https://github.com/tbaederr created https://github.com/llvm/llvm-project/pull/151088
This has been a long-standing problem, but we didn't use to call the destructors of items on the stack unless we explicitly `pop()` or `discard()` them. When interpretation was interrupted midway-through (because something failed), we left `Pointer`s on the stack. Since all `Block`s track what `Pointer`s point to them (via a doubly-linked list in the `Pointer`), that meant we potentially leave deallocated pointers in that list. We used to work around this by removing the `Pointer` from the list before deallocating the block. However, we now want to track pointers to global blocks as well, which poses a problem since the blocks are never deallocated and thus those pointers are always left dangling. I've tried a few different approaches to fixing this but in the end I just gave up on the idea of never knowing what items are in the stack. We already have an `ItemTypes` vector that we use for debugging assertions. This patch simply enables this vector unconditionally and uses it in the abort case to properly `discard()` all elements from the stack. That's a little sad IMO but I don't know of another way of solving this problem. As expected, this is a slight hit to compile times: https://llvm-compile-time-tracker.com/compare.php?from=574d0a92060bf4808776b7a0239ffe91a092b15d&to=0317105f559093cfb909bfb01857a6b837991940&stat=instructions:u >From a41e7d4e8ade678f8d3c16633478788f4eb5a375 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Timm=20B=C3=A4der?= <tbae...@redhat.com> Date: Fri, 25 Jul 2025 15:33:00 +0200 Subject: [PATCH] Always do ItemTypes --- clang/lib/AST/ByteCode/Context.cpp | 14 ++----- clang/lib/AST/ByteCode/Context.h | 2 +- clang/lib/AST/ByteCode/Descriptor.h | 2 +- clang/lib/AST/ByteCode/Function.h | 2 +- clang/lib/AST/ByteCode/InterpBlock.cpp | 12 ------ clang/lib/AST/ByteCode/InterpBlock.h | 4 +- clang/lib/AST/ByteCode/InterpStack.cpp | 57 +++++++++----------------- clang/lib/AST/ByteCode/InterpStack.h | 26 ++++-------- clang/lib/AST/ByteCode/InterpState.cpp | 15 ++++--- clang/lib/AST/ByteCode/Pointer.h | 2 +- clang/lib/AST/ByteCode/PrimType.h | 7 ++-- 11 files changed, 52 insertions(+), 91 deletions(-) diff --git a/clang/lib/AST/ByteCode/Context.cpp b/clang/lib/AST/ByteCode/Context.cpp index aaeb52e0fa449..db10f830f4d4c 100644 --- a/clang/lib/AST/ByteCode/Context.cpp +++ b/clang/lib/AST/ByteCode/Context.cpp @@ -397,17 +397,11 @@ const llvm::fltSemantics &Context::getFloatSemantics(QualType T) const { } bool Context::Run(State &Parent, const Function *Func) { - - { - InterpState State(Parent, *P, Stk, *this, Func); - if (Interpret(State)) { - assert(Stk.empty()); - return true; - } - // State gets destroyed here, so the Stk.clear() below doesn't accidentally - // remove values the State's destructor might access. + InterpState State(Parent, *P, Stk, *this, Func); + if (Interpret(State)) { + assert(Stk.empty()); + return true; } - Stk.clear(); return false; } diff --git a/clang/lib/AST/ByteCode/Context.h b/clang/lib/AST/ByteCode/Context.h index 62ef5297bd19f..d290b994cc32e 100644 --- a/clang/lib/AST/ByteCode/Context.h +++ b/clang/lib/AST/ByteCode/Context.h @@ -30,7 +30,7 @@ namespace interp { class Function; class Program; class State; -enum PrimType : unsigned; +enum PrimType : uint8_t; struct ParamOffset { unsigned Offset; diff --git a/clang/lib/AST/ByteCode/Descriptor.h b/clang/lib/AST/ByteCode/Descriptor.h index 4c925f6f0af1e..497789293a15a 100644 --- a/clang/lib/AST/ByteCode/Descriptor.h +++ b/clang/lib/AST/ByteCode/Descriptor.h @@ -24,7 +24,7 @@ class Record; class SourceInfo; struct InitMap; struct Descriptor; -enum PrimType : unsigned; +enum PrimType : uint8_t; using DeclTy = llvm::PointerUnion<const Decl *, const Expr *>; using InitMapPtr = std::optional<std::pair<bool, std::shared_ptr<InitMap>>>; diff --git a/clang/lib/AST/ByteCode/Function.h b/clang/lib/AST/ByteCode/Function.h index de88f3ded34dc..18274c2b53644 100644 --- a/clang/lib/AST/ByteCode/Function.h +++ b/clang/lib/AST/ByteCode/Function.h @@ -28,7 +28,7 @@ namespace interp { class Program; class ByteCodeEmitter; class Pointer; -enum PrimType : uint32_t; +enum PrimType : uint8_t; /// Describes a scope block. /// diff --git a/clang/lib/AST/ByteCode/InterpBlock.cpp b/clang/lib/AST/ByteCode/InterpBlock.cpp index f60307870ffcc..ef1203b6a1b10 100644 --- a/clang/lib/AST/ByteCode/InterpBlock.cpp +++ b/clang/lib/AST/ByteCode/InterpBlock.cpp @@ -18,10 +18,6 @@ using namespace clang::interp; void Block::addPointer(Pointer *P) { assert(P); - if (IsStatic) { - assert(!Pointers); - return; - } #ifndef NDEBUG assert(!hasPointer(P)); @@ -39,10 +35,6 @@ void Block::addPointer(Pointer *P) { void Block::removePointer(Pointer *P) { assert(P->isBlockPointer()); assert(P); - if (IsStatic) { - assert(!Pointers); - return; - } #ifndef NDEBUG assert(hasPointer(P)); @@ -70,10 +62,6 @@ void Block::replacePointer(Pointer *Old, Pointer *New) { assert(Old); assert(New); assert(Old != New); - if (IsStatic) { - assert(!Pointers); - return; - } #ifndef NDEBUG assert(hasPointer(Old)); #endif diff --git a/clang/lib/AST/ByteCode/InterpBlock.h b/clang/lib/AST/ByteCode/InterpBlock.h index 51622238e275c..e1765cd564cb8 100644 --- a/clang/lib/AST/ByteCode/InterpBlock.h +++ b/clang/lib/AST/ByteCode/InterpBlock.h @@ -22,7 +22,7 @@ class Block; class DeadBlock; class InterpState; class Pointer; -enum PrimType : unsigned; +enum PrimType : uint8_t; /// A memory block, either on the stack or in the heap. /// @@ -126,7 +126,7 @@ class Block final { void dump() const { dump(llvm::errs()); } void dump(llvm::raw_ostream &OS) const; -private: +public: friend class Pointer; friend class DeadBlock; friend class InterpState; diff --git a/clang/lib/AST/ByteCode/InterpStack.cpp b/clang/lib/AST/ByteCode/InterpStack.cpp index 6b748d62b83bd..7920378f365f9 100644 --- a/clang/lib/AST/ByteCode/InterpStack.cpp +++ b/clang/lib/AST/ByteCode/InterpStack.cpp @@ -26,33 +26,33 @@ InterpStack::~InterpStack() { std::free(Chunk); Chunk = nullptr; StackSize = 0; -#ifndef NDEBUG ItemTypes.clear(); -#endif } // We keep the last chunk around to reuse. void InterpStack::clear() { - if (!Chunk) - return; - - if (Chunk->Next) - std::free(Chunk->Next); - - assert(Chunk); - StackSize = 0; -#ifndef NDEBUG - ItemTypes.clear(); -#endif + for (PrimType Item : llvm::reverse(ItemTypes)) { + TYPE_SWITCH(Item, { this->discard<T>(); }); + } + assert(ItemTypes.empty()); + assert(empty()); } void InterpStack::clearTo(size_t NewSize) { - assert(NewSize <= size()); - size_t ToShrink = size() - NewSize; - if (ToShrink == 0) + if (NewSize == 0) + return clear(); + if (NewSize == size()) return; - shrink(ToShrink); + assert(NewSize <= size()); + for (PrimType Item : llvm::reverse(ItemTypes)) { + TYPE_SWITCH(Item, { this->discard<T>(); }); + + if (size() == NewSize) + break; + } + + // Note: discard() above already removed the types from ItemTypes. assert(size() == NewSize); } @@ -105,25 +105,9 @@ void InterpStack::shrink(size_t Size) { Chunk->End -= Size; StackSize -= Size; - -#ifndef NDEBUG - size_t TypesSize = 0; - for (PrimType T : ItemTypes) - TYPE_SWITCH(T, { TypesSize += aligned_size<T>(); }); - - size_t StackSize = size(); - while (TypesSize > StackSize) { - TYPE_SWITCH(ItemTypes.back(), { - TypesSize -= aligned_size<T>(); - ItemTypes.pop_back(); - }); - } - assert(TypesSize == StackSize); -#endif } void InterpStack::dump() const { -#ifndef NDEBUG llvm::errs() << "Items: " << ItemTypes.size() << ". Size: " << size() << '\n'; if (ItemTypes.empty()) return; @@ -133,11 +117,11 @@ void InterpStack::dump() const { // The type of the item on the top of the stack is inserted to the back // of the vector, so the iteration has to happen backwards. - for (auto TyIt = ItemTypes.rbegin(); TyIt != ItemTypes.rend(); ++TyIt) { - Offset += align(primSize(*TyIt)); + for (PrimType Item : llvm::reverse(ItemTypes)) { + Offset += align(primSize(Item)); llvm::errs() << Index << '/' << Offset << ": "; - TYPE_SWITCH(*TyIt, { + TYPE_SWITCH(Item, { const T &V = peek<T>(Offset); llvm::errs() << V; }); @@ -145,5 +129,4 @@ void InterpStack::dump() const { ++Index; } -#endif } diff --git a/clang/lib/AST/ByteCode/InterpStack.h b/clang/lib/AST/ByteCode/InterpStack.h index 0b76f1d650580..b0f9f6e225682 100644 --- a/clang/lib/AST/ByteCode/InterpStack.h +++ b/clang/lib/AST/ByteCode/InterpStack.h @@ -14,12 +14,9 @@ #define LLVM_CLANG_AST_INTERP_INTERPSTACK_H #include "FixedPoint.h" -#include "FunctionPointer.h" #include "IntegralAP.h" #include "MemberPointer.h" #include "PrimType.h" -#include <memory> -#include <vector> namespace clang { namespace interp { @@ -35,18 +32,14 @@ class InterpStack final { /// Constructs a value in place on the top of the stack. template <typename T, typename... Tys> void push(Tys &&...Args) { new (grow(aligned_size<T>())) T(std::forward<Tys>(Args)...); -#ifndef NDEBUG ItemTypes.push_back(toPrimType<T>()); -#endif } /// Returns the value from the top of the stack and removes it. template <typename T> T pop() { -#ifndef NDEBUG assert(!ItemTypes.empty()); assert(ItemTypes.back() == toPrimType<T>()); ItemTypes.pop_back(); -#endif T *Ptr = &peekInternal<T>(); T Value = std::move(*Ptr); shrink(aligned_size<T>()); @@ -55,22 +48,20 @@ class InterpStack final { /// Discards the top value from the stack. template <typename T> void discard() { -#ifndef NDEBUG assert(!ItemTypes.empty()); assert(ItemTypes.back() == toPrimType<T>()); ItemTypes.pop_back(); -#endif T *Ptr = &peekInternal<T>(); - Ptr->~T(); + if constexpr (!std::is_trivially_destructible_v<T>) { + Ptr->~T(); + } shrink(aligned_size<T>()); } /// Returns a reference to the value on the top of the stack. template <typename T> T &peek() const { -#ifndef NDEBUG assert(!ItemTypes.empty()); assert(ItemTypes.back() == toPrimType<T>()); -#endif return peekInternal<T>(); } @@ -85,7 +76,7 @@ class InterpStack final { /// Returns the size of the stack in bytes. size_t size() const { return StackSize; } - /// Clears the stack without calling any destructors. + /// Clears the stack. void clear(); void clearTo(size_t NewSize); @@ -148,9 +139,11 @@ class InterpStack final { /// Total size of the stack. size_t StackSize = 0; -#ifndef NDEBUG - /// vector recording the type of data we pushed into the stack. - std::vector<PrimType> ItemTypes; + /// SmallVector recording the type of data we pushed into the stack. + /// We don't usually need this during normal code interpretation but + /// when aborting, we need type information to call the destructors + /// for what's left on the stack. + llvm::SmallVector<PrimType> ItemTypes; template <typename T> static constexpr PrimType toPrimType() { if constexpr (std::is_same_v<T, Pointer>) @@ -194,7 +187,6 @@ class InterpStack final { llvm_unreachable("unknown type push()'ed into InterpStack"); } -#endif }; } // namespace interp diff --git a/clang/lib/AST/ByteCode/InterpState.cpp b/clang/lib/AST/ByteCode/InterpState.cpp index 7848f298cfec8..76dbc8dc654bb 100644 --- a/clang/lib/AST/ByteCode/InterpState.cpp +++ b/clang/lib/AST/ByteCode/InterpState.cpp @@ -43,6 +43,12 @@ InterpState::~InterpState() { while (DeadBlocks) { DeadBlock *Next = DeadBlocks->Next; + + // There might be a pointer in a global structure pointing to the dead + // block. + for (Pointer *P = DeadBlocks->B.Pointers; P; P = P->Next) + DeadBlocks->B.removePointer(P); + std::free(DeadBlocks); DeadBlocks = Next; } @@ -51,12 +57,6 @@ InterpState::~InterpState() { void InterpState::cleanup() { // As a last resort, make sure all pointers still pointing to a dead block // don't point to it anymore. - for (DeadBlock *DB = DeadBlocks; DB; DB = DB->Next) { - for (Pointer *P = DB->B.Pointers; P; P = P->Next) { - P->PointeeStorage.BS.Pointee = nullptr; - } - } - Alloc.cleanup(); } @@ -77,6 +77,9 @@ void InterpState::deallocate(Block *B) { const Descriptor *Desc = B->getDescriptor(); assert(Desc); + assert(!B->isStatic()); + assert(!B->IsDead); + if (B->hasPointers()) { size_t Size = B->getSize(); diff --git a/clang/lib/AST/ByteCode/Pointer.h b/clang/lib/AST/ByteCode/Pointer.h index d17eba5da9ca6..cd052eb978bc1 100644 --- a/clang/lib/AST/ByteCode/Pointer.h +++ b/clang/lib/AST/ByteCode/Pointer.h @@ -29,7 +29,7 @@ class DeadBlock; class Pointer; class Context; template <unsigned A, bool B> class Integral; -enum PrimType : unsigned; +enum PrimType : uint8_t; class Pointer; inline llvm::raw_ostream &operator<<(llvm::raw_ostream &OS, const Pointer &P); diff --git a/clang/lib/AST/ByteCode/PrimType.h b/clang/lib/AST/ByteCode/PrimType.h index 38c29b9f82672..d2ad7716e5e9c 100644 --- a/clang/lib/AST/ByteCode/PrimType.h +++ b/clang/lib/AST/ByteCode/PrimType.h @@ -32,7 +32,7 @@ template <bool Signed> class IntegralAP; template <unsigned Bits, bool Signed> class Integral; /// Enumeration of the primitive types of the VM. -enum PrimType : unsigned { +enum PrimType : uint8_t { PT_Sint8 = 0, PT_Uint8 = 1, PT_Sint16 = 2, @@ -52,14 +52,15 @@ enum PrimType : unsigned { // Like std::optional<PrimType>, but only sizeof(PrimType). class OptPrimType final { - unsigned V = ~0u; + static constexpr uint8_t None = 255; + uint8_t V = None; public: OptPrimType() = default; OptPrimType(std::nullopt_t) {} OptPrimType(PrimType T) : V(static_cast<unsigned>(T)) {} - explicit constexpr operator bool() const { return V != ~0u; } + explicit constexpr operator bool() const { return V != None; } PrimType operator*() const { assert(operator bool()); return static_cast<PrimType>(V); _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
