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Diffstat (limited to 'contrib/llvm/lib/CodeGen/AsmPrinter/DIEHash.cpp')
| -rw-r--r-- | contrib/llvm/lib/CodeGen/AsmPrinter/DIEHash.cpp | 507 |
1 files changed, 507 insertions, 0 deletions
diff --git a/contrib/llvm/lib/CodeGen/AsmPrinter/DIEHash.cpp b/contrib/llvm/lib/CodeGen/AsmPrinter/DIEHash.cpp new file mode 100644 index 0000000..95eca90 --- /dev/null +++ b/contrib/llvm/lib/CodeGen/AsmPrinter/DIEHash.cpp @@ -0,0 +1,507 @@ +//===-- 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 "DIEHash.h" + +#include "DIE.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(const 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(const 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<const DIE *, 1> Parents; + const DIE *Cur = &Parent; + while (Cur->getTag() != dwarf::DW_TAG_compile_unit) { + Parents.push_back(Cur); + Cur = Cur->getParent(); + } + + // Reverse iterate over our list to go from the outermost construct to the + // innermost. + for (SmallVectorImpl<const DIE *>::reverse_iterator I = Parents.rbegin(), + E = Parents.rend(); + I != E; ++I) { + const 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(const DIE &Die, DIEAttrs &Attrs) { + const SmallVectorImpl<DIEValue *> &Values = Die.getValues(); + const DIEAbbrev &Abbrevs = Die.getAbbrev(); + +#define COLLECT_ATTR(NAME) \ + case dwarf::NAME: \ + Attrs.NAME.Val = Values[i]; \ + Attrs.NAME.Desc = &Abbrevs.getData()[i]; \ + break + + 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()) { + COLLECT_ATTR(DW_AT_name); + COLLECT_ATTR(DW_AT_accessibility); + COLLECT_ATTR(DW_AT_address_class); + COLLECT_ATTR(DW_AT_allocated); + COLLECT_ATTR(DW_AT_artificial); + COLLECT_ATTR(DW_AT_associated); + COLLECT_ATTR(DW_AT_binary_scale); + COLLECT_ATTR(DW_AT_bit_offset); + COLLECT_ATTR(DW_AT_bit_size); + COLLECT_ATTR(DW_AT_bit_stride); + COLLECT_ATTR(DW_AT_byte_size); + COLLECT_ATTR(DW_AT_byte_stride); + COLLECT_ATTR(DW_AT_const_expr); + COLLECT_ATTR(DW_AT_const_value); + COLLECT_ATTR(DW_AT_containing_type); + COLLECT_ATTR(DW_AT_count); + COLLECT_ATTR(DW_AT_data_bit_offset); + COLLECT_ATTR(DW_AT_data_location); + COLLECT_ATTR(DW_AT_data_member_location); + COLLECT_ATTR(DW_AT_decimal_scale); + COLLECT_ATTR(DW_AT_decimal_sign); + COLLECT_ATTR(DW_AT_default_value); + COLLECT_ATTR(DW_AT_digit_count); + COLLECT_ATTR(DW_AT_discr); + COLLECT_ATTR(DW_AT_discr_list); + COLLECT_ATTR(DW_AT_discr_value); + COLLECT_ATTR(DW_AT_encoding); + COLLECT_ATTR(DW_AT_enum_class); + COLLECT_ATTR(DW_AT_endianity); + COLLECT_ATTR(DW_AT_explicit); + COLLECT_ATTR(DW_AT_is_optional); + COLLECT_ATTR(DW_AT_location); + COLLECT_ATTR(DW_AT_lower_bound); + COLLECT_ATTR(DW_AT_mutable); + COLLECT_ATTR(DW_AT_ordering); + COLLECT_ATTR(DW_AT_picture_string); + COLLECT_ATTR(DW_AT_prototyped); + COLLECT_ATTR(DW_AT_small); + COLLECT_ATTR(DW_AT_segment); + COLLECT_ATTR(DW_AT_string_length); + COLLECT_ATTR(DW_AT_threads_scaled); + COLLECT_ATTR(DW_AT_upper_bound); + COLLECT_ATTR(DW_AT_use_location); + COLLECT_ATTR(DW_AT_use_UTF8); + COLLECT_ATTR(DW_AT_variable_parameter); + COLLECT_ATTR(DW_AT_virtuality); + COLLECT_ATTR(DW_AT_visibility); + COLLECT_ATTR(DW_AT_vtable_elem_location); + COLLECT_ATTR(DW_AT_type); + default: + break; + } + } +} + +void DIEHash::hashShallowTypeReference(dwarf::Attribute Attribute, + const DIE &Entry, StringRef Name) { + // append the letter 'N' + addULEB128('N'); + + // the DWARF attribute code (DW_AT_type or DW_AT_friend), + addULEB128(Attribute); + + // the context of the tag, + if (const DIE *Parent = Entry.getParent()) + addParentContext(*Parent); + + // the letter 'E', + addULEB128('E'); + + // and the name of the type. + addString(Name); + + // Currently DW_TAG_friends are not used by Clang, but if they do become so, + // here's the relevant spec text to implement: + // + // For DW_TAG_friend, if the referenced entry is the DW_TAG_subprogram, + // the context is omitted and the name to be used is the ABI-specific name + // of the subprogram (e.g., the mangled linker name). +} + +void DIEHash::hashRepeatedTypeReference(dwarf::Attribute Attribute, + unsigned DieNumber) { + // a) If T is in the list of [previously hashed types], use the letter + // 'R' as the marker + addULEB128('R'); + + addULEB128(Attribute); + + // and use the unsigned LEB128 encoding of [the index of T in the + // list] as the attribute value; + addULEB128(DieNumber); +} + +void DIEHash::hashDIEEntry(dwarf::Attribute Attribute, dwarf::Tag Tag, + const DIE &Entry) { + assert(Tag != dwarf::DW_TAG_friend && "No current LLVM clients emit friend " + "tags. Add support here when there's " + "a use case"); + // Step 5 + // If the tag in Step 3 is one of [the below tags] + if ((Tag == dwarf::DW_TAG_pointer_type || + Tag == dwarf::DW_TAG_reference_type || + Tag == dwarf::DW_TAG_rvalue_reference_type || + Tag == dwarf::DW_TAG_ptr_to_member_type) && + // and the referenced type (via the [below attributes]) + // FIXME: This seems overly restrictive, and causes hash mismatches + // there's a decl/def difference in the containing type of a + // ptr_to_member_type, but it's what DWARF says, for some reason. + Attribute == dwarf::DW_AT_type) { + // ... has a DW_AT_name attribute, + StringRef Name = getDIEStringAttr(Entry, dwarf::DW_AT_name); + if (!Name.empty()) { + hashShallowTypeReference(Attribute, Entry, Name); + return; + } + } + + unsigned &DieNumber = Numbering[&Entry]; + if (DieNumber) { + hashRepeatedTypeReference(Attribute, DieNumber); + return; + } + + // otherwise, b) use the letter 'T' as a the marker, ... + addULEB128('T'); + + addULEB128(Attribute); + + // ... process the type T recursively by performing Steps 2 through 7, and + // use the result as the attribute value. + DieNumber = Numbering.size(); + computeHash(Entry); +} + +// Hash an individual attribute \param Attr based on the type of attribute and +// the form. +void DIEHash::hashAttribute(AttrEntry Attr, dwarf::Tag Tag) { + const DIEValue *Value = Attr.Val; + const DIEAbbrevData *Desc = Attr.Desc; + dwarf::Attribute Attribute = Desc->getAttribute(); + + // 7.27 Step 3 + // ... An attribute that refers to another type entry T is processed as + // follows: + if (const DIEEntry *EntryAttr = dyn_cast<DIEEntry>(Value)) { + hashDIEEntry(Attribute, Tag, *EntryAttr->getEntry()); + return; + } + + // Other attribute values use the letter 'A' as the marker, ... + addULEB128('A'); + + addULEB128(Attribute); + + // ... and the value consists of the form code (encoded as an unsigned LEB128 + // value) followed by the encoding of the value according to the form code. 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. + 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_GNU_str_index: + 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; + default: + llvm_unreachable("Add support for additional forms"); + } +} + +// Go through the attributes from \param Attrs in the order specified in 7.27.4 +// and hash them. +void DIEHash::hashAttributes(const DIEAttrs &Attrs, dwarf::Tag Tag) { +#define ADD_ATTR(ATTR) \ + { \ + if (ATTR.Val != 0) \ + hashAttribute(ATTR, Tag); \ + } + + 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); + ADD_ATTR(Attrs.DW_AT_type); + + // FIXME: Add the extended attributes. +} + +// Add all of the attributes for \param Die to the hash. +void DIEHash::addAttributes(const DIE &Die) { + DIEAttrs Attrs = {}; + collectAttributes(Die, Attrs); + hashAttributes(Attrs, Die.getTag()); +} + +void DIEHash::hashNestedType(const DIE &Die, StringRef Name) { + // 7.27 Step 7 + // ... append the letter 'S', + addULEB128('S'); + + // the tag of C, + addULEB128(Die.getTag()); + + // and the name. + addString(Name); +} + +// 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(const 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) { + // 7.27 Step 7 + // If C is a nested type entry or a member function entry, ... + if (isType((*I)->getTag()) || (*I)->getTag() == dwarf::DW_TAG_subprogram) { + StringRef Name = getDIEStringAttr(**I, dwarf::DW_AT_name); + // ... and has a DW_AT_name attribute + if (!Name.empty()) { + hashNestedType(**I, Name); + continue; + } + } + 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(const 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. + if (const DIE *Parent = Die.getParent()) + 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(const DIE &Die) { + Numbering.clear(); + Numbering[&Die] = 1; + + // 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(const DIE &Die) { + Numbering.clear(); + Numbering[&Die] = 1; + + if (const DIE *Parent = Die.getParent()) + addParentContext(*Parent); + + // 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); +} |
