8*, i32, [1 x i16] } { i64 -5640069336071256030, i64 [[FOO_HASH]], i64* getelementptr inbounds ([1 x i64], [1 x i64]* @__profc__stdin__foo.[[FOO_HASH]], i32 0, i32 0), i8* null
 ; CHECK-NOT: bitcast (i32 ()* @foo to i8*)
 ; CHECK-SAME: , i8* null, i32 1, [1 x i16] zeroinitializer }, section "__llvm_prf_data", comdat($__profv__stdin__foo.[[FOO_HASH]]), align 8
 ; CHECK: @__llvm_prf_nm
diff --git a/llvm/test/Transforms/PGOProfile/comdat_rename.ll b/llvm/test/Transforms/PGOProfile/comdat_rename.ll
index b69c802093b..eb9ddb4a1ce 100644
--- a/llvm/test/Transforms/PGOProfile/comdat_rename.ll
+++ b/llvm/test/Transforms/PGOProfile/comdat_rename.ll
@@ -1,7 +1,7 @@
-; RUN: opt < %s -mtriple=x86_64-unknown-linux -pgo-instr-gen -S | FileCheck --check-prefixes COMMON,ELFONLY %s
-; RUN: opt < %s -mtriple=x86_64-unknown-linux -passes=pgo-instr-gen -S | FileCheck --check-prefixes COMMON,ELFONLY %s
-; RUN: opt < %s -mtriple=x86_64-pc-win32-coff -pgo-instr-gen -S | FileCheck --check-prefixes COMMON,COFFONLY %s
-; RUN: opt < %s -mtriple=x86_64-pc-win32-coff -passes=pgo-instr-gen -S | FileCheck --check-prefixes COMMON,COFFONLY %s
+; RUN: opt < %s -mtriple=x86_64-unknown-linux -pgo-instr-gen -do-comdat-renaming=true -S | FileCheck --check-prefixes COMMON,ELFONLY %s
+; RUN: opt < %s -mtriple=x86_64-unknown-linux -passes=pgo-instr-gen -do-comdat-renaming=true -S | FileCheck --check-prefixes COMMON,ELFONLY %s
+; RUN: opt < %s -mtriple=x86_64-pc-win32-coff -pgo-instr-gen -do-comdat-renaming=true -S | FileCheck --check-prefixes COMMON,COFFONLY %s
+; RUN: opt < %s -mtriple=x86_64-pc-win32-coff -passes=pgo-instr-gen -do-comdat-renaming=true -S | FileCheck --check-prefixes COMMON,COFFONLY %s
 
 ; Rename Comdat group and its function.
 $f = comdat any
@@ -38,22 +38,10 @@ define linkonce void @tf2() comdat($tf) {
   ret void
 }
 
-; Renaming Comdat with aliases.
-$f_with_alias = comdat any
-; COMMON: $f_with_alias.[[SINGLEBB_HASH]] = comdat any
-@af = alias void (...), bitcast (void ()* @f_with_alias to void (...)*)
-; COFFONLY: @af.[[SINGLEBB_HASH]] = alias void (...), bitcast (void ()* @f_with_alias.[[SINGLEBB_HASH]] to
-; ELFONLY-DAG: @af.[[SINGLEBB_HASH]] = alias void (...), bitcast (void ()* @f_with_alias.[[SINGLEBB_HASH]] to
-define linkonce_odr void @f_with_alias() comdat($f_with_alias) {
-  ret void
-}
-
 ; Rename AvailableExternallyLinkage functions
 ; ELFONLY-DAG: $aef.[[SINGLEBB_HASH]] = comdat any
 
 ; ELFONLY: @f = weak alias void (), void ()* @f.[[SINGLEBB_HASH]]
-; ELFONLY: @f_with_alias = weak alias void (), void ()* @f_with_alias.[[SINGLEBB_HASH]]
-; ELFONLY: @af = weak alias void (...), void (...)* @af.[[SINGLEBB_HASH]]
 ; ELFONLY: @aef = weak alias void (), void ()* @aef.[[SINGLEBB_HASH]]
 
 define available_externally void @aef() {
diff --git a/llvm/test/Transforms/PGOProfile/indirect_call_profile.ll b/llvm/test/Transforms/PGOProfile/indirect_call_profile.ll
index 409c29ef872..e1f499c08a7 100644
--- a/llvm/test/Transforms/PGOProfile/indirect_call_profile.ll
+++ b/llvm/test/Transforms/PGOProfile/indirect_call_profile.ll
@@ -54,7 +54,7 @@ bb11:                                             ; preds = %bb2
 }
 
 ; Test that comdat function's address is recorded.
-; LOWER: @__profd_foo3.[[FOO3_HASH:[0-9]+]] = linkonce_odr{{.*}}@foo3.[[FOO3_HASH]]
+; LOWER: @__profd_foo3.[[FOO3_HASH:[0-9]+]] = linkonce_odr{{.*}}@__profc_foo3.[[FOO3_HASH]]
 ; Function Attrs: nounwind uwtable
 define linkonce_odr i32 @foo3()  comdat  {
   ret i32 1
diff --git a/llvm/test/Transforms/PGOProfile/multiple_hash_profile.ll b/llvm/test/Transforms/PGOProfile/multiple_hash_profile.ll
new file mode 100644
index 00000000000..f4041830f8f
--- /dev/null
+++ b/llvm/test/Transforms/PGOProfile/multiple_hash_profile.ll
@@ -0,0 +1,36 @@
+; RUN: llvm-profdata merge %S/Inputs/multiple_hash_profile.proftext -o %t.profdata
+; RUN: opt < %s -pgo-instr-use -pgo-test-profile-file=%t.profdata  -S | FileCheck %s
+; RUN: opt < %s -passes=pgo-instr-use -pgo-test-profile-file=%t.profdata -S | FileCheck %s
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+$_Z3fooi = comdat any
+
+@g2 = local_unnamed_addr global i32 (i32)* null, align 8
+
+define i32 @_Z3bari(i32 %i) {
+entry:
+  %cmp = icmp sgt i32 %i, 2
+  %mul = select i1 %cmp, i32 1, i32 %i
+  %retval.0 = mul nsw i32 %mul, %i
+  ret i32 %retval.0
+}
+
+define void @_Z4m2f1v() {
+entry:
+  store i32 (i32)* @_Z3fooi, i32 (i32)** @g2, align 8
+  ret void
+}
+
+define linkonce_odr i32 @_Z3fooi(i32 %i) comdat {
+entry:
+  %cmp.i = icmp sgt i32 %i, 2
+  %mul.i = select i1 %cmp.i, i32 1, i32 %i
+; CHECK: %mul.i = select i1 %cmp.i, i32 1, i32 %i
+; CHECK-SAME !prof ![[BW:[0-9]+]]
+; CHECK ![[BW]] = !{!"branch_weights", i32 12, i32 6}
+  %retval.0.i = mul nsw i32 %mul.i, %i
+  ret i32 %retval.0.i
+}
+
+