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2bddab25db
Instead of hashing DIE offsets, hash DIE references the same as they would be when used outside of a loclist - that is, deep hash the type on first use, and hash the numbering on subsequent uses. This does produce different hashes for different type references, where it did not before (because we were hashing zero all the time - so it didn't matter what type was referenced, the hash would be identical). This also allows us to enforce that the DIE offset (& size) is not queried before it is used (which came up while investigating another bug recently).
113 lines
3.5 KiB
C++
113 lines
3.5 KiB
C++
//===-- llvm/CodeGen/DIEHash.h - Dwarf Hashing Framework -------*- 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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//
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// This file contains support for DWARF4 hashing of DIEs.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_LIB_CODEGEN_ASMPRINTER_DIEHASH_H
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#define LLVM_LIB_CODEGEN_ASMPRINTER_DIEHASH_H
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#include "llvm/ADT/DenseMap.h"
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#include "llvm/CodeGen/DIE.h"
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#include "llvm/Support/MD5.h"
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namespace llvm {
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class AsmPrinter;
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/// An object containing the capability of hashing and adding hash
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/// attributes onto a DIE.
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class DIEHash {
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// Collection of all attributes used in hashing a particular DIE.
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struct DIEAttrs {
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#define HANDLE_DIE_HASH_ATTR(NAME) DIEValue NAME;
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#include "DIEHashAttributes.def"
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};
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public:
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DIEHash(AsmPrinter *A = nullptr, DwarfCompileUnit *CU = nullptr)
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: AP(A), CU(CU) {}
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/// Computes the CU signature.
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uint64_t computeCUSignature(StringRef DWOName, const DIE &Die);
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/// Computes the type signature.
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uint64_t computeTypeSignature(const DIE &Die);
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// Helper routines to process parts of a DIE.
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private:
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/// Adds the parent context of \param Parent to the hash.
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void addParentContext(const DIE &Parent);
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/// Adds the attributes of \param Die to the hash.
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void addAttributes(const DIE &Die);
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/// Computes the full DWARF4 7.27 hash of the DIE.
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void computeHash(const DIE &Die);
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// Routines that add DIEValues to the hash.
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public:
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/// Adds \param Value to the hash.
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void update(uint8_t Value) { Hash.update(Value); }
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/// Encodes and adds \param Value to the hash as a ULEB128.
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void addULEB128(uint64_t Value);
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/// Encodes and adds \param Value to the hash as a SLEB128.
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void addSLEB128(int64_t Value);
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void hashRawTypeReference(const DIE &Entry);
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private:
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/// Adds \param Str to the hash and includes a NULL byte.
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void addString(StringRef Str);
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/// Collects the attributes of DIE \param Die into the \param Attrs
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/// structure.
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void collectAttributes(const DIE &Die, DIEAttrs &Attrs);
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/// Hashes the attributes in \param Attrs in order.
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void hashAttributes(const DIEAttrs &Attrs, dwarf::Tag Tag);
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/// Hashes the data in a block like DIEValue, e.g. DW_FORM_block or
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/// DW_FORM_exprloc.
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void hashBlockData(const DIE::const_value_range &Values);
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/// Hashes the contents pointed to in the .debug_loc section.
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void hashLocList(const DIELocList &LocList);
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/// Hashes an individual attribute.
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void hashAttribute(const DIEValue &Value, dwarf::Tag Tag);
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/// Hashes an attribute that refers to another DIE.
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void hashDIEEntry(dwarf::Attribute Attribute, dwarf::Tag Tag,
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const DIE &Entry);
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/// Hashes a reference to a named type in such a way that is
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/// independent of whether that type is described by a declaration or a
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/// definition.
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void hashShallowTypeReference(dwarf::Attribute Attribute, const DIE &Entry,
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StringRef Name);
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/// Hashes a reference to a previously referenced type DIE.
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void hashRepeatedTypeReference(dwarf::Attribute Attribute,
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unsigned DieNumber);
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void hashNestedType(const DIE &Die, StringRef Name);
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private:
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MD5 Hash;
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AsmPrinter *AP;
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DwarfCompileUnit *CU;
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DenseMap<const DIE *, unsigned> Numbering;
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};
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}
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#endif
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