jankratochvil updated this revision to Diff 146523.
jankratochvil retitled this revision from "DWZ 03/07: Protect
DWARFCompileUnit::m_die_array by a new mutex" to "Protect
DWARFCompileUnit::m_die_array by a new mutex".
jankratochvil edited the summary of this revision.
https://reviews.llvm.org/D40470
Files:
source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp
source/Plugins/SymbolFile/DWARF/DWARFUnit.h
Index: source/Plugins/SymbolFile/DWARF/DWARFUnit.h
===================================================================
--- source/Plugins/SymbolFile/DWARF/DWARFUnit.h
+++ source/Plugins/SymbolFile/DWARF/DWARFUnit.h
@@ -13,6 +13,7 @@
#include "DWARFDIE.h"
#include "DWARFDebugInfoEntry.h"
#include "lldb/lldb-enumerations.h"
+#include "llvm/Support/RWMutex.h"
class DWARFUnit;
class DWARFCompileUnit;
@@ -196,6 +197,12 @@
// If this is a dwo compile unit this is the offset of the base compile unit
// in the main object file
dw_offset_t m_base_obj_offset = DW_INVALID_OFFSET;
+ mutable llvm::sys::RWMutex m_extractdies_mutex;
+ // It gets increased by ExtractDIEsIfNeeded(false) and decreased by ClearDIEs.
+ // BuildAddressRangeTable and SymbolFileDWARF::Index can populate m_die_array
+ // only temporarily while other functions calling only
+ // ExtractDIEsIfNeeded(false) will keep m_die_array populated forever.
+ uint32_t m_extractdies_count = 0;
static void
IndexPrivate(DWARFUnit *dwarf_cu, const lldb::LanguageType cu_language,
@@ -215,14 +222,17 @@
// if needed.
const DWARFDebugInfoEntry *GetUnitDIEPtrOnly() {
ExtractDIEsIfNeeded(true);
+ // m_extractdies_mutex is not required as m_first_die is never cleared.
if (!m_first_die)
return NULL;
return &m_first_die;
}
// Get all DWARF debug informration entries. Parse all DIEs if needed.
const DWARFDebugInfoEntry *DIEPtr() {
ExtractDIEsIfNeeded(false);
+ // m_extractdies_mutex is not required as ExtractDIEsIfNeeded(false) has not
+ // been matched by ClearDIEs.
if (m_die_array.empty())
return NULL;
return &m_die_array[0];
Index: source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp
===================================================================
--- source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp
+++ source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp
@@ -41,9 +41,24 @@
// Parses a compile unit and indexes its DIEs if it hasn't already been done.
//----------------------------------------------------------------------
size_t DWARFUnit::ExtractDIEsIfNeeded(bool cu_die_only) {
- const size_t initial_die_array_size = m_die_array_size();
- if ((cu_die_only && initial_die_array_size > 0) || initial_die_array_size > 1)
- return 0; // Already parsed
+ size_t initial_die_array_size;
+ auto already_parsed = [cu_die_only, &initial_die_array_size, this]() -> bool {
+ initial_die_array_size = m_die_array_size();
+ return (cu_die_only && initial_die_array_size > 0)
+ || initial_die_array_size > 1;
+ };
+ {
+ llvm::sys::ScopedReader lock(m_extractdies_mutex);
+ if (already_parsed())
+ return 0;
+ }
+ llvm::sys::ScopedWriter lock(m_extractdies_mutex);
+ if (already_parsed())
+ return 0;
+ // Protect against use count overflow.
+ if (!cu_die_only && m_extractdies_count
+ < std::numeric_limits<decltype(m_extractdies_count)>::max())
+ ++m_extractdies_count;
static Timer::Category func_cat(LLVM_PRETTY_FUNCTION);
Timer scoped_timer(
@@ -213,6 +228,7 @@
return m_first_die ? 1 : 0;
}
+// m_extractdies_mutex must be already held as read/write.
void DWARFUnit::AddUnitDIE(DWARFDebugInfoEntry &die) {
assert(m_die_array.empty() && "Compile unit DIE already added");
assert(!m_first_die);
@@ -265,11 +281,14 @@
DWARFDIECollection &dies,
uint32_t depth) const {
size_t old_size = dies.Size();
- DWARFDebugInfoEntry::const_iterator pos;
- DWARFDebugInfoEntry::const_iterator end = m_die_array.end();
- for (pos = m_die_array.begin(); pos != end; ++pos) {
- if (pos->Tag() == tag)
- dies.Append(DWARFDIE(this, &(*pos)));
+ {
+ llvm::sys::ScopedReader lock(m_extractdies_mutex);
+ DWARFDebugInfoEntry::const_iterator pos;
+ DWARFDebugInfoEntry::const_iterator end = m_die_array.end();
+ for (pos = m_die_array.begin(); pos != end; ++pos) {
+ if (pos->Tag() == tag)
+ dies.Append(DWARFDIE(this, &(*pos)));
+ }
}
// Return the number of DIEs added to the collection
@@ -310,9 +329,18 @@
m_base_obj_offset = base_obj_offset;
}
+// It may be called only after: ExtractDIEsIfNeeded(false) > 1
void DWARFUnit::ClearDIEs(bool keep_compile_unit_die) {
- m_die_array.clear();
- m_die_array.shrink_to_fit();
+ {
+ llvm::sys::ScopedWriter lock(m_extractdies_mutex);
+ lldbassert(m_die_array.size() > 1);
+ lldbassert(m_extractdies_count > 0);
+ if (--m_extractdies_count > 0)
+ return;
+
+ m_die_array.clear();
+ m_die_array.shrink_to_fit();
+ }
if (m_dwo_symbol_file)
m_dwo_symbol_file->GetCompileUnit()->ClearDIEs(keep_compile_unit_die);
@@ -434,7 +462,10 @@
void DWARFUnit::SetBaseAddress(dw_addr_t base_addr) { m_base_addr = base_addr; }
-bool DWARFUnit::HasDIEsParsed() const { return m_die_array.size() > 1; }
+bool DWARFUnit::HasDIEsParsed() const {
+ llvm::sys::ScopedReader lock(m_extractdies_mutex);
+ return m_die_array.size() > 1;
+}
//----------------------------------------------------------------------
// Compare function DWARFDebugAranges::Range structures
@@ -459,6 +490,8 @@
if (ContainsDIEOffset(die_offset)) {
ExtractDIEsIfNeeded(false);
+ // m_extractdies_mutex is not required as ExtractDIEsIfNeeded(false) has
+ // not been matched by ClearDIEs.
DWARFDebugInfoEntry::const_iterator end = m_die_array.cend();
DWARFDebugInfoEntry::const_iterator pos =
lower_bound(m_die_array.cbegin(), end, die_offset, CompareDIEOffset);
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