[compiler-rt] 0adc577 - Revert "Reland "[pgo] Avoid introducing relocations by using private alias"""

Paul Kirth via llvm-commits llvm-commits at lists.llvm.org
Thu Dec 8 10:16:08 PST 2022


Author: Paul Kirth
Date: 2022-12-08T18:15:55Z
New Revision: 0adc577c119fa4f5a1ab9df8ca6e8e90c75d87aa

URL: https://github.com/llvm/llvm-project/commit/0adc577c119fa4f5a1ab9df8ca6e8e90c75d87aa
DIFF: https://github.com/llvm/llvm-project/commit/0adc577c119fa4f5a1ab9df8ca6e8e90c75d87aa.diff

LOG: Revert "Reland "[pgo] Avoid introducing relocations by using private alias"""

This reverts commit 071c39df8632561b599f7b1debd81b3cf6b5b396.

One of the new runtimes tests causes a failure with MSVC, so I'm
reverting until the test can be fixed.

Added: 
    

Modified: 
    llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp
    llvm/test/Transforms/PGOProfile/comdat.ll

Removed: 
    compiler-rt/test/profile/instrprof-discarded-comdat.cpp
    llvm/test/Transforms/PGOProfile/prof_avoid_relocs.ll


################################################################################
diff  --git a/compiler-rt/test/profile/instrprof-discarded-comdat.cpp b/compiler-rt/test/profile/instrprof-discarded-comdat.cpp
deleted file mode 100644
index bfc65415c6fe7..0000000000000
--- a/compiler-rt/test/profile/instrprof-discarded-comdat.cpp
+++ /dev/null
@@ -1,49 +0,0 @@
-// Check that instrprof does not introduce references to discarded sections when
-// using comdats.
-//
-// Occasionally, it is possible that the same function can be compiled in
-// 
diff erent TUs with slightly 
diff erent linkages, e.g., due to 
diff erent
-// compiler options. However, if these are comdat functions, a single
-// implementation will be chosen at link time. we want to ensure that the
-// profiling data does not contain a reference to the discarded section.
-
-// RUN: mkdir -p %t.d
-// RUN: %clangxx_pgogen -O2 -fPIC -ffunction-sections -fdata-sections -c %s -o %t.d/a1.o -DOBJECT_1 -mllvm -disable-preinline
-// RUN: %clangxx_pgogen -O2 -fPIC -ffunction-sections -fdata-sections -c %s -o %t.d/a2.o
-// RUN: %clangxx -fPIC -shared -o %t.d/liba.so %t.d/a1.o %t.d/a2.o 2>&1 | FileCheck %s --allow-empty
-
-// Ensure that we don't get an error when linking
-// CHECK-NOT: relocation refers to a discarded section: .text._ZN1CIiE1fEi
-
-template <typename T> struct C {
-  void f(T x);
-  int g(T x) {
-    f(x);
-    return v;
-  }
-  int v;
-};
-
-template <typename T>
-#ifdef OBJECT_1
-__attribute__((weak))
-#else
-__attribute__((noinline))
-#endif
-void C<T>::f(T x) {
-  v += x;
-}
-
-#ifdef OBJECT_1
-int foo() {
-  C<int> c;
-  c.f(1);
-  return c.g(2);
-}
-#else
-int bar() {
-  C<int> c;
-  c.f(3);
-  return c.g(4);
-}
-#endif

diff  --git a/llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp b/llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp
index 0c6ab14928260..3af3f908ea5b2 100644
--- a/llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp
+++ b/llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp
@@ -823,36 +823,6 @@ static inline bool shouldRecordFunctionAddr(Function *F) {
   return F->hasAddressTaken() || F->hasLinkOnceLinkage();
 }
 
-static inline Constant *getFuncAddrForProfData(Function *Fn) {
-  auto *Int8PtrTy = Type::getInt8PtrTy(Fn->getContext());
-  // Store a nullptr in __llvm_profd, if we shouldn't use a real address
-  if (!shouldRecordFunctionAddr(Fn))
-    return ConstantPointerNull::get(Int8PtrTy);
-
-  // If we can't use an alias, we must use the public symbol, even though this
-  // may require a symbolic relocation. When the function has local linkage, we
-  // can use the symbol directly without introducing relocations.
-  if (Fn->isDeclarationForLinker() || Fn->hasLocalLinkage())
-    return ConstantExpr::getBitCast(Fn, Int8PtrTy);
-
-  // When possible use a private alias to avoid symbolic relocations.
-  auto *GA = GlobalAlias::create(GlobalValue::LinkageTypes::PrivateLinkage,
-                                 Fn->getName(), Fn);
-
-  // When the instrumented function is a COMDAT function, we cannot use a
-  // private alias. If we did, we would create reference to a local label in
-  // this function's section. If this version of the function isn't selected by
-  // the linker, then the metadata would introduce a reference to a discarded
-  // section. So, for COMDAT functions, we need to adjust the linkage of the
-  // alias. Using hidden visibility avoids a dynamic relocation and an entry in
-  // the dynamic symbol table.
-  if (Fn->hasComdat()) {
-    GA->setLinkage(Fn->getLinkage());
-    GA->setVisibility(GlobalValue::VisibilityTypes::HiddenVisibility);
-  }
-  return ConstantExpr::getBitCast(GA, Int8PtrTy);
-}
-
 static bool needsRuntimeRegistrationOfSectionRange(const Triple &TT) {
   // Don't do this for Darwin.  compiler-rt uses linker magic.
   if (TT.isOSDarwin())
@@ -1044,7 +1014,9 @@ InstrProfiling::getOrCreateRegionCounters(InstrProfInstBase *Inc) {
   };
   auto *DataTy = StructType::get(Ctx, makeArrayRef(DataTypes));
 
-  Constant *FunctionAddr = getFuncAddrForProfData(Fn);
+  Constant *FunctionAddr = shouldRecordFunctionAddr(Fn)
+                               ? ConstantExpr::getBitCast(Fn, Int8PtrTy)
+                               : ConstantPointerNull::get(Int8PtrTy);
 
   Constant *Int16ArrayVals[IPVK_Last + 1];
   for (uint32_t Kind = IPVK_First; Kind <= IPVK_Last; ++Kind)

diff  --git a/llvm/test/Transforms/PGOProfile/comdat.ll b/llvm/test/Transforms/PGOProfile/comdat.ll
index 7bd4180ca0aac..9f5c0ee848ca5 100644
--- a/llvm/test/Transforms/PGOProfile/comdat.ll
+++ b/llvm/test/Transforms/PGOProfile/comdat.ll
@@ -4,8 +4,6 @@
 
 $linkonceodr = comdat any
 $weakodr = comdat any
-$weak = comdat any
-$linkonce = comdat any
 
 ;; profc/profd have hash suffixes. This definition doesn't have value profiling,
 ;; so definitions with the same name in other modules must have the same CFG and
@@ -29,32 +27,3 @@ define linkonce_odr void @linkonceodr() comdat {
 define weak_odr void @weakodr() comdat {
   ret void
 }
-
-;; weak in a comdat is not renamed. There is no guarantee that definitions in
-;; other modules don't have value profiling. profd should be conservatively
-;; non-private to prevent a caller from referencing a non-prevailing profd,
-;; causing a linker error.
-; ELF:   @__profc_weak = weak hidden global {{.*}} comdat, align 8
-; ELF:   @__profd_weak = weak hidden global {{.*}} comdat($__profc_weak), align 8
-; COFF:  @__profc_weak = weak hidden global {{.*}} comdat, align 8
-; COFF:  @__profd_weak = weak hidden global {{.*}} comdat, align 8
-define weak void @weak() comdat {
-  ret void
-}
-
-;; profc/profd have hash suffixes. This definition doesn't have value profiling,
-;; so definitions with the same name in other modules must have the same CFG and
-;; cannot have value profiling, either. profd can be made private for ELF.
-; ELF:   @__profc_linkonce.[[#]] = linkonce hidden global {{.*}} comdat, align 8
-; ELF:   @__profd_linkonce.[[#]] = private global {{.*}} comdat($__profc_linkonce.[[#]]), align 8
-; COFF:  @__profc_linkonce.[[#]] = linkonce hidden global {{.*}} comdat, align 8
-; COFF:  @__profd_linkonce.[[#]] = linkonce hidden global {{.*}} comdat, align 8
-define linkonce void @linkonce() comdat {
-  ret void
-}
-
-; Check that comdat aliases are hidden for all linkage types
-; ELF:   @linkonceodr.1 = linkonce_odr hidden alias void (), ptr @linkonceodr
-; ELF:   @weakodr.2 = weak_odr hidden alias void (), ptr @weakodr
-; ELF:   @weak.3 = weak hidden alias void (), ptr @weak
-; ELF:   @linkonce.4 = linkonce hidden alias void (), ptr @linkonce

diff  --git a/llvm/test/Transforms/PGOProfile/prof_avoid_relocs.ll b/llvm/test/Transforms/PGOProfile/prof_avoid_relocs.ll
deleted file mode 100644
index 8d22e4a63354e..0000000000000
--- a/llvm/test/Transforms/PGOProfile/prof_avoid_relocs.ll
+++ /dev/null
@@ -1,86 +0,0 @@
-; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --check-globals
-; RUN: opt -S -passes=pgo-instr-gen,instrprof < %s | FileCheck %s
-
-target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
-target triple = "x86_64-unknown-linux-gnu"
-
-;; Test that we use private aliases to reference function addresses inside profile data
-; CHECK: @__profd_foo = private global {{.*}}, ptr @foo.1,
-; CHECK-NOT: @__profd_foo = private global {{.*}}, ptr @foo,
-; CHECK: @[[__PROFC_WEAK:[a-zA-Z0-9_$"\\.-]+]] = weak hidden global [1 x i64] zeroinitializer, section "__llvm_prf_cnts", comdat, align 8
-; CHECK: @[[__PROFD_WEAK:[a-zA-Z0-9_$"\\.-]+]] = private global { i64, i64, i64, ptr, ptr, i32, [2 x i16] } { i64 -5028622335731970946, i64 742261418966908927, i64 sub (i64 ptrtoint (ptr @__profc_weak to i64), i64 ptrtoint (ptr @__profd_weak to i64)), ptr @weak.2, ptr null, i32 1, [2 x i16] zeroinitializer }, section "__llvm_prf_data", comdat($__profc_weak), align 8
-; CHECK: @[[__PROFC_LINKONCE:[a-zA-Z0-9_$"\\.-]+]] = linkonce hidden global [1 x i64] zeroinitializer, section "__llvm_prf_cnts", comdat, align 8
-; CHECK: @[[__PROFD_LINKONCE:[a-zA-Z0-9_$"\\.-]+]] = private global { i64, i64, i64, ptr, ptr, i32, [2 x i16] } { i64 -121947654961992603, i64 742261418966908927, i64 sub (i64 ptrtoint (ptr @__profc_linkonce to i64), i64 ptrtoint (ptr @__profd_linkonce to i64)), ptr @linkonce.3, ptr null, i32 1, [2 x i16] zeroinitializer }, section "__llvm_prf_data", comdat($__profc_linkonce), align 8
-; CHECK: @[[__PROFC_WEAKODR:[a-zA-Z0-9_$"\\.-]+]] = weak_odr hidden global [1 x i64] zeroinitializer, section "__llvm_prf_cnts", comdat, align 8
-; CHECK: @[[__PROFD_WEAKODR:[a-zA-Z0-9_$"\\.-]+]] = private global { i64, i64, i64, ptr, ptr, i32, [2 x i16] } { i64 -4807837289933096997, i64 742261418966908927, i64 sub (i64 ptrtoint (ptr @__profc_weakodr to i64), i64 ptrtoint (ptr @__profd_weakodr to i64)), ptr @weakodr.4, ptr null, i32 1, [2 x i16] zeroinitializer }, section "__llvm_prf_data", comdat($__profc_weakodr), align 8
-; CHECK: @[[__PROFC_LINKONCEODR:[a-zA-Z0-9_$"\\.-]+]] = linkonce_odr hidden global [1 x i64] zeroinitializer, section "__llvm_prf_cnts", comdat, align 8
-; CHECK: @[[__PROFD_LINKONCEODR:[a-zA-Z0-9_$"\\.-]+]] = private global { i64, i64, i64, ptr, ptr, i32, [2 x i16] } { i64 4214081367395809689, i64 742261418966908927, i64 sub (i64 ptrtoint (ptr @__profc_linkonceodr to i64), i64 ptrtoint (ptr @__profd_linkonceodr to i64)), ptr @linkonceodr.5, ptr null, i32 1, [2 x i16] zeroinitializer }, section "__llvm_prf_data", comdat($__profc_linkonceodr), align 8
-; CHECK: @[[__PROFC_AVAILABLE_EXTERNALLY_742261418966908927:[a-zA-Z0-9_$"\\.-]+]] = linkonce_odr hidden global [1 x i64] zeroinitializer, section "__llvm_prf_cnts", comdat, align 8
-; CHECK: @[[__PROFD_AVAILABLE_EXTERNALLY_742261418966908927:[a-zA-Z0-9_$"\\.-]+]] = private global { i64, i64, i64, ptr, ptr, i32, [2 x i16] } { i64 -8510055422695886042, i64 742261418966908927, i64 sub (i64 ptrtoint (ptr @__profc_available_externally.742261418966908927 to i64), i64 ptrtoint (ptr @__profd_available_externally.742261418966908927 to i64)), ptr null, ptr null, i32 1, [2 x i16] zeroinitializer }, section "__llvm_prf_data", comdat($__profc_available_externally.742261418966908927), align 8
-
-;; Ensure when not instrumenting a non-comdat function, then if we generate an
-;; alias, then it is private. We check comdat versions in comdat.ll
-; CHECK: @foo.1 = private alias i32 (i32), ptr @foo
-; CHECK: @[[WEAK_2:[a-zA-Z0-9_$"\\.-]+]] = private alias void (), ptr @weak
-; CHECK: @[[LINKONCE_3:[a-zA-Z0-9_$"\\.-]+]] = private alias void (), ptr @linkonce
-; CHECK: @[[WEAKODR_4:[a-zA-Z0-9_$"\\.-]+]] = private alias void (), ptr @weakodr
-; CHECK: @[[LINKONCEODR_5:[a-zA-Z0-9_$"\\.-]+]] = private alias void (), ptr @linkonceodr
-
-;; We should never generate an alias for available_externally functions
-; CHECK-NOT: @[[AVAILABLE_EXTERNALLY_6:[a-zA-Z0-9_$"\\.-]+]] = private alias void (), ptr @available_externally
-
-define i32 @foo(i32 %0) {
-; CHECK-LABEL: @foo(
-; CHECK-NEXT:  entry:
-; CHECK-NEXT:    [[PGOCOUNT:%.*]] = load i64, ptr @__profc_foo, align 8
-; CHECK-NEXT:    [[TMP1:%.*]] = add i64 [[PGOCOUNT]], 1
-; CHECK-NEXT:    store i64 [[TMP1]], ptr @__profc_foo, align 8
-; CHECK-NEXT:    ret i32 0
-entry:
-  ret i32 0
-}
-
-define weak void @weak() {
-; CHECK-LABEL: @weak(
-; CHECK-NEXT:    [[PGOCOUNT:%.*]] = load i64, ptr @__profc_weak, align 8
-; CHECK-NEXT:    [[TMP1:%.*]] = add i64 [[PGOCOUNT]], 1
-; CHECK-NEXT:    store i64 [[TMP1]], ptr @__profc_weak, align 8
-; CHECK-NEXT:    ret void
-  ret void
-}
-
-define linkonce void @linkonce() {
-; CHECK-LABEL: @linkonce(
-; CHECK-NEXT:    [[PGOCOUNT:%.*]] = load i64, ptr @__profc_linkonce, align 8
-; CHECK-NEXT:    [[TMP1:%.*]] = add i64 [[PGOCOUNT]], 1
-; CHECK-NEXT:    store i64 [[TMP1]], ptr @__profc_linkonce, align 8
-; CHECK-NEXT:    ret void
-  ret void
-}
-
-define weak_odr void @weakodr() {
-; CHECK-LABEL: @weakodr(
-; CHECK-NEXT:    [[PGOCOUNT:%.*]] = load i64, ptr @__profc_weakodr, align 8
-; CHECK-NEXT:    [[TMP1:%.*]] = add i64 [[PGOCOUNT]], 1
-; CHECK-NEXT:    store i64 [[TMP1]], ptr @__profc_weakodr, align 8
-; CHECK-NEXT:    ret void
-  ret void
-}
-
-define linkonce_odr void @linkonceodr() {
-; CHECK-LABEL: @linkonceodr(
-; CHECK-NEXT:    [[PGOCOUNT:%.*]] = load i64, ptr @__profc_linkonceodr, align 8
-; CHECK-NEXT:    [[TMP1:%.*]] = add i64 [[PGOCOUNT]], 1
-; CHECK-NEXT:    store i64 [[TMP1]], ptr @__profc_linkonceodr, align 8
-; CHECK-NEXT:    ret void
-  ret void
-}
-
-define available_externally void @available_externally(){
-; CHECK-LABEL: @available_externally(
-; CHECK-NEXT:    [[PGOCOUNT:%.*]] = load i64, ptr @__profc_available_externally.742261418966908927, align 8
-; CHECK-NEXT:    [[TMP1:%.*]] = add i64 [[PGOCOUNT]], 1
-; CHECK-NEXT:    store i64 [[TMP1]], ptr @__profc_available_externally.742261418966908927, align 8
-; CHECK-NEXT:    ret void
-  ret void
-}


        


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