[llvm] [BOLT] Fix possibly incorrect CU-indicies in gdb-index (PR #151927)
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llvm-commits at lists.llvm.org
Tue Aug 5 01:47:41 PDT 2025
https://github.com/itrofimow updated https://github.com/llvm/llvm-project/pull/151927
>From 78ce26965bb15a197d73a1d7ce7d5fbfb37c70da Mon Sep 17 00:00:00 2001
From: Ivan Trofimov <i.trofimow at yandex.ru>
Date: Mon, 4 Aug 2025 12:07:11 +0300
Subject: [PATCH 1/4] [BOLT] Fix possibly incorrect CU-indicies in gdb-index
---
bolt/lib/Core/GDBIndex.cpp | 75 +++++++++++++++++++++++++++++++++++++-
1 file changed, 73 insertions(+), 2 deletions(-)
diff --git a/bolt/lib/Core/GDBIndex.cpp b/bolt/lib/Core/GDBIndex.cpp
index c7fb4889646b4..0fe1c5de94138 100644
--- a/bolt/lib/Core/GDBIndex.cpp
+++ b/bolt/lib/Core/GDBIndex.cpp
@@ -130,6 +130,26 @@ void GDBIndex::updateGdbIndexSection(
[](const MapEntry &E1, const MapEntry &E2) -> bool {
return E1.second.Offset < E2.second.Offset;
});
+ // Create the original CU index -> updated CU index mapping,
+ // as the sort above could've changed the order and we have to update
+ // indexes correspondingly in address map and constant pool.
+ std::unordered_map<uint32_t, uint32_t> OriginalCUIndexToUpdatedCUIndexMap;
+ OriginalCUIndexToUpdatedCUIndexMap.reserve(CUVector.size());
+ for (uint32_t I = 0; I < CUVector.size(); ++I) {
+ OriginalCUIndexToUpdatedCUIndexMap[OffsetToIndexMap.at(CUVector[I].first)] =
+ I;
+ }
+ const auto RemapCUIndex =
+ [&OriginalCUIndexToUpdatedCUIndexMap](uint32_t OriginalIndex) {
+ const auto it = OriginalCUIndexToUpdatedCUIndexMap.find(OriginalIndex);
+ if (it == OriginalCUIndexToUpdatedCUIndexMap.end()) {
+ errs() << "BOLT-ERROR: .gdb_index unknown CU index\n";
+ exit(1);
+ }
+
+ return it->second;
+ };
+
// Writing out CU List <Offset, Size>
for (auto &CUInfo : CUVector) {
// Skipping TU for DWARF5 when they are not included in CU list.
@@ -160,12 +180,13 @@ void GDBIndex::updateGdbIndexSection(
// Generate new address table.
for (const std::pair<const uint64_t, DebugAddressRangesVector> &CURangesPair :
ARangesSectionWriter.getCUAddressRanges()) {
- const uint32_t CUIndex = OffsetToIndexMap[CURangesPair.first];
+ const uint32_t OriginalCUIndex = OffsetToIndexMap[CURangesPair.first];
+ const uint32_t UpdatedCUIndex = RemapCUIndex(OriginalCUIndex);
const DebugAddressRangesVector &Ranges = CURangesPair.second;
for (const DebugAddressRange &Range : Ranges) {
write64le(Buffer, Range.LowPC);
write64le(Buffer + 8, Range.HighPC);
- write32le(Buffer + 16, CUIndex);
+ write32le(Buffer + 16, UpdatedCUIndex);
Buffer += 20;
}
}
@@ -178,6 +199,56 @@ void GDBIndex::updateGdbIndexSection(
// Copy over the rest of the original data.
memcpy(Buffer, Data, TrailingSize);
+ // Fixup CU-indicies in constant pool.
+ const char *const OriginalConstantPoolData =
+ GdbIndexContents.data() + ConstantPoolOffset;
+ uint8_t *const UpdatedConstantPoolData =
+ NewGdbIndexContents + ConstantPoolOffset + Delta;
+
+ const char *OriginalSymbolTableData =
+ GdbIndexContents.data() + SymbolTableOffset;
+ std::set<uint32_t> CUVectorOffsets;
+ // Parse the symbol map and extract constant pool CU offsets from it.
+ while (OriginalSymbolTableData < OriginalConstantPoolData) {
+ const uint32_t NameOffset = read32le(OriginalSymbolTableData);
+ const uint32_t CUVectorOffset = read32le(OriginalSymbolTableData + 4);
+ OriginalSymbolTableData += 8;
+
+ // Iff both are zero, then the slot is considered empty in the hash-map.
+ if (NameOffset || CUVectorOffset) {
+ CUVectorOffsets.insert(CUVectorOffset);
+ }
+ }
+
+ // Update the CU-indicies in the constant pool
+ for (const auto CUVectorOffset : CUVectorOffsets) {
+ const char *CurrentOriginalConstantPoolData =
+ OriginalConstantPoolData + CUVectorOffset;
+ uint8_t *CurrentUpdatedConstantPoolData =
+ UpdatedConstantPoolData + CUVectorOffset;
+
+ const uint32_t Num = read32le(CurrentOriginalConstantPoolData);
+ CurrentOriginalConstantPoolData += 4;
+ CurrentUpdatedConstantPoolData += 4;
+
+ for (uint32_t J = 0; J < Num; ++J) {
+ const uint32_t OriginalCUIndexAndAttributes =
+ read32le(CurrentOriginalConstantPoolData);
+ CurrentOriginalConstantPoolData += 4;
+
+ // We only care for the index, which is the lowest 24 bits, other bits are
+ // left as is.
+ const uint32_t OriginalCUIndex =
+ OriginalCUIndexAndAttributes & ((1 << 24) - 1);
+ const uint32_t Attributes = OriginalCUIndexAndAttributes >> 24;
+ const uint32_t UpdatedCUIndexAndAttributes =
+ RemapCUIndex(OriginalCUIndex) | (Attributes << 24);
+
+ write32le(CurrentUpdatedConstantPoolData, UpdatedCUIndexAndAttributes);
+ CurrentUpdatedConstantPoolData += 4;
+ }
+ }
+
// Register the new section.
BC.registerOrUpdateNoteSection(".gdb_index", NewGdbIndexContents,
NewGdbIndexSize);
>From e7880538e7911cfe2d502f1628d4f48ce9080467 Mon Sep 17 00:00:00 2001
From: Ivan Trofimov <i.trofimow at yandex.ru>
Date: Mon, 4 Aug 2025 12:17:12 +0300
Subject: [PATCH 2/4] typo fixes
---
bolt/lib/Core/GDBIndex.cpp | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/bolt/lib/Core/GDBIndex.cpp b/bolt/lib/Core/GDBIndex.cpp
index 0fe1c5de94138..fbbbac1ee910f 100644
--- a/bolt/lib/Core/GDBIndex.cpp
+++ b/bolt/lib/Core/GDBIndex.cpp
@@ -132,7 +132,7 @@ void GDBIndex::updateGdbIndexSection(
});
// Create the original CU index -> updated CU index mapping,
// as the sort above could've changed the order and we have to update
- // indexes correspondingly in address map and constant pool.
+ // indices correspondingly in address map and constant pool.
std::unordered_map<uint32_t, uint32_t> OriginalCUIndexToUpdatedCUIndexMap;
OriginalCUIndexToUpdatedCUIndexMap.reserve(CUVector.size());
for (uint32_t I = 0; I < CUVector.size(); ++I) {
@@ -199,7 +199,7 @@ void GDBIndex::updateGdbIndexSection(
// Copy over the rest of the original data.
memcpy(Buffer, Data, TrailingSize);
- // Fixup CU-indicies in constant pool.
+ // Fixup CU-indices in constant pool.
const char *const OriginalConstantPoolData =
GdbIndexContents.data() + ConstantPoolOffset;
uint8_t *const UpdatedConstantPoolData =
>From 82a7610e46daec7e2f23b047875af14256d77057 Mon Sep 17 00:00:00 2001
From: Ivan Trofimov <i.trofimow at yandex.ru>
Date: Mon, 4 Aug 2025 20:45:11 +0300
Subject: [PATCH 3/4] fix the remapping logic for skipped CUs and indices into
CU TU List
---
bolt/lib/Core/GDBIndex.cpp | 40 ++++++++++++++++++++++++++------------
1 file changed, 28 insertions(+), 12 deletions(-)
diff --git a/bolt/lib/Core/GDBIndex.cpp b/bolt/lib/Core/GDBIndex.cpp
index fbbbac1ee910f..95d016292df86 100644
--- a/bolt/lib/Core/GDBIndex.cpp
+++ b/bolt/lib/Core/GDBIndex.cpp
@@ -125,6 +125,14 @@ void GDBIndex::updateGdbIndexSection(
using MapEntry = std::pair<uint32_t, CUInfo>;
std::vector<MapEntry> CUVector(CUMap.begin(), CUMap.end());
+ // Remove the CUs we won't emit anyway.
+ CUVector.erase(std::remove_if(CUVector.begin(), CUVector.end(),
+ [&OriginalOffsets](const MapEntry &It) {
+ // Skipping TU for DWARF5 when they are not
+ // included in CU list.
+ return OriginalOffsets.count(It.first) == 0;
+ }),
+ CUVector.end());
// Need to sort since we write out all of TUs in .debug_info before CUs.
std::sort(CUVector.begin(), CUVector.end(),
[](const MapEntry &E1, const MapEntry &E2) -> bool {
@@ -139,22 +147,30 @@ void GDBIndex::updateGdbIndexSection(
OriginalCUIndexToUpdatedCUIndexMap[OffsetToIndexMap.at(CUVector[I].first)] =
I;
}
- const auto RemapCUIndex =
- [&OriginalCUIndexToUpdatedCUIndexMap](uint32_t OriginalIndex) {
- const auto it = OriginalCUIndexToUpdatedCUIndexMap.find(OriginalIndex);
- if (it == OriginalCUIndexToUpdatedCUIndexMap.end()) {
- errs() << "BOLT-ERROR: .gdb_index unknown CU index\n";
- exit(1);
- }
+ const auto RemapCUIndex = [&OriginalCUIndexToUpdatedCUIndexMap,
+ CUVectorSize = CUVector.size(),
+ TUVectorSize = getGDBIndexTUEntryVector().size()](
+ uint32_t OriginalIndex) {
+ if (OriginalIndex >= CUVectorSize) {
+ if (OriginalIndex >= CUVectorSize + TUVectorSize) {
+ errs() << "BOLT-ERROR: .gdb_index unknown CU index\n";
+ exit(1);
+ }
+ // The index is into TU CU List, which we don't reorder, so return as is.
+ return OriginalIndex;
+ }
- return it->second;
- };
+ const auto It = OriginalCUIndexToUpdatedCUIndexMap.find(OriginalIndex);
+ if (It == OriginalCUIndexToUpdatedCUIndexMap.end()) {
+ errs() << "BOLT-ERROR: .gdb_index unknown CU index\n";
+ exit(1);
+ }
+
+ return It->second;
+ };
// Writing out CU List <Offset, Size>
for (auto &CUInfo : CUVector) {
- // Skipping TU for DWARF5 when they are not included in CU list.
- if (!OriginalOffsets.count(CUInfo.first))
- continue;
write64le(Buffer, CUInfo.second.Offset);
// Length encoded in CU doesn't contain first 4 bytes that encode length.
write64le(Buffer + 8, CUInfo.second.Length + 4);
>From c9cb15e738ca86c90d25e259446ae948627554d9 Mon Sep 17 00:00:00 2001
From: Ivan Trofimov <i.trofimow at yandex.ru>
Date: Tue, 5 Aug 2025 11:46:58 +0300
Subject: [PATCH 4/4] fix calculation of OffsetToIndexMap
---
bolt/lib/Core/GDBIndex.cpp | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/bolt/lib/Core/GDBIndex.cpp b/bolt/lib/Core/GDBIndex.cpp
index 95d016292df86..7ccbd2e50db68 100644
--- a/bolt/lib/Core/GDBIndex.cpp
+++ b/bolt/lib/Core/GDBIndex.cpp
@@ -77,7 +77,8 @@ void GDBIndex::updateGdbIndexSection(
exit(1);
}
DenseSet<uint64_t> OriginalOffsets;
- for (unsigned Index = 0, Units = BC.DwCtx->getNumCompileUnits();
+ for (unsigned Index = 0, PresentUnitsIndex = 0,
+ Units = BC.DwCtx->getNumCompileUnits();
Index < Units; ++Index) {
const DWARFUnit *CU = BC.DwCtx->getUnitAtIndex(Index);
if (SkipTypeUnits && CU->isTypeUnit())
@@ -90,7 +91,7 @@ void GDBIndex::updateGdbIndexSection(
}
OriginalOffsets.insert(Offset);
- OffsetToIndexMap[Offset] = Index;
+ OffsetToIndexMap[Offset] = PresentUnitsIndex++;
}
// Ignore old address table.
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