[llvm] Adding Matching and Inference Functionality to Propeller-PR2 (PR #162963)
via llvm-commits
llvm-commits at lists.llvm.org
Tue Oct 21 02:30:49 PDT 2025
https://github.com/wdx727 updated https://github.com/llvm/llvm-project/pull/162963
>From d59773e31aa1015a63c96aa22aa8bcc305878ac7 Mon Sep 17 00:00:00 2001
From: wudexin <wudexin at kuaishou.com>
Date: Wed, 24 Sep 2025 18:42:21 +0800
Subject: [PATCH] Adding Matching and Inference Functionality to Propeller-PR2:
Compute basic block hash and emit to ELF.
Co-authored-by: lifengxiang1025 <lifengxiang at kuaishou.com>
Co-authored-by: zcfh <wuminghui03 at kuaishou.com>
---
.../llvm/CodeGen/MachineBlockHashInfo.h | 110 +++++++++++++++++
llvm/include/llvm/CodeGen/Passes.h | 3 +
llvm/include/llvm/InitializePasses.h | 1 +
llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp | 14 ++-
llvm/lib/CodeGen/CMakeLists.txt | 1 +
llvm/lib/CodeGen/MachineBlockHashInfo.cpp | 115 ++++++++++++++++++
llvm/lib/CodeGen/TargetPassConfig.cpp | 8 ++
...sic-block-address-map-with-emit-bb-hash.ll | 94 ++++++++++++++
8 files changed, 345 insertions(+), 1 deletion(-)
create mode 100644 llvm/include/llvm/CodeGen/MachineBlockHashInfo.h
create mode 100644 llvm/lib/CodeGen/MachineBlockHashInfo.cpp
create mode 100644 llvm/test/CodeGen/X86/basic-block-address-map-with-emit-bb-hash.ll
diff --git a/llvm/include/llvm/CodeGen/MachineBlockHashInfo.h b/llvm/include/llvm/CodeGen/MachineBlockHashInfo.h
new file mode 100644
index 0000000000000..f3ad4b1e81ed1
--- /dev/null
+++ b/llvm/include/llvm/CodeGen/MachineBlockHashInfo.h
@@ -0,0 +1,110 @@
+//===- llvm/CodeGen/MachineBlockHashInfo.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
+//
+//===----------------------------------------------------------------------===//
+//
+// Compute the hashes of basic blocks.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CODEGEN_MACHINEBLOCKHASHINFO_H
+#define LLVM_CODEGEN_MACHINEBLOCKHASHINFO_H
+
+#include "llvm/CodeGen/MachineFunctionPass.h"
+
+namespace llvm {
+
+/// An object wrapping several components of a basic block hash. The combined
+/// (blended) hash is represented and stored as one uint64_t, while individual
+/// components are of smaller size (e.g., uint16_t or uint8_t).
+struct BlendedBlockHash {
+public:
+ explicit BlendedBlockHash(uint16_t Offset, uint16_t OpcodeHash,
+ uint16_t InstrHash, uint16_t NeighborHash)
+ : Offset(Offset), OpcodeHash(OpcodeHash), InstrHash(InstrHash),
+ NeighborHash(NeighborHash) {}
+
+ explicit BlendedBlockHash(uint64_t CombinedHash) {
+ uint64_t OffsetMask = 0xffffULL;
+ uint64_t OpcodeHashMask = 0xffffULL << 16;
+ uint64_t InstrHashMask = 0xffffULL << 32;
+ uint64_t NeighborHashMask = 0xffffULL << 48;
+
+ Offset = CombinedHash & OffsetMask;
+ OpcodeHash = CombinedHash & OpcodeHashMask;
+ InstrHash = CombinedHash & InstrHashMask;
+ NeighborHash = CombinedHash & NeighborHashMask;
+ }
+
+ /// Combine the blended hash into uint64_t.
+ uint64_t combine() const {
+
+ uint64_t Hash = 0;
+
+ Hash |= uint64_t(NeighborHash);
+ Hash <<= 16;
+
+ Hash |= uint64_t(InstrHash);
+ Hash <<= 16;
+
+ Hash |= uint64_t(OpcodeHash);
+ Hash <<= 16;
+
+ Hash |= uint64_t(Offset);
+
+ return Hash;
+ }
+
+ /// Compute a distance between two given blended hashes. The smaller the
+ /// distance, the more similar two blocks are. For identical basic blocks,
+ /// the distance is zero.
+ uint64_t distance(const BlendedBlockHash &BBH) const {
+ assert(OpcodeHash == BBH.OpcodeHash &&
+ "incorrect blended hash distance computation");
+ uint64_t Dist = 0;
+ // Account for NeighborHash
+ Dist += NeighborHash == BBH.NeighborHash ? 0 : 1;
+ Dist <<= 16;
+ // Account for InstrHash
+ Dist += InstrHash == BBH.InstrHash ? 0 : 1;
+ Dist <<= 16;
+ // Account for Offset
+ Dist += (Offset >= BBH.Offset ? Offset - BBH.Offset : BBH.Offset - Offset);
+ return Dist;
+ }
+
+private:
+ /// The offset of the basic block from the function start.
+ uint16_t Offset{0};
+ /// Hash of the basic block instructions, excluding operands.
+ uint16_t OpcodeHash{0};
+ /// Hash of the basic block instructions, including opcodes and
+ /// operands.
+ uint16_t InstrHash{0};
+ /// OpcodeHash of the basic block together with OpcodeHashes of its
+ /// successors and predecessors.
+ uint16_t NeighborHash{0};
+};
+
+class MachineBlockHashInfo : public MachineFunctionPass {
+ DenseMap<const MachineBasicBlock *, uint64_t> MBBHashInfo;
+
+public:
+ static char ID;
+ MachineBlockHashInfo();
+
+ StringRef getPassName() const override { return "Basic Block Hash Compute"; }
+
+ void getAnalysisUsage(AnalysisUsage &AU) const override;
+
+ bool runOnMachineFunction(MachineFunction &F) override;
+
+ uint64_t getMBBHash(const MachineBasicBlock &MBB);
+};
+
+} // end namespace llvm
+
+#endif // LLVM_CODEGEN_MACHINEBLOCKHASHINFO_H
diff --git a/llvm/include/llvm/CodeGen/Passes.h b/llvm/include/llvm/CodeGen/Passes.h
index 272b4acf950c5..8482dbbc2a368 100644
--- a/llvm/include/llvm/CodeGen/Passes.h
+++ b/llvm/include/llvm/CodeGen/Passes.h
@@ -69,6 +69,9 @@ LLVM_ABI MachineFunctionPass *createBasicBlockSectionsPass();
LLVM_ABI MachineFunctionPass *createBasicBlockPathCloningPass();
+/// createMachineBlockHashInfoPass - This pass computes basic block hashes.
+LLVM_ABI MachineFunctionPass *createMachineBlockHashInfoPass();
+
/// createMachineFunctionSplitterPass - This pass splits machine functions
/// using profile information.
LLVM_ABI MachineFunctionPass *createMachineFunctionSplitterPass();
diff --git a/llvm/include/llvm/InitializePasses.h b/llvm/include/llvm/InitializePasses.h
index cd774e7888e64..024397dab236c 100644
--- a/llvm/include/llvm/InitializePasses.h
+++ b/llvm/include/llvm/InitializePasses.h
@@ -62,6 +62,7 @@ LLVM_ABI void initializeBasicBlockSectionsPass(PassRegistry &);
LLVM_ABI void initializeBarrierNoopPass(PassRegistry &);
LLVM_ABI void initializeBasicAAWrapperPassPass(PassRegistry &);
LLVM_ABI void initializeBlockFrequencyInfoWrapperPassPass(PassRegistry &);
+LLVM_ABI void initializeMachineBlockHashInfoPass(PassRegistry &);
LLVM_ABI void initializeBranchFolderLegacyPass(PassRegistry &);
LLVM_ABI void initializeBranchProbabilityInfoWrapperPassPass(PassRegistry &);
LLVM_ABI void initializeBranchRelaxationLegacyPass(PassRegistry &);
diff --git a/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
index e2af0c5925248..2b871cd11b571 100644
--- a/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -41,6 +41,7 @@
#include "llvm/CodeGen/GCMetadataPrinter.h"
#include "llvm/CodeGen/LazyMachineBlockFrequencyInfo.h"
#include "llvm/CodeGen/MachineBasicBlock.h"
+#include "llvm/CodeGen/MachineBlockHashInfo.h"
#include "llvm/CodeGen/MachineBranchProbabilityInfo.h"
#include "llvm/CodeGen/MachineConstantPool.h"
#include "llvm/CodeGen/MachineDominators.h"
@@ -184,6 +185,8 @@ static cl::opt<bool> PrintLatency(
cl::desc("Print instruction latencies as verbose asm comments"), cl::Hidden,
cl::init(false));
+extern cl::opt<bool> EmitBBHash;
+
STATISTIC(EmittedInsts, "Number of machine instrs printed");
char AsmPrinter::ID = 0;
@@ -474,6 +477,8 @@ void AsmPrinter::getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequired<GCModuleInfo>();
AU.addRequired<LazyMachineBlockFrequencyInfoPass>();
AU.addRequired<MachineBranchProbabilityInfoWrapperPass>();
+ if (EmitBBHash)
+ AU.addRequired<MachineBlockHashInfo>();
}
bool AsmPrinter::doInitialization(Module &M) {
@@ -1440,7 +1445,7 @@ getBBAddrMapFeature(const MachineFunction &MF, int NumMBBSectionRanges,
MF.hasBBSections() && NumMBBSectionRanges > 1,
static_cast<bool>(BBAddrMapSkipEmitBBEntries),
HasCalls,
- false};
+ static_cast<bool>(EmitBBHash)};
}
void AsmPrinter::emitBBAddrMapSection(const MachineFunction &MF) {
@@ -1499,6 +1504,9 @@ void AsmPrinter::emitBBAddrMapSection(const MachineFunction &MF) {
PrevMBBEndSymbol = MBBSymbol;
}
+ auto MBHI =
+ Features.BBHash ? &getAnalysis<MachineBlockHashInfo>() : nullptr;
+
if (!Features.OmitBBEntries) {
OutStreamer->AddComment("BB id");
// Emit the BB ID for this basic block.
@@ -1526,6 +1534,10 @@ void AsmPrinter::emitBBAddrMapSection(const MachineFunction &MF) {
emitLabelDifferenceAsULEB128(MBB.getEndSymbol(), CurrentLabel);
// Emit the Metadata.
OutStreamer->emitULEB128IntValue(getBBAddrMapMetadata(MBB));
+ // Emit the Hash.
+ if (MBHI) {
+ OutStreamer->emitInt64(MBHI->getMBBHash(MBB));
+ }
}
PrevMBBEndSymbol = MBB.getEndSymbol();
}
diff --git a/llvm/lib/CodeGen/CMakeLists.txt b/llvm/lib/CodeGen/CMakeLists.txt
index b6872605e22aa..4373c5397a3c6 100644
--- a/llvm/lib/CodeGen/CMakeLists.txt
+++ b/llvm/lib/CodeGen/CMakeLists.txt
@@ -108,6 +108,7 @@ add_llvm_component_library(LLVMCodeGen
LowerEmuTLS.cpp
MachineBasicBlock.cpp
MachineBlockFrequencyInfo.cpp
+ MachineBlockHashInfo.cpp
MachineBlockPlacement.cpp
MachineBranchProbabilityInfo.cpp
MachineCFGPrinter.cpp
diff --git a/llvm/lib/CodeGen/MachineBlockHashInfo.cpp b/llvm/lib/CodeGen/MachineBlockHashInfo.cpp
new file mode 100644
index 0000000000000..0e3227dbdee4c
--- /dev/null
+++ b/llvm/lib/CodeGen/MachineBlockHashInfo.cpp
@@ -0,0 +1,115 @@
+//===- llvm/CodeGen/MachineBlockHashInfo.cpp---------------------*- 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
+//
+//===----------------------------------------------------------------------===//
+//
+// Compute the hashes of basic blocks.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/CodeGen/MachineBlockHashInfo.h"
+#include "llvm/CodeGen/Passes.h"
+#include "llvm/InitializePasses.h"
+#include "llvm/Target/TargetMachine.h"
+
+using namespace llvm;
+
+uint64_t hashBlock(const MachineBasicBlock &MBB, bool HashOperands) {
+ uint64_t Hash = 0;
+ for (const MachineInstr &MI : MBB) {
+ if (MI.isMetaInstruction())
+ continue;
+ // Ignore terminator instruction
+ if (MI.isTerminator())
+ continue;
+ Hash = hashing::detail::hash_16_bytes(Hash, MI.getOpcode());
+ if (HashOperands) {
+ for (unsigned i = 0; i < MI.getNumOperands(); i++) {
+ Hash =
+ hashing::detail::hash_16_bytes(Hash, hash_value(MI.getOperand(i)));
+ }
+ }
+ }
+ return Hash;
+}
+
+/// Fold a 64-bit integer to a 16-bit one.
+uint16_t fold_64_to_16(const uint64_t Value) {
+ uint16_t Res = static_cast<uint16_t>(Value);
+ Res ^= static_cast<uint16_t>(Value >> 16);
+ Res ^= static_cast<uint16_t>(Value >> 32);
+ Res ^= static_cast<uint16_t>(Value >> 48);
+ return Res;
+}
+
+INITIALIZE_PASS(MachineBlockHashInfo, "machine-block-hash",
+ "Machine Block Hash Analysis", true, true)
+
+char MachineBlockHashInfo::ID = 0;
+
+MachineBlockHashInfo::MachineBlockHashInfo() : MachineFunctionPass(ID) {
+ initializeMachineBlockHashInfoPass(*PassRegistry::getPassRegistry());
+}
+
+void MachineBlockHashInfo::getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.setPreservesAll();
+ MachineFunctionPass::getAnalysisUsage(AU);
+}
+
+bool MachineBlockHashInfo::runOnMachineFunction(MachineFunction &F) {
+ DenseMap<MachineBasicBlock *, uint64_t> Offsets;
+ DenseMap<MachineBasicBlock *, uint64_t> OpcodeHashes;
+ DenseMap<MachineBasicBlock *, uint64_t> InstrHashes;
+ DenseMap<MachineBasicBlock *, uint64_t> NeighborHashes;
+ uint16_t Offset = 0;
+ // Initialize hash components
+ for (MachineBasicBlock &MBB : F) {
+ // offset of the machine basic block
+ Offsets[&MBB] = Offset;
+ Offset += MBB.size();
+ // Hashing opcodes
+ OpcodeHashes[&MBB] = hashBlock(MBB, false);
+ // Hash complete instructions
+ InstrHashes[&MBB] = hashBlock(MBB, true);
+ }
+
+ // Initialize neighbor hash
+ for (MachineBasicBlock &MBB : F) {
+ uint64_t Hash = OpcodeHashes[&MBB];
+ // Append hashes of successors
+ for (MachineBasicBlock *SuccMBB : MBB.successors()) {
+ uint64_t SuccHash = OpcodeHashes[SuccMBB];
+ Hash = hashing::detail::hash_16_bytes(Hash, SuccHash);
+ }
+ // Append hashes of predecessors
+ for (MachineBasicBlock *PredMBB : MBB.predecessors()) {
+ uint64_t PredHash = OpcodeHashes[PredMBB];
+ Hash = hashing::detail::hash_16_bytes(Hash, PredHash);
+ }
+ NeighborHashes[&MBB] = Hash;
+ }
+
+ // Assign hashes
+ for (MachineBasicBlock &MBB : F) {
+ if (MBB.getBBID()) {
+ BlendedBlockHash BlendedHash(fold_64_to_16(Offsets[&MBB]),
+ fold_64_to_16(OpcodeHashes[&MBB]),
+ fold_64_to_16(InstrHashes[&MBB]),
+ fold_64_to_16(NeighborHashes[&MBB]));
+ MBBHashInfo[&MBB] = BlendedHash.combine();
+ }
+ }
+
+ return false;
+}
+
+uint64_t MachineBlockHashInfo::getMBBHash(const MachineBasicBlock &MBB) {
+ return MBBHashInfo[&MBB];
+}
+
+MachineFunctionPass *llvm::createMachineBlockHashInfoPass() {
+ return new MachineBlockHashInfo();
+}
diff --git a/llvm/lib/CodeGen/TargetPassConfig.cpp b/llvm/lib/CodeGen/TargetPassConfig.cpp
index b6169e6c4dc34..10b723887b21f 100644
--- a/llvm/lib/CodeGen/TargetPassConfig.cpp
+++ b/llvm/lib/CodeGen/TargetPassConfig.cpp
@@ -272,6 +272,12 @@ static cl::opt<bool>
cl::desc("Split static data sections into hot and cold "
"sections using profile information"));
+cl::opt<bool> EmitBBHash(
+ "emit-bb-hash",
+ cl::desc(
+ "Emit the hash of basic block in the SHT_LLVM_BB_ADDR_MAP section."),
+ cl::init(false), cl::Optional);
+
/// Allow standard passes to be disabled by command line options. This supports
/// simple binary flags that either suppress the pass or do nothing.
/// i.e. -disable-mypass=false has no effect.
@@ -1281,6 +1287,8 @@ void TargetPassConfig::addMachinePasses() {
// address map (or both).
if (TM->getBBSectionsType() != llvm::BasicBlockSection::None ||
TM->Options.BBAddrMap) {
+ if (EmitBBHash)
+ addPass(llvm::createMachineBlockHashInfoPass());
if (TM->getBBSectionsType() == llvm::BasicBlockSection::List) {
addPass(llvm::createBasicBlockSectionsProfileReaderWrapperPass(
TM->getBBSectionsFuncListBuf()));
diff --git a/llvm/test/CodeGen/X86/basic-block-address-map-with-emit-bb-hash.ll b/llvm/test/CodeGen/X86/basic-block-address-map-with-emit-bb-hash.ll
new file mode 100644
index 0000000000000..b89f783adbf9b
--- /dev/null
+++ b/llvm/test/CodeGen/X86/basic-block-address-map-with-emit-bb-hash.ll
@@ -0,0 +1,94 @@
+; Check the basic block sections labels option works when used along with -emit-bb-hash.
+; RUN: llc < %s -mtriple=x86_64 -function-sections -unique-section-names=true -basic-block-address-map -emit-bb-hash | FileCheck %s --check-prefixes=CHECK,UNIQ
+
+define void @_Z3bazb(i1 zeroext, i1 zeroext) personality ptr @__gxx_personality_v0 {
+ br i1 %0, label %3, label %8
+
+3:
+ %4 = invoke i32 @_Z3barv()
+ to label %8 unwind label %6
+ br label %10
+
+6:
+ landingpad { ptr, i32 }
+ catch ptr null
+ br label %12
+
+8:
+ %9 = call i32 @_Z3foov()
+ br i1 %1, label %12, label %10
+
+10:
+ %11 = select i1 %1, ptr blockaddress(@_Z3bazb, %3), ptr blockaddress(@_Z3bazb, %12) ; <ptr> [#uses=1]
+ indirectbr ptr %11, [label %3, label %12]
+
+12:
+ ret void
+}
+
+declare i32 @_Z3barv() #1
+
+declare i32 @_Z3foov() #1
+
+declare i32 @__gxx_personality_v0(...)
+
+; UNIQ: .section .text._Z3bazb,"ax", at progbits{{$}}
+; NOUNIQ: .section .text,"ax", at progbits,unique,1
+; CHECK-LABEL: _Z3bazb:
+; CHECK-LABEL: .Lfunc_begin0:
+; CHECK-LABEL: .LBB_END0_0:
+; CHECK-LABEL: .LBB0_1:
+; CHECK-LABEL: .LBB0_1_CS0:
+; CHECK-LABEL: .LBB_END0_1:
+; CHECK-LABEL: .LBB0_2:
+; CHECK-LABEL: .LBB0_2_CS0:
+; CHECK-LABEL: .LBB_END0_2:
+; CHECK-LABEL: .LBB0_3:
+; CHECK-LABEL: .LBB_END0_3:
+; CHECK-LABEL: .Lfunc_end0:
+
+; UNIQ: .section .llvm_bb_addr_map,"o", at llvm_bb_addr_map,.text._Z3bazb{{$}}
+;; Verify that with -unique-section-names=false, the unique id of the text section gets assigned to the llvm_bb_addr_map section.
+; NOUNIQ: .section .llvm_bb_addr_map,"o", at llvm_bb_addr_map,.text,unique,1
+; CHECK-NEXT: .byte 3 # version
+; CHECK-NEXT: .byte 96 # feature
+; CHECK-NEXT: .quad .Lfunc_begin0 # function address
+; CHECK-NEXT: .byte 6 # number of basic blocks
+; CHECK-NEXT: .byte 0 # BB id
+; CHECK-NEXT: .uleb128 .Lfunc_begin0-.Lfunc_begin0
+; CHECK-NEXT: .byte 0 # number of callsites
+; CHECK-NEXT: .uleb128 .LBB_END0_0-.Lfunc_begin0
+; CHECK-NEXT: .byte 8
+; CHECK-NEXT: .quad {{-?[0-9]+}}
+; CHECK-NEXT: .byte 1 # BB id
+; CHECK-NEXT: .uleb128 .LBB0_1-.LBB_END0_0
+; CHECK-NEXT: .byte 1 # number of callsites
+; CHECK-NEXT: .uleb128 .LBB0_1_CS0-.LBB0_1
+; CHECK-NEXT: .uleb128 .LBB_END0_1-.LBB0_1_CS0
+; CHECK-NEXT: .byte 8
+; CHECK-NEXT: .quad {{-?[0-9]+}}
+; CHECK-NEXT: .byte 3 # BB id
+; CHECK-NEXT: .uleb128 .LBB0_2-.LBB_END0_1
+; CHECK-NEXT: .byte 1 # number of callsites
+; CHECK-NEXT: .uleb128 .LBB0_2_CS0-.LBB0_2
+; CHECK-NEXT: .uleb128 .LBB_END0_2-.LBB0_2_CS0
+; CHECK-NEXT: .byte 8
+; CHECK-NEXT: .quad {{-?[0-9]+}}
+; CHECK-NEXT: .byte 4 # BB id
+; CHECK-NEXT: .uleb128 .LBB0_3-.LBB_END0_2
+; CHECK-NEXT: .byte 0 # number of callsites
+; CHECK-NEXT: .uleb128 .LBB_END0_3-.LBB0_3
+; CHECK-NEXT: .byte 16
+; CHECK-NEXT: .quad {{-?[0-9]+}}
+; CHECK-NEXT: .byte 5 # BB id
+; CHECK-NEXT: .uleb128 .LBB0_4-.LBB_END0_3
+; CHECK-NEXT: .byte 0 # number of callsites
+; CHECK-NEXT: .uleb128 .LBB_END0_4-.LBB0_4
+; CHECK-NEXT: .byte 1
+; CHECK-NEXT: .quad {{-?[0-9]+}}
+; CHECK-NEXT: .byte 2 # BB id
+; CHECK-NEXT: .uleb128 .LBB0_5-.LBB_END0_4
+; CHECK-NEXT: .byte 0 # number of callsites
+; CHECK-NEXT: .uleb128 .LBB_END0_5-.LBB0_5
+; CHECK-NEXT: .byte 5
+; CHECK-NEXT: .quad {{-?[0-9]+}}
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