6ce13ae1c2
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
133 lines
3.2 KiB
C++
133 lines
3.2 KiB
C++
//===--- InterpStack.cpp - Stack implementation for the VM ------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "InterpStack.h"
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#include "Boolean.h"
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#include "FixedPoint.h"
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#include "Floating.h"
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#include "Integral.h"
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#include "MemberPointer.h"
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#include "Pointer.h"
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#include <cassert>
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#include <cstdlib>
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using namespace clang;
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using namespace clang::interp;
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InterpStack::~InterpStack() {
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if (Chunk && Chunk->Next)
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std::free(Chunk->Next);
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if (Chunk)
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std::free(Chunk);
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Chunk = nullptr;
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StackSize = 0;
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ItemTypes.clear();
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}
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// We keep the last chunk around to reuse.
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void InterpStack::clear() {
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for (PrimType Item : llvm::reverse(ItemTypes)) {
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TYPE_SWITCH(Item, { this->discard<T>(); });
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}
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assert(ItemTypes.empty());
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assert(empty());
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}
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void InterpStack::clearTo(size_t NewSize) {
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if (NewSize == 0)
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return clear();
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if (NewSize == size())
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return;
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assert(NewSize <= size());
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for (PrimType Item : llvm::reverse(ItemTypes)) {
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TYPE_SWITCH(Item, { this->discard<T>(); });
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if (size() == NewSize)
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break;
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}
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// Note: discard() above already removed the types from ItemTypes.
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assert(size() == NewSize);
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}
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void *InterpStack::grow(size_t Size) {
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assert(Size < ChunkSize - sizeof(StackChunk) && "Object too large");
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if (!Chunk || sizeof(StackChunk) + Chunk->size() + Size > ChunkSize) {
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if (Chunk && Chunk->Next) {
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Chunk = Chunk->Next;
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} else {
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StackChunk *Next = new (std::malloc(ChunkSize)) StackChunk(Chunk);
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if (Chunk)
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Chunk->Next = Next;
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Chunk = Next;
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}
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}
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auto *Object = reinterpret_cast<void *>(Chunk->End);
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Chunk->End += Size;
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StackSize += Size;
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return Object;
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}
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void *InterpStack::peekData(size_t Size) const {
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assert(Chunk && "Stack is empty!");
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StackChunk *Ptr = Chunk;
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while (Size > Ptr->size()) {
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Size -= Ptr->size();
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Ptr = Ptr->Prev;
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assert(Ptr && "Offset too large");
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}
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return reinterpret_cast<void *>(Ptr->End - Size);
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}
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void InterpStack::shrink(size_t Size) {
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assert(Chunk && "Chunk is empty!");
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while (Size > Chunk->size()) {
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Size -= Chunk->size();
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if (Chunk->Next) {
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std::free(Chunk->Next);
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Chunk->Next = nullptr;
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}
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Chunk->End = Chunk->start();
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Chunk = Chunk->Prev;
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assert(Chunk && "Offset too large");
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}
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Chunk->End -= Size;
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StackSize -= Size;
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}
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void InterpStack::dump() const {
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llvm::errs() << "Items: " << ItemTypes.size() << ". Size: " << size() << '\n';
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if (ItemTypes.empty())
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return;
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size_t Index = 0;
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size_t Offset = 0;
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// The type of the item on the top of the stack is inserted to the back
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// of the vector, so the iteration has to happen backwards.
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for (PrimType Item : llvm::reverse(ItemTypes)) {
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Offset += align(primSize(Item));
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llvm::errs() << Index << '/' << Offset << ": ";
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TYPE_SWITCH(Item, {
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const T &V = peek<T>(Offset);
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llvm::errs() << V;
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});
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llvm::errs() << '\n';
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++Index;
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}
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}
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