Author: Mikhail Zakharov Date: 2025-05-01T11:10:41-07:00 New Revision: 6aa963f780d63d4c8fa80de97dd79c932bc35f4e
URL: https://github.com/llvm/llvm-project/commit/6aa963f780d63d4c8fa80de97dd79c932bc35f4e DIFF: https://github.com/llvm/llvm-project/commit/6aa963f780d63d4c8fa80de97dd79c932bc35f4e.diff LOG: [lldb] Do not bump memory modificator ID when "internal" debugger memory is updated (#129092) This change adds a setting `target.process.track-memory-cache-changes`. Disabling this setting prevents invalidating and updating values in `ValueObject::UpdateValueIfNeeded` when only "internal" debugger memory is updated. Writing to "internal" debugger memory happens when, for instance, expressions are evaluated by visualizers (pretty printers). One of the examples when cache invalidation has a particularly heavy impact is visualizations of some collections: in some collections getting collection size is an expensive operation (it requires traversal of the collection). At the same time evaluating user expression with side effects (visible to target, not only to debugger) will still bump memory ID because: - If expression is evaluated via interpreter: it will cause write to "non-internal" memory - If expression is JIT-compiled: then to call the function LLDB will write to "non-internal" stack memory The downside of disabled `target.process.track-memory-cache-changes` setting is that convenience variables won't reevaluate synthetic children automatically. --------- Co-authored-by: Mikhail Zakharov <mikhail.zakha...@jetbrains.com> Added: lldb/test/Shell/Expr/TestExprWithSideEffect.cpp lldb/test/Shell/Expr/TestExprWithSideEffectOnConvenienceVar.cpp lldb/test/Shell/Expr/TestExprWithSideEffectOnConvenienceVarWindows.cpp lldb/test/Shell/Expr/TestProcessModificationIdOnExpr.cpp Modified: lldb/include/lldb/Target/Memory.h lldb/include/lldb/Target/Process.h lldb/source/Commands/CommandObjectProcess.cpp lldb/source/Commands/Options.td lldb/source/Target/Memory.cpp lldb/source/Target/Process.cpp lldb/source/Target/TargetProperties.td lldb/test/API/commands/settings/TestSettings.py Removed: ################################################################################ diff --git a/lldb/include/lldb/Target/Memory.h b/lldb/include/lldb/Target/Memory.h index 2d1489a2c96ea..864ef6ca00802 100644 --- a/lldb/include/lldb/Target/Memory.h +++ b/lldb/include/lldb/Target/Memory.h @@ -125,6 +125,8 @@ class AllocatedMemoryCache { bool DeallocateMemory(lldb::addr_t ptr); + bool IsInCache(lldb::addr_t addr) const; + protected: typedef std::shared_ptr<AllocatedBlock> AllocatedBlockSP; @@ -133,7 +135,7 @@ class AllocatedMemoryCache { // Classes that inherit from MemoryCache can see and modify these Process &m_process; - std::recursive_mutex m_mutex; + mutable std::recursive_mutex m_mutex; typedef std::multimap<uint32_t, AllocatedBlockSP> PermissionsToBlockMap; PermissionsToBlockMap m_memory_map; diff --git a/lldb/include/lldb/Target/Process.h b/lldb/include/lldb/Target/Process.h index f5ee01d3fa713..536a69fb89759 100644 --- a/lldb/include/lldb/Target/Process.h +++ b/lldb/include/lldb/Target/Process.h @@ -111,6 +111,7 @@ class ProcessProperties : public Properties { void SetOSPluginReportsAllThreads(bool does_report); bool GetSteppingRunsAllThreads() const; FollowForkMode GetFollowForkMode() const; + bool TrackMemoryCacheChanges() const; protected: Process *m_process; // Can be nullptr for global ProcessProperties @@ -312,6 +313,18 @@ class ProcessModID { return lldb::EventSP(); } + void Dump(Stream &stream) const { + stream.Format("ProcessModID:\n" + " m_stop_id: {0}\n m_last_natural_stop_id: {1}\n" + " m_resume_id: {2}\n m_memory_id: {3}\n" + " m_last_user_expression_resume: {4}\n" + " m_running_user_expression: {5}\n" + " m_running_utility_function: {6}\n", + m_stop_id, m_last_natural_stop_id, m_resume_id, m_memory_id, + m_last_user_expression_resume, m_running_user_expression, + m_running_utility_function); + } + private: uint32_t m_stop_id = 0; uint32_t m_last_natural_stop_id = 0; diff --git a/lldb/source/Commands/CommandObjectProcess.cpp b/lldb/source/Commands/CommandObjectProcess.cpp index ed80c854ed66e..d0f5eaf2dfd9a 100644 --- a/lldb/source/Commands/CommandObjectProcess.cpp +++ b/lldb/source/Commands/CommandObjectProcess.cpp @@ -1388,6 +1388,9 @@ class CommandObjectProcessStatus : public CommandObjectParsed { case 'v': m_verbose = true; break; + case 'd': + m_dump = true; + break; default: llvm_unreachable("Unimplemented option"); } @@ -1397,6 +1400,7 @@ class CommandObjectProcessStatus : public CommandObjectParsed { void OptionParsingStarting(ExecutionContext *execution_context) override { m_verbose = false; + m_dump = false; } llvm::ArrayRef<OptionDefinition> GetDefinitions() override { @@ -1405,6 +1409,7 @@ class CommandObjectProcessStatus : public CommandObjectParsed { // Instance variables to hold the values for command options. bool m_verbose = false; + bool m_dump = false; }; protected: @@ -1459,6 +1464,14 @@ class CommandObjectProcessStatus : public CommandObjectParsed { crash_info_sp->GetDescription(strm); } } + + if (m_options.m_dump) { + StateType state = process->GetState(); + if (state == eStateStopped) { + ProcessModID process_mod_id = process->GetModID(); + process_mod_id.Dump(result.GetOutputStream()); + } + } } private: diff --git a/lldb/source/Commands/Options.td b/lldb/source/Commands/Options.td index 53864ff29327d..14ade96832c68 100644 --- a/lldb/source/Commands/Options.td +++ b/lldb/source/Commands/Options.td @@ -788,6 +788,8 @@ let Command = "process handle" in { let Command = "process status" in { def process_status_verbose : Option<"verbose", "v">, Group<1>, Desc<"Show verbose process status including extended crash information.">; + def process_status_dump : Option<"dump-modification-id", "d">, Group<1>, + Desc<"Dump the state of the ProcessModID of the stopped process.">; } let Command = "process save_core" in { diff --git a/lldb/source/Target/Memory.cpp b/lldb/source/Target/Memory.cpp index 5cdd84f6640f0..9bfb8c349aa2c 100644 --- a/lldb/source/Target/Memory.cpp +++ b/lldb/source/Target/Memory.cpp @@ -433,3 +433,11 @@ bool AllocatedMemoryCache::DeallocateMemory(lldb::addr_t addr) { (uint64_t)addr, success); return success; } + +bool AllocatedMemoryCache::IsInCache(lldb::addr_t addr) const { + std::lock_guard guard(m_mutex); + + return llvm::any_of(m_memory_map, [addr](const auto &block) { + return block.second->Contains(addr); + }); +} diff --git a/lldb/source/Target/Process.cpp b/lldb/source/Target/Process.cpp index 73557eb767c72..7694175ee29d9 100644 --- a/lldb/source/Target/Process.cpp +++ b/lldb/source/Target/Process.cpp @@ -370,6 +370,12 @@ FollowForkMode ProcessProperties::GetFollowForkMode() const { g_process_properties[idx].default_uint_value)); } +bool ProcessProperties::TrackMemoryCacheChanges() const { + const uint32_t idx = ePropertyTrackMemoryCacheChanges; + return GetPropertyAtIndexAs<bool>( + idx, g_process_properties[idx].default_uint_value != 0); +} + ProcessSP Process::FindPlugin(lldb::TargetSP target_sp, llvm::StringRef plugin_name, ListenerSP listener_sp, @@ -2285,6 +2291,7 @@ size_t Process::WriteMemoryPrivate(addr_t addr, const void *buf, size_t size, return bytes_written; } +#define USE_ALLOCATE_MEMORY_CACHE 1 size_t Process::WriteMemory(addr_t addr, const void *buf, size_t size, Status &error) { if (ABISP abi_sp = GetABI()) @@ -2297,7 +2304,12 @@ size_t Process::WriteMemory(addr_t addr, const void *buf, size_t size, if (buf == nullptr || size == 0) return 0; +#if defined(USE_ALLOCATE_MEMORY_CACHE) + if (TrackMemoryCacheChanges() || !m_allocated_memory_cache.IsInCache(addr)) + m_mod_id.BumpMemoryID(); +#else m_mod_id.BumpMemoryID(); +#endif // We need to write any data that would go where any current software traps // (enabled software breakpoints) any software traps (breakpoints) that we @@ -2426,7 +2438,6 @@ Status Process::WriteObjectFile(std::vector<ObjectFile::LoadableData> entries) { return error; } -#define USE_ALLOCATE_MEMORY_CACHE 1 addr_t Process::AllocateMemory(size_t size, uint32_t permissions, Status &error) { if (GetPrivateState() != eStateStopped) { diff --git a/lldb/source/Target/TargetProperties.td b/lldb/source/Target/TargetProperties.td index 3940ac00a2bd9..14fa33cc22c18 100644 --- a/lldb/source/Target/TargetProperties.td +++ b/lldb/source/Target/TargetProperties.td @@ -299,6 +299,9 @@ let Definition = "process" in { DefaultEnumValue<"eFollowParent">, EnumValues<"OptionEnumValues(g_follow_fork_mode_values)">, Desc<"Debugger's behavior upon fork or vfork.">; + def TrackMemoryCacheChanges: Property<"track-memory-cache-changes", "Boolean">, + DefaultTrue, + Desc<"If true, memory cache modifications (which happen often during expressions evaluation) will bump process state ID (and invalidate all synthetic children). Disabling this option helps to avoid synthetic children reevaluation when pretty printers heavily use expressions. The downside of disabled setting is that convenience variables won't reevaluate synthetic children automatically.">; } let Definition = "platform" in { diff --git a/lldb/test/API/commands/settings/TestSettings.py b/lldb/test/API/commands/settings/TestSettings.py index 4eb868430b006..4f4fa0e032b50 100644 --- a/lldb/test/API/commands/settings/TestSettings.py +++ b/lldb/test/API/commands/settings/TestSettings.py @@ -905,6 +905,7 @@ def test_all_settings_exist(self): "target.use-hex-immediates", "target.process.disable-memory-cache", "target.process.extra-startup-command", + "target.process.track-memory-cache-changes", "target.process.thread.trace-thread", "target.process.thread.step-avoid-regexp", ], diff --git a/lldb/test/Shell/Expr/TestExprWithSideEffect.cpp b/lldb/test/Shell/Expr/TestExprWithSideEffect.cpp new file mode 100644 index 0000000000000..4fc88b62730c7 --- /dev/null +++ b/lldb/test/Shell/Expr/TestExprWithSideEffect.cpp @@ -0,0 +1,55 @@ +// Tests evaluating expressions with side effects. +// Applied side effect should be visible to the debugger. + +// RUN: %build %s -o %t +// RUN: %lldb %t \ +// RUN: -o "settings set target.process.track-memory-cache-changes false" \ +// RUN: -o "run" \ +// RUN: -o "frame variable x" \ +// RUN: -o "expr x.inc()" \ +// RUN: -o "frame variable x" \ +// RUN: -o "continue" \ +// RUN: -o "frame variable x" \ +// RUN: -o "expr x.i = 10" \ +// RUN: -o "frame variable x" \ +// RUN: -o "continue" \ +// RUN: -o "frame variable x" \ +// RUN: -o "exit" | FileCheck %s -dump-input=fail + +class X { + int i = 0; + +public: + void inc() { ++i; } +}; + +int main() { + X x; + x.inc(); + + __builtin_debugtrap(); + __builtin_debugtrap(); + __builtin_debugtrap(); + return 0; +} + +// CHECK-LABEL: frame variable x +// CHECK: (X) x = (i = 1) + +// CHECK-LABEL: expr x.inc() +// CHECK-LABEL: frame variable x +// CHECK: (X) x = (i = 2) + +// CHECK-LABEL: continue +// CHECK-LABEL: frame variable x +// CHECK: (X) x = (i = 2) + +// CHECK-LABEL: expr x.i = 10 +// CHECK: (int) $0 = 10 + +// CHECK-LABEL: frame variable x +// CHECK: (X) x = (i = 10) + +// CHECK-LABEL: continue +// CHECK-LABEL: frame variable x +// CHECK: (X) x = (i = 10) diff --git a/lldb/test/Shell/Expr/TestExprWithSideEffectOnConvenienceVar.cpp b/lldb/test/Shell/Expr/TestExprWithSideEffectOnConvenienceVar.cpp new file mode 100644 index 0000000000000..b41a81f6f31a9 --- /dev/null +++ b/lldb/test/Shell/Expr/TestExprWithSideEffectOnConvenienceVar.cpp @@ -0,0 +1,52 @@ +// Tests evaluating expressions with side effects on convenience variable. +// Applied side effect should be visible to the debugger. + +// UNSUPPORTED: system-windows + +// RUN: %build %s -o %t +// RUN: %lldb %t \ +// RUN: -o "settings set target.process.track-memory-cache-changes false" \ +// RUN: -o "run" \ +// RUN: -o "expr int \$y = 11" \ +// RUN: -o "expr \$y" \ +// RUN: -o "expr \$y = 100" \ +// RUN: -o "expr \$y" \ +// RUN: -o "continue" \ +// RUN: -o "expr \$y" \ +// RUN: -o "expr X \$mine = {100, 200}" \ +// RUN: -o "expr \$mine.a = 300" \ +// RUN: -o "expr \$mine" \ +// RUN: -o "exit" | FileCheck %s -dump-input=fail + +struct X { + int a; + int b; +}; + +int main() { + X x; + + __builtin_debugtrap(); + __builtin_debugtrap(); + return 0; +} + +// CHECK-LABEL: expr int $y = 11 +// CHECK-LABEL: expr $y +// CHECK: (int) $y = 11 + +// CHECK-LABEL: expr $y = 100 +// CHECK: (int) $0 = 100 + +// CHECK-LABEL: expr $y +// CHECK: (int) $y = 100 + +// CHECK-LABEL: continue +// CHECK-LABEL: expr $y +// CHECK: (int) $y = 100 + +// CHECK-LABEL: expr X $mine = {100, 200} +// CHECK-LABEL: expr $mine.a = 300 +// CHECK: (int) $1 = 300 +// CHECK-LABEL: expr $mine +// CHECK: (X) $mine = (a = 300, b = 200) diff --git a/lldb/test/Shell/Expr/TestExprWithSideEffectOnConvenienceVarWindows.cpp b/lldb/test/Shell/Expr/TestExprWithSideEffectOnConvenienceVarWindows.cpp new file mode 100644 index 0000000000000..8ac4b961f1ca9 --- /dev/null +++ b/lldb/test/Shell/Expr/TestExprWithSideEffectOnConvenienceVarWindows.cpp @@ -0,0 +1,51 @@ +// Same as TestExprWithSideEffectOnConvenienceVar.cpp but without $ escaping + +// REQUIRES: target-windows + +// RUN: %build %s -o %t +// RUN: %lldb %t \ +// RUN: -o "settings set target.process.track-memory-cache-changes false" \ +// RUN: -o "run" \ +// RUN: -o "expr int $y = 11" \ +// RUN: -o "expr $y" \ +// RUN: -o "expr $y = 100" \ +// RUN: -o "expr $y" \ +// RUN: -o "continue" \ +// RUN: -o "expr $y" \ +// RUN: -o "expr X $mine = {100, 200}" \ +// RUN: -o "expr $mine.a = 300" \ +// RUN: -o "expr $mine" \ +// RUN: -o "exit" | FileCheck %s -dump-input=fail + +struct X { + int a; + int b; +}; + +int main() { + X x; + + __builtin_debugtrap(); + __builtin_debugtrap(); + return 0; +} + +// CHECK-LABEL: expr int $y = 11 +// CHECK-LABEL: expr $y +// CHECK: (int) $y = 11 + +// CHECK-LABEL: expr $y = 100 +// CHECK: (int) $0 = 100 + +// CHECK-LABEL: expr $y +// CHECK: (int) $y = 100 + +// CHECK-LABEL: continue +// CHECK-LABEL: expr $y +// CHECK: (int) $y = 100 + +// CHECK-LABEL: expr X $mine = {100, 200} +// CHECK-LABEL: expr $mine.a = 300 +// CHECK: (int) $1 = 300 +// CHECK-LABEL: expr $mine +// CHECK: (X) $mine = (a = 300, b = 200) diff --git a/lldb/test/Shell/Expr/TestProcessModificationIdOnExpr.cpp b/lldb/test/Shell/Expr/TestProcessModificationIdOnExpr.cpp new file mode 100644 index 0000000000000..eea02665c0749 --- /dev/null +++ b/lldb/test/Shell/Expr/TestProcessModificationIdOnExpr.cpp @@ -0,0 +1,67 @@ +// Tests that ProcessModID.m_memory_id is not bumped when evaluating expressions without side effects. + +// REQUIRES: target-windows +// Due to diff erent implementations exact numbers (m_stop_id) are diff erent on diff erent OSs. So we lock this test to specific platform. + +// RUN: %build %s -o %t +// RUN: %lldb %t \ +// RUN: -o "settings set target.process.track-memory-cache-changes false" \ +// RUN: -o "run" \ +// RUN: -o "process status -d" \ +// RUN: -o "expr x.i != 42" \ +// RUN: -o "process status -d" \ +// RUN: -o "expr x.get()" \ +// RUN: -o "process status -d" \ +// RUN: -o "expr x.i = 10" \ +// RUN: -o "process status -d" \ +// RUN: -o "continue" \ +// RUN: -o "process status -d" \ +// RUN: -o "exit" | FileCheck %s -dump-input=fail + +class X { + int i = 0; + +public: + int get() { return i; } +}; + +int main() { + X x; + x.get(); + + __builtin_debugtrap(); + __builtin_debugtrap(); + return 0; +} + +// CHECK-LABEL: process status -d +// CHECK: m_stop_id: 2 +// CHECK: m_memory_id: 0 + +// CHECK-LABEL: expr x.i != 42 +// IDs are not changed when executing simple expressions + +// CHECK-LABEL: process status -d +// CHECK: m_stop_id: 2 +// CHECK: m_memory_id: 0 + +// CHECK-LABEL: expr x.get() +// Expression causes ID to be bumped because LLDB has to execute function + +// CHECK-LABEL: process status -d +// CHECK: m_stop_id: 3 +// CHECK: m_memory_id: 1 + +// CHECK-LABEL: expr x.i = 10 +// Expression causes MemoryID to be bumped because LLDB writes to non-cache memory + +// CHECK-LABEL: process status -d +// CHECK: m_stop_id: 3 +// CHECK: m_memory_id: 2 + +// CHECK-LABEL: continue +// Continue causes StopID to be bumped because process is resumed + +// CHECK-LABEL: process status -d +// CHECK: m_stop_id: 4 +// CHECK: m_memory_id: 2 _______________________________________________ lldb-commits mailing list lldb-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits
