[BPF] Handling type conversions correctly for CO-RE
With newly added debuginfo type
metadata for preserve_array_access_index() intrinsic,
this patch did the following two things:
(1). checking validity before adding a new access index
to the access chain.
(2). calculating access byte offset in IR phase
BPFAbstractMemberAccess instead of when BTF is emitted.
For (1), the metadata provided by all preserve_*_access_index()
intrinsics are used to check whether the to-be-added type
is a proper struct/union member or array element.
For (2), with all available metadata, calculating access byte
offset becomes easier in BPFAbstractMemberAccess IR phase.
This enables us to remove the unnecessary complexity in
BTFDebug.cpp.
New tests are added for
. user explicit casting to array/structure/union
. global variable (or its dereference) as the source of base
. multi demensional arrays
. array access given a base pointer
. cases where we won't generate relocation if we cannot find
type name.
Differential Revision: https://reviews.llvm.org/D65618
llvm-svn: 367735
diff --git a/llvm/lib/Target/BPF/BTFDebug.cpp b/llvm/lib/Target/BPF/BTFDebug.cpp
index 5c542e7..9b966eb 100644
--- a/llvm/lib/Target/BPF/BTFDebug.cpp
+++ b/llvm/lib/Target/BPF/BTFDebug.cpp
@@ -30,18 +30,6 @@
#include "BTF.def"
};
-static const DIType * stripQualifiers(const DIType *Ty) {
- while (const auto *DTy = dyn_cast<DIDerivedType>(Ty)) {
- unsigned Tag = DTy->getTag();
- if (Tag != dwarf::DW_TAG_typedef && Tag != dwarf::DW_TAG_const_type &&
- Tag != dwarf::DW_TAG_volatile_type && Tag != dwarf::DW_TAG_restrict_type)
- break;
- Ty = DTy->getBaseType();
- }
-
- return Ty;
-}
-
/// Emit a BTF common type.
void BTFTypeBase::emitType(MCStreamer &OS) {
OS.AddComment(std::string(BTFKindStr[Kind]) + "(id = " + std::to_string(Id) +
@@ -196,9 +184,7 @@
}
}
-BTFTypeArray::BTFTypeArray(const DIType *Ty, uint32_t ElemTypeId,
- uint32_t ElemSize, uint32_t NumElems)
- : ElemTyNoQual(Ty), ElemSize(ElemSize) {
+BTFTypeArray::BTFTypeArray(uint32_t ElemTypeId, uint32_t NumElems) {
Kind = BTF::BTF_KIND_ARRAY;
BTFType.NameOff = 0;
BTFType.Info = Kind << 24;
@@ -219,9 +205,6 @@
// created during initial type traversal. Just
// retrieve that type id.
ArrayInfo.IndexType = BDebug.getArrayIndexTypeId();
-
- ElemTypeNoQual = ElemTyNoQual ? BDebug.getTypeId(ElemTyNoQual)
- : ArrayInfo.ElemType;
}
void BTFTypeArray::emitType(MCStreamer &OS) {
@@ -231,12 +214,6 @@
OS.EmitIntValue(ArrayInfo.Nelems, 4);
}
-void BTFTypeArray::getLocInfo(uint32_t Loc, uint32_t &LocOffset,
- uint32_t &ElementTypeId) {
- ElementTypeId = ElemTypeNoQual;
- LocOffset = Loc * ElemSize;
-}
-
/// Represent either a struct or a union.
BTFTypeStruct::BTFTypeStruct(const DICompositeType *STy, bool IsStruct,
bool HasBitField, uint32_t Vlen)
@@ -268,7 +245,6 @@
}
const auto *BaseTy = DDTy->getBaseType();
BTFMember.Type = BDebug.getTypeId(BaseTy);
- MemberTypeNoQual.push_back(BDebug.getTypeId(stripQualifiers(BaseTy)));
Members.push_back(BTFMember);
}
}
@@ -285,15 +261,6 @@
std::string BTFTypeStruct::getName() { return STy->getName(); }
-void BTFTypeStruct::getMemberInfo(uint32_t Loc, uint32_t &MemberOffset,
- uint32_t &MemberType) {
- MemberType = MemberTypeNoQual[Loc];
- MemberOffset =
- HasBitField ? Members[Loc].Offset & 0xffffff : Members[Loc].Offset;
-}
-
-uint32_t BTFTypeStruct::getStructSize() { return STy->getSizeInBits() >> 3; }
-
/// The Func kind represents both subprogram and pointee of function
/// pointers. If the FuncName is empty, it represents a pointee of function
/// pointer. Otherwise, it represents a subprogram. The func arg names
@@ -511,12 +478,10 @@
visitTypeEntry(ElemType, ElemTypeId, false, false);
// Strip qualifiers from element type to get accurate element size.
- ElemType = stripQualifiers(ElemType);
ElemSize = ElemType->getSizeInBits() >> 3;
if (!CTy->getSizeInBits()) {
- auto TypeEntry = llvm::make_unique<BTFTypeArray>(ElemType, ElemTypeId, 0, 0);
- ArrayTypes.push_back(TypeEntry.get());
+ auto TypeEntry = llvm::make_unique<BTFTypeArray>(ElemTypeId, 0);
ElemTypeId = addType(std::move(TypeEntry), CTy);
} else {
// Visit array dimensions.
@@ -527,12 +492,9 @@
const DISubrange *SR = cast<DISubrange>(Element);
auto *CI = SR->getCount().dyn_cast<ConstantInt *>();
int64_t Count = CI->getSExtValue();
- const DIType *ArrayElemTy = (I == 0) ? ElemType : nullptr;
auto TypeEntry =
- llvm::make_unique<BTFTypeArray>(ArrayElemTy, ElemTypeId,
- ElemSize, Count);
- ArrayTypes.push_back(TypeEntry.get());
+ llvm::make_unique<BTFTypeArray>(ElemTypeId, Count);
if (I == 0)
ElemTypeId = addType(std::move(TypeEntry), CTy);
else
@@ -1002,74 +964,22 @@
return Id;
}
-// Find struct/array debuginfo types given a type id.
-void BTFDebug::setTypeFromId(uint32_t TypeId, BTFTypeStruct **PrevStructType,
- BTFTypeArray **PrevArrayType) {
- for (const auto &StructType : StructTypes) {
- if (StructType->getId() == TypeId) {
- *PrevStructType = StructType;
- return;
- }
- }
- for (const auto &ArrayType : ArrayTypes) {
- if (ArrayType->getId() == TypeId) {
- *PrevArrayType = ArrayType;
- return;
- }
- }
-}
-
/// Generate a struct member offset relocation.
void BTFDebug::generateOffsetReloc(const MachineInstr *MI,
const MCSymbol *ORSym, DIType *RootTy,
StringRef AccessPattern) {
- BTFTypeStruct *PrevStructType = nullptr;
- BTFTypeArray *PrevArrayType = nullptr;
unsigned RootId = populateStructType(RootTy);
- setTypeFromId(RootId, &PrevStructType, &PrevArrayType);
- unsigned RootTySize = PrevStructType->getStructSize();
- StringRef IndexPattern = AccessPattern.substr(AccessPattern.find_first_of(':') + 1);
+ size_t FirstDollar = AccessPattern.find_first_of('$');
+ size_t FirstColon = AccessPattern.find_first_of(':');
+ StringRef IndexPattern = AccessPattern.substr(FirstDollar + 1);
+ StringRef OffsetStr = AccessPattern.substr(FirstColon + 1,
+ FirstDollar - FirstColon);
BTFOffsetReloc OffsetReloc;
OffsetReloc.Label = ORSym;
- OffsetReloc.OffsetNameOff = addString(IndexPattern.drop_back());
+ OffsetReloc.OffsetNameOff = addString(IndexPattern);
OffsetReloc.TypeID = RootId;
-
- uint32_t Start = 0, End = 0, Offset = 0;
- bool FirstAccess = true;
- for (auto C : IndexPattern) {
- if (C != ':') {
- End++;
- } else {
- std::string SubStr = IndexPattern.substr(Start, End - Start);
- int Loc = std::stoi(SubStr);
-
- if (FirstAccess) {
- Offset = Loc * RootTySize;
- FirstAccess = false;
- } else if (PrevStructType) {
- uint32_t MemberOffset, MemberTypeId;
- PrevStructType->getMemberInfo(Loc, MemberOffset, MemberTypeId);
-
- Offset += MemberOffset >> 3;
- PrevStructType = nullptr;
- setTypeFromId(MemberTypeId, &PrevStructType, &PrevArrayType);
- } else if (PrevArrayType) {
- uint32_t LocOffset, ElementTypeId;
- PrevArrayType->getLocInfo(Loc, LocOffset, ElementTypeId);
-
- Offset += LocOffset;
- PrevArrayType = nullptr;
- setTypeFromId(ElementTypeId, &PrevStructType, &PrevArrayType);
- } else {
- llvm_unreachable("Internal Error: BTF offset relocation type traversal error");
- }
-
- Start = End + 1;
- End = Start;
- }
- }
- AccessOffsets[AccessPattern.str()] = Offset;
+ AccessOffsets[AccessPattern.str()] = std::stoi(OffsetStr);
OffsetRelocTable[SecNameOff].push_back(OffsetReloc);
}