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**Context** Follow-up to [#147460](https://github.com/llvm/llvm-project/pull/147460), which added the ability to surface register-resident variable locations. This PR moves the annotation logic out of `Instruction::Dump()` and into `Disassembler::PrintInstructions()`, and adds lightweight state tracking so we only print changes at range starts and when variables go out of scope. --- ## What this does While iterating the instructions for a function, we maintain a “live variable map” keyed by `lldb::user_id_t` (the `Variable`’s ID) to remember each variable’s last emitted location string. For each instruction: - **New (or newly visible) variable** → print `name = <location>` once at the start of its DWARF location range, cache it. - **Location changed** (e.g., DWARF range switched to a different register/const) → print the updated mapping. - **Out of scope** (was tracked previously but not found for the current PC) → print `name = <undef>` and drop it. This produces **concise, stateful annotations** that highlight variable lifetime transitions without spamming every line. --- ## Why in `PrintInstructions()`? - Keeps `Instruction` stateless and avoids changing the `Instruction::Dump()` virtual API. - Makes it straightforward to diff state across instructions (`prev → current`) inside the single driver loop. --- ## How it works (high-level) 1. For the current PC, get in-scope variables via `StackFrame::GetInScopeVariableList(/*get_parent=*/true)`. 2. For each `Variable`, query `DWARFExpressionList::GetExpressionEntryAtAddress(func_load_addr, current_pc)` (added in #144238). 3. If the entry exists, call `DumpLocation(..., eDescriptionLevelBrief, abi)` to get a short, ABI-aware location string (e.g., `DW_OP_reg3 RBX → RBX`). 4. Compare against the last emitted location in the live map: - If not present → emit `name = <location>` and record it. - If different → emit updated mapping and record it. 5. After processing current in-scope variables, compute the set difference vs. the previous map and emit `name = <undef>` for any that disappeared. Internally: - We respect file↔load address translation already provided by `DWARFExpressionList`. - We reuse the ABI to map LLVM register numbers to arch register names. --- ## Example output (x86_64, simplified) ``` -> 0x55c6f5f6a140 <+0>: cmpl $0x2, %edi ; argc = RDI, argv = RSI 0x55c6f5f6a143 <+3>: jl 0x55c6f5f6a176 ; <+54> at d_original_example.c:6:3 0x55c6f5f6a145 <+5>: pushq %r15 0x55c6f5f6a147 <+7>: pushq %r14 0x55c6f5f6a149 <+9>: pushq %rbx 0x55c6f5f6a14a <+10>: movq %rsi, %rbx 0x55c6f5f6a14d <+13>: movl %edi, %r14d 0x55c6f5f6a150 <+16>: movl $0x1, %r15d ; argc = R14 0x55c6f5f6a156 <+22>: nopw %cs:(%rax,%rax) ; i = R15, argv = RBX 0x55c6f5f6a160 <+32>: movq (%rbx,%r15,8), %rdi 0x55c6f5f6a164 <+36>: callq 0x55c6f5f6a030 ; symbol stub for: puts 0x55c6f5f6a169 <+41>: incq %r15 0x55c6f5f6a16c <+44>: cmpq %r15, %r14 0x55c6f5f6a16f <+47>: jne 0x55c6f5f6a160 ; <+32> at d_original_example.c:5:10 0x55c6f5f6a171 <+49>: popq %rbx ; i = <undef> 0x55c6f5f6a172 <+50>: popq %r14 ; argv = RSI 0x55c6f5f6a174 <+52>: popq %r15 ; argc = RDI 0x55c6f5f6a176 <+54>: xorl %eax, %eax 0x55c6f5f6a178 <+56>: retq ``` Only transitions are shown: the start of a location, changes, and end-of-lifetime. --- ## Scope & limitations (by design) - Handles **simple locations** first (registers, const-in-register cases surfaced by `DumpLocation`). - **Memory/composite locations** are out of scope for this PR. - Annotations appear **only at range boundaries** (start/change/end) to minimize noise. - Output is **target-independent**; register names come from the target ABI. ## Implementation notes - All annotation printing now happens in `Disassembler::PrintInstructions()`. - Uses `std::unordered_map<lldb::user_id_t, std::string>` as the live map. - No persistent state across calls; the map is rebuilt while walking instruction by instruction. - **No changes** to the `Instruction` interface. --- ## Requested feedback - Placement and wording of the `<undef>` marker. - Whether we should optionally gate this behind a setting (currently always on when disassembling with an `ExecutionContext`). - Preference for immediate inclusion of tests vs. follow-up patch. --- Thanks for reviewing! Happy to adjust behavior/format based on feedback. --------- Co-authored-by: Jonas Devlieghere <jonas@devlieghere.com> Co-authored-by: Adrian Prantl <adrian.prantl@gmail.com>
113 lines
3.6 KiB
C++
113 lines
3.6 KiB
C++
//===-- CommandObjectDisassemble.h ------------------------------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLDB_SOURCE_COMMANDS_COMMANDOBJECTDISASSEMBLE_H
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#define LLDB_SOURCE_COMMANDS_COMMANDOBJECTDISASSEMBLE_H
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#include "lldb/Interpreter/CommandObject.h"
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#include "lldb/Interpreter/Options.h"
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#include "lldb/Utility/ArchSpec.h"
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namespace lldb_private {
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// CommandObjectDisassemble
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class CommandObjectDisassemble : public CommandObjectParsed {
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public:
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class CommandOptions : public Options {
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public:
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CommandOptions();
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~CommandOptions() override;
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Status SetOptionValue(uint32_t option_idx, llvm::StringRef option_arg,
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ExecutionContext *execution_context) override;
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void OptionParsingStarting(ExecutionContext *execution_context) override;
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llvm::ArrayRef<OptionDefinition> GetDefinitions() override;
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const char *GetPluginName() {
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return (plugin_name.empty() ? nullptr : plugin_name.c_str());
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}
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const char *GetFlavorString() {
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if (flavor_string.empty() || flavor_string == "default")
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return nullptr;
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return flavor_string.c_str();
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}
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const char *GetCPUString() {
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if (cpu_string.empty() || cpu_string == "default")
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return nullptr;
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return cpu_string.c_str();
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}
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const char *GetFeaturesString() {
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if (features_string.empty() || features_string == "default")
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return nullptr;
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return features_string.c_str();
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}
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Status OptionParsingFinished(ExecutionContext *execution_context) override;
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bool show_mixed; // Show mixed source/assembly
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bool show_bytes;
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bool show_control_flow_kind;
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uint32_t num_lines_context = 0;
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uint32_t num_instructions = 0;
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bool raw;
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std::string func_name;
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bool current_function = false;
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lldb::addr_t start_addr = 0;
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lldb::addr_t end_addr = 0;
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bool at_pc = false;
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bool frame_line = false;
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std::string plugin_name;
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std::string flavor_string;
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std::string cpu_string;
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std::string features_string;
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ArchSpec arch;
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bool some_location_specified = false; // If no location was specified, we'll
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// select "at_pc". This should be set
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// in SetOptionValue if anything the selects a location is set.
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lldb::addr_t symbol_containing_addr = 0;
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bool force = false;
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bool enable_variable_annotations = false;
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};
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CommandObjectDisassemble(CommandInterpreter &interpreter);
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~CommandObjectDisassemble() override;
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Options *GetOptions() override { return &m_options; }
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protected:
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void DoExecute(Args &command, CommandReturnObject &result) override;
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llvm::Expected<std::vector<AddressRange>>
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GetRangesForSelectedMode(CommandReturnObject &result);
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llvm::Expected<std::vector<AddressRange>> GetContainingAddressRanges();
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llvm::Expected<std::vector<AddressRange>> GetCurrentFunctionRanges();
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llvm::Expected<std::vector<AddressRange>> GetCurrentLineRanges();
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llvm::Expected<std::vector<AddressRange>>
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GetNameRanges(CommandReturnObject &result);
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llvm::Expected<std::vector<AddressRange>> GetPCRanges();
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llvm::Expected<std::vector<AddressRange>> GetStartEndAddressRanges();
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llvm::Expected<std::vector<AddressRange>>
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CheckRangeSize(std::vector<AddressRange> ranges, llvm::StringRef what);
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CommandOptions m_options;
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};
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} // namespace lldb_private
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#endif // LLDB_SOURCE_COMMANDS_COMMANDOBJECTDISASSEMBLE_H
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