[llvm] [PGO] Sampled instrumentation in PGO to speed up instrumentation binary (PR #69535)
via llvm-commits
llvm-commits at lists.llvm.org
Wed Oct 18 16:02:39 PDT 2023
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-llvm-transforms
Author: None (xur-llvm)
<details>
<summary>Changes</summary>
PGO instrumentation binary can be very slow comparing to the non-instrumented binary. It's not uncommon to see 10x slowdown for highly threaded programs, due to data race of false sharing to the counters.
This patch uses sampling in PGO instrumentation to speed up instrumentation binary. The basic idea is the same as one: here: https://reviews.llvm.org/D63949
This patch makes some improvements so that we only use one condition. We now fix the WholeDuring at 65536 and use the wraparound of unsigned short.
With this sampled instrumentation, the binary runs much faster. We measure 5x speedup using the default duration. We now only see about 20% to 30% slow down (comparing to 8 to 10x slowdown without sampling).
The profile quality is pretty good with sampling: the edge counts usually report >90% overlap.
For the apps that program behaviors change due to binary speed, sampling instrumentation can improve the performance. We have observed some apps getting up ~2% improvement in PGO.
One potential issue of this patch is the increased binary size and compilation time.
---
Patch is 26.63 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/69535.diff
11 Files Affected:
- (modified) llvm/include/llvm/ProfileData/InstrProfData.inc (+1)
- (modified) llvm/include/llvm/Transforms/Instrumentation.h (+6)
- (modified) llvm/include/llvm/Transforms/Instrumentation/InstrProfiling.h (+6)
- (modified) llvm/include/llvm/Transforms/Instrumentation/PGOInstrumentation.h (+4-2)
- (modified) llvm/lib/Passes/PassBuilderPipelines.cpp (+9-1)
- (modified) llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp (+116-15)
- (modified) llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp (+2)
- (added) llvm/test/Transforms/PGOProfile/Inputs/cspgo_bar_sample.ll (+82)
- (added) llvm/test/Transforms/PGOProfile/counter_promo_sampling.ll (+78)
- (added) llvm/test/Transforms/PGOProfile/cspgo_sample.ll (+112)
- (added) llvm/test/Transforms/PGOProfile/instrprof_sample.ll (+47)
``````````diff
diff --git a/llvm/include/llvm/ProfileData/InstrProfData.inc b/llvm/include/llvm/ProfileData/InstrProfData.inc
index 13be2753e514efe..6294505ac396856 100644
--- a/llvm/include/llvm/ProfileData/InstrProfData.inc
+++ b/llvm/include/llvm/ProfileData/InstrProfData.inc
@@ -676,6 +676,7 @@ serializeValueProfDataFrom(ValueProfRecordClosure *Closure,
#define INSTR_PROF_PROFILE_RUNTIME_VAR __llvm_profile_runtime
#define INSTR_PROF_PROFILE_COUNTER_BIAS_VAR __llvm_profile_counter_bias
#define INSTR_PROF_PROFILE_SET_TIMESTAMP __llvm_profile_set_timestamp
+#define INSTR_PROF_PROFILE_SAMPLING_VAR __llvm_profile_sampling
/* The variable that holds the name of the profile data
* specified via command line. */
diff --git a/llvm/include/llvm/Transforms/Instrumentation.h b/llvm/include/llvm/Transforms/Instrumentation.h
index 392983a19844451..76d4e1de75154ff 100644
--- a/llvm/include/llvm/Transforms/Instrumentation.h
+++ b/llvm/include/llvm/Transforms/Instrumentation.h
@@ -116,12 +116,18 @@ struct InstrProfOptions {
// Use BFI to guide register promotion
bool UseBFIInPromotion = false;
+ // Use sampling to reduce the profile instrumentation runtime overhead.
+ bool Sampling = false;
+
// Name of the profile file to use as output
std::string InstrProfileOutput;
InstrProfOptions() = default;
};
+// Create the variable for profile sampling.
+void createProfileSamplingVar(Module &M);
+
// Options for sanitizer coverage instrumentation.
struct SanitizerCoverageOptions {
enum Type {
diff --git a/llvm/include/llvm/Transforms/Instrumentation/InstrProfiling.h b/llvm/include/llvm/Transforms/Instrumentation/InstrProfiling.h
index cb0c055dcb74ae8..d0581ff72a15864 100644
--- a/llvm/include/llvm/Transforms/Instrumentation/InstrProfiling.h
+++ b/llvm/include/llvm/Transforms/Instrumentation/InstrProfiling.h
@@ -86,6 +86,9 @@ class InstrProfiling : public PassInfoMixin<InstrProfiling> {
/// Returns true if profile counter update register promotion is enabled.
bool isCounterPromotionEnabled() const;
+ /// Return true if profile sampling is enabled.
+ bool isSamplingEnabled() const;
+
/// Count the number of instrumented value sites for the function.
void computeNumValueSiteCounts(InstrProfValueProfileInst *Ins);
@@ -109,6 +112,9 @@ class InstrProfiling : public PassInfoMixin<InstrProfiling> {
/// acts on.
Value *getCounterAddress(InstrProfInstBase *I);
+ /// Lower the incremental instructions under profile sampling predicates.
+ void doSampling(Instruction *I);
+
/// Get the region counters for an increment, creating them if necessary.
///
/// If the counter array doesn't yet exist, the profile data variables
diff --git a/llvm/include/llvm/Transforms/Instrumentation/PGOInstrumentation.h b/llvm/include/llvm/Transforms/Instrumentation/PGOInstrumentation.h
index 5b1977b7de9a2ae..7199f27dbc991a8 100644
--- a/llvm/include/llvm/Transforms/Instrumentation/PGOInstrumentation.h
+++ b/llvm/include/llvm/Transforms/Instrumentation/PGOInstrumentation.h
@@ -43,12 +43,14 @@ class FileSystem;
class PGOInstrumentationGenCreateVar
: public PassInfoMixin<PGOInstrumentationGenCreateVar> {
public:
- PGOInstrumentationGenCreateVar(std::string CSInstrName = "")
- : CSInstrName(CSInstrName) {}
+ PGOInstrumentationGenCreateVar(std::string CSInstrName = "",
+ bool Sampling = false)
+ : CSInstrName(CSInstrName), ProfileSampling(Sampling) {}
PreservedAnalyses run(Module &M, ModuleAnalysisManager &MAM);
private:
std::string CSInstrName;
+ bool ProfileSampling;
};
/// The instrumentation (profile-instr-gen) pass for IR based PGO.
diff --git a/llvm/lib/Passes/PassBuilderPipelines.cpp b/llvm/lib/Passes/PassBuilderPipelines.cpp
index 600f8d43caaf216..5595f92e24aa861 100644
--- a/llvm/lib/Passes/PassBuilderPipelines.cpp
+++ b/llvm/lib/Passes/PassBuilderPipelines.cpp
@@ -273,6 +273,9 @@ static cl::opt<AttributorRunOption> AttributorRun(
clEnumValN(AttributorRunOption::NONE, "none",
"disable attributor runs")));
+static cl::opt<bool> EnableSampledInstr(
+ "enable-sampled-instr", cl::init(false), cl::Hidden,
+ cl::desc("Enable profile instrumentation sampling (default = off)"));
static cl::opt<bool> UseLoopVersioningLICM(
"enable-loop-versioning-licm", cl::init(false), cl::Hidden,
cl::desc("Enable the experimental Loop Versioning LICM pass"));
@@ -805,6 +808,10 @@ void PassBuilder::addPGOInstrPasses(ModulePassManager &MPM,
// Do counter promotion at Level greater than O0.
Options.DoCounterPromotion = true;
Options.UseBFIInPromotion = IsCS;
+ if (EnableSampledInstr) {
+ Options.Sampling = true;
+ Options.DoCounterPromotion = false;
+ }
Options.Atomic = AtomicCounterUpdate;
MPM.addPass(InstrProfiling(Options, IsCS));
}
@@ -1117,7 +1124,8 @@ PassBuilder::buildModuleSimplificationPipeline(OptimizationLevel Level,
}
if (PGOOpt && Phase != ThinOrFullLTOPhase::ThinLTOPostLink &&
PGOOpt->CSAction == PGOOptions::CSIRInstr)
- MPM.addPass(PGOInstrumentationGenCreateVar(PGOOpt->CSProfileGenFile));
+ MPM.addPass(PGOInstrumentationGenCreateVar(PGOOpt->CSProfileGenFile,
+ EnableSampledInstr));
if (PGOOpt && Phase != ThinOrFullLTOPhase::ThinLTOPostLink &&
!PGOOpt->MemoryProfile.empty())
diff --git a/llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp b/llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp
index 57fcfd53836911b..89e8e152fcee7e4 100644
--- a/llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp
+++ b/llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp
@@ -36,6 +36,7 @@
#include "llvm/IR/Instruction.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
+#include "llvm/IR/MDBuilder.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Type.h"
#include "llvm/InitializePasses.h"
@@ -48,6 +49,7 @@
#include "llvm/Support/ErrorHandling.h"
#include "llvm/TargetParser/Triple.h"
#include "llvm/Transforms/Instrumentation/PGOInstrumentation.h"
+#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/ModuleUtils.h"
#include "llvm/Transforms/Utils/SSAUpdater.h"
#include <algorithm>
@@ -148,6 +150,16 @@ cl::opt<bool> SkipRetExitBlock(
"skip-ret-exit-block", cl::init(true),
cl::desc("Suppress counter promotion if exit blocks contain ret."));
+static cl::opt<bool>
+ SampledInstrument("sampled-instr", cl::ZeroOrMore, cl::init(false),
+ cl::desc("Do PGO instrumentation sampling"));
+
+static cl::opt<unsigned> SampledInstrumentDuration(
+ "sampled-instr-duration",
+ cl::desc("Set the sample rate for profile instrumentation, with a value "
+ "range 0 to 65535. We will record this number of samples for "
+ "every 65536 count updates"),
+ cl::init(200));
///
/// A helper class to promote one counter RMW operation in the loop
/// into register update.
@@ -412,30 +424,91 @@ PreservedAnalyses InstrProfiling::run(Module &M, ModuleAnalysisManager &AM) {
return PreservedAnalyses::none();
}
+// Perform instrumentation sampling.
+// We transform:
+// Increment_Instruction;
+// to:
+// if (__llvm_profile_sampling__ <= SampleDuration) {
+// Increment_Instruction;
+// }
+// __llvm_profile_sampling__ += 1;
+//
+// "__llvm_profile_sampling__" is a thread-local global shared by all PGO
+// instrumentation variables (value-instrumentation and edge instrumentation).
+// It has a unsigned short type and will wrapper around when overflow.
+//
+// Note that, the code snippet after the transformation can still be
+// counter promoted. But I don't see a reason for that because the
+// counter updated should be sparse. That's the reason we disable
+// counter promotion by default when sampling is enabled.
+// This can be overwritten by the internal option.
+//
+void InstrProfiling::doSampling(Instruction *I) {
+ if (!isSamplingEnabled())
+ return;
+ int SampleDuration = SampledInstrumentDuration.getValue();
+ unsigned WrapToZeroValue = USHRT_MAX + 1;
+ assert(SampleDuration < USHRT_MAX);
+ auto *Int16Ty = Type::getInt16Ty(M->getContext());
+ auto *CountVar =
+ M->getGlobalVariable(INSTR_PROF_QUOTE(INSTR_PROF_PROFILE_SAMPLING_VAR));
+ assert(CountVar && "CountVar not set properly");
+ IRBuilder<> CondBuilder(I);
+ auto *LoadCountVar = CondBuilder.CreateLoad(Int16Ty, CountVar);
+ auto *DurationCond = CondBuilder.CreateICmpULE(
+ LoadCountVar, CondBuilder.getInt16(SampleDuration));
+ MDBuilder MDB(I->getContext());
+ MDNode *BranchWeight =
+ MDB.createBranchWeights(SampleDuration, WrapToZeroValue - SampleDuration);
+ Instruction *ThenTerm = SplitBlockAndInsertIfThen(
+ DurationCond, I, /* Unreacheable */ false, BranchWeight);
+ IRBuilder<> IncBuilder(I);
+ auto *NewVal = IncBuilder.CreateAdd(LoadCountVar, IncBuilder.getInt16(1));
+ IncBuilder.CreateStore(NewVal, CountVar);
+ I->moveBefore(ThenTerm);
+}
+
bool InstrProfiling::lowerIntrinsics(Function *F) {
bool MadeChange = false;
PromotionCandidates.clear();
+ SmallVector<InstrProfInstBase *, 8> InstrProfInsts;
+
for (BasicBlock &BB : *F) {
for (Instruction &Instr : llvm::make_early_inc_range(BB)) {
- if (auto *IPIS = dyn_cast<InstrProfIncrementInstStep>(&Instr)) {
- lowerIncrement(IPIS);
- MadeChange = true;
- } else if (auto *IPI = dyn_cast<InstrProfIncrementInst>(&Instr)) {
- lowerIncrement(IPI);
- MadeChange = true;
- } else if (auto *IPC = dyn_cast<InstrProfTimestampInst>(&Instr)) {
- lowerTimestamp(IPC);
- MadeChange = true;
- } else if (auto *IPC = dyn_cast<InstrProfCoverInst>(&Instr)) {
- lowerCover(IPC);
- MadeChange = true;
- } else if (auto *IPVP = dyn_cast<InstrProfValueProfileInst>(&Instr)) {
- lowerValueProfileInst(IPVP);
- MadeChange = true;
+ if (auto *IP = dyn_cast<InstrProfInstBase>(&Instr)) {
+ InstrProfInsts.push_back(IP);
}
}
}
+ for (auto *IP : InstrProfInsts) {
+ if (auto *IPIS = dyn_cast<InstrProfIncrementInstStep>(IP)) {
+ doSampling(IP);
+ lowerIncrement(IPIS);
+ MadeChange = true;
+ } else if (auto *IPI = dyn_cast<InstrProfIncrementInst>(IP)) {
+ doSampling(IP);
+ lowerIncrement(IPI);
+ MadeChange = true;
+ } else if (auto *IPC = dyn_cast<InstrProfTimestampInst>(IP)) {
+ doSampling(IP);
+ lowerTimestamp(IPC);
+ MadeChange = true;
+ } else if (auto *IPC = dyn_cast<InstrProfCoverInst>(IP)) {
+ doSampling(IP);
+ lowerCover(IPC);
+ MadeChange = true;
+ } else if (auto *IPVP = dyn_cast<InstrProfValueProfileInst>(IP)) {
+ doSampling(IP);
+ lowerValueProfileInst(IPVP);
+ MadeChange = true;
+ } else {
+ LLVM_DEBUG(dbgs() << "Invalid InstroProf intrinsic: " << *IP << "\n");
+ // ?? Seeing "call void @llvm.memcpy.p0.p0.i64..." here ??
+ // llvm_unreachable("Invalid InstroProf intrinsic");
+ }
+ }
+
if (!MadeChange)
return false;
@@ -455,6 +528,12 @@ bool InstrProfiling::isRuntimeCounterRelocationEnabled() const {
return TT.isOSFuchsia();
}
+bool InstrProfiling::isSamplingEnabled() const {
+ if (SampledInstrument.getNumOccurrences() > 0)
+ return SampledInstrument;
+ return Options.Sampling;
+}
+
bool InstrProfiling::isCounterPromotionEnabled() const {
if (DoCounterPromotion.getNumOccurrences() > 0)
return DoCounterPromotion;
@@ -535,6 +614,9 @@ bool InstrProfiling::run(
if (NeedsRuntimeHook)
MadeChange = emitRuntimeHook();
+ if (!IsCS && isSamplingEnabled())
+ createProfileSamplingVar(M);
+
bool ContainsProfiling = containsProfilingIntrinsics(M);
GlobalVariable *CoverageNamesVar =
M.getNamedGlobal(getCoverageUnusedNamesVarName());
@@ -1372,3 +1454,22 @@ void InstrProfiling::emitInitialization() {
appendToGlobalCtors(*M, F, 0);
}
+
+namespace llvm {
+// Create the variable for profile sampling.
+void createProfileSamplingVar(Module &M) {
+ const StringRef VarName(INSTR_PROF_QUOTE(INSTR_PROF_PROFILE_SAMPLING_VAR));
+ Type *IntTy16 = Type::getInt16Ty(M.getContext());
+ auto SamplingVar = new GlobalVariable(
+ M, IntTy16, false, GlobalValue::WeakAnyLinkage,
+ Constant::getIntegerValue(IntTy16, APInt(16, 0)), VarName);
+ SamplingVar->setVisibility(GlobalValue::DefaultVisibility);
+ SamplingVar->setThreadLocal(true);
+ Triple TT(M.getTargetTriple());
+ if (TT.supportsCOMDAT()) {
+ SamplingVar->setLinkage(GlobalValue::ExternalLinkage);
+ SamplingVar->setComdat(M.getOrInsertComdat(VarName));
+ }
+ appendToCompilerUsed(M, SamplingVar);
+}
+} // namespace llvm
diff --git a/llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp b/llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
index 7ad1c9bc54f3780..0ea6398fbdedc1f 100644
--- a/llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
+++ b/llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
@@ -1820,6 +1820,8 @@ PGOInstrumentationGenCreateVar::run(Module &M, ModuleAnalysisManager &MAM) {
// The variable in a comdat may be discarded by LTO. Ensure the declaration
// will be retained.
appendToCompilerUsed(M, createIRLevelProfileFlagVar(M, /*IsCS=*/true));
+ if (ProfileSampling)
+ createProfileSamplingVar(M);
PreservedAnalyses PA;
PA.preserve<FunctionAnalysisManagerModuleProxy>();
PA.preserveSet<AllAnalysesOn<Function>>();
diff --git a/llvm/test/Transforms/PGOProfile/Inputs/cspgo_bar_sample.ll b/llvm/test/Transforms/PGOProfile/Inputs/cspgo_bar_sample.ll
new file mode 100644
index 000000000000000..1c8be82715f2531
--- /dev/null
+++ b/llvm/test/Transforms/PGOProfile/Inputs/cspgo_bar_sample.ll
@@ -0,0 +1,82 @@
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+$__llvm_profile_filename = comdat any
+$__llvm_profile_raw_version = comdat any
+$__llvm_profile_sampling = comdat any
+
+ at odd = common dso_local local_unnamed_addr global i32 0, align 4
+ at even = common dso_local local_unnamed_addr global i32 0, align 4
+ at __llvm_profile_filename = local_unnamed_addr constant [25 x i8] c"pass2/default_%m.profraw\00", comdat
+ at __llvm_profile_raw_version = local_unnamed_addr constant i64 216172782113783812, comdat
+ at __llvm_profile_sampling = thread_local global i16 0, comdat
+ at llvm.used = appending global [1 x i8*] [i8* bitcast (i64* @__llvm_profile_sampling to i8*)], section "llvm.metadata"
+
+define dso_local void @bar(i32 %n) !prof !30 {
+entry:
+ %call = tail call fastcc i32 @cond(i32 %n)
+ %tobool = icmp eq i32 %call, 0
+ br i1 %tobool, label %if.else, label %if.then, !prof !31
+
+if.then:
+ %0 = load i32, i32* @odd, align 4, !tbaa !32
+ %inc = add i32 %0, 1
+ store i32 %inc, i32* @odd, align 4, !tbaa !32
+ br label %if.end
+
+if.else:
+ %1 = load i32, i32* @even, align 4, !tbaa !32
+ %inc1 = add i32 %1, 1
+ store i32 %inc1, i32* @even, align 4, !tbaa !32
+ br label %if.end
+
+if.end:
+ ret void
+}
+
+define internal fastcc i32 @cond(i32 %i) #1 !prof !30 !PGOFuncName !36 {
+entry:
+ %rem = srem i32 %i, 2
+ ret i32 %rem
+}
+
+attributes #1 = { inlinehint noinline }
+
+!llvm.module.flags = !{!0, !1, !2}
+
+!0 = !{i32 1, !"wchar_size", i32 4}
+!1 = !{i32 1, !"EnableSplitLTOUnit", i32 0}
+!2 = !{i32 1, !"ProfileSummary", !3}
+!3 = !{!4, !5, !6, !7, !8, !9, !10, !11}
+!4 = !{!"ProfileFormat", !"InstrProf"}
+!5 = !{!"TotalCount", i64 500002}
+!6 = !{!"MaxCount", i64 200000}
+!7 = !{!"MaxInternalCount", i64 100000}
+!8 = !{!"MaxFunctionCount", i64 200000}
+!9 = !{!"NumCounts", i64 6}
+!10 = !{!"NumFunctions", i64 4}
+!11 = !{!"DetailedSummary", !12}
+!12 = !{!13, !14, !15, !16, !17, !18, !19, !20, !21, !22, !23, !24, !25, !26, !27, !28}
+!13 = !{i32 10000, i64 200000, i32 1}
+!14 = !{i32 100000, i64 200000, i32 1}
+!15 = !{i32 200000, i64 200000, i32 1}
+!16 = !{i32 300000, i64 200000, i32 1}
+!17 = !{i32 400000, i64 200000, i32 1}
+!18 = !{i32 500000, i64 100000, i32 4}
+!19 = !{i32 600000, i64 100000, i32 4}
+!20 = !{i32 700000, i64 100000, i32 4}
+!21 = !{i32 800000, i64 100000, i32 4}
+!22 = !{i32 900000, i64 100000, i32 4}
+!23 = !{i32 950000, i64 100000, i32 4}
+!24 = !{i32 990000, i64 100000, i32 4}
+!25 = !{i32 999000, i64 100000, i32 4}
+!26 = !{i32 999900, i64 100000, i32 4}
+!27 = !{i32 999990, i64 100000, i32 4}
+!28 = !{i32 999999, i64 1, i32 6}
+!30 = !{!"function_entry_count", i64 200000}
+!31 = !{!"branch_weights", i32 100000, i32 100000}
+!32 = !{!33, !33, i64 0}
+!33 = !{!"int", !34, i64 0}
+!34 = !{!"omnipotent char", !35, i64 0}
+!35 = !{!"Simple C/C++ TBAA"}
+!36 = !{!"cspgo_bar.c:cond"}
diff --git a/llvm/test/Transforms/PGOProfile/counter_promo_sampling.ll b/llvm/test/Transforms/PGOProfile/counter_promo_sampling.ll
new file mode 100644
index 000000000000000..6f13196a724994e
--- /dev/null
+++ b/llvm/test/Transforms/PGOProfile/counter_promo_sampling.ll
@@ -0,0 +1,78 @@
+; RUN: opt < %s --passes=pgo-instr-gen,instrprof -do-counter-promotion=true -sampled-instr=true -skip-ret-exit-block=0 -S | FileCheck --check-prefixes=SAMPLING,PROMO %s
+
+; SAMPLING: $__llvm_profile_sampling = comdat any
+; SAMPLING: @__llvm_profile_sampling = thread_local global i16 0, comdat
+
+define void @foo(i32 %n, i32 %N) {
+; SAMPLING-LABEL: @foo
+; SAMPLING: %[[VV0:[0-9]+]] = load i16, ptr @__llvm_profile_sampling, align 2
+; SAMPLING: %[[VV1:[0-9]+]] = icmp ule i16 %[[VV0]], 200
+; SAMPLING: br i1 %[[VV1]], label {{.*}}, label {{.*}}, !prof !0
+; SAMPLING: {{.*}} = load {{.*}} @__profc_foo{{.*}} 3)
+; SAMPLING-NEXT: add
+; SAMPLING-NEXT: store {{.*}}@__profc_foo{{.*}}3)
+bb:
+ %tmp = add nsw i32 %n, 1
+ %tmp1 = add nsw i32 %n, -1
+ br label %bb2
+
+bb2:
+; PROMO: phi {{.*}}
+; PROMO-NEXT: phi {{.*}}
+; PROMO-NEXT: phi {{.*}}
+; PROMO-NEXT: phi {{.*}}
+ %i.0 = phi i32 [ 0, %bb ], [ %tmp10, %bb9 ]
+ %tmp3 = icmp slt i32 %i.0, %tmp
+ br i1 %tmp3, label %bb4, label %bb5
+
+bb4:
+ tail call void @bar(i32 1)
+ br label %bb9
+
+bb5:
+ %tmp6 = icmp slt i32 %i.0, %tmp1
+ br i1 %tmp6, label %bb7, label %bb8
+
+bb7:
+ tail call void @bar(i32 2)
+ br label %bb9
+
+bb8:
+ tail call void @bar(i32 3)
+ br label %bb9
+
+bb9:
+; SAMPLING: phi {{.*}}
+; SAMPLING-NEXT: %[[V1:[0-9]+]] = add i16 {{.*}}, 1
+; SAMPLING-NEXT: store i16 %[[V1]], ptr @__llvm_profile_sampling, align 2
+; SAMPLING: phi {{.*}}
+; SAMPLING-NEXT: %[[V2:[0-9]+]] = add i16 {{.*}}, 1
+; SAMPLING-NEXT: store i16 %[[V2]], ptr @__llvm_profile_sampling, align 2
+; SAMPLING: phi {{.*}}
+; SAMPLING-NEXT: %[[V3:[0-9]+]] = add i16 {{.*}}, 1
+; SAMPLING-NEXT: store i16 %[[V3]], ptr @__llvm_profile_sampling, align 2
+; PROMO: %[[LIVEOUT3:[a-z0-9]+]] = phi {{.*}}
+; PROMO-NEXT: %[[LIVEOUT2:[a-z0-9]+]] = phi {{.*}}
+; PROMO-NEXT: %[[LIVEOUT1:[a-z0-9]+]] = phi {{.*}}
+ %tmp10 = add nsw i32 %i.0, 1
+ %tmp11 = icmp slt i32 %tmp10, %N
+ br i1 %tmp11, label %bb2, label %bb12
+
+bb12:
+ ret void
+; PROMO: %[[CHECK1:[a-z0-9.]+]] = load {{.*}} @__profc_foo{{.*}}
+; PROMO-NEXT: add {{.*}} %[[CHECK1]], %[[LIVEOUT1]]
+; PROMO-NEXT: store {{.*}}@__profc_foo{{.*}}
+; PROMO-NEXT: %[[CHECK2:[a-z0-9.]+]] = load {{.*}} @__profc_foo{{.*}} 1)
+; PROMO-NEXT: add {{.*}} %[[CHECK2]], %[[LIVEOUT2]]
+; PROMO-NEXT: store {{.*}}@__profc_foo{{.*}}1)
+; PROMO-NEXT: %[[CHECK3:[a-z0-9.]+]] = load {{.*}} @__profc_foo{{.*}} 2)
+; PROMO-NEXT: add {{.*}} %[[CHECK3]], %[[LIVEOUT3]]
+; PROMO-NEXT: store {{.*}}@__profc_foo{{.*}}2)
+; PROMO-NOT: @__profc_foo{{.*}})
+
+}
+
+declare void @bar(i32)
+
+; SAMPLING: !0 = !{!"branch_weights", i32 200, i32 65336}
diff --git a/llvm/test/Transforms/PGOProfile/cspgo_sample.ll b/llvm/test/Transforms/PGOProfile/cspgo_sample.ll
new file mode 100644
index 000000000000000..6683cae4e64c10d
--- /dev/null
+++ b/llvm/test/Transforms/PGOProfile/cspgo_sample.ll
@@ -0,0 +1,112 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 2
+; REQUIRES: x86-registered-target
+
+; RUN: opt -module-summary %s -o %t1.bc
+; RUN: opt -module-summary %S/Inputs/cspgo_bar_sample.ll -o %t2.bc
+; RUN: llvm-lto2 run -lto-cspgo-profile-file=alloc -enable-sampled-instr -lto-cspgo-gen -save-temps -o %t %t1.bc %t2.bc \
+; RUN: -r=%t1.bc,foo,pl \
+; RUN: -r=%t1.bc,bar,l \
+; RUN: -r=%t1.bc,main,plx \
+; RUN: -r=%t1.bc,__llvm_profile_filename,plx \
+; RUN: -r=%t1.bc,__llvm_profile_raw_version,p...
[truncated]
``````````
</details>
https://github.com/llvm/llvm-project/pull/69535
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