hwasan: add tag_offset DWARF attribute to optimized debug info
Summary:
Support alloca-referencing dbg.value in hwasan instrumentation.
Update AsmPrinter to emit DW_AT_LLVM_tag_offset when location is in
loclist format.
Reviewers: pcc
Subscribers: srhines, aprantl, hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D70753
diff --git a/llvm/lib/CodeGen/AsmPrinter/DebugLocStream.cpp b/llvm/lib/CodeGen/AsmPrinter/DebugLocStream.cpp
index f483d53..8c61098 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DebugLocStream.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DebugLocStream.cpp
@@ -42,4 +42,6 @@
return;
V.initializeDbgValue(&MI);
V.setDebugLocListIndex(ListIndex);
+ if (TagOffset)
+ V.setDebugLocListTagOffset(*TagOffset);
}
diff --git a/llvm/lib/CodeGen/AsmPrinter/DebugLocStream.h b/llvm/lib/CodeGen/AsmPrinter/DebugLocStream.h
index 0db86b0..10019a4 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DebugLocStream.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DebugLocStream.h
@@ -159,11 +159,17 @@
DbgVariable &V;
const MachineInstr &MI;
size_t ListIndex;
+ Optional<uint8_t> TagOffset;
public:
ListBuilder(DebugLocStream &Locs, DwarfCompileUnit &CU, AsmPrinter &Asm,
DbgVariable &V, const MachineInstr &MI)
- : Locs(Locs), Asm(Asm), V(V), MI(MI), ListIndex(Locs.startList(&CU)) {}
+ : Locs(Locs), Asm(Asm), V(V), MI(MI), ListIndex(Locs.startList(&CU)),
+ TagOffset(None) {}
+
+ void setTagOffset(uint8_t TO) {
+ TagOffset = TO;
+ }
/// Finalize the list.
///
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
index 4e90c10..0f3d8c6 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
@@ -615,6 +615,10 @@
unsigned Offset = DV.getDebugLocListIndex();
if (Offset != ~0U) {
addLocationList(*VariableDie, dwarf::DW_AT_location, Offset);
+ auto TagOffset = DV.getDebugLocListTagOffset();
+ if (TagOffset)
+ addUInt(*VariableDie, dwarf::DW_AT_LLVM_tag_offset, dwarf::DW_FORM_data1,
+ *TagOffset);
return VariableDie;
}
@@ -632,6 +636,10 @@
DwarfExpr.addUnsignedConstant(DVal->getInt());
DwarfExpr.addExpression(Expr);
addBlock(*VariableDie, dwarf::DW_AT_location, DwarfExpr.finalize());
+ if (DwarfExpr.TagOffset)
+ addUInt(*VariableDie, dwarf::DW_AT_LLVM_tag_offset,
+ dwarf::DW_FORM_data1, *DwarfExpr.TagOffset);
+
} else
addConstantValue(*VariableDie, DVal->getInt(), DV.getType());
} else if (DVal->isConstantFP()) {
@@ -1198,6 +1206,10 @@
// Now attach the location information to the DIE.
addBlock(Die, Attribute, DwarfExpr.finalize());
+
+ if (DwarfExpr.TagOffset)
+ addUInt(Die, dwarf::DW_AT_LLVM_tag_offset, dwarf::DW_FORM_data1,
+ *DwarfExpr.TagOffset);
}
/// Start with the address based on the location provided, and generate the
@@ -1228,6 +1240,10 @@
// Now attach the location information to the DIE.
addBlock(Die, Attribute, DwarfExpr.finalize());
+
+ if (DwarfExpr.TagOffset)
+ addUInt(Die, dwarf::DW_AT_LLVM_tag_offset, dwarf::DW_FORM_data1,
+ *DwarfExpr.TagOffset);
}
/// Add a Dwarf loclistptr attribute data and value.
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index 0a20de5..098b5a9 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -2275,6 +2275,8 @@
DwarfDebug::emitDebugLocValue(AP, BT, Value, DwarfExpr);
}
DwarfExpr.finalize();
+ if (DwarfExpr.TagOffset)
+ List.setTagOffset(*DwarfExpr.TagOffset);
}
void DwarfDebug::emitDebugLocEntryLocation(const DebugLocStream::Entry &Entry,
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
index 03949db..bdd1b25 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
@@ -118,6 +118,9 @@
class DbgVariable : public DbgEntity {
/// Offset in DebugLocs.
unsigned DebugLocListIndex = ~0u;
+ /// DW_OP_LLVM_tag_offset value from DebugLocs.
+ Optional<uint8_t> DebugLocListTagOffset;
+
/// Single value location description.
std::unique_ptr<DbgValueLoc> ValueLoc = nullptr;
@@ -174,6 +177,8 @@
void setDebugLocListIndex(unsigned O) { DebugLocListIndex = O; }
unsigned getDebugLocListIndex() const { return DebugLocListIndex; }
+ void setDebugLocListTagOffset(uint8_t O) { DebugLocListTagOffset = O; }
+ Optional<uint8_t> getDebugLocListTagOffset() const { return DebugLocListTagOffset; }
StringRef getName() const { return getVariable()->getName(); }
const DbgValueLoc *getValueLoc() const { return ValueLoc.get(); }
/// Get the FI entries, sorted by fragment offset.
diff --git a/llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp b/llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
index be5abd2..7e8f8e2 100644
--- a/llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/HWAddressSanitizer.cpp
@@ -222,7 +222,7 @@
Value *untagPointer(IRBuilder<> &IRB, Value *PtrLong);
bool instrumentStack(
SmallVectorImpl<AllocaInst *> &Allocas,
- DenseMap<AllocaInst *, std::vector<DbgDeclareInst *>> &AllocaDeclareMap,
+ DenseMap<AllocaInst *, std::vector<DbgVariableIntrinsic *>> &AllocaDbgMap,
SmallVectorImpl<Instruction *> &RetVec, Value *StackTag);
Value *readRegister(IRBuilder<> &IRB, StringRef Name);
bool instrumentLandingPads(SmallVectorImpl<Instruction *> &RetVec);
@@ -1016,7 +1016,7 @@
bool HWAddressSanitizer::instrumentStack(
SmallVectorImpl<AllocaInst *> &Allocas,
- DenseMap<AllocaInst *, std::vector<DbgDeclareInst *>> &AllocaDeclareMap,
+ DenseMap<AllocaInst *, std::vector<DbgVariableIntrinsic *>> &AllocaDbgMap,
SmallVectorImpl<Instruction *> &RetVec, Value *StackTag) {
// Ideally, we want to calculate tagged stack base pointer, and rewrite all
// alloca addresses using that. Unfortunately, offsets are not known yet
@@ -1038,11 +1038,15 @@
AI->replaceUsesWithIf(Replacement,
[AILong](Use &U) { return U.getUser() != AILong; });
- for (auto *DDI : AllocaDeclareMap.lookup(AI)) {
- DIExpression *OldExpr = DDI->getExpression();
- DIExpression *NewExpr = DIExpression::append(
- OldExpr, {dwarf::DW_OP_LLVM_tag_offset, RetagMask(N)});
- DDI->setArgOperand(2, MetadataAsValue::get(*C, NewExpr));
+ for (auto *DDI : AllocaDbgMap.lookup(AI)) {
+ // Prepend "tag_offset, N" to the dwarf expression.
+ // Tag offset logically applies to the alloca pointer, and it makes sense
+ // to put it at the beginning of the expression.
+ SmallVector<uint64_t, 8> NewOps = {dwarf::DW_OP_LLVM_tag_offset,
+ RetagMask(N)};
+ DDI->setArgOperand(
+ 2, MetadataAsValue::get(*C, DIExpression::prependOpcodes(
+ DDI->getExpression(), NewOps)));
}
size_t Size = getAllocaSizeInBytes(*AI);
@@ -1089,7 +1093,7 @@
SmallVector<AllocaInst*, 8> AllocasToInstrument;
SmallVector<Instruction*, 8> RetVec;
SmallVector<Instruction*, 8> LandingPadVec;
- DenseMap<AllocaInst *, std::vector<DbgDeclareInst *>> AllocaDeclareMap;
+ DenseMap<AllocaInst *, std::vector<DbgVariableIntrinsic *>> AllocaDbgMap;
for (auto &BB : F) {
for (auto &Inst : BB) {
if (ClInstrumentStack)
@@ -1103,9 +1107,10 @@
isa<CleanupReturnInst>(Inst))
RetVec.push_back(&Inst);
- if (auto *DDI = dyn_cast<DbgDeclareInst>(&Inst))
- if (auto *Alloca = dyn_cast_or_null<AllocaInst>(DDI->getAddress()))
- AllocaDeclareMap[Alloca].push_back(DDI);
+ if (auto *DDI = dyn_cast<DbgVariableIntrinsic>(&Inst))
+ if (auto *Alloca =
+ dyn_cast_or_null<AllocaInst>(DDI->getVariableLocation()))
+ AllocaDbgMap[Alloca].push_back(DDI);
if (InstrumentLandingPads && isa<LandingPadInst>(Inst))
LandingPadVec.push_back(&Inst);
@@ -1148,7 +1153,7 @@
if (!AllocasToInstrument.empty()) {
Value *StackTag =
ClGenerateTagsWithCalls ? nullptr : getStackBaseTag(EntryIRB);
- Changed |= instrumentStack(AllocasToInstrument, AllocaDeclareMap, RetVec,
+ Changed |= instrumentStack(AllocasToInstrument, AllocaDbgMap, RetVec,
StackTag);
}