[llvm] Fix non-determinism in debuginfo (PR #68332)
Paul Kirth via llvm-commits
llvm-commits at lists.llvm.org
Thu Oct 5 14:10:56 PDT 2023
https://github.com/ilovepi updated https://github.com/llvm/llvm-project/pull/68332
>From bad7cc5eaa1ca0dfd04f92ecb053ff6ed93daba7 Mon Sep 17 00:00:00 2001
From: Paul Kirth <paulkirth at google.com>
Date: Wed, 4 Oct 2023 16:21:19 -0700
Subject: [PATCH 1/2] Fix non-determinism in debuginfo
Assignment tracking iterates over a SmallSet when adding metadata,
which eventually results in debug metadata being added to the module in
non-deterministic order.
As reported in #63921, we saw some cases where DWARF DebugLoc entries
could have their order reversed, even though there was no functional
difference.
This patch replaces the SmallSet with a SmallVector, and adds the
required DenseMapInfo specialization.
Fixes: #63921
---
llvm/include/llvm/IR/DebugInfo.h | 24 +++++++++++++++++++++++-
1 file changed, 23 insertions(+), 1 deletion(-)
diff --git a/llvm/include/llvm/IR/DebugInfo.h b/llvm/include/llvm/IR/DebugInfo.h
index 26a7cfbbb350234..c5ded71406d885e 100644
--- a/llvm/include/llvm/IR/DebugInfo.h
+++ b/llvm/include/llvm/IR/DebugInfo.h
@@ -16,7 +16,9 @@
#ifndef LLVM_IR_DEBUGINFO_H
#define LLVM_IR_DEBUGINFO_H
+#include "llvm/ADT/DenseMapInfo.h"
#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/SmallVector.h"
@@ -263,7 +265,8 @@ struct VarRecord {
/// TODO: Backing storage shouldn't be limited to allocas only. Some local
/// variables have their storage allocated by the calling function (addresses
/// passed in with sret & byval parameters).
-using StorageToVarsMap = DenseMap<const AllocaInst *, SmallSet<VarRecord, 2>>;
+using StorageToVarsMap =
+ DenseMap<const AllocaInst *, SmallSetVector<VarRecord, 2>>;
/// Track assignments to \p Vars between \p Start and \p End.
@@ -314,6 +317,25 @@ class AssignmentTrackingPass : public PassInfoMixin<AssignmentTrackingPass> {
/// Return true if assignment tracking is enabled for module \p M.
bool isAssignmentTrackingEnabled(const Module &M);
+
+template <> struct DenseMapInfo<at::VarRecord> {
+ static inline at::VarRecord getEmptyKey() {
+ return at::VarRecord{nullptr, nullptr};
+ }
+
+ static inline at::VarRecord getTombstoneKey() {
+ return at::VarRecord{nullptr, nullptr};
+ }
+
+ static unsigned getHashValue(const at::VarRecord &Var) {
+ return hash_combine(Var.Var, Var.DL);
+ }
+
+ static bool isEqual(const at::VarRecord &A, const at::VarRecord &B) {
+ return A == B;
+ }
+};
+
} // end namespace llvm
#endif // LLVM_IR_DEBUGINFO_H
>From 81ad540477ef1b27b63fe5448400ea1b49c39a4e Mon Sep 17 00:00:00 2001
From: Paul Kirth <paulkirth at google.com>
Date: Thu, 5 Oct 2023 14:05:09 -0700
Subject: [PATCH 2/2] [llvm][debuginfo] Use DenseMapInfo keys from component
types
The naive implementation would break DenseMap, and yield wrong results.
Instead use the Tobstone and Empty Keys from the field types of
VarRecord.
---
llvm/include/llvm/IR/DebugInfo.h | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/llvm/include/llvm/IR/DebugInfo.h b/llvm/include/llvm/IR/DebugInfo.h
index c5ded71406d885e..42bfba1c085b747 100644
--- a/llvm/include/llvm/IR/DebugInfo.h
+++ b/llvm/include/llvm/IR/DebugInfo.h
@@ -320,11 +320,13 @@ bool isAssignmentTrackingEnabled(const Module &M);
template <> struct DenseMapInfo<at::VarRecord> {
static inline at::VarRecord getEmptyKey() {
- return at::VarRecord{nullptr, nullptr};
+ return at::VarRecord{DenseMapInfo<DILocalVariable *>::getEmptyKey(),
+ DenseMapInfo<DILocation *>::getEmptyKey()};
}
static inline at::VarRecord getTombstoneKey() {
- return at::VarRecord{nullptr, nullptr};
+ return at::VarRecord{DenseMapInfo<DILocalVariable *>::getTombstoneKey(),
+ DenseMapInfo<DILocation *>::getTombstoneKey()};
}
static unsigned getHashValue(const at::VarRecord &Var) {
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