[llvm] [ctxprof] Only prune the profile in modules containing only context trees (PR #134340)
Mircea Trofin via llvm-commits
llvm-commits at lists.llvm.org
Thu Apr 3 20:04:55 PDT 2025
https://github.com/mtrofin updated https://github.com/llvm/llvm-project/pull/134340
>From bbb3874a8544cfb3b010258268ceb40fcb455efa Mon Sep 17 00:00:00 2001
From: Mircea Trofin <mtrofin at google.com>
Date: Thu, 3 Apr 2025 18:51:53 -0700
Subject: [PATCH] [ctxprof] Only prune the profile in modules containing only
context trees
---
llvm/include/llvm/Analysis/CtxProfAnalysis.h | 5 ++
llvm/lib/Analysis/CtxProfAnalysis.cpp | 54 ++++++++++-----
llvm/lib/Transforms/IPO/ElimAvailExtern.cpp | 2 +-
llvm/test/Analysis/CtxProfAnalysis/load.ll | 4 ++
llvm/test/Analysis/CtxProfAnalysis/pruning.ll | 69 +++++++++++++++++++
.../transform-to-local.ll | 16 ++++-
6 files changed, 128 insertions(+), 22 deletions(-)
create mode 100644 llvm/test/Analysis/CtxProfAnalysis/pruning.ll
diff --git a/llvm/include/llvm/Analysis/CtxProfAnalysis.h b/llvm/include/llvm/Analysis/CtxProfAnalysis.h
index ede8bd2fe5001..f7f65458c16a9 100644
--- a/llvm/include/llvm/Analysis/CtxProfAnalysis.h
+++ b/llvm/include/llvm/Analysis/CtxProfAnalysis.h
@@ -33,6 +33,7 @@ class PGOContextualProfile {
FunctionInfo(StringRef Name) : Name(Name) {}
};
PGOCtxProfile Profiles;
+ bool IsInSpecializedModule = false;
// For the GUIDs in this module, associate metadata about each function which
// we'll need when we maintain the profiles during IPO transformations.
std::map<GlobalValue::GUID, FunctionInfo> FuncInfo;
@@ -56,6 +57,10 @@ class PGOContextualProfile {
const PGOCtxProfile &profiles() const { return Profiles; }
+ // True if this module is a post-thinlto module containing just functions
+ // participating in one or more contextual profiles.
+ bool isInSpecializedModule() const { return IsInSpecializedModule; }
+
bool isFunctionKnown(const Function &F) const {
return getDefinedFunctionGUID(F) != 0;
}
diff --git a/llvm/lib/Analysis/CtxProfAnalysis.cpp b/llvm/lib/Analysis/CtxProfAnalysis.cpp
index e021e2a801006..3ae333b09d0ce 100644
--- a/llvm/lib/Analysis/CtxProfAnalysis.cpp
+++ b/llvm/lib/Analysis/CtxProfAnalysis.cpp
@@ -12,6 +12,7 @@
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/CtxProfAnalysis.h"
+#include "llvm/ADT/APInt.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/IR/Analysis.h"
#include "llvm/IR/IntrinsicInst.h"
@@ -20,6 +21,7 @@
#include "llvm/ProfileData/PGOCtxProfReader.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/MemoryBuffer.h"
+#include "llvm/Support/Path.h"
#define DEBUG_TYPE "ctx_prof"
@@ -95,26 +97,42 @@ PGOContextualProfile CtxProfAnalysis::run(Module &M,
return {};
}
- DenseSet<GlobalValue::GUID> ProfileRootsInModule;
- for (const auto &F : M)
- if (!F.isDeclaration())
- if (auto GUID = AssignGUIDPass::getGUID(F);
- MaybeProfiles->Contexts.find(GUID) != MaybeProfiles->Contexts.end())
- ProfileRootsInModule.insert(GUID);
-
- // Trim first the roots that aren't in this module.
- for (auto &[RootGuid, _] :
- llvm::make_early_inc_range(MaybeProfiles->Contexts))
- if (!ProfileRootsInModule.contains(RootGuid))
- MaybeProfiles->Contexts.erase(RootGuid);
- // If none of the roots are in the module, we have no profile (for this
- // module)
- if (MaybeProfiles->Contexts.empty())
- return {};
-
- // OK, so we have a valid profile and it's applicable to roots in this module.
+ // FIXME: We should drive this from ThinLTO, but for the time being, use the
+ // module name as indicator.
+ // We want to *only* keep the contextual profiles in modules that capture
+ // context trees. That allows us to compute specific PSIs, for example.
+ auto DetermineRootsInModule = [&M]() -> const DenseSet<GlobalValue::GUID> {
+ DenseSet<GlobalValue::GUID> ProfileRootsInModule;
+ auto ModName = M.getName();
+ auto Filename = sys::path::filename(ModName);
+ // Drop the file extension.
+ Filename = Filename.substr(0, Filename.find_last_of('.'));
+ // See if it parses
+ APInt Guid;
+ // getAsInteger returns true if there are more chars to read other than the
+ // integer. So the "false" test is what we want.
+ if (!Filename.getAsInteger(0, Guid))
+ ProfileRootsInModule.insert(Guid.getZExtValue());
+ return ProfileRootsInModule;
+ };
+ const auto ProfileRootsInModule = DetermineRootsInModule();
PGOContextualProfile Result;
+ // the logic from here on allows for modules that contain - by design - more
+ // than one root. We currently don't support that, because the determination
+ // happens based on the module name matching the root guid, but the logic can
+ // avoid assuming that.
+ if (!ProfileRootsInModule.empty()) {
+ Result.IsInSpecializedModule = true;
+ // Trim first the roots that aren't in this module.
+ for (auto &[RootGuid, _] :
+ llvm::make_early_inc_range(MaybeProfiles->Contexts))
+ if (!ProfileRootsInModule.contains(RootGuid))
+ MaybeProfiles->Contexts.erase(RootGuid);
+ // we can also drop the flat profiles
+ MaybeProfiles->FlatProfiles.clear();
+ }
+
for (const auto &F : M) {
if (F.isDeclaration())
continue;
diff --git a/llvm/lib/Transforms/IPO/ElimAvailExtern.cpp b/llvm/lib/Transforms/IPO/ElimAvailExtern.cpp
index de11f7f6b123d..718452fc02764 100644
--- a/llvm/lib/Transforms/IPO/ElimAvailExtern.cpp
+++ b/llvm/lib/Transforms/IPO/ElimAvailExtern.cpp
@@ -134,7 +134,7 @@ EliminateAvailableExternallyPass::run(Module &M, ModuleAnalysisManager &MAM) {
// for this contextual information. Eliding it in favor of the original would
// undo these optimizations.
if (!eliminateAvailableExternally(
- M, /*Convert=*/(CtxProf && !CtxProf->contexts().empty())))
+ M, /*Convert=*/(CtxProf && CtxProf->isInSpecializedModule())))
return PreservedAnalyses::all();
return PreservedAnalyses::none();
}
diff --git a/llvm/test/Analysis/CtxProfAnalysis/load.ll b/llvm/test/Analysis/CtxProfAnalysis/load.ll
index 6091a99ed3680..bd21a4b710630 100644
--- a/llvm/test/Analysis/CtxProfAnalysis/load.ll
+++ b/llvm/test/Analysis/CtxProfAnalysis/load.ll
@@ -46,6 +46,9 @@ Function Info:
Current Profile:
Contexts:
+ - Guid: 12341
+ TotalRootEntryCount: 90
+ Counters: [ 9 ]
- Guid: 11872291593386833696
TotalRootEntryCount: 4
Counters: [ 1 ]
@@ -57,6 +60,7 @@ Contexts:
Counters: [ 5 ]
Flat Profile:
+12341 : 9
728453322856651412 : 6 7
11872291593386833696 : 1
12074870348631550642 : 5
diff --git a/llvm/test/Analysis/CtxProfAnalysis/pruning.ll b/llvm/test/Analysis/CtxProfAnalysis/pruning.ll
new file mode 100644
index 0000000000000..65fa328ef820b
--- /dev/null
+++ b/llvm/test/Analysis/CtxProfAnalysis/pruning.ll
@@ -0,0 +1,69 @@
+; REQUIRES: x86_64-linux
+;
+; Check that we don't prune the contextual profile, unless the module name
+; matches the guid of the root.
+;
+; RUN: rm -rf %t
+; RUN: split-file %s %t
+; RUN: llvm-ctxprof-util fromYAML --input=%t/profile.yaml --output=%t/profile.ctxprofdata
+;
+; RUN: cp %t/example.ll %t/1234.ll
+; RUN: cp %t/example.ll %t/0x4d2.ll
+;
+; RUN: opt -passes='require<ctx-prof-analysis>,print<ctx-prof-analysis>' \
+; RUN: -use-ctx-profile=%t/profile.ctxprofdata \
+; RUN: -ctx-profile-printer-level=everything \
+; RUN: %t/example.ll -S 2>&1 | FileCheck %s
+
+; RUN: opt -passes='require<ctx-prof-analysis>,print<ctx-prof-analysis>' \
+; RUN: -use-ctx-profile=%t/profile.ctxprofdata \
+; RUN: -ctx-profile-printer-level=everything \
+; RUN: %t/not-matching.ll -S 2>&1 | FileCheck %s
+
+; RUN: opt -passes='require<ctx-prof-analysis>,print<ctx-prof-analysis>' \
+; RUN: -use-ctx-profile=%t/profile.ctxprofdata \
+; RUN: -ctx-profile-printer-level=everything \
+; RUN: %t/0x4d2.ll -S 2>&1 | FileCheck %s --check-prefix=PRUNED
+
+; CHECK: Contexts:
+; CHECK: - Guid: 1234
+; CHECK: - Guid: 5678
+; CHECK: FlatProfiles:
+; PRUNED-NOT: - Guid: 5678
+; PRUNED-NOT: FlatProfiles
+;
+; pick a large GUID that would be negative, if signed, to test a few ways the
+; file name may be formatted.
+;--- profile.yaml
+Contexts:
+ - Guid: 1234
+ TotalRootEntryCount: 24
+ Counters: [9]
+ Callsites: -
+ - Guid: 1000
+ Counters: [6, 7]
+
+ - Guid: 5678
+ TotalRootEntryCount: 24
+ Counters: [9]
+ Callsites: -
+ - Guid: 1000
+ Counters: [6, 7]
+FlatProfiles:
+ - Guid: 777
+ Counters: [2]
+;--- example.ll
+define void @an_entrypoint(i32 %a) !guid !0 {
+ ret void
+}
+
+attributes #0 = { noinline }
+!0 = !{ i64 1234 }
+
+;--- not-matching.ll
+define void @an_entrypoint(i32 %a) !guid !0 {
+ ret void
+}
+
+attributes #0 = { noinline }
+!0 = !{ i64 1000 }
diff --git a/llvm/test/Transforms/EliminateAvailableExternally/transform-to-local.ll b/llvm/test/Transforms/EliminateAvailableExternally/transform-to-local.ll
index b6465f44faa18..c24e4925fe78f 100644
--- a/llvm/test/Transforms/EliminateAvailableExternally/transform-to-local.ll
+++ b/llvm/test/Transforms/EliminateAvailableExternally/transform-to-local.ll
@@ -1,16 +1,26 @@
; REQUIRES: asserts
-; RUN: opt -passes=elim-avail-extern -avail-extern-to-local -stats -S 2>&1 < %s | FileCheck %s
+; RUN: rm -rf %t
+; RUN: mkdir %t
+; RUN: cp %s %t/1234.ll
+;
+; default behavior
+; RUN: opt -passes=elim-avail-extern -stats -S 2>&1 %s | FileCheck %s --check-prefix=NOOP
+;
+; check the -avail-extern-to-local flag works as intended
+; RUN: opt -passes=elim-avail-extern -avail-extern-to-local -stats -S 2>&1 %t/1234.ll | FileCheck %s
+; RUN: opt -passes=elim-avail-extern -avail-extern-to-local -stats -S 2>&1 %s | FileCheck %s
;
; RUN: echo '{"Contexts": [{"Guid":1234, "TotalRootEntryCount": 5, "Counters": [1]}]}' | llvm-ctxprof-util fromYAML --input=- --output=%t_profile.ctxprofdata
;
; Because we pass a contextual profile with a root defined in this module, we expect the outcome to be the same as-if
; we passed -avail-extern-to-local, i.e. available_externally don't get elided and instead get converted to local linkage
-; RUN: opt -passes='assign-guid,require<ctx-prof-analysis>,elim-avail-extern' -use-ctx-profile=%t_profile.ctxprofdata -stats -S 2>&1 < %s | FileCheck %s
+;
+; RUN: opt -passes='assign-guid,require<ctx-prof-analysis>,elim-avail-extern' -use-ctx-profile=%t_profile.ctxprofdata -stats -S 2>&1 %t/1234.ll | FileCheck %s
; If the profile doesn't apply to this module, available_externally won't get converted to internal linkage, and will be
; removed instead.
; RUN: echo '{"Contexts": [{"Guid":5678, "TotalRootEntryCount": 3, "Counters": [1]}]}' | llvm-ctxprof-util fromYAML --input=- --output=%t_profile_bad.ctxprofdata
-; RUN: opt -passes='assign-guid,require<ctx-prof-analysis>,elim-avail-extern' -use-ctx-profile=%t_profile_bad.ctxprofdata -stats -S 2>&1 < %s | FileCheck %s --check-prefix=NOOP
+; RUN: opt -passes='assign-guid,require<ctx-prof-analysis>,elim-avail-extern' -use-ctx-profile=%t_profile_bad.ctxprofdata -stats -S %s 2>&1 | FileCheck %s --check-prefix=NOOP
declare void @call_out(ptr %fct)
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