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https://github.com/c64scene-ar/llvm-6502.git
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@188422 91177308-0d34-0410-b5e6-96231b3b80d8
241 lines
7.9 KiB
C++
241 lines
7.9 KiB
C++
//===-- llvm/CodeGen/DIEHash.cpp - Dwarf Hashing Framework ----------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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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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#define DEBUG_TYPE "dwarfdebug"
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#include "DIE.h"
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#include "DIEHash.h"
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#include "DwarfCompileUnit.h"
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#include "llvm/ADT/ArrayRef.h"
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#include "llvm/ADT/StringRef.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/Dwarf.h"
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#include "llvm/Support/Endian.h"
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#include "llvm/Support/MD5.h"
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#include "llvm/Support/raw_ostream.h"
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using namespace llvm;
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/// \brief Grabs the string in whichever attribute is passed in and returns
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/// a reference to it.
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static StringRef getDIEStringAttr(DIE *Die, uint16_t Attr) {
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const SmallVectorImpl<DIEValue *> &Values = Die->getValues();
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const DIEAbbrev &Abbrevs = Die->getAbbrev();
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// Iterate through all the attributes until we find the one we're
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// looking for, if we can't find it return an empty string.
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for (size_t i = 0; i < Values.size(); ++i) {
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if (Abbrevs.getData()[i].getAttribute() == Attr) {
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DIEValue *V = Values[i];
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assert(isa<DIEString>(V) && "String requested. Not a string.");
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DIEString *S = cast<DIEString>(V);
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return S->getString();
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}
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}
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return StringRef("");
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}
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/// \brief Adds the string in \p Str to the hash. This also hashes
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/// a trailing NULL with the string.
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void DIEHash::addString(StringRef Str) {
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DEBUG(dbgs() << "Adding string " << Str << " to hash.\n");
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Hash.update(Str);
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Hash.update(makeArrayRef((uint8_t)'\0'));
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}
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// FIXME: The LEB128 routines are copied and only slightly modified out of
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// LEB128.h.
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/// \brief Adds the unsigned in \p Value to the hash encoded as a ULEB128.
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void DIEHash::addULEB128(uint64_t Value) {
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DEBUG(dbgs() << "Adding ULEB128 " << Value << " to hash.\n");
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do {
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uint8_t Byte = Value & 0x7f;
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Value >>= 7;
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if (Value != 0)
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Byte |= 0x80; // Mark this byte to show that more bytes will follow.
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Hash.update(Byte);
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} while (Value != 0);
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}
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/// \brief Including \p Parent adds the context of Parent to the hash..
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void DIEHash::addParentContext(DIE *Parent) {
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DEBUG(dbgs() << "Adding parent context to hash...\n");
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// [7.27.2] For each surrounding type or namespace beginning with the
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// outermost such construct...
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SmallVector<DIE *, 1> Parents;
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while (Parent->getTag() != dwarf::DW_TAG_compile_unit) {
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Parents.push_back(Parent);
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Parent = Parent->getParent();
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}
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// Reverse iterate over our list to go from the outermost construct to the
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// innermost.
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for (SmallVectorImpl<DIE *>::reverse_iterator I = Parents.rbegin(),
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E = Parents.rend();
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I != E; ++I) {
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DIE *Die = *I;
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// ... Append the letter "C" to the sequence...
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addULEB128('C');
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// ... Followed by the DWARF tag of the construct...
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addULEB128(Die->getTag());
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// ... Then the name, taken from the DW_AT_name attribute.
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StringRef Name = getDIEStringAttr(Die, dwarf::DW_AT_name);
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DEBUG(dbgs() << "... adding context: " << Name << "\n");
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if (!Name.empty())
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addString(Name);
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}
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}
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// Collect all of the attributes for a particular DIE in single structure.
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void DIEHash::collectAttributes(DIE *Die, DIEAttrs &Attrs) {
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const SmallVectorImpl<DIEValue *> &Values = Die->getValues();
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const DIEAbbrev &Abbrevs = Die->getAbbrev();
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#define COLLECT_ATTR(NAME) \
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Attrs.NAME.Val = Values[i]; \
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Attrs.NAME.Desc = &Abbrevs.getData()[i];
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for (size_t i = 0, e = Values.size(); i != e; ++i) {
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DEBUG(dbgs() << "Attribute: "
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<< dwarf::AttributeString(Abbrevs.getData()[i].getAttribute())
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<< " added.\n");
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switch (Abbrevs.getData()[i].getAttribute()) {
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case dwarf::DW_AT_name:
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COLLECT_ATTR(DW_AT_name);
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break;
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default:
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break;
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}
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}
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}
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// Hash an individual attribute \param Attr based on the type of attribute and
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// the form.
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void DIEHash::hashAttribute(AttrEntry Attr) {
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const DIEValue *Value = Attr.Val;
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const DIEAbbrevData *Desc = Attr.Desc;
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// TODO: Add support for types.
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// Add the letter A to the hash.
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addULEB128('A');
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// Then the attribute code and form.
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addULEB128(Desc->getAttribute());
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addULEB128(Desc->getForm());
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// TODO: Add support for additional forms.
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switch (Desc->getForm()) {
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case dwarf::DW_FORM_strp:
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addString(cast<DIEString>(Value)->getString());
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break;
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}
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}
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// Go through the attributes from \param Attrs in the order specified in 7.27.4
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// and hash them.
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void DIEHash::hashAttributes(const DIEAttrs &Attrs) {
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#define ADD_ATTR(ATTR) \
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{ \
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if (ATTR.Val != 0) \
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hashAttribute(ATTR); \
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}
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// FIXME: Add the rest.
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ADD_ATTR(Attrs.DW_AT_name);
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}
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// Add all of the attributes for \param Die to the hash.
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void DIEHash::addAttributes(DIE *Die) {
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DIEAttrs Attrs;
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memset(&Attrs, 0, sizeof(Attrs));
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collectAttributes(Die, Attrs);
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hashAttributes(Attrs);
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}
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// Compute the hash of a DIE. This is based on the type signature computation
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// given in section 7.27 of the DWARF4 standard. It is the md5 hash of a
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// flattened description of the DIE.
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void DIEHash::computeHash(DIE *Die) {
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// Append the letter 'D', followed by the DWARF tag of the DIE.
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addULEB128('D');
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addULEB128(Die->getTag());
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// Add each of the attributes of the DIE.
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addAttributes(Die);
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// Then hash each of the children of the DIE.
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for (std::vector<DIE *>::const_iterator I = Die->getChildren().begin(),
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E = Die->getChildren().end();
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I != E; ++I)
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computeHash(*I);
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}
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/// This is based on the type signature computation given in section 7.27 of the
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/// DWARF4 standard. It is the md5 hash of a flattened description of the DIE
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/// with the exception that we are hashing only the context and the name of the
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/// type.
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uint64_t DIEHash::computeDIEODRSignature(DIE *Die) {
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// Add the contexts to the hash. We won't be computing the ODR hash for
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// function local types so it's safe to use the generic context hashing
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// algorithm here.
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// FIXME: If we figure out how to account for linkage in some way we could
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// actually do this with a slight modification to the parent hash algorithm.
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DIE *Parent = Die->getParent();
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if (Parent)
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addParentContext(Parent);
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// Add the current DIE information.
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// Add the DWARF tag of the DIE.
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addULEB128(Die->getTag());
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// Add the name of the type to the hash.
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addString(getDIEStringAttr(Die, dwarf::DW_AT_name));
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// Now get the result.
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MD5::MD5Result Result;
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Hash.final(Result);
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// ... take the least significant 8 bytes and return those. Our MD5
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// implementation always returns its results in little endian, swap bytes
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// appropriately.
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return *reinterpret_cast<support::ulittle64_t *>(Result + 8);
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}
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/// This is based on the type signature computation given in section 7.27 of the
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/// DWARF4 standard. It is an md5 hash of the flattened description of the DIE
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/// with the inclusion of the full CU and all top level CU entities.
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uint64_t DIEHash::computeCUSignature(DIE *Die) {
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// Hash the DIE.
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computeHash(Die);
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// Now return the result.
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MD5::MD5Result Result;
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Hash.final(Result);
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// ... take the least significant 8 bytes and return those. Our MD5
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// implementation always returns its results in little endian, swap bytes
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// appropriately.
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return *reinterpret_cast<support::ulittle64_t *>(Result + 8);
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}
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