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[DebugInfo/AccelTable] Fix inconsistency in getDIEOffset implementations

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Summary:
Even though the getDIEOffset offset function was common for the two
accelerator table implementations, it was doing two different things:
for the Apple tables, it was returning the die offset relative to the
start of the section, whereas for DWARF v5 tables, it was relative to
the start of the CU.

I resolve this by renaming the function to getDIESectionOffset to make
it obvious what the function returns, and change the DWARF
implementation to return the section offset. I also keep the CU-relative
accessor, but only in the DWARF implementation (there is no way to get
this information for the Apple tables). This was not caught by existing
tests because the hand-written inputs also erroneously used section
offsets instead of CU-relative ones.

While looking at this, I noticed that the Apple implementation was not
fully correct either -- the header contains a DIEOffsetBase field, which
should be added to offsets encoded with the DW_FORM_ref*** family, but
this was not being used. This went unnoticed because all current writers
set this field to zero anyway. I fix this as well and add a hand-written
test which demonstrates the issue.

Reviewers: JDevlieghere, dblaikie

Subscribers: aprantl, llvm-commits

Differential Revision: https://reviews.llvm.org/D44202

llvm-svn: 327116
This commit is contained in:
Pavel Labath 2018-03-09 11:58:59 +00:00
parent 97a6546bf9
commit d9d89d6390
6 changed files with 204 additions and 20 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
include/llvm/DebugInfo/DWARF/DWARFAcceleratorTable.h
View File

@ -56,10 +56,11 @@ public:
/// in this Accelerator Entry.
virtual Optional<uint64_t> getCUOffset() const = 0;
/// Returns the Offset of the Debug Info Entry associated with this
/// Returns the Section Offset of the Debug Info Entry associated with this
/// Accelerator Entry or None if the DIE offset is not recorded in this
/// Accelerator Entry.
virtual Optional<uint64_t> getDIEOffset() const = 0;
/// Accelerator Entry. The returned offset is relative to the start of the
/// Section containing the DIE.
virtual Optional<uint64_t> getDIESectionOffset() const = 0;
/// Returns the Tag of the Debug Info Entry associated with this
/// Accelerator Entry or None if the Tag is not recorded in this
@ -104,6 +105,8 @@ class AppleAcceleratorTable : public DWARFAcceleratorTable {
uint32_t DIEOffsetBase;
SmallVector<std::pair<AtomType, Form>, 3> Atoms;
Optional<uint64_t> extractOffset(Optional<DWARFFormValue> Value) const;
};
struct Header Hdr;
@ -127,7 +130,7 @@ public:
public:
Optional<uint64_t> getCUOffset() const override;
Optional<uint64_t> getDIEOffset() const override;
Optional<uint64_t> getDIESectionOffset() const override;
Optional<dwarf::Tag> getTag() const override;
/// Returns the value of the Atom in this Accelerator Entry, if the Entry
@ -284,18 +287,24 @@ public:
/// Index or None if this Accelerator Entry does not have an associated
/// Compilation Unit. It is up to the user to verify that the returned Index
/// is valid in the owning NameIndex (or use getCUOffset(), which will
/// handle that check itself).
/// handle that check itself). Note that entries in NameIndexes which index
/// just a single Compilation Unit are implicitly associated with that unit,
/// so this function will return 0 even without an explicit
/// DW_IDX_compile_unit attribute.
Optional<uint64_t> getCUIndex() const;
public:
Optional<uint64_t> getCUOffset() const override;
Optional<uint64_t> getDIEOffset() const override;
Optional<uint64_t> getDIESectionOffset() const override;
Optional<dwarf::Tag> getTag() const override { return tag(); }
/// .debug_names-specific getter, which always succeeds (DWARF v5 index
/// entries always have a tag).
dwarf::Tag tag() const { return Abbr->Tag; }
/// Returns the Offset of the DIE within the containing CU or TU.
Optional<uint64_t> getDIEUnitOffset() const;
/// Return the Abbreviation that can be used to interpret the raw values of
/// this Accelerator Entry.
const Abbrev &getAbbrev() const { return *Abbr; }

41
lib/DebugInfo/DWARF/DWARFAcceleratorTable.cpp
View File

@ -159,6 +159,23 @@ void AppleAcceleratorTable::Header::dump(ScopedPrinter &W) const {
W.printNumber("HeaderData length", HeaderDataLength);
}
Optional<uint64_t> AppleAcceleratorTable::HeaderData::extractOffset(
Optional<DWARFFormValue> Value) const {
if (!Value)
return None;
switch (Value->getForm()) {
case dwarf::DW_FORM_ref1:
case dwarf::DW_FORM_ref2:
case dwarf::DW_FORM_ref4:
case dwarf::DW_FORM_ref8:
case dwarf::DW_FORM_ref_udata:
return Value->getRawUValue() + DIEOffsetBase;
default:
return Value->getAsSectionOffset();
}
}
bool AppleAcceleratorTable::dumpName(ScopedPrinter &W,
SmallVectorImpl<DWARFFormValue> &AtomForms,
uint32_t *DataOffset) const {
@ -276,16 +293,12 @@ AppleAcceleratorTable::Entry::lookup(HeaderData::AtomType Atom) const {
return None;
}
Optional<uint64_t> AppleAcceleratorTable::Entry::getDIEOffset() const {
if (Optional<DWARFFormValue> Off = lookup(dwarf::DW_ATOM_die_offset))
return Off->getAsSectionOffset();
return None;
Optional<uint64_t> AppleAcceleratorTable::Entry::getDIESectionOffset() const {
return HdrData->extractOffset(lookup(dwarf::DW_ATOM_die_offset));
}
Optional<uint64_t> AppleAcceleratorTable::Entry::getCUOffset() const {
if (Optional<DWARFFormValue> Off = lookup(dwarf::DW_ATOM_cu_offset))
return Off->getAsSectionOffset();
return None;
return HdrData->extractOffset(lookup(dwarf::DW_ATOM_cu_offset));
}
Optional<dwarf::Tag> AppleAcceleratorTable::Entry::getTag() const {
@ -537,7 +550,7 @@ DWARFDebugNames::Entry::lookup(dwarf::Index Index) const {
return None;
}
Optional<uint64_t> DWARFDebugNames::Entry::getDIEOffset() const {
Optional<uint64_t> DWARFDebugNames::Entry::getDIEUnitOffset() const {
if (Optional<DWARFFormValue> Off = lookup(dwarf::DW_IDX_die_offset))
return Off->getAsSectionOffset();
return None;
@ -546,6 +559,10 @@ Optional<uint64_t> DWARFDebugNames::Entry::getDIEOffset() const {
Optional<uint64_t> DWARFDebugNames::Entry::getCUIndex() const {
if (Optional<DWARFFormValue> Off = lookup(dwarf::DW_IDX_compile_unit))
return Off->getAsUnsignedConstant();
// In a per-CU index, the entries without a DW_IDX_compile_unit attribute
// implicitly refer to the single CU.
if (NameIdx->getCUCount() == 1)
return 0;
return None;
}
@ -556,6 +573,14 @@ Optional<uint64_t> DWARFDebugNames::Entry::getCUOffset() const {
return NameIdx->getCUOffset(*Index);
}
Optional<uint64_t> DWARFDebugNames::Entry::getDIESectionOffset() const {
Optional<uint64_t> CUOff = getCUOffset();
Optional<uint64_t> DIEOff = getDIEUnitOffset();
if (CUOff && DIEOff)
return *CUOff + *DIEOff;
return None;
}
void DWARFDebugNames::Entry::dump(ScopedPrinter &W) const {
W.printHex("Abbrev", Abbr->Code);
W.startLine() << "Tag: " << formatTag(Abbr->Tag) << "\n";

75
test/tools/llvm-dwarfdump/X86/apple-names-die-offset-data.s Normal file
View File

@ -0,0 +1,75 @@
# This test sets non-zero Die Offset Base field in the accelerator table header,
# and makes sure it is *not* added to the DW_FORM_data*** forms.
# RUN: llvm-mc -triple x86_64-apple-darwin %s -filetype=obj -o %t
# RUN: llvm-dwarfdump -find=main %t | FileCheck %s
# CHECK: DW_TAG_subprogram
# CHECK-NEXT: DW_AT_name ("main")
# CHECK-NEXT: DW_AT_external
.section __DWARF,__debug_str,regular,debug
Ldebug_str:
Lstring_producer:
.asciz "Hand-written dwarf"
Lstring_main:
.asciz "main"
.section __DWARF,__debug_abbrev,regular,debug
.byte 1 # Abbreviation Code
.byte 17 # DW_TAG_compile_unit
.byte 1 # DW_CHILDREN_yes
.byte 37 # DW_AT_producer
.byte 14 # DW_FORM_strp
.byte 19 # DW_AT_language
.byte 5 # DW_FORM_data2
.byte 0 # EOM(1)
.byte 0 # EOM(2)
.byte 2 # Abbreviation Code
.byte 46 # DW_TAG_subprogram
.byte 0 # DW_CHILDREN_no
.byte 3 # DW_AT_name
.byte 14 # DW_FORM_strp
.byte 63 # DW_AT_external
.byte 25 # DW_FORM_flag_present
.byte 0 # EOM(1)
.byte 0 # EOM(2)
.byte 0 # EOM(3)
.section __DWARF,__debug_info,regular,debug
Ldebug_info:
.long Lcu_end0-Lcu_start0 # Length of Unit
Lcu_start0:
.short 4 # DWARF version number
.long 0 # Offset Into Abbrev. Section
.byte 8 # Address Size (in bytes)
.byte 1 # Abbrev [1] DW_TAG_compile_unit
.long Lstring_producer-Ldebug_str # DW_AT_producer
.short 12 # DW_AT_language
Ldie_main:
.byte 2 # Abbrev [2] DW_TAG_subprogram
.long Lstring_main-Ldebug_str # DW_AT_name
# DW_AT_external
.byte 0 # End Of Children Mark
Lcu_end0:
.section __DWARF,__apple_names,regular,debug
Lnames_begin:
.long 1212240712 ## Header Magic
.short 1 ## Header Version
.short 0 ## Header Hash Function
.long 1 ## Header Bucket Count
.long 1 ## Header Hash Count
.long 12 ## Header Data Length
.long 1 ## HeaderData Die Offset Base
.long 1 ## HeaderData Atom Count
.short 1 ## DW_ATOM_die_offset
.short 6 ## DW_FORM_data4
.long 0 ## Bucket 0
.long 2090499946 ## Hash in Bucket 0
.long LNames0-Lnames_begin ## Offset in Bucket 0
LNames0:
.long Lstring_main-Ldebug_str ## main
.long 1 ## Num DIEs
.long Ldie_main-Ldebug_info
.long 0

75
test/tools/llvm-dwarfdump/X86/apple-names-die-offset-ref.s Normal file
View File

@ -0,0 +1,75 @@
# This test sets non-zero Die Offset Base field in the accelerator table header,
# and makes sure it is added to the DW_FORM_ref*** forms.
# RUN: llvm-mc -triple x86_64-apple-darwin %s -filetype=obj -o %t
# RUN: llvm-dwarfdump -find=main %t | FileCheck %s
# CHECK: DW_TAG_subprogram
# CHECK-NEXT: DW_AT_name ("main")
# CHECK-NEXT: DW_AT_external
.section __DWARF,__debug_str,regular,debug
Ldebug_str:
Lstring_producer:
.asciz "Hand-written dwarf"
Lstring_main:
.asciz "main"
.section __DWARF,__debug_abbrev,regular,debug
.byte 1 # Abbreviation Code
.byte 17 # DW_TAG_compile_unit
.byte 1 # DW_CHILDREN_yes
.byte 37 # DW_AT_producer
.byte 14 # DW_FORM_strp
.byte 19 # DW_AT_language
.byte 5 # DW_FORM_data2
.byte 0 # EOM(1)
.byte 0 # EOM(2)
.byte 2 # Abbreviation Code
.byte 46 # DW_TAG_subprogram
.byte 0 # DW_CHILDREN_no
.byte 3 # DW_AT_name
.byte 14 # DW_FORM_strp
.byte 63 # DW_AT_external
.byte 25 # DW_FORM_flag_present
.byte 0 # EOM(1)
.byte 0 # EOM(2)
.byte 0 # EOM(3)
.section __DWARF,__debug_info,regular,debug
Ldebug_info:
.long Lcu_end0-Lcu_start0 # Length of Unit
Lcu_start0:
.short 4 # DWARF version number
.long 0 # Offset Into Abbrev. Section
.byte 8 # Address Size (in bytes)
.byte 1 # Abbrev [1] DW_TAG_compile_unit
.long Lstring_producer-Ldebug_str # DW_AT_producer
.short 12 # DW_AT_language
Ldie_main:
.byte 2 # Abbrev [2] DW_TAG_subprogram
.long Lstring_main-Ldebug_str # DW_AT_name
# DW_AT_external
.byte 0 # End Of Children Mark
Lcu_end0:
.section __DWARF,__apple_names,regular,debug
Lnames_begin:
.long 1212240712 ## Header Magic
.short 1 ## Header Version
.short 0 ## Header Hash Function
.long 1 ## Header Bucket Count
.long 1 ## Header Hash Count
.long 12 ## Header Data Length
.long 1 ## HeaderData Die Offset Base
.long 1 ## HeaderData Atom Count
.short 1 ## DW_ATOM_die_offset
.short 0x13 ## DW_FORM_ref4
.long 0 ## Bucket 0
.long 2090499946 ## Hash in Bucket 0
.long LNames0-Lnames_begin ## Offset in Bucket 0
LNames0:
.long Lstring_main-Ldebug_str ## main
.long 1 ## Num DIEs
.long Ldie_main-Ldebug_info-1
.long 0

10
test/tools/llvm-dwarfdump/X86/debug-names-find.s
View File

@ -129,15 +129,15 @@
.Lnames_entries0:
.Lnames0:
.byte 46 # Abbrev code
.long .Ldie_bar # DW_IDX_die_offset
.long .Ldie_bar-.Lcu_begin0 # DW_IDX_die_offset
.long 0 # End of list: bar
.Lnames1:
.byte 46 # Abbrev code
.long .Ldie_foo # DW_IDX_die_offset
.long .Ldie_foo-.Lcu_begin0 # DW_IDX_die_offset
.long 0 # End of list: foo
.Lnames2:
.byte 46 # Abbrev code
.long .Ldie_foo # DW_IDX_die_offset
.long .Ldie_foo-.Lcu_begin0 # DW_IDX_die_offset
.long 0 # End of list: _Z3foov
.p2align 2
.Lnames_end0:
@ -171,12 +171,12 @@
.Lnames_entries1:
.Lnames3:
.byte 46 # Abbrev code
.long .Ldie_baz # DW_IDX_die_offset
.long .Ldie_baz-.Lcu_begin1 # DW_IDX_die_offset
.long 0 # End of list: baz
.p2align 2
.Lnames4:
.byte 46 # Abbrev code
.long .Ldie_bazz # DW_IDX_die_offset
.long .Ldie_bazz-.Lcu_begin1 # DW_IDX_die_offset
.long 0 # End of list: baz
.p2align 2
.Lnames_end1:

2
tools/llvm-dwarfdump/llvm-dwarfdump.cpp
View File

@ -340,7 +340,7 @@ template <typename AccelTable>
static llvm::Optional<uint64_t> getDIEOffset(const AccelTable &Accel,
StringRef Name) {
for (const auto &Entry : Accel.equal_range(Name))
if (llvm::Optional<uint64_t> Off = Entry.getDIEOffset())
if (llvm::Optional<uint64_t> Off = Entry.getDIESectionOffset())
return *Off;
return None;
}