[llvm-branch-commits] [llvm] [DLCov] Origin-Tracking: Collect stack traces in DebugLoc (PR #143592)
Stephen Tozer via llvm-branch-commits
llvm-branch-commits at lists.llvm.org
Wed Jun 11 05:13:18 PDT 2025
https://github.com/SLTozer updated https://github.com/llvm/llvm-project/pull/143592
>From 5e5629149de6f5929a4a1a1986281a201046fd01 Mon Sep 17 00:00:00 2001
From: Stephen Tozer <stephen.tozer at sony.com>
Date: Tue, 10 Jun 2025 20:00:51 +0100
Subject: [PATCH] [DLCov] Origin-Tracking: Core implementation
---
llvm/include/llvm/IR/DebugLoc.h | 49 +++++++++++++++++++++++++-----
llvm/include/llvm/IR/Instruction.h | 2 +-
llvm/lib/CodeGen/BranchFolding.cpp | 7 +++++
llvm/lib/IR/DebugLoc.cpp | 22 +++++++++++++-
4 files changed, 71 insertions(+), 9 deletions(-)
diff --git a/llvm/include/llvm/IR/DebugLoc.h b/llvm/include/llvm/IR/DebugLoc.h
index c3d0fb80354a4..1930199607204 100644
--- a/llvm/include/llvm/IR/DebugLoc.h
+++ b/llvm/include/llvm/IR/DebugLoc.h
@@ -27,6 +27,21 @@ namespace llvm {
class Function;
#if LLVM_ENABLE_DEBUGLOC_COVERAGE_TRACKING
+#if LLVM_ENABLE_DEBUGLOC_ORIGIN_TRACKING
+ struct DbgLocOrigin {
+ static constexpr unsigned long MaxDepth = 16;
+ using StackTracesTy =
+ SmallVector<std::pair<int, std::array<void *, MaxDepth>>, 0>;
+ StackTracesTy StackTraces;
+ DbgLocOrigin(bool ShouldCollectTrace);
+ void addTrace();
+ const StackTracesTy &getOriginStackTraces() const { return StackTraces; };
+ };
+#else
+ struct DbgLocOrigin {
+ DbgLocOrigin(bool) {}
+ };
+#endif
// Used to represent different "kinds" of DebugLoc, expressing that the
// instruction it is part of is either normal and should contain a valid
// DILocation, or otherwise describing the reason why the instruction does
@@ -55,22 +70,29 @@ namespace llvm {
Temporary
};
- // Extends TrackingMDNodeRef to also store a DebugLocKind, allowing Debugify
- // to ignore intentionally-empty DebugLocs.
- class DILocAndCoverageTracking : public TrackingMDNodeRef {
+ // Extends TrackingMDNodeRef to also store a DebugLocKind and Origin,
+ // allowing Debugify to ignore intentionally-empty DebugLocs and display the
+ // code responsible for generating unintentionally-empty DebugLocs.
+ // Currently we only need to track the Origin of this DILoc when using a
+ // DebugLoc that is not annotated (i.e. has DebugLocKind::Normal) and has a
+ // null DILocation, so only collect the origin stacktrace in those cases.
+ class DILocAndCoverageTracking : public TrackingMDNodeRef,
+ public DbgLocOrigin {
public:
DebugLocKind Kind;
// Default constructor for empty DebugLocs.
DILocAndCoverageTracking()
- : TrackingMDNodeRef(nullptr), Kind(DebugLocKind::Normal) {}
- // Valid or nullptr MDNode*, normal DebugLocKind.
+ : TrackingMDNodeRef(nullptr), DbgLocOrigin(true),
+ Kind(DebugLocKind::Normal) {}
+ // Valid or nullptr MDNode*, no annotative DebugLocKind.
DILocAndCoverageTracking(const MDNode *Loc)
- : TrackingMDNodeRef(const_cast<MDNode *>(Loc)),
+ : TrackingMDNodeRef(const_cast<MDNode *>(Loc)), DbgLocOrigin(!Loc),
Kind(DebugLocKind::Normal) {}
LLVM_ABI DILocAndCoverageTracking(const DILocation *Loc);
// Explicit DebugLocKind, which always means a nullptr MDNode*.
DILocAndCoverageTracking(DebugLocKind Kind)
- : TrackingMDNodeRef(nullptr), Kind(Kind) {}
+ : TrackingMDNodeRef(nullptr),
+ DbgLocOrigin(Kind == DebugLocKind::Normal), Kind(Kind) {}
};
template <> struct simplify_type<DILocAndCoverageTracking> {
using SimpleType = MDNode *;
@@ -142,6 +164,19 @@ namespace llvm {
static inline DebugLoc getDropped() { return DebugLoc(); }
#endif // LLVM_ENABLE_DEBUGLOC_COVERAGE_TRACKING
+#if LLVM_ENABLE_DEBUGLOC_ORIGIN_TRACKING
+ const DbgLocOrigin::StackTracesTy &getOriginStackTraces() const {
+ return Loc.getOriginStackTraces();
+ }
+ DebugLoc getCopied() const {
+ DebugLoc NewDL = *this;
+ NewDL.Loc.addTrace();
+ return NewDL;
+ }
+#else
+ DebugLoc getCopied() const { return *this; }
+#endif
+
/// Get the underlying \a DILocation.
///
/// \pre !*this or \c isa<DILocation>(getAsMDNode()).
diff --git a/llvm/include/llvm/IR/Instruction.h b/llvm/include/llvm/IR/Instruction.h
index 10fc9c1298607..1d22bdb0c3f43 100644
--- a/llvm/include/llvm/IR/Instruction.h
+++ b/llvm/include/llvm/IR/Instruction.h
@@ -507,7 +507,7 @@ class Instruction : public User,
LLVM_ABI bool extractProfTotalWeight(uint64_t &TotalVal) const;
/// Set the debug location information for this instruction.
- void setDebugLoc(DebugLoc Loc) { DbgLoc = std::move(Loc); }
+ void setDebugLoc(DebugLoc Loc) { DbgLoc = std::move(Loc).getCopied(); }
/// Return the debug location for this node as a DebugLoc.
const DebugLoc &getDebugLoc() const { return DbgLoc; }
diff --git a/llvm/lib/CodeGen/BranchFolding.cpp b/llvm/lib/CodeGen/BranchFolding.cpp
index e0f7466ceacff..47fc0ec7549e0 100644
--- a/llvm/lib/CodeGen/BranchFolding.cpp
+++ b/llvm/lib/CodeGen/BranchFolding.cpp
@@ -42,6 +42,7 @@
#include "llvm/CodeGen/TargetPassConfig.h"
#include "llvm/CodeGen/TargetRegisterInfo.h"
#include "llvm/CodeGen/TargetSubtargetInfo.h"
+#include "llvm/Config/llvm-config.h"
#include "llvm/IR/DebugInfoMetadata.h"
#include "llvm/IR/DebugLoc.h"
#include "llvm/IR/Function.h"
@@ -933,7 +934,13 @@ bool BranchFolder::TryTailMergeBlocks(MachineBasicBlock *SuccBB,
// Sort by hash value so that blocks with identical end sequences sort
// together.
+#if LLVM_ENABLE_DEBUGLOC_ORIGIN_TRACKING
+ // If origin-tracking is enabled then MergePotentialElt is no longer a POD
+ // type, so we need std::sort instead.
+ std::sort(MergePotentials.begin(), MergePotentials.end());
+#else
array_pod_sort(MergePotentials.begin(), MergePotentials.end());
+#endif
// Walk through equivalence sets looking for actual exact matches.
while (MergePotentials.size() > 1) {
diff --git a/llvm/lib/IR/DebugLoc.cpp b/llvm/lib/IR/DebugLoc.cpp
index 0e65ddcec8934..05aad5d393547 100644
--- a/llvm/lib/IR/DebugLoc.cpp
+++ b/llvm/lib/IR/DebugLoc.cpp
@@ -9,11 +9,31 @@
#include "llvm/IR/DebugLoc.h"
#include "llvm/Config/llvm-config.h"
#include "llvm/IR/DebugInfo.h"
+
+#if LLVM_ENABLE_DEBUGLOC_ORIGIN_TRACKING
+#include "llvm/Support/Signals.h"
+
+namespace llvm {
+DbgLocOrigin::DbgLocOrigin(bool ShouldCollectTrace) {
+ if (ShouldCollectTrace) {
+ auto &[Depth, StackTrace] = StackTraces.emplace_back();
+ Depth = sys::getStackTrace(StackTrace);
+ }
+}
+void DbgLocOrigin::addTrace() {
+ if (StackTraces.empty())
+ return;
+ auto &[Depth, StackTrace] = StackTraces.emplace_back();
+ Depth = sys::getStackTrace(StackTrace);
+}
+} // namespace llvm
+#endif
+
using namespace llvm;
#if LLVM_ENABLE_DEBUGLOC_COVERAGE_TRACKING
DILocAndCoverageTracking::DILocAndCoverageTracking(const DILocation *L)
- : TrackingMDNodeRef(const_cast<DILocation *>(L)),
+ : TrackingMDNodeRef(const_cast<DILocation *>(L)), DbgLocOrigin(!L),
Kind(DebugLocKind::Normal) {}
#endif // LLVM_ENABLE_DEBUGLOC_COVERAGE_TRACKING
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