[llvm] [ctx_prof] Remove the dependency on the "name" GlobalVariable (PR #105731)

Mircea Trofin via llvm-commits llvm-commits at lists.llvm.org
Thu Aug 22 13:50:44 PDT 2024


https://github.com/mtrofin updated https://github.com/llvm/llvm-project/pull/105731

>From f9f3d0848e9cc0d15f212096af2eb15de8df81dd Mon Sep 17 00:00:00 2001
From: Mircea Trofin <mtrofin at google.com>
Date: Thu, 22 Aug 2024 13:27:44 -0700
Subject: [PATCH] [ctx_prof] Remove the dependency on the "name" GlobalVariable

We don't need that name variable for contextual instrumentation, we just
use the function to get its GUID which we pass to the runtime, and rely
on metadata to capture it through the various optimization passes. This
change removes the need for the name global variable.
---
 llvm/include/llvm/IR/IntrinsicInst.h          | 14 +++++--
 .../Instrumentation/PGOCtxProfLowering.cpp    |  3 +-
 .../Instrumentation/PGOInstrumentation.cpp    | 19 +++++----
 .../PGOProfile/ctx-instrumentation.ll         | 41 +++++++------------
 .../PGOProfile/ctx-prof-use-prelink.ll        | 11 ++---
 5 files changed, 41 insertions(+), 47 deletions(-)

diff --git a/llvm/include/llvm/IR/IntrinsicInst.h b/llvm/include/llvm/IR/IntrinsicInst.h
index 2f1e2c08c3ecec..65c4361767be93 100644
--- a/llvm/include/llvm/IR/IntrinsicInst.h
+++ b/llvm/include/llvm/IR/IntrinsicInst.h
@@ -1495,11 +1495,19 @@ class InstrProfInstBase : public IntrinsicInst {
       return isCounterBase(*Instr) || isMCDCBitmapBase(*Instr);
     return false;
   }
-  // The name of the instrumented function.
+
+  // The name of the instrumented function, assuming it is a global variable.
   GlobalVariable *getName() const {
-    return cast<GlobalVariable>(
-        const_cast<Value *>(getArgOperand(0))->stripPointerCasts());
+    return cast<GlobalVariable>(getNameValue());
+  }
+
+  // The "name" operand of the profile instrumentation instruction - this is the
+  // operand that can be used to relate the instruction to the function it
+  // belonged to at instrumentation time.
+  Value *getNameValue() const {
+    return const_cast<Value *>(getArgOperand(0))->stripPointerCasts();
   }
+
   // The hash of the CFG for the instrumented function.
   ConstantInt *getHash() const {
     return cast<ConstantInt>(const_cast<Value *>(getArgOperand(1)));
diff --git a/llvm/lib/Transforms/Instrumentation/PGOCtxProfLowering.cpp b/llvm/lib/Transforms/Instrumentation/PGOCtxProfLowering.cpp
index 9b10cbba84075a..43bebc99316e06 100644
--- a/llvm/lib/Transforms/Instrumentation/PGOCtxProfLowering.cpp
+++ b/llvm/lib/Transforms/Instrumentation/PGOCtxProfLowering.cpp
@@ -226,7 +226,8 @@ bool CtxInstrumentationLowerer::lowerFunction(Function &F) {
 
       IRBuilder<> Builder(Mark);
 
-      Guid = Builder.getInt64(AssignGUIDPass::getGUID(F));
+      Guid = Builder.getInt64(
+          AssignGUIDPass::getGUID(cast<Function>(*Mark->getNameValue())));
       // The type of the context of this function is now knowable since we have
       // NrCallsites and NrCounters. We delcare it here because it's more
       // convenient - we have the Builder.
diff --git a/llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp b/llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
index b3644031c5a44b..450f69556ddd22 100644
--- a/llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
+++ b/llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
@@ -464,7 +464,7 @@ struct SelectInstVisitor : public InstVisitor<SelectInstVisitor> {
   VisitMode Mode = VM_counting;  // Visiting mode.
   unsigned *CurCtrIdx = nullptr; // Pointer to current counter index.
   unsigned TotalNumCtrs = 0;     // Total number of counters
-  GlobalVariable *FuncNameVar = nullptr;
+  GlobalValue *FuncNameVar = nullptr;
   uint64_t FuncHash = 0;
   PGOUseFunc *UseFunc = nullptr;
   bool HasSingleByteCoverage;
@@ -482,7 +482,7 @@ struct SelectInstVisitor : public InstVisitor<SelectInstVisitor> {
   // Ind is a pointer to the counter index variable; \p TotalNC
   // is the total number of counters; \p FNV is the pointer to the
   // PGO function name var; \p FHash is the function hash.
-  void instrumentSelects(unsigned *Ind, unsigned TotalNC, GlobalVariable *FNV,
+  void instrumentSelects(unsigned *Ind, unsigned TotalNC, GlobalValue *FNV,
                          uint64_t FHash) {
     Mode = VM_instrument;
     CurCtrIdx = Ind;
@@ -901,13 +901,14 @@ void FunctionInstrumenter::instrument() {
     SplitIndirectBrCriticalEdges(F, /*IgnoreBlocksWithoutPHI=*/false, BPI, BFI);
   }
 
+  const bool IsCtxProf = InstrumentationType == PGOInstrumentationType::CTXPROF;
   FuncPGOInstrumentation<PGOEdge, PGOBBInfo> FuncInfo(
-      F, TLI, ComdatMembers, true, BPI, BFI,
+      F, TLI, ComdatMembers, /*CreateGlobalVar=*/!IsCtxProf, BPI, BFI,
       InstrumentationType == PGOInstrumentationType::CSFDO,
       shouldInstrumentEntryBB(), PGOBlockCoverage);
 
-  auto Name = FuncInfo.FuncNameVar;
-  auto CFGHash =
+  auto *const Name = IsCtxProf ? cast<GlobalValue>(&F) : FuncInfo.FuncNameVar;
+  auto *const CFGHash =
       ConstantInt::get(Type::getInt64Ty(M.getContext()), FuncInfo.FunctionHash);
   if (PGOFunctionEntryCoverage) {
     auto &EntryBB = F.getEntryBlock();
@@ -925,7 +926,7 @@ void FunctionInstrumenter::instrument() {
   unsigned NumCounters =
       InstrumentBBs.size() + FuncInfo.SIVisitor.getNumOfSelectInsts();
 
-  if (InstrumentationType == PGOInstrumentationType::CTXPROF) {
+  if (IsCtxProf) {
     auto *CSIntrinsic =
         Intrinsic::getDeclaration(&M, Intrinsic::instrprof_callsite);
     // We want to count the instrumentable callsites, then instrument them. This
@@ -989,7 +990,7 @@ void FunctionInstrumenter::instrument() {
   }
 
   // Now instrument select instructions:
-  FuncInfo.SIVisitor.instrumentSelects(&I, NumCounters, FuncInfo.FuncNameVar,
+  FuncInfo.SIVisitor.instrumentSelects(&I, NumCounters, Name,
                                        FuncInfo.FunctionHash);
   assert(I == NumCounters);
 
@@ -1032,8 +1033,8 @@ void FunctionInstrumenter::instrument() {
       populateEHOperandBundle(Cand, BlockColors, OpBundles);
       Builder.CreateCall(
           Intrinsic::getDeclaration(&M, Intrinsic::instrprof_value_profile),
-          {FuncInfo.FuncNameVar, Builder.getInt64(FuncInfo.FunctionHash),
-           ToProfile, Builder.getInt32(Kind), Builder.getInt32(SiteIndex++)},
+          {Name, Builder.getInt64(FuncInfo.FunctionHash), ToProfile,
+           Builder.getInt32(Kind), Builder.getInt32(SiteIndex++)},
           OpBundles);
     }
   } // IPVK_First <= Kind <= IPVK_Last
diff --git a/llvm/test/Transforms/PGOProfile/ctx-instrumentation.ll b/llvm/test/Transforms/PGOProfile/ctx-instrumentation.ll
index df4e467567c46e..c94c2b4da57a98 100644
--- a/llvm/test/Transforms/PGOProfile/ctx-instrumentation.ll
+++ b/llvm/test/Transforms/PGOProfile/ctx-instrumentation.ll
@@ -9,19 +9,6 @@
 declare void @bar()
 
 ;.
-; INSTRUMENT: @__profn_foo = private constant [3 x i8] c"foo"
-; INSTRUMENT: @__profn_an_entrypoint = private constant [13 x i8] c"an_entrypoint"
-; INSTRUMENT: @__profn_another_entrypoint_no_callees = private constant [29 x i8] c"another_entrypoint_no_callees"
-; INSTRUMENT: @__profn_simple = private constant [6 x i8] c"simple"
-; INSTRUMENT: @__profn_no_callsites = private constant [12 x i8] c"no_callsites"
-; INSTRUMENT: @__profn_no_counters = private constant [11 x i8] c"no_counters"
-;.
-; LOWERING: @__profn_foo = private constant [3 x i8] c"foo"
-; LOWERING: @__profn_an_entrypoint = private constant [13 x i8] c"an_entrypoint"
-; LOWERING: @__profn_another_entrypoint_no_callees = private constant [29 x i8] c"another_entrypoint_no_callees"
-; LOWERING: @__profn_simple = private constant [6 x i8] c"simple"
-; LOWERING: @__profn_no_callsites = private constant [12 x i8] c"no_callsites"
-; LOWERING: @__profn_no_counters = private constant [11 x i8] c"no_counters"
 ; LOWERING: @an_entrypoint_ctx_root = global { ptr, ptr, ptr, i8 } zeroinitializer
 ; LOWERING: @another_entrypoint_no_callees_ctx_root = global { ptr, ptr, ptr, i8 } zeroinitializer
 ; LOWERING: @__llvm_ctx_profile_callsite = external hidden thread_local global ptr
@@ -30,16 +17,16 @@ declare void @bar()
 define void @foo(i32 %a, ptr %fct) {
 ; INSTRUMENT-LABEL: define void @foo(
 ; INSTRUMENT-SAME: i32 [[A:%.*]], ptr [[FCT:%.*]]) {
-; INSTRUMENT-NEXT:    call void @llvm.instrprof.increment(ptr @__profn_foo, i64 728453322856651412, i32 2, i32 0)
+; INSTRUMENT-NEXT:    call void @llvm.instrprof.increment(ptr @foo, i64 728453322856651412, i32 2, i32 0)
 ; INSTRUMENT-NEXT:    [[T:%.*]] = icmp eq i32 [[A]], 0
 ; INSTRUMENT-NEXT:    br i1 [[T]], label [[YES:%.*]], label [[NO:%.*]]
 ; INSTRUMENT:       yes:
-; INSTRUMENT-NEXT:    call void @llvm.instrprof.increment(ptr @__profn_foo, i64 728453322856651412, i32 2, i32 1)
-; INSTRUMENT-NEXT:    call void @llvm.instrprof.callsite(ptr @__profn_foo, i64 728453322856651412, i32 2, i32 0, ptr [[FCT]])
+; INSTRUMENT-NEXT:    call void @llvm.instrprof.increment(ptr @foo, i64 728453322856651412, i32 2, i32 1)
+; INSTRUMENT-NEXT:    call void @llvm.instrprof.callsite(ptr @foo, i64 728453322856651412, i32 2, i32 0, ptr [[FCT]])
 ; INSTRUMENT-NEXT:    call void [[FCT]](i32 [[A]])
 ; INSTRUMENT-NEXT:    br label [[EXIT:%.*]]
 ; INSTRUMENT:       no:
-; INSTRUMENT-NEXT:    call void @llvm.instrprof.callsite(ptr @__profn_foo, i64 728453322856651412, i32 2, i32 1, ptr @bar)
+; INSTRUMENT-NEXT:    call void @llvm.instrprof.callsite(ptr @foo, i64 728453322856651412, i32 2, i32 1, ptr @bar)
 ; INSTRUMENT-NEXT:    call void @bar()
 ; INSTRUMENT-NEXT:    br label [[EXIT]]
 ; INSTRUMENT:       exit:
@@ -92,12 +79,12 @@ exit:
 define void @an_entrypoint(i32 %a) {
 ; INSTRUMENT-LABEL: define void @an_entrypoint(
 ; INSTRUMENT-SAME: i32 [[A:%.*]]) {
-; INSTRUMENT-NEXT:    call void @llvm.instrprof.increment(ptr @__profn_an_entrypoint, i64 784007058953177093, i32 2, i32 0)
+; INSTRUMENT-NEXT:    call void @llvm.instrprof.increment(ptr @an_entrypoint, i64 784007058953177093, i32 2, i32 0)
 ; INSTRUMENT-NEXT:    [[T:%.*]] = icmp eq i32 [[A]], 0
 ; INSTRUMENT-NEXT:    br i1 [[T]], label [[YES:%.*]], label [[NO:%.*]]
 ; INSTRUMENT:       yes:
-; INSTRUMENT-NEXT:    call void @llvm.instrprof.increment(ptr @__profn_an_entrypoint, i64 784007058953177093, i32 2, i32 1)
-; INSTRUMENT-NEXT:    call void @llvm.instrprof.callsite(ptr @__profn_an_entrypoint, i64 784007058953177093, i32 1, i32 0, ptr @foo)
+; INSTRUMENT-NEXT:    call void @llvm.instrprof.increment(ptr @an_entrypoint, i64 784007058953177093, i32 2, i32 1)
+; INSTRUMENT-NEXT:    call void @llvm.instrprof.callsite(ptr @an_entrypoint, i64 784007058953177093, i32 1, i32 0, ptr @foo)
 ; INSTRUMENT-NEXT:    call void @foo(i32 1, ptr null)
 ; INSTRUMENT-NEXT:    ret void
 ; INSTRUMENT:       no:
@@ -144,11 +131,11 @@ no:
 define void @another_entrypoint_no_callees(i32 %a) {
 ; INSTRUMENT-LABEL: define void @another_entrypoint_no_callees(
 ; INSTRUMENT-SAME: i32 [[A:%.*]]) {
-; INSTRUMENT-NEXT:    call void @llvm.instrprof.increment(ptr @__profn_another_entrypoint_no_callees, i64 784007058953177093, i32 2, i32 0)
+; INSTRUMENT-NEXT:    call void @llvm.instrprof.increment(ptr @another_entrypoint_no_callees, i64 784007058953177093, i32 2, i32 0)
 ; INSTRUMENT-NEXT:    [[T:%.*]] = icmp eq i32 [[A]], 0
 ; INSTRUMENT-NEXT:    br i1 [[T]], label [[YES:%.*]], label [[NO:%.*]]
 ; INSTRUMENT:       yes:
-; INSTRUMENT-NEXT:    call void @llvm.instrprof.increment(ptr @__profn_another_entrypoint_no_callees, i64 784007058953177093, i32 2, i32 1)
+; INSTRUMENT-NEXT:    call void @llvm.instrprof.increment(ptr @another_entrypoint_no_callees, i64 784007058953177093, i32 2, i32 1)
 ; INSTRUMENT-NEXT:    ret void
 ; INSTRUMENT:       no:
 ; INSTRUMENT-NEXT:    ret void
@@ -184,7 +171,7 @@ no:
 define void @simple(i32 %a) {
 ; INSTRUMENT-LABEL: define void @simple(
 ; INSTRUMENT-SAME: i32 [[A:%.*]]) {
-; INSTRUMENT-NEXT:    call void @llvm.instrprof.increment(ptr @__profn_simple, i64 742261418966908927, i32 1, i32 0)
+; INSTRUMENT-NEXT:    call void @llvm.instrprof.increment(ptr @simple, i64 742261418966908927, i32 1, i32 0)
 ; INSTRUMENT-NEXT:    ret void
 ;
 ; LOWERING-LABEL: define void @simple(
@@ -202,11 +189,11 @@ define void @simple(i32 %a) {
 define i32 @no_callsites(i32 %a) {
 ; INSTRUMENT-LABEL: define i32 @no_callsites(
 ; INSTRUMENT-SAME: i32 [[A:%.*]]) {
-; INSTRUMENT-NEXT:    call void @llvm.instrprof.increment(ptr @__profn_no_callsites, i64 784007058953177093, i32 2, i32 0)
+; INSTRUMENT-NEXT:    call void @llvm.instrprof.increment(ptr @no_callsites, i64 784007058953177093, i32 2, i32 0)
 ; INSTRUMENT-NEXT:    [[C:%.*]] = icmp eq i32 [[A]], 0
 ; INSTRUMENT-NEXT:    br i1 [[C]], label [[YES:%.*]], label [[NO:%.*]]
 ; INSTRUMENT:       yes:
-; INSTRUMENT-NEXT:    call void @llvm.instrprof.increment(ptr @__profn_no_callsites, i64 784007058953177093, i32 2, i32 1)
+; INSTRUMENT-NEXT:    call void @llvm.instrprof.increment(ptr @no_callsites, i64 784007058953177093, i32 2, i32 1)
 ; INSTRUMENT-NEXT:    ret i32 1
 ; INSTRUMENT:       no:
 ; INSTRUMENT-NEXT:    ret i32 0
@@ -238,8 +225,8 @@ no:
 
 define void @no_counters() {
 ; INSTRUMENT-LABEL: define void @no_counters() {
-; INSTRUMENT-NEXT:    call void @llvm.instrprof.increment(ptr @__profn_no_counters, i64 742261418966908927, i32 1, i32 0)
-; INSTRUMENT-NEXT:    call void @llvm.instrprof.callsite(ptr @__profn_no_counters, i64 742261418966908927, i32 1, i32 0, ptr @bar)
+; INSTRUMENT-NEXT:    call void @llvm.instrprof.increment(ptr @no_counters, i64 742261418966908927, i32 1, i32 0)
+; INSTRUMENT-NEXT:    call void @llvm.instrprof.callsite(ptr @no_counters, i64 742261418966908927, i32 1, i32 0, ptr @bar)
 ; INSTRUMENT-NEXT:    call void @bar()
 ; INSTRUMENT-NEXT:    ret void
 ;
diff --git a/llvm/test/Transforms/PGOProfile/ctx-prof-use-prelink.ll b/llvm/test/Transforms/PGOProfile/ctx-prof-use-prelink.ll
index cb8ab78dc0f414..7959e4d0760edb 100644
--- a/llvm/test/Transforms/PGOProfile/ctx-prof-use-prelink.ll
+++ b/llvm/test/Transforms/PGOProfile/ctx-prof-use-prelink.ll
@@ -7,22 +7,19 @@
 
 declare void @bar()
 
-;.
-; CHECK: @__profn_foo = private constant [3 x i8] c"foo"
-;.
 define void @foo(i32 %a, ptr %fct) {
 ; CHECK-LABEL: define void @foo(
 ; CHECK-SAME: i32 [[A:%.*]], ptr [[FCT:%.*]]) local_unnamed_addr !guid [[META0:![0-9]+]] {
-; CHECK-NEXT:    call void @llvm.instrprof.increment(ptr @__profn_foo, i64 728453322856651412, i32 2, i32 0)
+; CHECK-NEXT:    call void @llvm.instrprof.increment(ptr @foo, i64 728453322856651412, i32 2, i32 0)
 ; CHECK-NEXT:    [[T:%.*]] = icmp eq i32 [[A]], 0
 ; CHECK-NEXT:    br i1 [[T]], label %[[YES:.*]], label %[[NO:.*]]
 ; CHECK:       [[YES]]:
-; CHECK-NEXT:    call void @llvm.instrprof.increment(ptr @__profn_foo, i64 728453322856651412, i32 2, i32 1)
-; CHECK-NEXT:    call void @llvm.instrprof.callsite(ptr @__profn_foo, i64 728453322856651412, i32 2, i32 0, ptr [[FCT]])
+; CHECK-NEXT:    call void @llvm.instrprof.increment(ptr @foo, i64 728453322856651412, i32 2, i32 1)
+; CHECK-NEXT:    call void @llvm.instrprof.callsite(ptr @foo, i64 728453322856651412, i32 2, i32 0, ptr [[FCT]])
 ; CHECK-NEXT:    call void [[FCT]](i32 0)
 ; CHECK-NEXT:    br label %[[EXIT:.*]]
 ; CHECK:       [[NO]]:
-; CHECK-NEXT:    call void @llvm.instrprof.callsite(ptr @__profn_foo, i64 728453322856651412, i32 2, i32 1, ptr @bar)
+; CHECK-NEXT:    call void @llvm.instrprof.callsite(ptr @foo, i64 728453322856651412, i32 2, i32 1, ptr @bar)
 ; CHECK-NEXT:    call void @bar()
 ; CHECK-NEXT:    br label %[[EXIT]]
 ; CHECK:       [[EXIT]]:



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