[llvm-branch-commits] [llvm] 64fa8cc - [CSSPGO] Pseudo probe instrumentation pass
Hongtao Yu via llvm-branch-commits
llvm-branch-commits at lists.llvm.org
Mon Nov 30 10:21:09 PST 2020
Author: Hongtao Yu
Date: 2020-11-30T10:16:54-08:00
New Revision: 64fa8cce225f7d8bd499e3a99caa850b764ff109
URL: https://github.com/llvm/llvm-project/commit/64fa8cce225f7d8bd499e3a99caa850b764ff109
DIFF: https://github.com/llvm/llvm-project/commit/64fa8cce225f7d8bd499e3a99caa850b764ff109.diff
LOG: [CSSPGO] Pseudo probe instrumentation pass
This change introduces a pseudo probe instrumentation pass for block instrumentation. Please refer to https://reviews.llvm.org/D86193 for the whole story.
Given the following LLVM IR:
```
define internal void @foo2(i32 %x, void (i32)* %f) !dbg !4 {
bb0:
%cmp = icmp eq i32 %x, 0
br i1 %cmp, label %bb1, label %bb2
bb1:
br label %bb3
bb2:
br label %bb3
bb3:
ret void
}
```
The instrumented IR will look like below. Note that each llvm.pseudoprobe intrinsic call represents a pseudo probe at a block, of which the first parameter is the GUID of the probe’s owner function and the second parameter is the probe’s ID.
```
define internal void @foo2(i32 %x, void (i32)* %f) !dbg !4 {
bb0:
%cmp = icmp eq i32 %x, 0
call void @llvm.pseudoprobe(i64 837061429793323041, i64 1)
br i1 %cmp, label %bb1, label %bb2
bb1:
call void @llvm.pseudoprobe(i64 837061429793323041, i64 2)
br label %bb3
bb2:
call void @llvm.pseudoprobe(i64 837061429793323041, i64 3)
br label %bb3
bb3:
call void @llvm.pseudoprobe(i64 837061429793323041, i64 4)
ret void
}
```
Reviewed By: wmi
Differential Revision: https://reviews.llvm.org/D86499
Added:
llvm/include/llvm/Transforms/IPO/SampleProfileProbe.h
llvm/lib/Transforms/IPO/SampleProfileProbe.cpp
llvm/test/Transforms/SampleProfile/pseudo-probe-emit.ll
Modified:
llvm/lib/Passes/PassBuilder.cpp
llvm/lib/Passes/PassRegistry.def
llvm/lib/Transforms/IPO/CMakeLists.txt
Removed:
################################################################################
diff --git a/llvm/include/llvm/Transforms/IPO/SampleProfileProbe.h b/llvm/include/llvm/Transforms/IPO/SampleProfileProbe.h
new file mode 100644
index 0000000000000..d0165a1cbc71a
--- /dev/null
+++ b/llvm/include/llvm/Transforms/IPO/SampleProfileProbe.h
@@ -0,0 +1,65 @@
+//===- Transforms/IPO/SampleProfileProbe.h ----------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+/// \file
+/// This file provides the interface for the pseudo probe implementation for
+/// AutoFDO.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TRANSFORMS_IPO_SAMPLEPROFILEPROBE_H
+#define LLVM_TRANSFORMS_IPO_SAMPLEPROFILEPROBE_H
+
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/IR/PassManager.h"
+#include "llvm/Target/TargetMachine.h"
+#include <unordered_map>
+
+namespace llvm {
+
+class Module;
+
+using BlockIdMap = std::unordered_map<BasicBlock *, uint32_t>;
+
+enum class PseudoProbeReservedId { Invalid = 0, Last = Invalid };
+
+enum class PseudoProbeType { Block = 0 };
+
+/// Sample profile pseudo prober.
+///
+/// Insert pseudo probes for block sampling and value sampling.
+class SampleProfileProber {
+public:
+ // Give an empty module id when the prober is not used for instrumentation.
+ SampleProfileProber(Function &F);
+ void instrumentOneFunc(Function &F, TargetMachine *TM);
+
+private:
+ Function *getFunction() const { return F; }
+ uint32_t getBlockId(const BasicBlock *BB) const;
+ void computeProbeIdForBlocks();
+
+ Function *F;
+
+ /// Map basic blocks to the their pseudo probe ids.
+ BlockIdMap BlockProbeIds;
+
+ /// The ID of the last probe, Can be used to number a new probe.
+ uint32_t LastProbeId;
+};
+
+class SampleProfileProbePass : public PassInfoMixin<SampleProfileProbePass> {
+ TargetMachine *TM;
+
+public:
+ SampleProfileProbePass(TargetMachine *TM) : TM(TM) {}
+ PreservedAnalyses run(Module &M, ModuleAnalysisManager &AM);
+};
+
+} // end namespace llvm
+#endif // LLVM_TRANSFORMS_IPO_SAMPLEPROFILEPROBE_H
diff --git a/llvm/lib/Passes/PassBuilder.cpp b/llvm/lib/Passes/PassBuilder.cpp
index 2a9b0c1e4f6ba..6d6ddd0012fa9 100644
--- a/llvm/lib/Passes/PassBuilder.cpp
+++ b/llvm/lib/Passes/PassBuilder.cpp
@@ -110,6 +110,7 @@
#include "llvm/Transforms/IPO/PartialInlining.h"
#include "llvm/Transforms/IPO/SCCP.h"
#include "llvm/Transforms/IPO/SampleProfile.h"
+#include "llvm/Transforms/IPO/SampleProfileProbe.h"
#include "llvm/Transforms/IPO/StripDeadPrototypes.h"
#include "llvm/Transforms/IPO/StripSymbols.h"
#include "llvm/Transforms/IPO/SyntheticCountsPropagation.h"
diff --git a/llvm/lib/Passes/PassRegistry.def b/llvm/lib/Passes/PassRegistry.def
index 7f0f51ad09773..2871282be639b 100644
--- a/llvm/lib/Passes/PassRegistry.def
+++ b/llvm/lib/Passes/PassRegistry.def
@@ -101,6 +101,7 @@ MODULE_PASS("oz-module-optimizer",
buildModuleOptimizationPipeline(OptimizationLevel::Oz, /*LTOPreLink*/false))
MODULE_PASS("strip", StripSymbolsPass())
MODULE_PASS("strip-dead-debug-info", StripDeadDebugInfoPass())
+MODULE_PASS("pseudo-probe", SampleProfileProbePass(TM))
MODULE_PASS("strip-dead-prototypes", StripDeadPrototypesPass())
MODULE_PASS("strip-debug-declare", StripDebugDeclarePass())
MODULE_PASS("strip-nondebug", StripNonDebugSymbolsPass())
diff --git a/llvm/lib/Transforms/IPO/CMakeLists.txt b/llvm/lib/Transforms/IPO/CMakeLists.txt
index 66e772c61b0a4..05e6f4355efe7 100644
--- a/llvm/lib/Transforms/IPO/CMakeLists.txt
+++ b/llvm/lib/Transforms/IPO/CMakeLists.txt
@@ -32,6 +32,7 @@ add_llvm_component_library(LLVMipo
PassManagerBuilder.cpp
PruneEH.cpp
SampleProfile.cpp
+ SampleProfileProbe.cpp
SCCP.cpp
StripDeadPrototypes.cpp
StripSymbols.cpp
diff --git a/llvm/lib/Transforms/IPO/SampleProfileProbe.cpp b/llvm/lib/Transforms/IPO/SampleProfileProbe.cpp
new file mode 100644
index 0000000000000..e158bc9c148fa
--- /dev/null
+++ b/llvm/lib/Transforms/IPO/SampleProfileProbe.cpp
@@ -0,0 +1,117 @@
+//===- SampleProfileProbe.cpp - Pseudo probe Instrumentation -------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the SampleProfileProber transformation.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/IPO/SampleProfileProbe.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/Analysis/TargetLibraryInfo.h"
+#include "llvm/IR/BasicBlock.h"
+#include "llvm/IR/CFG.h"
+#include "llvm/IR/Constant.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/DebugInfoMetadata.h"
+#include "llvm/IR/GlobalValue.h"
+#include "llvm/IR/GlobalVariable.h"
+#include "llvm/IR/IRBuilder.h"
+#include "llvm/IR/Instruction.h"
+#include "llvm/IR/MDBuilder.h"
+#include "llvm/ProfileData/SampleProf.h"
+#include "llvm/Support/CRC.h"
+#include "llvm/Transforms/Instrumentation.h"
+#include "llvm/Transforms/Utils/ModuleUtils.h"
+#include <vector>
+
+using namespace llvm;
+#define DEBUG_TYPE "sample-profile-probe"
+
+STATISTIC(ArtificialDbgLine,
+ "Number of probes that have an artificial debug line");
+
+SampleProfileProber::SampleProfileProber(Function &Func) : F(&Func) {
+ BlockProbeIds.clear();
+ LastProbeId = (uint32_t)PseudoProbeReservedId::Last;
+ computeProbeIdForBlocks();
+}
+
+void SampleProfileProber::computeProbeIdForBlocks() {
+ for (auto &BB : *F) {
+ BlockProbeIds[&BB] = ++LastProbeId;
+ }
+}
+
+uint32_t SampleProfileProber::getBlockId(const BasicBlock *BB) const {
+ auto I = BlockProbeIds.find(const_cast<BasicBlock *>(BB));
+ return I == BlockProbeIds.end() ? 0 : I->second;
+}
+
+void SampleProfileProber::instrumentOneFunc(Function &F, TargetMachine *TM) {
+ Module *M = F.getParent();
+ MDBuilder MDB(F.getContext());
+ // Compute a GUID without considering the function's linkage type. This is
+ // fine since function name is the only key in the profile database.
+ uint64_t Guid = Function::getGUID(F.getName());
+
+ // Probe basic blocks.
+ for (auto &I : BlockProbeIds) {
+ BasicBlock *BB = I.first;
+ uint32_t Index = I.second;
+ // Insert a probe before an instruction with a valid debug line number which
+ // will be assigned to the probe. The line number will be used later to
+ // model the inline context when the probe is inlined into other functions.
+ // Debug instructions, phi nodes and lifetime markers do not have an valid
+ // line number. Real instructions generated by optimizations may not come
+ // with a line number either.
+ auto HasValidDbgLine = [](Instruction *J) {
+ return !isa<PHINode>(J) && !isa<DbgInfoIntrinsic>(J) &&
+ !J->isLifetimeStartOrEnd() && J->getDebugLoc();
+ };
+
+ Instruction *J = &*BB->getFirstInsertionPt();
+ while (J != BB->getTerminator() && !HasValidDbgLine(J)) {
+ J = J->getNextNode();
+ }
+
+ IRBuilder<> Builder(J);
+ assert(Builder.GetInsertPoint() != BB->end() &&
+ "Cannot get the probing point");
+ Function *ProbeFn =
+ llvm::Intrinsic::getDeclaration(M, Intrinsic::pseudoprobe);
+ Value *Args[] = {Builder.getInt64(Guid), Builder.getInt64(Index),
+ Builder.getInt32(0)};
+ auto *Probe = Builder.CreateCall(ProbeFn, Args);
+ // Assign an artificial debug line to a probe that doesn't come with a real
+ // line. A probe not having a debug line will get an incomplete inline
+ // context. This will cause samples collected on the probe to be counted
+ // into the base profile instead of a context profile. The line number
+ // itself is not important though.
+ if (!Probe->getDebugLoc()) {
+ if (auto *SP = F.getSubprogram()) {
+ auto DIL = DebugLoc::get(0, 0, SP);
+ Probe->setDebugLoc(DIL);
+ ArtificialDbgLine++;
+ LLVM_DEBUG(dbgs() << "\nIn Function " << F.getName() << " Probe "
+ << Index << " gets an artificial debug line\n";);
+ }
+ }
+ }
+}
+
+PreservedAnalyses SampleProfileProbePass::run(Module &M,
+ ModuleAnalysisManager &AM) {
+ for (auto &F : M) {
+ if (F.isDeclaration())
+ continue;
+ SampleProfileProber ProbeManager(F);
+ ProbeManager.instrumentOneFunc(F, TM);
+ }
+
+ return PreservedAnalyses::none();
+}
diff --git a/llvm/test/Transforms/SampleProfile/pseudo-probe-emit.ll b/llvm/test/Transforms/SampleProfile/pseudo-probe-emit.ll
new file mode 100644
index 0000000000000..0d3579dda3bc6
--- /dev/null
+++ b/llvm/test/Transforms/SampleProfile/pseudo-probe-emit.ll
@@ -0,0 +1,48 @@
+; RUN: opt < %s -passes=pseudo-probe -function-sections -S -o %t
+; RUN: FileCheck %s < %t --check-prefix=CHECK-IL
+; RUN: llc %t -stop-after=instruction-select -o - | FileCheck %s --check-prefix=CHECK-MIR
+;
+;; Check the generation of pseudoprobe intrinsic call.
+
+define void @foo(i32 %x) !dbg !3 {
+bb0:
+ %cmp = icmp eq i32 %x, 0
+; CHECK-IL: call void @llvm.pseudoprobe(i64 [[#GUID:]], i64 1, i32 0), !dbg ![[#FAKELINE:]]
+; CHECK-MIR: PSEUDO_PROBE [[#GUID:]], 1, 0, 0
+ br i1 %cmp, label %bb1, label %bb2
+
+bb1:
+; CHECK-IL: call void @llvm.pseudoprobe(i64 [[#GUID:]], i64 2, i32 0), !dbg ![[#FAKELINE]]
+; CHECK-MIR: PSEUDO_PROBE [[#GUID]], 3, 0, 0
+; CHECK-MIR: PSEUDO_PROBE [[#GUID]], 4, 0, 0
+ br label %bb3
+
+bb2:
+; CHECK-IL: call void @llvm.pseudoprobe(i64 [[#GUID:]], i64 3, i32 0), !dbg ![[#FAKELINE]]
+; CHECK-MIR: PSEUDO_PROBE [[#GUID]], 2, 0, 0
+; CHECK-MIR: PSEUDO_PROBE [[#GUID]], 4, 0, 0
+ br label %bb3
+
+bb3:
+; CHECK-IL: call void @llvm.pseudoprobe(i64 [[#GUID]], i64 4, i32 0), !dbg ![[#REALLINE:]]
+ ret void, !dbg !12
+}
+
+; CHECK-IL: ![[#FOO:]] = distinct !DISubprogram(name: "foo"
+; CHECK-IL: ![[#FAKELINE]] = !DILocation(line: 0, scope: ![[#FOO]])
+; CHECK-IL: ![[#REALLINE]] = !DILocation(line: 2, scope: ![[#FOO]])
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!9, !10}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1)
+!1 = !DIFile(filename: "test.c", directory: "")
+!2 = !{}
+!3 = distinct !DISubprogram(name: "foo", scope: !1, file: !1, line: 1, type: !5, unit: !0, retainedNodes: !2)
+!5 = !DISubroutineType(types: !6)
+!6 = !{!7}
+!7 = !DIBasicType(name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
+!9 = !{i32 2, !"Dwarf Version", i32 4}
+!10 = !{i32 2, !"Debug Info Version", i32 3}
+!11 = !{!"clang version 3.9.0"}
+!12 = !DILocation(line: 2, scope: !3)
\ No newline at end of file
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