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[lldb] Don't put compile unit name into the support file list and support DWARF5 line tables 

Summary:
Lldb's "format-independent" debug info made use of the fact that DWARF
(<=4) did not use the file index zero, and reused the support file index
zero for storing the compile unit name.

While this provided some convenience for DWARF<=4, it meant that the PDB
plugin needed to artificially remap file indices in order to free up
index 0. Furthermore, DWARF v5 make file index 0 legal, which meant that
similar remapping would be needed in the dwarf plugin too.

What this patch does instead is remove the requirement of having the
compile unit name in the index 0. It is not that useful since the name
can always be fetched from the CompileUnit object. Remapping code in the
pdb plugin(s) has been removed or simplified.

DWARF plugin has started inserting an empty FileSpec at index 0 to
ensure the indices keep matching up (in case of DWARF<=4). For DWARF5,
we insert the file 0 from the line table.

I add a test to ensure we can correctly lookup line table entries
referencing file 0, and in particular the case where the file 0 is also
duplicated in another file entry, as this is how clang produces line
tables in some circumstances (see pr44170). Though this is probably a
bug in clang, this is not forbidden by DWARF, and lldb already has
support for that in some (but not all) cases -- this adds a test for the
code path which was not fixed in this patch.

Reviewers: clayborg, JDevlieghere, jdoerfert

Subscribers: aprantl, lldb-commits

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D70954
This commit is contained in:
Pavel Labath 2019-11-28 10:19:23 +01:00
parent f0355bc4d1
commit 57f8a998ce
5 changed files with 163 additions and 45 deletions
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23
lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
View File

@ -198,15 +198,23 @@ GetFileByIndex(const llvm::DWARFDebugLine::Prologue &prologue, size_t idx,
return std::move(rel_path);
}
static FileSpecList ParseSupportFilesFromPrologue(
const lldb::ModuleSP &module,
const llvm::DWARFDebugLine::Prologue &prologue, FileSpec::Style style,
llvm::StringRef compile_dir = {}, FileSpec first_file = {}) {
static FileSpecList
ParseSupportFilesFromPrologue(const lldb::ModuleSP &module,
const llvm::DWARFDebugLine::Prologue &prologue,
FileSpec::Style style,
llvm::StringRef compile_dir = {}) {
FileSpecList support_files;
support_files.Append(first_file);
size_t first_file = 0;
if (prologue.getVersion() <= 4) {
// File index 0 is not valid before DWARF v5. Add a dummy entry to ensure
// support file list indices match those we get from the debug info and line
// tables.
support_files.Append(FileSpec());
first_file = 1;
}
const size_t number_of_files = prologue.FileNames.size();
for (size_t idx = 1; idx <= number_of_files; ++idx) {
for (size_t idx = first_file; idx <= number_of_files; ++idx) {
std::string remapped_file;
if (auto file_path = GetFileByIndex(prologue, idx, compile_dir, style))
if (!module->RemapSourceFile(llvm::StringRef(*file_path), remapped_file))
@ -1046,8 +1054,7 @@ bool SymbolFileDWARF::ParseLineTable(CompileUnit &comp_unit) {
comp_unit.SetSupportFiles(ParseSupportFilesFromPrologue(
comp_unit.GetModule(), line_table->Prologue, dwarf_cu->GetPathStyle(),
dwarf_cu->GetCompilationDirectory().GetCString(),
comp_unit.GetPrimaryFile()));
dwarf_cu->GetCompilationDirectory().GetCString()));
return true;
}

12
lldb/source/Plugins/SymbolFile/NativePDB/SymbolFileNativePDB.cpp
View File

@ -1110,9 +1110,7 @@ bool SymbolFileNativePDB::ParseLineTable(CompileUnit &comp_unit) {
// LLDB wants the index of the file in the list of support files.
auto fn_iter = llvm::find(cci->m_file_list, *efn);
lldbassert(fn_iter != cci->m_file_list.end());
// LLDB support file indices are 1-based.
uint32_t file_index =
1 + std::distance(cci->m_file_list.begin(), fn_iter);
uint32_t file_index = std::distance(cci->m_file_list.begin(), fn_iter);
std::unique_ptr<LineSequence> sequence(
line_table->CreateLineSequenceContainer());
@ -1155,14 +1153,6 @@ bool SymbolFileNativePDB::ParseSupportFiles(CompileUnit &comp_unit,
FileSpec spec(f, style);
support_files.Append(spec);
}
llvm::SmallString<64> main_source_file =
m_index->compilands().GetMainSourceFile(*cci);
FileSpec::Style style = main_source_file.startswith("/")
? FileSpec::Style::posix
: FileSpec::Style::windows;
FileSpec spec(main_source_file, style);
support_files.Insert(0, spec);
return true;
}

8
lldb/source/Plugins/SymbolFile/PDB/SymbolFilePDB.cpp
View File

@ -371,10 +371,6 @@ bool SymbolFilePDB::ParseSupportFiles(
support_files.AppendIfUnique(spec);
}
// LLDB uses the DWARF-like file numeration (one based),
// the zeroth file is the compile unit itself
support_files.Insert(0, comp_unit.GetPrimaryFile());
return true;
}
@ -1881,9 +1877,7 @@ void SymbolFilePDB::BuildSupportFileIdToSupportFileIndexMap(
if (!source_files)
return;
// LLDB uses the DWARF-like file numeration (one based)
int index = 1;
int index = 0;
while (auto file = source_files->getNext()) {
uint32_t source_id = file->getUniqueId();
index_map[source_id] = index++;

36
lldb/source/Symbol/CompileUnit.cpp
View File

@ -207,30 +207,28 @@ VariableListSP CompileUnit::GetVariableList(bool can_create) {
return m_variables;
}
std::vector<uint32_t> FindFileIndexes(const FileSpecList &files, const FileSpec &file) {
std::vector<uint32_t> result;
uint32_t idx = -1;
while ((idx = files.FindFileIndex(idx + 1, file, /*full=*/true)) !=
UINT32_MAX)
result.push_back(idx);
return result;
}
uint32_t CompileUnit::FindLineEntry(uint32_t start_idx, uint32_t line,
const FileSpec *file_spec_ptr, bool exact,
LineEntry *line_entry_ptr) {
uint32_t file_idx = 0;
if (!file_spec_ptr)
file_spec_ptr = &GetPrimaryFile();
std::vector<uint32_t> file_indexes = FindFileIndexes(GetSupportFiles(), *file_spec_ptr);
if (file_indexes.empty())
return UINT32_MAX;
if (file_spec_ptr) {
file_idx = GetSupportFiles().FindFileIndex(1, *file_spec_ptr, true);
if (file_idx == UINT32_MAX)
return UINT32_MAX;
} else {
// All the line table entries actually point to the version of the Compile
// Unit that is in the support files (the one at 0 was artificially added.)
// So prefer the one further on in the support files if it exists...
const FileSpecList &support_files = GetSupportFiles();
const bool full = true;
file_idx = support_files.FindFileIndex(
1, support_files.GetFileSpecAtIndex(0), full);
if (file_idx == UINT32_MAX)
file_idx = 0;
}
LineTable *line_table = GetLineTable();
if (line_table)
return line_table->FindLineEntryIndexByFileIndex(start_idx, file_idx, line,
exact, line_entry_ptr);
return line_table->FindLineEntryIndexByFileIndex(
start_idx, file_indexes, line, exact, line_entry_ptr);
return UINT32_MAX;
}
@ -252,7 +250,7 @@ void CompileUnit::ResolveSymbolContext(const FileSpec &file_spec,
return;
uint32_t file_idx =
GetSupportFiles().FindFileIndex(1, file_spec, true);
GetSupportFiles().FindFileIndex(0, file_spec, true);
while (file_idx != UINT32_MAX) {
file_indexes.push_back(file_idx);
file_idx = GetSupportFiles().FindFileIndex(file_idx + 1, file_spec, true);

129
lldb/test/Shell/SymbolFile/DWARF/dwarf5-debug_line.s Normal file
View File

@ -0,0 +1,129 @@
# Test handling of DWARF5 line tables. In particular, test that we handle files
# which are present in the line table more than once.
# REQUIRES: x86
# RUN: llvm-mc -filetype=obj -o %t -triple x86_64-pc-linux %s
# RUN: %lldb %t -o "source info -f file0.c" -o "source info -f file1.c" \
# RUN: -o "breakpoint set -f file0.c -l 42" \
# RUN: -o "breakpoint set -f file0.c -l 47" \
# RUN: -o exit | FileCheck %s
# CHECK-LABEL: source info -f file0.c
# CHECK: [0x0000000000000000-0x0000000000000001): /file0.c:42
# CHECK-LABEL: source info -f file1.c
# CHECK: [0x0000000000000001-0x0000000000000002): /file1.c:47
# CHECK-LABEL: breakpoint set -f file0.c -l 42
# CHECK: Breakpoint 1: {{.*}}`foo,
# CHECK-LABEL: breakpoint set -f file0.c -l 47
# CHECK: Breakpoint 2: {{.*}}`foo + 2,
.text
.globl foo
foo:
nop
nop
nop
.Lfoo_end:
.section .debug_abbrev,"",@progbits
.byte 1 # Abbreviation Code
.byte 17 # DW_TAG_compile_unit
.byte 0 # DW_CHILDREN_no
.byte 37 # DW_AT_producer
.byte 8 # DW_FORM_string
.byte 19 # DW_AT_language
.byte 5 # DW_FORM_data2
.byte 3 # DW_AT_name
.byte 8 # DW_FORM_string
.byte 16 # DW_AT_stmt_list
.byte 23 # DW_FORM_sec_offset
.byte 27 # DW_AT_comp_dir
.byte 8 # DW_FORM_string
.byte 17 # DW_AT_low_pc
.byte 1 # DW_FORM_addr
.byte 18 # DW_AT_high_pc
.byte 6 # DW_FORM_data4
.byte 0 # EOM(1)
.byte 0 # EOM(2)
.byte 0 # EOM(3)
.section .debug_info,"",@progbits
.Lcu_begin0:
.long .Ldebug_info_end0-.Ldebug_info_start0 # Length of Unit
.Ldebug_info_start0:
.short 5 # DWARF version number
.byte 1 # DWARF Unit Type
.byte 8 # Address Size (in bytes)
.long .debug_abbrev # Offset Into Abbrev. Section
.byte 1 # Abbrev [1] 0xc:0x23 DW_TAG_compile_unit
.asciz "Hand-written DWARF" # DW_AT_producer
.short 12 # DW_AT_language
.asciz "file0.c" # DW_AT_name
.long .Lline_table_begin # DW_AT_stmt_list
.asciz "/" # DW_AT_comp_dir
.quad foo # DW_AT_low_pc
.long .Lfoo_end-foo # DW_AT_high_pc
.Ldebug_info_end0:
.section .debug_line,"",@progbits
.Lline_table_begin:
.long .Lline_end-.Lline_start
.Lline_start:
.short 5 # DWARF version number
.byte 8 # Address Size (in bytes)
.byte 0 # Segment Selector Size
.long .Lheader_end-.Lheader_start
.Lheader_start:
.byte 1 # Minimum Instruction Length
.byte 1 # Maximum Operations per Instruction
.byte 1 # Default is_stmt
.byte 0 # Line Base
.byte 0 # Line Range
.byte 5 # Opcode Base
.byte 0, 1, 1, 1 # Standard Opcode Lengths
# Directory table format
.byte 1 # One element per directory entry
.byte 1 # DW_LNCT_path
.byte 0x08 # DW_FORM_string
# Directory table entries
.byte 1 # 1 directory
.asciz "/"
# File table format
.byte 2 # 2 elements per file entry
.byte 1 # DW_LNCT_path
.byte 0x08 # DW_FORM_string
.byte 2 # DW_LNCT_directory_index
.byte 0x0b # DW_FORM_data1
# File table entries
.byte 3 # 3 files
.asciz "file0.c"
.byte 0
.asciz "file1.c"
.byte 0
.asciz "file0.c"
.byte 0
.Lheader_end:
.byte 4, 0 # DW_LNS_set_file 0
.byte 0, 9, 2 # DW_LNE_set_address
.quad foo
.byte 3, 41 # DW_LNS_advance_line 41
.byte 1 # DW_LNS_copy
.byte 4, 1 # DW_LNS_set_file 1
.byte 2, 1 # DW_LNS_advance_pc 1
.byte 3, 5 # DW_LNS_advance_line 5
.byte 1 # DW_LNS_copy
.byte 4, 2 # DW_LNS_set_file 2
.byte 2, 1 # DW_LNS_advance_pc 1
.byte 1 # DW_LNS_copy
.byte 2, 1 # DW_LNS_advance_pc 1
.byte 0, 1, 1 # DW_LNE_end_sequence
.Lline_end: