[llvm] [CSSPGO] Fix the issue of missing callee profile matches (PR #85715)
Lei Wang via llvm-commits
llvm-commits at lists.llvm.org
Wed Mar 20 12:40:41 PDT 2024
https://github.com/wlei-llvm updated https://github.com/llvm/llvm-project/pull/85715
>From 9d34f38c158e46f1468d9ffe08a48eb707dca8ee Mon Sep 17 00:00:00 2001
From: wlei <wlei at fb.com>
Date: Mon, 18 Mar 2024 10:43:48 -0700
Subject: [PATCH 1/2] [CSSPGO] Fix the issue of missing callee profile matches
---
llvm/lib/Transforms/IPO/SampleProfile.cpp | 50 ++++++++------
.../pseudo-probe-callee-profile-mismatch.prof | 13 ++++
.../csspgo-profile-checksum-mismatch-attr.ll | 67 +++++++++++++++++++
.../pseudo-probe-callee-profile-mismatch.ll | 59 ++++++++++++++++
4 files changed, 170 insertions(+), 19 deletions(-)
create mode 100644 llvm/test/Transforms/SampleProfile/Inputs/pseudo-probe-callee-profile-mismatch.prof
create mode 100644 llvm/test/Transforms/SampleProfile/csspgo-profile-checksum-mismatch-attr.ll
create mode 100644 llvm/test/Transforms/SampleProfile/pseudo-probe-callee-profile-mismatch.ll
diff --git a/llvm/lib/Transforms/IPO/SampleProfile.cpp b/llvm/lib/Transforms/IPO/SampleProfile.cpp
index ffc26f1a0a972d..877ec56cb26fe8 100644
--- a/llvm/lib/Transforms/IPO/SampleProfile.cpp
+++ b/llvm/lib/Transforms/IPO/SampleProfile.cpp
@@ -438,6 +438,7 @@ class SampleProfileMatcher {
Module &M;
SampleProfileReader &Reader;
const PseudoProbeManager *ProbeManager;
+ const ThinOrFullLTOPhase LTOPhase;
SampleProfileMap FlattenedProfiles;
// For each function, the matcher generates a map, of which each entry is a
// mapping from the source location of current build to the source location in
@@ -489,8 +490,9 @@ class SampleProfileMatcher {
public:
SampleProfileMatcher(Module &M, SampleProfileReader &Reader,
- const PseudoProbeManager *ProbeManager)
- : M(M), Reader(Reader), ProbeManager(ProbeManager){};
+ const PseudoProbeManager *ProbeManager,
+ ThinOrFullLTOPhase LTOPhase)
+ : M(M), Reader(Reader), ProbeManager(ProbeManager), LTOPhase(LTOPhase){};
void runOnModule();
void clearMatchingData() {
// Do not clear FuncMappings, it stores IRLoc to ProfLoc remappings which
@@ -506,7 +508,7 @@ class SampleProfileMatcher {
return &It->second;
return nullptr;
}
- void runOnFunction(const Function &F);
+ void runOnFunction(Function &F);
void findIRAnchors(const Function &F,
std::map<LineLocation, StringRef> &IRAnchors);
void findProfileAnchors(
@@ -2177,8 +2179,8 @@ bool SampleProfileLoader::doInitialization(Module &M,
if (ReportProfileStaleness || PersistProfileStaleness ||
SalvageStaleProfile) {
- MatchingManager =
- std::make_unique<SampleProfileMatcher>(M, *Reader, ProbeManager.get());
+ MatchingManager = std::make_unique<SampleProfileMatcher>(
+ M, *Reader, ProbeManager.get(), LTOPhase);
}
return true;
@@ -2383,7 +2385,7 @@ void SampleProfileMatcher::runStaleProfileMatching(
}
}
-void SampleProfileMatcher::runOnFunction(const Function &F) {
+void SampleProfileMatcher::runOnFunction(Function &F) {
// We need to use flattened function samples for matching.
// Unlike IR, which includes all callsites from the source code, the callsites
// in profile only show up when they are hit by samples, i,e. the profile
@@ -2410,17 +2412,26 @@ void SampleProfileMatcher::runOnFunction(const Function &F) {
// Run profile matching for checksum mismatched profile, currently only
// support for pseudo-probe.
- if (SalvageStaleProfile && FunctionSamples::ProfileIsProbeBased &&
- !ProbeManager->profileIsValid(F, *FSFlattened)) {
- // The matching result will be saved to IRToProfileLocationMap, create a new
- // map for each function.
- auto &IRToProfileLocationMap = getIRToProfileLocationMap(F);
- runStaleProfileMatching(F, IRAnchors, ProfileAnchors,
- IRToProfileLocationMap);
- // Find and update callsite match states after matching.
- if (ReportProfileStaleness || PersistProfileStaleness)
- recordCallsiteMatchStates(F, IRAnchors, ProfileAnchors,
- &IRToProfileLocationMap);
+ if (SalvageStaleProfile && FunctionSamples::ProfileIsProbeBased) {
+ const auto *Desc = ProbeManager->getDesc(F);
+ // For imported functions, the checksum metadata(pseudo_probe_desc) are
+ // dropped, so we leverage function attribute(profile-checksum-mismatch) to
+ // transfer the info: add the attribute during pre-link phase and check it
+ // during post-link phase.
+ if ((Desc && ProbeManager->profileIsHashMismatched(*Desc, *FSFlattened)) ||
+ F.hasFnAttribute("profile-checksum-mismatch")) {
+ if (LTOPhase == ThinOrFullLTOPhase::ThinLTOPreLink)
+ F.addFnAttr("profile-checksum-mismatch");
+ // The matching result will be saved to IRToProfileLocationMap, create a
+ // new map for each function.
+ auto &IRToProfileLocationMap = getIRToProfileLocationMap(F);
+ runStaleProfileMatching(F, IRAnchors, ProfileAnchors,
+ IRToProfileLocationMap);
+ // Find and update callsite match states after matching.
+ if (ReportProfileStaleness || PersistProfileStaleness)
+ recordCallsiteMatchStates(F, IRAnchors, ProfileAnchors,
+ &IRToProfileLocationMap);
+ }
}
}
@@ -2689,8 +2700,9 @@ void SampleProfileMatcher::distributeIRToProfileLocationMap(
FS.setIRToProfileLocationMap(&(ProfileMappings->second));
}
- for (auto &Inlinees : FS.getCallsiteSamples()) {
- for (auto FS : Inlinees.second) {
+ for (auto &Callees :
+ const_cast<CallsiteSampleMap &>(FS.getCallsiteSamples())) {
+ for (auto &FS : Callees.second) {
distributeIRToProfileLocationMap(FS.second);
}
}
diff --git a/llvm/test/Transforms/SampleProfile/Inputs/pseudo-probe-callee-profile-mismatch.prof b/llvm/test/Transforms/SampleProfile/Inputs/pseudo-probe-callee-profile-mismatch.prof
new file mode 100644
index 00000000000000..ff8456486ca610
--- /dev/null
+++ b/llvm/test/Transforms/SampleProfile/Inputs/pseudo-probe-callee-profile-mismatch.prof
@@ -0,0 +1,13 @@
+main:252:0
+ 1: 0
+ 2: 50
+ 5: 50
+ 7: bar:102
+ 1: 51
+ 2: baz:51
+ 1: 51
+ !CFGChecksum: 4294967295
+ !Attributes: 3
+ !CFGChecksum: 281479271677951
+ !Attributes: 2
+ !CFGChecksum: 281582081721716
diff --git a/llvm/test/Transforms/SampleProfile/csspgo-profile-checksum-mismatch-attr.ll b/llvm/test/Transforms/SampleProfile/csspgo-profile-checksum-mismatch-attr.ll
new file mode 100644
index 00000000000000..df56b55dcdf3c0
--- /dev/null
+++ b/llvm/test/Transforms/SampleProfile/csspgo-profile-checksum-mismatch-attr.ll
@@ -0,0 +1,67 @@
+; REQUIRES: x86_64-linux
+; REQUIRES: asserts
+; RUN: opt < %s -passes='thinlto-pre-link<O2>' -pgo-kind=pgo-sample-use-pipeline -sample-profile-file=%S/Inputs/pseudo-probe-callee-profile-mismatch.prof -pass-remarks=inline -S -o %t 2>&1 | FileCheck %s --check-prefix=INLINE
+; RUN: FileCheck %s < %t
+; RUN: FileCheck %s < %t --check-prefix=MERGE
+
+
+; Make sure bar is inlined into main for attr merging verification.
+; INLINE: 'bar' inlined into 'main'
+
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+define i32 @baz() #0 {
+entry:
+ ret i32 0
+}
+
+define i32 @bar() #0 !dbg !11 {
+; CHECK: define {{.*}} @bar() {{.*}} #[[#BAR_ATTR:]] !
+entry:
+ %call = call i32 @baz()
+ ret i32 0
+}
+
+define i32 @main() #0 {
+; MERGE: define {{.*}} @main() {{.*}} #[[#MAIN_ATTR:]] !
+entry:
+ br label %for.cond
+
+for.cond: ; preds = %for.cond, %entry
+ %call = call i32 @bar(), !dbg !14
+ br label %for.cond
+}
+
+; CHECK: attributes #[[#BAR_ATTR]] = {{{.*}} "profile-checksum-mismatch" {{.*}}}
+
+; Verify the attribute is not merged into the caller.
+; MERGE-NOT: attributes #[[#MAIN_ATTR]] = {{{.*}} "profile-checksum-mismatch" {{.*}}}
+
+attributes #0 = { "use-sample-profile" }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!7}
+!llvm.pseudo_probe_desc = !{!8, !9, !10}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C11, file: !1, producer: "clang version 19.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, globals: !2, splitDebugInlining: false, nameTableKind: None)
+!1 = !DIFile(filename: "test.c", directory: "/home", checksumkind: CSK_MD5, checksum: "0df0c950a93a603a7d13f0a9d4623642")
+!2 = !{!3}
+!3 = !DIGlobalVariableExpression(var: !4, expr: !DIExpression())
+!4 = distinct !DIGlobalVariable(name: "x", scope: !0, file: !1, line: 2, type: !5, isLocal: false, isDefinition: true)
+!5 = !DIDerivedType(tag: DW_TAG_volatile_type, baseType: !6)
+!6 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!7 = !{i32 2, !"Debug Info Version", i32 3}
+!8 = !{i64 7546896869197086323, i64 4294967295, !"baz"}
+!9 = !{i64 -2012135647395072713, i64 281530612780802, !"bar"}
+!10 = !{i64 -2624081020897602054, i64 281582081721716, !"main"}
+!11 = distinct !DISubprogram(name: "bar", scope: !1, file: !1, line: 5, type: !12, scopeLine: 5, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !13)
+!12 = distinct !DISubroutineType(types: !13)
+!13 = !{}
+!14 = !DILocation(line: 15, column: 10, scope: !15)
+!15 = !DILexicalBlockFile(scope: !16, file: !1, discriminator: 186646591)
+!16 = distinct !DILexicalBlock(scope: !17, file: !1, line: 14, column: 40)
+!17 = distinct !DILexicalBlock(scope: !18, file: !1, line: 14, column: 3)
+!18 = distinct !DILexicalBlock(scope: !19, file: !1, line: 14, column: 3)
+!19 = distinct !DISubprogram(name: "main", scope: !1, file: !1, line: 12, type: !20, scopeLine: 13, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !13)
+!20 = !DISubroutineType(types: !13)
diff --git a/llvm/test/Transforms/SampleProfile/pseudo-probe-callee-profile-mismatch.ll b/llvm/test/Transforms/SampleProfile/pseudo-probe-callee-profile-mismatch.ll
new file mode 100644
index 00000000000000..19bc26f131d7b3
--- /dev/null
+++ b/llvm/test/Transforms/SampleProfile/pseudo-probe-callee-profile-mismatch.ll
@@ -0,0 +1,59 @@
+; REQUIRES: x86_64-linux
+; REQUIRES: asserts
+; RUN: opt < %s -passes=sample-profile -sample-profile-file=%S/Inputs/pseudo-probe-callee-profile-mismatch.prof --salvage-stale-profile -S --debug-only=sample-profile,sample-profile-impl -pass-remarks=inline 2>&1 | FileCheck %s
+
+
+; CHECK: Run stale profile matching for bar
+; CHECK: Callsite with callee:baz is matched from 4 to 2
+; CHECK: 'baz' inlined into 'main' to match profiling context with (cost=always): preinliner at callsite bar:3:8.4 @ main:3:10.7
+
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+define i32 @main() #0 {
+ %1 = call i32 @bar(), !dbg !13
+ ret i32 0
+}
+
+define available_externally i32 @bar() #1 !dbg !21 {
+ %1 = call i32 @baz(), !dbg !23
+ ret i32 0
+}
+
+define available_externally i32 @baz() #0 !dbg !25 {
+ ret i32 0
+}
+
+attributes #0 = { "use-sample-profile" }
+attributes #1 = { "profile-checksum-mismatch" "use-sample-profile" }
+
+!llvm.dbg.cu = !{!0, !7, !9}
+!llvm.module.flags = !{!11}
+!llvm.pseudo_probe_desc = !{!12}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C11, file: !1, producer: "clang version 19.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, globals: !2, splitDebugInlining: false, nameTableKind: None)
+!1 = !DIFile(filename: "test.c", directory: "/home/test", checksumkind: CSK_MD5, checksum: "7220f1a2d70ff869f1a6ab7958e3c393")
+!2 = !{!3}
+!3 = !DIGlobalVariableExpression(var: !4, expr: !DIExpression())
+!4 = distinct !DIGlobalVariable(name: "x", scope: !0, file: !1, line: 2, type: !5, isLocal: false, isDefinition: true)
+!5 = !DIDerivedType(tag: DW_TAG_volatile_type, baseType: !6)
+!6 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!7 = distinct !DICompileUnit(language: DW_LANG_C11, file: !8, producer: "clang version 19.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, splitDebugInlining: false, nameTableKind: None)
+!8 = !DIFile(filename: "test1.v1.c", directory: "/home/test", checksumkind: CSK_MD5, checksum: "76696bd6bfe16a9f227fe03cfdb6a82c")
+!9 = distinct !DICompileUnit(language: DW_LANG_C11, file: !10, producer: "clang version 19.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, splitDebugInlining: false, nameTableKind: None)
+!10 = !DIFile(filename: "test2.c", directory: "/home/test", checksumkind: CSK_MD5, checksum: "553093afc026f9c73562eb3b0c5b7532")
+!11 = !{i32 2, !"Debug Info Version", i32 3}
+!12 = !{i64 -2624081020897602054, i64 281582081721716, !"main"}
+!13 = !DILocation(line: 8, column: 10, scope: !14)
+!14 = !DILexicalBlockFile(scope: !15, file: !1, discriminator: 186646591)
+!15 = distinct !DILexicalBlock(scope: !16, file: !1, line: 7, column: 40)
+!16 = distinct !DILexicalBlock(scope: !17, file: !1, line: 7, column: 3)
+!17 = distinct !DILexicalBlock(scope: !18, file: !1, line: 7, column: 3)
+!18 = distinct !DISubprogram(name: "main", scope: !1, file: !1, line: 5, type: !19, scopeLine: 6, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !20)
+!19 = distinct !DISubroutineType(types: !20)
+!20 = !{}
+!21 = distinct !DISubprogram(name: "bar", scope: !8, file: !8, line: 3, type: !22, scopeLine: 3, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !7, retainedNodes: !20)
+!22 = !DISubroutineType(types: !20)
+!23 = !DILocation(line: 6, column: 8, scope: !24)
+!24 = !DILexicalBlockFile(scope: !21, file: !8, discriminator: 186646567)
+!25 = distinct !DISubprogram(name: "baz", scope: !10, file: !10, line: 1, type: !22, scopeLine: 1, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !9, retainedNodes: !20)
>From 9007aed4524f2dafd4ad4dcbc6570d5a288a3bb8 Mon Sep 17 00:00:00 2001
From: wlei <wlei at fb.com>
Date: Wed, 20 Mar 2024 12:23:32 -0700
Subject: [PATCH 2/2] fix profileIsValid and related match statstics
---
.../Utils/SampleProfileLoaderBaseImpl.h | 16 +++----
llvm/lib/Transforms/IPO/SampleProfile.cpp | 45 ++++++++++---------
.../pseudo-probe-callee-profile-mismatch.prof | 3 ++
.../pseudo-probe-callee-profile-mismatch.ll | 4 ++
4 files changed, 39 insertions(+), 29 deletions(-)
diff --git a/llvm/include/llvm/Transforms/Utils/SampleProfileLoaderBaseImpl.h b/llvm/include/llvm/Transforms/Utils/SampleProfileLoaderBaseImpl.h
index 66814d39527301..7d61c1800230a9 100644
--- a/llvm/include/llvm/Transforms/Utils/SampleProfileLoaderBaseImpl.h
+++ b/llvm/include/llvm/Transforms/Utils/SampleProfileLoaderBaseImpl.h
@@ -125,17 +125,15 @@ class PseudoProbeManager {
}
bool profileIsValid(const Function &F, const FunctionSamples &Samples) const {
- const auto *Desc = getDesc(F);
- if (!Desc) {
- LLVM_DEBUG(dbgs() << "Probe descriptor missing for Function "
- << F.getName() << "\n");
+ // The desc for import function is unavailable. Check the function attribute
+ // for mismatch.
+ if (F.hasFnAttribute("profile-checksum-mismatch"))
return false;
- }
- if (Desc->getFunctionHash() != Samples.getFunctionHash()) {
- LLVM_DEBUG(dbgs() << "Hash mismatch for Function " << F.getName()
- << "\n");
+
+ const auto *Desc = getDesc(F);
+ if (Desc && profileIsHashMismatched(*Desc, Samples))
return false;
- }
+
return true;
}
};
diff --git a/llvm/lib/Transforms/IPO/SampleProfile.cpp b/llvm/lib/Transforms/IPO/SampleProfile.cpp
index 877ec56cb26fe8..05e776b2e90e03 100644
--- a/llvm/lib/Transforms/IPO/SampleProfile.cpp
+++ b/llvm/lib/Transforms/IPO/SampleProfile.cpp
@@ -1893,15 +1893,22 @@ bool SampleProfileLoader::emitAnnotations(Function &F) {
bool Changed = false;
if (FunctionSamples::ProfileIsProbeBased) {
- if (!ProbeManager->profileIsValid(F, *Samples)) {
+ LLVM_DEBUG({
+ if (!ProbeManager->getDesc(F))
+ dbgs() << "Probe descriptor missing for Function " << F.getName()
+ << "\n";
+ });
+
+ if (ProbeManager->profileIsValid(F, *Samples)) {
+ ++NumMatchedProfile;
+ } else {
+ ++NumMismatchedProfile;
LLVM_DEBUG(
dbgs() << "Profile is invalid due to CFG mismatch for Function "
<< F.getName() << "\n");
- ++NumMismatchedProfile;
if (!SalvageStaleProfile)
return false;
}
- ++NumMatchedProfile;
} else {
if (getFunctionLoc(F) == 0)
return false;
@@ -2412,26 +2419,24 @@ void SampleProfileMatcher::runOnFunction(Function &F) {
// Run profile matching for checksum mismatched profile, currently only
// support for pseudo-probe.
- if (SalvageStaleProfile && FunctionSamples::ProfileIsProbeBased) {
- const auto *Desc = ProbeManager->getDesc(F);
+ if (SalvageStaleProfile && FunctionSamples::ProfileIsProbeBased &&
+ !ProbeManager->profileIsValid(F, *FSFlattened)) {
// For imported functions, the checksum metadata(pseudo_probe_desc) are
// dropped, so we leverage function attribute(profile-checksum-mismatch) to
// transfer the info: add the attribute during pre-link phase and check it
- // during post-link phase.
- if ((Desc && ProbeManager->profileIsHashMismatched(*Desc, *FSFlattened)) ||
- F.hasFnAttribute("profile-checksum-mismatch")) {
- if (LTOPhase == ThinOrFullLTOPhase::ThinLTOPreLink)
- F.addFnAttr("profile-checksum-mismatch");
- // The matching result will be saved to IRToProfileLocationMap, create a
- // new map for each function.
- auto &IRToProfileLocationMap = getIRToProfileLocationMap(F);
- runStaleProfileMatching(F, IRAnchors, ProfileAnchors,
- IRToProfileLocationMap);
- // Find and update callsite match states after matching.
- if (ReportProfileStaleness || PersistProfileStaleness)
- recordCallsiteMatchStates(F, IRAnchors, ProfileAnchors,
- &IRToProfileLocationMap);
- }
+ // during post-link phase(see "profileIsValid").
+ if (LTOPhase == ThinOrFullLTOPhase::ThinLTOPreLink)
+ F.addFnAttr("profile-checksum-mismatch");
+
+ // The matching result will be saved to IRToProfileLocationMap, create a
+ // new map for each function.
+ auto &IRToProfileLocationMap = getIRToProfileLocationMap(F);
+ runStaleProfileMatching(F, IRAnchors, ProfileAnchors,
+ IRToProfileLocationMap);
+ // Find and update callsite match states after matching.
+ if (ReportProfileStaleness || PersistProfileStaleness)
+ recordCallsiteMatchStates(F, IRAnchors, ProfileAnchors,
+ &IRToProfileLocationMap);
}
}
diff --git a/llvm/test/Transforms/SampleProfile/Inputs/pseudo-probe-callee-profile-mismatch.prof b/llvm/test/Transforms/SampleProfile/Inputs/pseudo-probe-callee-profile-mismatch.prof
index ff8456486ca610..76a8fc9d19a85d 100644
--- a/llvm/test/Transforms/SampleProfile/Inputs/pseudo-probe-callee-profile-mismatch.prof
+++ b/llvm/test/Transforms/SampleProfile/Inputs/pseudo-probe-callee-profile-mismatch.prof
@@ -11,3 +11,6 @@ main:252:0
!CFGChecksum: 281479271677951
!Attributes: 2
!CFGChecksum: 281582081721716
+bar:1:1
+ 1: 1
+ !CFGChecksum: 281479271677951
diff --git a/llvm/test/Transforms/SampleProfile/pseudo-probe-callee-profile-mismatch.ll b/llvm/test/Transforms/SampleProfile/pseudo-probe-callee-profile-mismatch.ll
index 19bc26f131d7b3..e00b737cae4e85 100644
--- a/llvm/test/Transforms/SampleProfile/pseudo-probe-callee-profile-mismatch.ll
+++ b/llvm/test/Transforms/SampleProfile/pseudo-probe-callee-profile-mismatch.ll
@@ -7,6 +7,10 @@
; CHECK: Callsite with callee:baz is matched from 4 to 2
; CHECK: 'baz' inlined into 'main' to match profiling context with (cost=always): preinliner at callsite bar:3:8.4 @ main:3:10.7
+; CHECK: Probe descriptor missing for Function bar
+; CHECK: Profile is invalid due to CFG mismatch for Function bar
+
+
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"
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