[Lldb-commits] [lldb] dc04b18 - [lldb][NFC] Factor out code from SymbolFileDWARF::ParseVariableDIE
Felipe de Azevedo Piovezan via lldb-commits
lldb-commits at lists.llvm.org
Fri Jul 7 05:45:15 PDT 2023
Author: Felipe de Azevedo Piovezan
Date: 2023-07-07T08:44:59-04:00
New Revision: dc04b18ad7e45c67df4b8b3a756257eb62447970
URL: https://github.com/llvm/llvm-project/commit/dc04b18ad7e45c67df4b8b3a756257eb62447970
DIFF: https://github.com/llvm/llvm-project/commit/dc04b18ad7e45c67df4b8b3a756257eb62447970.diff
LOG: [lldb][NFC] Factor out code from SymbolFileDWARF::ParseVariableDIE
This function does a _lot_ of different things:
1. Parses a DIE,
2. Builds an ExpressionList
3. Figures out lifetime of variable
4. Remaps addresses for debug maps
5. Handles external variables
6. Figures out scope of variables
A lot of this functionality is coded in a complex nest of conditions, variables
that are declared and then initialized much later, variables that are updated in
multiple code paths. All of this makes the code really hard to follow.
This commit attempts to improve the state of things by factoring out (3), adding
documentation on how the expression list is built, and by reducing the scope of
variables.
Differential Revision: https://reviews.llvm.org/D154513
Added:
Modified:
lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
Removed:
################################################################################
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
index 37a8470cdf8b21..94baa5553c4bb3 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
@@ -3269,6 +3269,60 @@ VariableSP SymbolFileDWARF::ParseVariableDIECached(const SymbolContext &sc,
return var_sp;
}
+/// Creates a DWARFExpressionList from an DW_AT_location form_value.
+static DWARFExpressionList GetExprListFromAtLocation(DWARFFormValue form_value,
+ ModuleSP module,
+ const DWARFDIE &die,
+ const addr_t func_low_pc) {
+ if (DWARFFormValue::IsBlockForm(form_value.Form())) {
+ const DWARFDataExtractor &data = die.GetData();
+
+ uint32_t block_offset = form_value.BlockData() - data.GetDataStart();
+ uint32_t block_length = form_value.Unsigned();
+ return DWARFExpressionList(
+ module, DataExtractor(data, block_offset, block_length), die.GetCU());
+ }
+
+ DWARFExpressionList location_list(module, DWARFExpression(), die.GetCU());
+ DataExtractor data = die.GetCU()->GetLocationData();
+ dw_offset_t offset = form_value.Unsigned();
+ if (form_value.Form() == DW_FORM_loclistx)
+ offset = die.GetCU()->GetLoclistOffset(offset).value_or(-1);
+ if (data.ValidOffset(offset)) {
+ data = DataExtractor(data, offset, data.GetByteSize() - offset);
+ const DWARFUnit *dwarf_cu = form_value.GetUnit();
+ if (DWARFExpression::ParseDWARFLocationList(dwarf_cu, data, &location_list))
+ location_list.SetFuncFileAddress(func_low_pc);
+ }
+
+ return location_list;
+}
+
+/// Creates a DWARFExpressionList from an DW_AT_const_value. This is either a
+/// block form, or a string, or a data form. For data forms, this returns an
+/// empty list, as we cannot initialize it properly without a SymbolFileType.
+static DWARFExpressionList
+GetExprListFromAtConstValue(DWARFFormValue form_value, ModuleSP module,
+ const DWARFDIE &die) {
+ const DWARFDataExtractor &debug_info_data = die.GetData();
+ if (DWARFFormValue::IsBlockForm(form_value.Form())) {
+ // Retrieve the value as a block expression.
+ uint32_t block_offset =
+ form_value.BlockData() - debug_info_data.GetDataStart();
+ uint32_t block_length = form_value.Unsigned();
+ return DWARFExpressionList(
+ module, DataExtractor(debug_info_data, block_offset, block_length),
+ die.GetCU());
+ }
+ if (const char *str = form_value.AsCString())
+ return DWARFExpressionList(module,
+ DataExtractor(str, strlen(str) + 1,
+ die.GetCU()->GetByteOrder(),
+ die.GetCU()->GetAddressByteSize()),
+ die.GetCU());
+ return DWARFExpressionList(module, DWARFExpression(), die.GetCU());
+}
+
VariableSP SymbolFileDWARF::ParseVariableDIE(const SymbolContext &sc,
const DWARFDIE &die,
const lldb::addr_t func_low_pc) {
@@ -3290,7 +3344,6 @@ VariableSP SymbolFileDWARF::ParseVariableDIE(const SymbolContext &sc,
const char *mangled = nullptr;
Declaration decl;
DWARFFormValue type_die_form;
- DWARFExpressionList location_list(module, DWARFExpression(), die.GetCU());
bool is_external = false;
bool is_artificial = false;
DWARFFormValue const_value_form, location_form;
@@ -3355,57 +3408,16 @@ VariableSP SymbolFileDWARF::ParseVariableDIE(const SymbolContext &sc,
// for static constexpr member variables -- DW_AT_const_value will be
// present in the class declaration and DW_AT_location in the DIE defining
// the member.
- bool location_is_const_value_data = false;
- bool has_explicit_location = location_form.IsValid();
- bool use_type_size_for_value = false;
- if (location_form.IsValid()) {
- if (DWARFFormValue::IsBlockForm(location_form.Form())) {
- const DWARFDataExtractor &data = die.GetData();
-
- uint32_t block_offset = location_form.BlockData() - data.GetDataStart();
- uint32_t block_length = location_form.Unsigned();
- location_list = DWARFExpressionList(
- module, DataExtractor(data, block_offset, block_length), die.GetCU());
- } else {
- DataExtractor data = die.GetCU()->GetLocationData();
- dw_offset_t offset = location_form.Unsigned();
- if (location_form.Form() == DW_FORM_loclistx)
- offset = die.GetCU()->GetLoclistOffset(offset).value_or(-1);
- if (data.ValidOffset(offset)) {
- data = DataExtractor(data, offset, data.GetByteSize() - offset);
- const DWARFUnit *dwarf_cu = location_form.GetUnit();
- if (DWARFExpression::ParseDWARFLocationList(dwarf_cu, data,
- &location_list))
- location_list.SetFuncFileAddress(func_low_pc);
- }
- }
- } else if (const_value_form.IsValid()) {
- location_is_const_value_data = true;
- // The constant value will be either a block, a data value or a
- // string.
- const DWARFDataExtractor &debug_info_data = die.GetData();
- if (DWARFFormValue::IsBlockForm(const_value_form.Form())) {
- // Retrieve the value as a block expression.
- uint32_t block_offset =
- const_value_form.BlockData() - debug_info_data.GetDataStart();
- uint32_t block_length = const_value_form.Unsigned();
- location_list = DWARFExpressionList(
- module, DataExtractor(debug_info_data, block_offset, block_length),
- die.GetCU());
- } else if (DWARFFormValue::IsDataForm(const_value_form.Form())) {
- // Constant value size does not have to match the size of the
- // variable. We will fetch the size of the type after we create
- // it.
- use_type_size_for_value = true;
- } else if (const char *str = const_value_form.AsCString()) {
- uint32_t string_length = strlen(str) + 1;
- location_list = DWARFExpressionList(
- module,
- DataExtractor(str, string_length, die.GetCU()->GetByteOrder(),
- die.GetCU()->GetAddressByteSize()),
- die.GetCU());
- }
- }
+ bool location_is_const_value_data =
+ const_value_form.IsValid() && !location_form.IsValid();
+
+ DWARFExpressionList location_list = [&] {
+ if (location_form.IsValid())
+ return GetExprListFromAtLocation(location_form, module, die, func_low_pc);
+ if (const_value_form.IsValid())
+ return GetExprListFromAtConstValue(const_value_form, module, die);
+ return DWARFExpressionList(module, DWARFExpression(), die.GetCU());
+ }();
const DWARFDIE parent_context_die = GetDeclContextDIEContainingDIE(die);
const DWARFDIE sc_parent_die = GetParentSymbolContextDIE(die);
@@ -3448,6 +3460,7 @@ VariableSP SymbolFileDWARF::ParseVariableDIE(const SymbolContext &sc,
// Clang likes to combine small global variables into the same symbol
// with locations like: DW_OP_addr(0x1000), DW_OP_constu(2), DW_OP_plus
// so we need to look through the whole expression.
+ bool has_explicit_location = location_form.IsValid();
bool is_static_lifetime =
has_explicit_mangled ||
(has_explicit_location && !location_list.IsValid());
@@ -3597,6 +3610,9 @@ VariableSP SymbolFileDWARF::ParseVariableDIE(const SymbolContext &sc,
auto type_sp = std::make_shared<SymbolFileType>(
*this, type_die_form.Reference().GetID());
+ bool use_type_size_for_value =
+ location_is_const_value_data &&
+ DWARFFormValue::IsDataForm(const_value_form.Form());
if (use_type_size_for_value && type_sp->GetType()) {
DWARFExpression *location = location_list.GetMutableExpressionAtAddress();
location->UpdateValue(const_value_form.Unsigned(),
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