[llvm] [BOLT] Hash-based function matching (PR #97081)
via llvm-commits
llvm-commits at lists.llvm.org
Fri Jun 28 09:28:00 PDT 2024
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-bolt
Author: shaw young (shawbyoung)
<details>
<summary>Changes</summary>
Test Plan:
added
hashing-based-function-matching.test.
---
Full diff: https://github.com/llvm/llvm-project/pull/97081.diff
6 Files Affected:
- (modified) bolt/docs/CommandLineArgumentReference.md (+5-1)
- (modified) bolt/lib/Profile/YAMLProfileReader.cpp (+64-10)
- (modified) bolt/lib/Rewrite/RewriteInstance.cpp (+5-3)
- (modified) bolt/lib/Utils/CommandLineOpts.cpp (+8)
- (added) bolt/test/X86/hashing-based-function-matching.test (+63)
- (modified) llvm/docs/ReleaseNotes.rst (+6)
``````````diff
diff --git a/bolt/docs/CommandLineArgumentReference.md b/bolt/docs/CommandLineArgumentReference.md
index d95f30a299a285..e8bcc9f0128f4b 100644
--- a/bolt/docs/CommandLineArgumentReference.md
+++ b/bolt/docs/CommandLineArgumentReference.md
@@ -259,6 +259,10 @@
Always use long jumps/nops for Linux kernel static keys
+- `--match-profile-with-function-hash`
+
+ Match profile with function hash
+
- `--max-data-relocations=<uint>`
Maximum number of data relocations to process
@@ -1232,4 +1236,4 @@
- `--print-options`
- Print non-default options after command line parsing
\ No newline at end of file
+ Print non-default options after command line parsing
diff --git a/bolt/lib/Profile/YAMLProfileReader.cpp b/bolt/lib/Profile/YAMLProfileReader.cpp
index f25f59201f1cd9..c66bf298a9dfe4 100644
--- a/bolt/lib/Profile/YAMLProfileReader.cpp
+++ b/bolt/lib/Profile/YAMLProfileReader.cpp
@@ -22,6 +22,8 @@ namespace opts {
extern cl::opt<unsigned> Verbosity;
extern cl::OptionCategory BoltOptCategory;
extern cl::opt<bool> InferStaleProfile;
+extern cl::opt<bool> MatchProfileWithFunctionHash;
+extern cl::opt<bool> Lite;
static llvm::cl::opt<bool>
IgnoreHash("profile-ignore-hash",
@@ -363,9 +365,25 @@ Error YAMLProfileReader::readProfile(BinaryContext &BC) {
return Profile.Hash == static_cast<uint64_t>(BF.getHash());
};
- // We have to do 2 passes since LTO introduces an ambiguity in function
- // names. The first pass assigns profiles that match 100% by name and
- // by hash. The second pass allows name ambiguity for LTO private functions.
+ uint64_t MatchedWithExactName = 0;
+ uint64_t MatchedWithHash = 0;
+ uint64_t MatchedWithLTOCommonName = 0;
+
+ // Computes hash for binary functions.
+ if (opts::MatchProfileWithFunctionHash) {
+ for (auto &[_, BF] : BC.getBinaryFunctions()) {
+ BF.computeHash(YamlBP.Header.IsDFSOrder, YamlBP.Header.HashFunction);
+ }
+ }
+ else if (!opts::IgnoreHash) {
+ for (BinaryFunction *BF : ProfileBFs) {
+ if (!BF)
+ continue;
+ BF->computeHash(YamlBP.Header.IsDFSOrder, YamlBP.Header.HashFunction);
+ }
+ }
+
+ // This first pass assigns profiles that match 100% by name and by hash.
for (auto [YamlBF, BF] : llvm::zip_equal(YamlBP.Functions, ProfileBFs)) {
if (!BF)
continue;
@@ -374,15 +392,34 @@ Error YAMLProfileReader::readProfile(BinaryContext &BC) {
// the profile.
Function.setExecutionCount(BinaryFunction::COUNT_NO_PROFILE);
- // Recompute hash once per function.
- if (!opts::IgnoreHash)
- Function.computeHash(YamlBP.Header.IsDFSOrder,
- YamlBP.Header.HashFunction);
-
- if (profileMatches(YamlBF, Function))
+ if (profileMatches(YamlBF, Function)) {
matchProfileToFunction(YamlBF, Function);
+ ++MatchedWithExactName;
+ }
}
+ // Uses the strict hash of profiled and binary functions to match functions
+ // that are not matched by name or common name.
+ if (opts::MatchProfileWithFunctionHash) {
+ DenseMap<size_t, BinaryFunction *> StrictHashToBF;
+ StrictHashToBF.reserve(BC.getBinaryFunctions().size());
+
+ for (auto &[_, BF] : BC.getBinaryFunctions())
+ StrictHashToBF[BF.getHash()] = &BF;
+
+ for (yaml::bolt::BinaryFunctionProfile &YamlBF : YamlBP.Functions) {
+ if (YamlBF.Used)
+ continue;
+ auto It = StrictHashToBF.find(YamlBF.Hash);
+ if (It != StrictHashToBF.end() && !ProfiledFunctions.count(It->second)) {
+ BinaryFunction *BF = It->second;
+ matchProfileToFunction(YamlBF, *BF);
+ ++MatchedWithHash;
+ }
+ }
+ }
+
+ // This second pass allows name ambiguity for LTO private functions.
for (const auto &[CommonName, LTOProfiles] : LTOCommonNameMap) {
if (!LTOCommonNameFunctionMap.contains(CommonName))
continue;
@@ -396,6 +433,7 @@ Error YAMLProfileReader::readProfile(BinaryContext &BC) {
for (BinaryFunction *BF : Functions) {
if (!ProfiledFunctions.count(BF) && profileMatches(*YamlBF, *BF)) {
matchProfileToFunction(*YamlBF, *BF);
+ ++MatchedWithLTOCommonName;
return true;
}
}
@@ -407,8 +445,10 @@ Error YAMLProfileReader::readProfile(BinaryContext &BC) {
// partially.
if (!ProfileMatched && LTOProfiles.size() == 1 && Functions.size() == 1 &&
!LTOProfiles.front()->Used &&
- !ProfiledFunctions.count(*Functions.begin()))
+ !ProfiledFunctions.count(*Functions.begin())) {
matchProfileToFunction(*LTOProfiles.front(), **Functions.begin());
+ ++MatchedWithLTOCommonName;
+ }
}
for (auto [YamlBF, BF] : llvm::zip_equal(YamlBP.Functions, ProfileBFs))
@@ -420,6 +460,15 @@ Error YAMLProfileReader::readProfile(BinaryContext &BC) {
errs() << "BOLT-WARNING: profile ignored for function " << YamlBF.Name
<< '\n';
+ if (opts::Verbosity >= 1) {
+ outs() << "BOLT-INFO: matched " << MatchedWithExactName
+ << " functions with identical names\n";
+ outs() << "BOLT-INFO: matched " << MatchedWithHash
+ << " functions with hash\n";
+ outs() << "BOLT-INFO: matched " << MatchedWithLTOCommonName
+ << " functions with matching LTO common names\n";
+ }
+
// Set for parseFunctionProfile().
NormalizeByInsnCount = usesEvent("cycles") || usesEvent("instructions");
NormalizeByCalls = usesEvent("branches");
@@ -439,6 +488,11 @@ Error YAMLProfileReader::readProfile(BinaryContext &BC) {
BC.setNumUnusedProfiledObjects(NumUnused);
+ if (opts::Lite && opts::MatchProfileWithFunctionHash)
+ for (BinaryFunction *BF : BC.getAllBinaryFunctions())
+ if (!BF->hasProfile())
+ BF->setIgnored();
+
return Error::success();
}
diff --git a/bolt/lib/Rewrite/RewriteInstance.cpp b/bolt/lib/Rewrite/RewriteInstance.cpp
index 1a3a8af21d81b6..ee6ac1c7d57b51 100644
--- a/bolt/lib/Rewrite/RewriteInstance.cpp
+++ b/bolt/lib/Rewrite/RewriteInstance.cpp
@@ -82,6 +82,8 @@ extern cl::opt<bool> Hugify;
extern cl::opt<bool> Instrument;
extern cl::opt<JumpTableSupportLevel> JumpTables;
extern cl::opt<bool> KeepNops;
+extern cl::opt<bool> Lite;
+extern cl::opt<bool> MatchProfileWithFunctionHash;
extern cl::list<std::string> ReorderData;
extern cl::opt<bolt::ReorderFunctions::ReorderType> ReorderFunctions;
extern cl::opt<bool> TerminalTrap;
@@ -140,9 +142,6 @@ KeepTmp("keep-tmp",
cl::Hidden,
cl::cat(BoltCategory));
-cl::opt<bool> Lite("lite", cl::desc("skip processing of cold functions"),
- cl::cat(BoltCategory));
-
static cl::opt<unsigned>
LiteThresholdPct("lite-threshold-pct",
cl::desc("threshold (in percent) for selecting functions to process in lite "
@@ -2982,6 +2981,9 @@ void RewriteInstance::selectFunctionsToProcess() {
if (mustSkip(Function))
return false;
+ if (opts::MatchProfileWithFunctionHash)
+ return true;
+
// If the list is not empty, only process functions from the list.
if (!opts::ForceFunctionNames.empty() || !ForceFunctionsNR.empty()) {
// Regex check (-funcs and -funcs-file options).
diff --git a/bolt/lib/Utils/CommandLineOpts.cpp b/bolt/lib/Utils/CommandLineOpts.cpp
index 41c89bc8aeba4e..41de30f3f566b1 100644
--- a/bolt/lib/Utils/CommandLineOpts.cpp
+++ b/bolt/lib/Utils/CommandLineOpts.cpp
@@ -128,6 +128,14 @@ cl::opt<bool>
cl::desc("instrument code to generate accurate profile data"),
cl::cat(BoltOptCategory));
+cl::opt<bool> Lite("lite", cl::desc("skip processing of cold functions"),
+ cl::cat(BoltCategory));
+
+cl::opt<bool>
+ MatchProfileWithFunctionHash("match-profile-with-function-hash",
+ cl::desc("Match profile with function hash"),
+ cl::Hidden, cl::cat(BoltCategory));
+
cl::opt<std::string>
OutputFilename("o",
cl::desc("<output file>"),
diff --git a/bolt/test/X86/hashing-based-function-matching.test b/bolt/test/X86/hashing-based-function-matching.test
new file mode 100644
index 00000000000000..41c991b4612ece
--- /dev/null
+++ b/bolt/test/X86/hashing-based-function-matching.test
@@ -0,0 +1,63 @@
+## Tests function matching in YAMLProfileReader by function hash.
+
+# REQUIRES: system-linux
+# RUN: split-file %s %t
+# RUN: llvm-mc -filetype=obj -triple x86_64-unknown-unknown %t/main.s -o %t.o
+# RUN: %clang %cflags %t.o -o %t.exe -Wl,-q -nostdlib
+# RUN: llvm-bolt %t.exe -o %t.out --data %t/yaml -v=2 \
+# RUN: --print-cfg --match-profile-with-function-hash --profile-ignore-hash=0 2>&1 | FileCheck %s
+
+# CHECK: BOLT-INFO: matched 1 functions with hash
+
+#--- main.s
+.globl main
+.type main, @function
+main:
+ .cfi_startproc
+.LBB00:
+ pushq %rbp
+ movq %rsp, %rbp
+ subq $16, %rsp
+ testq %rax, %rax
+ js .LBB03
+.LBB01:
+ jne .LBB04
+.LBB02:
+ nop
+.LBB03:
+ xorl %eax, %eax
+ addq $16, %rsp
+ popq %rbp
+ retq
+.LBB04:
+ xorl %eax, %eax
+ addq $16, %rsp
+ popq %rbp
+ retq
+## For relocations against .text
+ .reloc 0, R_X86_64_NONE
+ .cfi_endproc
+ .size main, .-main
+
+#--- yaml
+---
+header:
+ profile-version: 1
+ binary-name: 'hashing-based-function-matching.s.tmp.exe'
+ binary-build-id: '<unknown>'
+ profile-flags: [ lbr ]
+ profile-origin: branch profile reader
+ profile-events: ''
+ dfs-order: false
+ hash-func: xxh3
+functions:
+ - name: main2
+ fid: 0
+ hash: 0x6E7F15254DE2478
+ exec: 1
+ nblocks: 6
+ blocks:
+ - bid: 1
+ insns: 1
+ succ: [ { bid: 3, cnt: 1} ]
+...
diff --git a/llvm/docs/ReleaseNotes.rst b/llvm/docs/ReleaseNotes.rst
index 7eafc49059dd6d..a110671bacf34d 100644
--- a/llvm/docs/ReleaseNotes.rst
+++ b/llvm/docs/ReleaseNotes.rst
@@ -372,6 +372,12 @@ Changes to the LLVM tools
Changes to LLDB
---------------------------------
+Changes to BOLT
+---------------------------------
+* Now supports ``--match-profile-with-function-hash`` to match profiled and
+ binary functions with exact hash, allowing for the matching of renamed but
+ identical functions.
+
Changes to Sanitizers
---------------------
``````````
</details>
https://github.com/llvm/llvm-project/pull/97081
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