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c098708220
llvm-6502/lib/CodeGen/AsmPrinter/DIEHash.cpp
David Blaikie c098708220 DIEHash: Use DW_FORM_sdata for integers, per spec. 
This allows us to produce the same hash as GCC for at least some simple
examples.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@192855 91177308-0d34-0410-b5e6-96231b3b80d8
2013-10-16 23:36:20 +00:00

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//===-- llvm/CodeGen/DIEHash.cpp - Dwarf Hashing Framework ----------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains support for DWARF4 hashing of DIEs.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "dwarfdebug"
#include "DIE.h"
#include "DIEHash.h"
#include "DwarfCompileUnit.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/Dwarf.h"
#include "llvm/Support/Endian.h"
#include "llvm/Support/MD5.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
/// \brief Grabs the string in whichever attribute is passed in and returns
/// a reference to it.
static StringRef getDIEStringAttr(DIE *Die, uint16_t Attr) {
const SmallVectorImpl<DIEValue *> &Values = Die->getValues();
const DIEAbbrev &Abbrevs = Die->getAbbrev();
// Iterate through all the attributes until we find the one we're
// looking for, if we can't find it return an empty string.
for (size_t i = 0; i < Values.size(); ++i) {
if (Abbrevs.getData()[i].getAttribute() == Attr) {
DIEValue *V = Values[i];
assert(isa<DIEString>(V) && "String requested. Not a string.");
DIEString *S = cast<DIEString>(V);
return S->getString();
}
}
return StringRef("");
}
/// \brief Adds the string in \p Str to the hash. This also hashes
/// a trailing NULL with the string.
void DIEHash::addString(StringRef Str) {
DEBUG(dbgs() << "Adding string " << Str << " to hash.\n");
Hash.update(Str);
Hash.update(makeArrayRef((uint8_t)'\0'));
}
// FIXME: The LEB128 routines are copied and only slightly modified out of
// LEB128.h.
/// \brief Adds the unsigned in \p Value to the hash encoded as a ULEB128.
void DIEHash::addULEB128(uint64_t Value) {
DEBUG(dbgs() << "Adding ULEB128 " << Value << " to hash.\n");
do {
uint8_t Byte = Value & 0x7f;
Value >>= 7;
if (Value != 0)
Byte |= 0x80; // Mark this byte to show that more bytes will follow.
Hash.update(Byte);
} while (Value != 0);
}
void DIEHash::addSLEB128(int64_t Value) {
DEBUG(dbgs() << "Adding ULEB128 " << Value << " to hash.\n");
bool More;
do {
uint8_t Byte = Value & 0x7f;
Value >>= 7;
More = !((((Value == 0 ) && ((Byte & 0x40) == 0)) ||
((Value == -1) && ((Byte & 0x40) != 0))));
if (More)
Byte |= 0x80; // Mark this byte to show that more bytes will follow.
Hash.update(Byte);
} while (More);
}
/// \brief Including \p Parent adds the context of Parent to the hash..
void DIEHash::addParentContext(DIE *Parent) {
DEBUG(dbgs() << "Adding parent context to hash...\n");
// [7.27.2] For each surrounding type or namespace beginning with the
// outermost such construct...
SmallVector<DIE *, 1> Parents;
while (Parent->getTag() != dwarf::DW_TAG_compile_unit) {
Parents.push_back(Parent);
Parent = Parent->getParent();
}
// Reverse iterate over our list to go from the outermost construct to the
// innermost.
for (SmallVectorImpl<DIE *>::reverse_iterator I = Parents.rbegin(),
E = Parents.rend();
I != E; ++I) {
DIE *Die = *I;
// ... Append the letter "C" to the sequence...
addULEB128('C');
// ... Followed by the DWARF tag of the construct...
addULEB128(Die->getTag());
// ... Then the name, taken from the DW_AT_name attribute.
StringRef Name = getDIEStringAttr(Die, dwarf::DW_AT_name);
DEBUG(dbgs() << "... adding context: " << Name << "\n");
if (!Name.empty())
addString(Name);
}
}
// Collect all of the attributes for a particular DIE in single structure.
void DIEHash::collectAttributes(DIE *Die, DIEAttrs &Attrs) {
const SmallVectorImpl<DIEValue *> &Values = Die->getValues();
const DIEAbbrev &Abbrevs = Die->getAbbrev();
#define COLLECT_ATTR(NAME) \
Attrs.NAME.Val = Values[i]; \
Attrs.NAME.Desc = &Abbrevs.getData()[i];
for (size_t i = 0, e = Values.size(); i != e; ++i) {
DEBUG(dbgs() << "Attribute: "
<< dwarf::AttributeString(Abbrevs.getData()[i].getAttribute())
<< " added.\n");
switch (Abbrevs.getData()[i].getAttribute()) {
case dwarf::DW_AT_name:
COLLECT_ATTR(DW_AT_name);
break;
case dwarf::DW_AT_accessibility:
COLLECT_ATTR(DW_AT_accessibility)
break;
case dwarf::DW_AT_address_class:
COLLECT_ATTR(DW_AT_address_class)
break;
case dwarf::DW_AT_allocated:
COLLECT_ATTR(DW_AT_allocated)
break;
case dwarf::DW_AT_artificial:
COLLECT_ATTR(DW_AT_artificial)
break;
case dwarf::DW_AT_associated:
COLLECT_ATTR(DW_AT_associated)
break;
case dwarf::DW_AT_binary_scale:
COLLECT_ATTR(DW_AT_binary_scale)
break;
case dwarf::DW_AT_bit_offset:
COLLECT_ATTR(DW_AT_bit_offset)
break;
case dwarf::DW_AT_bit_size:
COLLECT_ATTR(DW_AT_bit_size)
break;
case dwarf::DW_AT_bit_stride:
COLLECT_ATTR(DW_AT_bit_stride)
break;
case dwarf::DW_AT_byte_size:
COLLECT_ATTR(DW_AT_byte_size)
break;
case dwarf::DW_AT_byte_stride:
COLLECT_ATTR(DW_AT_byte_stride)
break;
case dwarf::DW_AT_const_expr:
COLLECT_ATTR(DW_AT_const_expr)
break;
case dwarf::DW_AT_const_value:
COLLECT_ATTR(DW_AT_const_value)
break;
case dwarf::DW_AT_containing_type:
COLLECT_ATTR(DW_AT_containing_type)
break;
case dwarf::DW_AT_count:
COLLECT_ATTR(DW_AT_count)
break;
case dwarf::DW_AT_data_bit_offset:
COLLECT_ATTR(DW_AT_data_bit_offset)
break;
case dwarf::DW_AT_data_location:
COLLECT_ATTR(DW_AT_data_location)
break;
case dwarf::DW_AT_data_member_location:
COLLECT_ATTR(DW_AT_data_member_location)
break;
case dwarf::DW_AT_decimal_scale:
COLLECT_ATTR(DW_AT_decimal_scale)
break;
case dwarf::DW_AT_decimal_sign:
COLLECT_ATTR(DW_AT_decimal_sign)
break;
case dwarf::DW_AT_default_value:
COLLECT_ATTR(DW_AT_default_value)
break;
case dwarf::DW_AT_digit_count:
COLLECT_ATTR(DW_AT_digit_count)
break;
case dwarf::DW_AT_discr:
COLLECT_ATTR(DW_AT_discr)
break;
case dwarf::DW_AT_discr_list:
COLLECT_ATTR(DW_AT_discr_list)
break;
case dwarf::DW_AT_discr_value:
COLLECT_ATTR(DW_AT_discr_value)
break;
case dwarf::DW_AT_encoding:
COLLECT_ATTR(DW_AT_encoding)
break;
case dwarf::DW_AT_enum_class:
COLLECT_ATTR(DW_AT_enum_class)
break;
case dwarf::DW_AT_endianity:
COLLECT_ATTR(DW_AT_endianity)
break;
case dwarf::DW_AT_explicit:
COLLECT_ATTR(DW_AT_explicit)
break;
case dwarf::DW_AT_is_optional:
COLLECT_ATTR(DW_AT_is_optional)
break;
case dwarf::DW_AT_location:
COLLECT_ATTR(DW_AT_location)
break;
case dwarf::DW_AT_lower_bound:
COLLECT_ATTR(DW_AT_lower_bound)
break;
case dwarf::DW_AT_mutable:
COLLECT_ATTR(DW_AT_mutable)
break;
case dwarf::DW_AT_ordering:
COLLECT_ATTR(DW_AT_ordering)
break;
case dwarf::DW_AT_picture_string:
COLLECT_ATTR(DW_AT_picture_string)
break;
case dwarf::DW_AT_prototyped:
COLLECT_ATTR(DW_AT_prototyped)
break;
case dwarf::DW_AT_small:
COLLECT_ATTR(DW_AT_small)
break;
case dwarf::DW_AT_segment:
COLLECT_ATTR(DW_AT_segment)
break;
case dwarf::DW_AT_string_length:
COLLECT_ATTR(DW_AT_string_length)
break;
case dwarf::DW_AT_threads_scaled:
COLLECT_ATTR(DW_AT_threads_scaled)
break;
case dwarf::DW_AT_upper_bound:
COLLECT_ATTR(DW_AT_upper_bound)
break;
case dwarf::DW_AT_use_location:
COLLECT_ATTR(DW_AT_use_location)
break;
case dwarf::DW_AT_use_UTF8:
COLLECT_ATTR(DW_AT_use_UTF8)
break;
case dwarf::DW_AT_variable_parameter:
COLLECT_ATTR(DW_AT_variable_parameter)
break;
case dwarf::DW_AT_virtuality:
COLLECT_ATTR(DW_AT_virtuality)
break;
case dwarf::DW_AT_visibility:
COLLECT_ATTR(DW_AT_visibility)
break;
case dwarf::DW_AT_vtable_elem_location:
COLLECT_ATTR(DW_AT_vtable_elem_location)
break;
default:
break;
}
}
}
// Hash an individual attribute \param Attr based on the type of attribute and
// the form.
void DIEHash::hashAttribute(AttrEntry Attr) {
const DIEValue *Value = Attr.Val;
const DIEAbbrevData *Desc = Attr.Desc;
// TODO: Add support for types.
// Add the letter A to the hash.
addULEB128('A');
// Then the attribute code.
addULEB128(Desc->getAttribute());
// To ensure reproducibility of the signature, the set of forms used in the
// signature computation is limited to the following: DW_FORM_sdata,
// DW_FORM_flag, DW_FORM_string, and DW_FORM_block.
// TODO: Add support for additional forms.
switch (Desc->getForm()) {
case dwarf::DW_FORM_string:
llvm_unreachable(
"Add support for DW_FORM_string if we ever start emitting them again");
case dwarf::DW_FORM_strp:
addULEB128(dwarf::DW_FORM_string);
addString(cast<DIEString>(Value)->getString());
break;
case dwarf::DW_FORM_data1:
case dwarf::DW_FORM_data2:
case dwarf::DW_FORM_data4:
case dwarf::DW_FORM_data8:
case dwarf::DW_FORM_udata:
addULEB128(dwarf::DW_FORM_sdata);
addSLEB128((int64_t)cast<DIEInteger>(Value)->getValue());
break;
}
}
// Go through the attributes from \param Attrs in the order specified in 7.27.4
// and hash them.
void DIEHash::hashAttributes(const DIEAttrs &Attrs) {
#define ADD_ATTR(ATTR) \
{ \
if (ATTR.Val != 0) \
hashAttribute(ATTR); \
}
ADD_ATTR(Attrs.DW_AT_name);
ADD_ATTR(Attrs.DW_AT_accessibility);
ADD_ATTR(Attrs.DW_AT_address_class);
ADD_ATTR(Attrs.DW_AT_allocated);
ADD_ATTR(Attrs.DW_AT_artificial);
ADD_ATTR(Attrs.DW_AT_associated);
ADD_ATTR(Attrs.DW_AT_binary_scale);
ADD_ATTR(Attrs.DW_AT_bit_offset);
ADD_ATTR(Attrs.DW_AT_bit_size);
ADD_ATTR(Attrs.DW_AT_bit_stride);
ADD_ATTR(Attrs.DW_AT_byte_size);
ADD_ATTR(Attrs.DW_AT_byte_stride);
ADD_ATTR(Attrs.DW_AT_const_expr);
ADD_ATTR(Attrs.DW_AT_const_value);
ADD_ATTR(Attrs.DW_AT_containing_type);
ADD_ATTR(Attrs.DW_AT_count);
ADD_ATTR(Attrs.DW_AT_data_bit_offset);
ADD_ATTR(Attrs.DW_AT_data_location);
ADD_ATTR(Attrs.DW_AT_data_member_location);
ADD_ATTR(Attrs.DW_AT_decimal_scale);
ADD_ATTR(Attrs.DW_AT_decimal_sign);
ADD_ATTR(Attrs.DW_AT_default_value);
ADD_ATTR(Attrs.DW_AT_digit_count);
ADD_ATTR(Attrs.DW_AT_discr);
ADD_ATTR(Attrs.DW_AT_discr_list);
ADD_ATTR(Attrs.DW_AT_discr_value);
ADD_ATTR(Attrs.DW_AT_encoding);
ADD_ATTR(Attrs.DW_AT_enum_class);
ADD_ATTR(Attrs.DW_AT_endianity);
ADD_ATTR(Attrs.DW_AT_explicit);
ADD_ATTR(Attrs.DW_AT_is_optional);
ADD_ATTR(Attrs.DW_AT_location);
ADD_ATTR(Attrs.DW_AT_lower_bound);
ADD_ATTR(Attrs.DW_AT_mutable);
ADD_ATTR(Attrs.DW_AT_ordering);
ADD_ATTR(Attrs.DW_AT_picture_string);
ADD_ATTR(Attrs.DW_AT_prototyped);
ADD_ATTR(Attrs.DW_AT_small);
ADD_ATTR(Attrs.DW_AT_segment);
ADD_ATTR(Attrs.DW_AT_string_length);
ADD_ATTR(Attrs.DW_AT_threads_scaled);
ADD_ATTR(Attrs.DW_AT_upper_bound);
ADD_ATTR(Attrs.DW_AT_use_location);
ADD_ATTR(Attrs.DW_AT_use_UTF8);
ADD_ATTR(Attrs.DW_AT_variable_parameter);
ADD_ATTR(Attrs.DW_AT_virtuality);
ADD_ATTR(Attrs.DW_AT_visibility);
ADD_ATTR(Attrs.DW_AT_vtable_elem_location);
// FIXME: Add the extended attributes.
}
// Add all of the attributes for \param Die to the hash.
void DIEHash::addAttributes(DIE *Die) {
DIEAttrs Attrs = {};
collectAttributes(Die, Attrs);
hashAttributes(Attrs);
}
// Compute the hash of a DIE. This is based on the type signature computation
// given in section 7.27 of the DWARF4 standard. It is the md5 hash of a
// flattened description of the DIE.
void DIEHash::computeHash(DIE *Die) {
// Append the letter 'D', followed by the DWARF tag of the DIE.
addULEB128('D');
addULEB128(Die->getTag());
// Add each of the attributes of the DIE.
addAttributes(Die);
// Then hash each of the children of the DIE.
for (std::vector<DIE *>::const_iterator I = Die->getChildren().begin(),
E = Die->getChildren().end();
I != E; ++I)
computeHash(*I);
// Following the last (or if there are no children), append a zero byte.
Hash.update(makeArrayRef((uint8_t)'\0'));
}
/// This is based on the type signature computation given in section 7.27 of the
/// DWARF4 standard. It is the md5 hash of a flattened description of the DIE
/// with the exception that we are hashing only the context and the name of the
/// type.
uint64_t DIEHash::computeDIEODRSignature(DIE *Die) {
// Add the contexts to the hash. We won't be computing the ODR hash for
// function local types so it's safe to use the generic context hashing
// algorithm here.
// FIXME: If we figure out how to account for linkage in some way we could
// actually do this with a slight modification to the parent hash algorithm.
DIE *Parent = Die->getParent();
if (Parent)
addParentContext(Parent);
// Add the current DIE information.
// Add the DWARF tag of the DIE.
addULEB128(Die->getTag());
// Add the name of the type to the hash.
addString(getDIEStringAttr(Die, dwarf::DW_AT_name));
// Now get the result.
MD5::MD5Result Result;
Hash.final(Result);
// ... take the least significant 8 bytes and return those. Our MD5
// implementation always returns its results in little endian, swap bytes
// appropriately.
return *reinterpret_cast<support::ulittle64_t *>(Result + 8);
}
/// This is based on the type signature computation given in section 7.27 of the
/// DWARF4 standard. It is an md5 hash of the flattened description of the DIE
/// with the inclusion of the full CU and all top level CU entities.
// TODO: Initialize the type chain at 0 instead of 1 for CU signatures.
uint64_t DIEHash::computeCUSignature(DIE *Die) {
// Hash the DIE.
computeHash(Die);
// Now return the result.
MD5::MD5Result Result;
Hash.final(Result);
// ... take the least significant 8 bytes and return those. Our MD5
// implementation always returns its results in little endian, swap bytes
// appropriately.
return *reinterpret_cast<support::ulittle64_t *>(Result + 8);
}
/// This is based on the type signature computation given in section 7.27 of the
/// DWARF4 standard. It is an md5 hash of the flattened description of the DIE
/// with the inclusion of additional forms not specifically called out in the
/// standard.
uint64_t DIEHash::computeTypeSignature(DIE *Die) {
// Hash the DIE.
computeHash(Die);
// Now return the result.
MD5::MD5Result Result;
Hash.final(Result);
// ... take the least significant 8 bytes and return those. Our MD5
// implementation always returns its results in little endian, swap bytes
// appropriately.
return *reinterpret_cast<support::ulittle64_t *>(Result + 8);
}
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