Chirag created this revision.
Chirag added a project: LLDB.
Herald added subscribers: lldb-commits, aprantl.
Chirag added a reviewer: jingham.
dwarf expression DW_OP_call2/DW_OP_call4 performs dwarf procedure calls during
evaluation of a dwarf expression or location description. The 2-byte unsigned
offset for DW_OP_call2 (4-byte unsigned offset for DW_OP_call4) is a die entry
in the current compilation unit. These operations transfer control of DWARF
expression evaluation to the DW_AT_location attribute of the referenced die
entry. If there is no such attribute present then there is no effect. the
evaluation stack is shared between caller/callee and callee may add to/remove
from the value on stack.
Repository:
rLLDB LLDB
https://reviews.llvm.org/D61587
Files:
include/lldb/Expression/DWARFExpression.h
source/Expression/DWARFExpression.cpp
source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp
source/Target/RegisterContext.cpp
unittests/Expression/DWARFExpressionTest.cpp
Index: unittests/Expression/DWARFExpressionTest.cpp
===================================================================
--- unittests/Expression/DWARFExpressionTest.cpp
+++ unittests/Expression/DWARFExpressionTest.cpp
@@ -22,11 +22,12 @@
Value result;
Status status;
+ std::vector<Value> stack;
if (!DWARFExpression::Evaluate(
/*exe_ctx*/ nullptr, /*reg_ctx*/ nullptr, /*opcode_ctx*/ nullptr,
extractor, /*dwarf_cu*/ nullptr, /*offset*/ 0, expr.size(),
lldb::eRegisterKindLLDB, /*initial_value_ptr*/ nullptr,
- /*object_address_ptr*/ nullptr, result, &status))
+ /*object_address_ptr*/ nullptr, stack, result, &status))
return status.ToError();
return result.GetScalar();
Index: source/Target/RegisterContext.cpp
===================================================================
--- source/Target/RegisterContext.cpp
+++ source/Target/RegisterContext.cpp
@@ -87,9 +87,10 @@
Value result;
Status error;
const lldb::offset_t offset = 0;
+ std::vector<Value> stack;
if (dwarf_expr.Evaluate(&exe_ctx, this, opcode_ctx, dwarf_data, nullptr,
offset, dwarf_opcode_len, eRegisterKindDWARF, nullptr,
- nullptr, result, &error)) {
+ nullptr, stack, result, &error)) {
expr_result = result.GetScalar().SInt(-1);
switch (expr_result) {
case 0:
Index: source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp
===================================================================
--- source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp
+++ source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp
@@ -2780,12 +2780,13 @@
uint32_t block_length = form_value.Unsigned();
uint32_t block_offset =
form_value.BlockData() - debug_info_data.GetDataStart();
+ std::vector<Value> stack;
if (DWARFExpression::Evaluate(
nullptr, // ExecutionContext *
nullptr, // RegisterContext *
module_sp, debug_info_data, die.GetCU(), block_offset,
block_length, eRegisterKindDWARF, &initialValue,
- nullptr, memberOffset, nullptr)) {
+ nullptr, stack, memberOffset, nullptr)) {
member_byte_offset = memberOffset.ResolveValue(NULL).UInt();
}
} else {
@@ -3229,6 +3230,7 @@
Value initialValue(0);
Value memberOffset(0);
const DWARFDataExtractor &debug_info_data = die.GetData();
+ std::vector<Value> stack;
uint32_t block_length = form_value.Unsigned();
uint32_t block_offset =
form_value.BlockData() - debug_info_data.GetDataStart();
@@ -3236,7 +3238,8 @@
debug_info_data, die.GetCU(),
block_offset, block_length,
eRegisterKindDWARF, &initialValue,
- nullptr, memberOffset, nullptr)) {
+ nullptr, stack, memberOffset,
+ nullptr)) {
member_byte_offset = memberOffset.ResolveValue(NULL).UInt();
}
} else {
Index: source/Expression/DWARFExpression.cpp
===================================================================
--- source/Expression/DWARFExpression.cpp
+++ source/Expression/DWARFExpression.cpp
@@ -1248,6 +1248,7 @@
const Value *object_address_ptr, Value &result,
Status *error_ptr) const {
ModuleSP module_sp = m_module_wp.lock();
+ std::vector<Value> stack;
if (IsLocationList()) {
lldb::offset_t offset = 0;
@@ -1293,7 +1294,7 @@
if (length > 0 && lo_pc <= pc && pc < hi_pc) {
return DWARFExpression::Evaluate(
exe_ctx, reg_ctx, module_sp, m_data, m_dwarf_cu, offset, length,
- m_reg_kind, initial_value_ptr, object_address_ptr, result,
+ m_reg_kind, initial_value_ptr, object_address_ptr, stack, result,
error_ptr);
}
offset += length;
@@ -1307,7 +1308,8 @@
// Not a location list, just a single expression.
return DWARFExpression::Evaluate(
exe_ctx, reg_ctx, module_sp, m_data, m_dwarf_cu, 0, m_data.GetByteSize(),
- m_reg_kind, initial_value_ptr, object_address_ptr, result, error_ptr);
+ m_reg_kind, initial_value_ptr, object_address_ptr, stack, result,
+ error_ptr);
}
bool DWARFExpression::Evaluate(
@@ -1316,7 +1318,7 @@
DWARFUnit *dwarf_cu, const lldb::offset_t opcodes_offset,
const lldb::offset_t opcodes_length, const lldb::RegisterKind reg_kind,
const Value *initial_value_ptr, const Value *object_address_ptr,
- Value &result, Status *error_ptr) {
+ std::vector<Value> &stack, Value &result, Status *error_ptr) {
if (opcodes_length == 0) {
if (error_ptr)
@@ -1324,7 +1326,6 @@
"no location, value may have been optimized out");
return false;
}
- std::vector<Value> stack;
Process *process = NULL;
StackFrame *frame = NULL;
@@ -2690,10 +2691,38 @@
// may be used as parameters by the called expression and values left on
// the stack by the called expression may be used as return values by prior
// agreement between the calling and called expressions.
- case DW_OP_call2:
- if (error_ptr)
- error_ptr->SetErrorString("Unimplemented opcode DW_OP_call2.");
- return false;
+ case DW_OP_call2: {
+ dw_offset_t die_ref_offset = opcodes.GetU16(&offset);
+ const DWARFDIE ref_die = dwarf_cu->GetDIE(die_ref_offset);
+ if (!ref_die.IsValid()) {
+ if (error_ptr)
+ error_ptr->SetErrorString("opcode DW_OP_call2 reference not found");
+ return false;
+ }
+
+ DWARFAttributes attributes;
+ const size_t num_attrib = ref_die.GetAttributes(attributes);
+ if (num_attrib == 0)
+ break;
+
+ const uint32_t attr_index = attributes.FindAttributeIndex(DW_AT_location);
+ if (attr_index == UINT32_MAX)
+ break;
+
+ DWARFFormValue form_value;
+ attributes.ExtractFormValueAtIndex(attr_index, form_value);
+
+ const DWARFDataExtractor &ref_debug_info_data = ref_die.GetData();
+ uint32_t location_offset =
+ form_value.BlockData() - ref_debug_info_data.GetDataStart();
+ uint32_t location_length = form_value.Unsigned();
+ Value memberOffset(0);
+ Evaluate(nullptr, nullptr, module_sp, ref_debug_info_data,
+ dwarf_cu, location_offset, location_length,
+ eRegisterKindDWARF, nullptr, nullptr, stack, memberOffset,
+ nullptr);
+ } break;
+
// OPCODE: DW_OP_call4
// OPERANDS: 1
// uint32_t compile unit relative offset of a DIE
@@ -2713,10 +2742,37 @@
// may be used as parameters by the called expression and values left on
// the stack by the called expression may be used as return values by prior
// agreement between the calling and called expressions.
- case DW_OP_call4:
- if (error_ptr)
- error_ptr->SetErrorString("Unimplemented opcode DW_OP_call4.");
- return false;
+ case DW_OP_call4: {
+ dw_offset_t die_ref_offset = opcodes.GetU32(&offset);
+ const DWARFDIE ref_die = dwarf_cu->GetDIE(die_ref_offset);
+ if (!ref_die.IsValid()) {
+ if (error_ptr)
+ error_ptr->SetErrorString("opcode DW_OP_call4 reference not found");
+ return false;
+ }
+
+ DWARFAttributes attributes;
+ const size_t num_attrib = ref_die.GetAttributes(attributes);
+ if (num_attrib == 0)
+ break;
+
+ const uint32_t attr_index = attributes.FindAttributeIndex(DW_AT_location);
+ if (attr_index == UINT32_MAX)
+ break;
+
+ DWARFFormValue form_value;
+ attributes.ExtractFormValueAtIndex(attr_index, form_value);
+
+ const DWARFDataExtractor &ref_debug_info_data = ref_die.GetData();
+ uint32_t location_offset =
+ form_value.BlockData() - ref_debug_info_data.GetDataStart();
+ uint32_t location_length = form_value.Unsigned();
+ Value memberOffset(0);
+ Evaluate(nullptr, nullptr, module_sp, ref_debug_info_data,
+ dwarf_cu, location_offset, location_length,
+ eRegisterKindDWARF, nullptr, nullptr, stack, memberOffset,
+ nullptr);
+ } break;
// OPCODE: DW_OP_stack_value
// OPERANDS: None
Index: include/lldb/Expression/DWARFExpression.h
===================================================================
--- include/lldb/Expression/DWARFExpression.h
+++ include/lldb/Expression/DWARFExpression.h
@@ -285,6 +285,10 @@
/// A value to put on top of the interpreter stack before evaluating
/// the expression, if the expression is parametrized. Can be NULL.
///
+ /// \param[in] stack
+ /// interpreter stack for evaluation of dwarf expression. It is shared
+ /// between calls in case of adding/removing entries from stack.
+ ///
/// \param[in] result
/// A value into which the result of evaluating the expression is
/// to be placed.
@@ -301,7 +305,9 @@
const lldb::offset_t length,
const lldb::RegisterKind reg_set,
const Value *initial_value_ptr,
- const Value *object_address_ptr, Value &result,
+ const Value *object_address_ptr,
+ std::vector<Value> &stack,
+ Value &result,
Status *error_ptr);
bool GetExpressionData(DataExtractor &data) const {
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