[Lldb-commits] [lldb] [lldb-dap] Add memory event (PR #158437)
Druzhkov Sergei via lldb-commits
lldb-commits at lists.llvm.org
Sat Sep 13 13:43:21 PDT 2025
https://github.com/DrSergei created https://github.com/llvm/llvm-project/pull/158437
This patch adds support for the `memory` event from the [DAP](https://microsoft.github.io/debug-adapter-protocol/specification#Events_Memory). After this event is emitted, VS Code refetches the corresponding memory range and re-renders the memory view. I think this patch and [PR](https://github.com/llvm/llvm-project/pull/151884) can improve experience for users who use `setVariable` request.
>From 181075379693af77cfde778102b62e72a789ba2a Mon Sep 17 00:00:00 2001
From: Druzhkov Sergei <serzhdruzhok at gmail.com>
Date: Sat, 13 Sep 2025 23:33:49 +0300
Subject: [PATCH] [lldb-dap] Add memory event
---
.../test/tools/lldb-dap/dap_server.py | 4 +++
.../test/tools/lldb-dap/lldbdap_testcase.py | 9 ++++++
lldb/tools/lldb-dap/EventHelper.cpp | 13 +++++++++
lldb/tools/lldb-dap/EventHelper.h | 2 ++
.../Handler/SetVariableRequestHandler.cpp | 3 ++
.../lldb-dap/Protocol/ProtocolEvents.cpp | 8 ++++++
lldb/tools/lldb-dap/Protocol/ProtocolEvents.h | 28 +++++++++++++++++++
lldb/unittests/DAP/ProtocolTypesTest.cpp | 13 +++++++++
8 files changed, 80 insertions(+)
diff --git a/lldb/packages/Python/lldbsuite/test/tools/lldb-dap/dap_server.py b/lldb/packages/Python/lldbsuite/test/tools/lldb-dap/dap_server.py
index 9fe8ca22e820b..3a9e076eff9f0 100644
--- a/lldb/packages/Python/lldbsuite/test/tools/lldb-dap/dap_server.py
+++ b/lldb/packages/Python/lldbsuite/test/tools/lldb-dap/dap_server.py
@@ -216,6 +216,7 @@ def __init__(
self.events: List[Event] = []
self.progress_events: List[Event] = []
self.invalidated_event: Optional[Event] = None
+ self.memory_event: Optional[Event] = None
self.reverse_requests: List[Request] = []
self.module_events: List[Dict] = []
self.sequence: int = 1
@@ -443,6 +444,8 @@ def _handle_event(self, packet: Event) -> None:
self.capabilities.update(body["capabilities"])
elif event == "invalidated":
self.invalidated_event = packet
+ elif event == "memory":
+ self.memory_event = packet
def _handle_reverse_request(self, request: Request) -> None:
if request in self.reverse_requests:
@@ -1018,6 +1021,7 @@ def request_initialize(self, sourceInitFile=False):
"supportsStartDebuggingRequest": True,
"supportsProgressReporting": True,
"supportsInvalidatedEvent": True,
+ "supportsMemoryEvent": True,
"$__lldb_sourceInitFile": sourceInitFile,
},
}
diff --git a/lldb/packages/Python/lldbsuite/test/tools/lldb-dap/lldbdap_testcase.py b/lldb/packages/Python/lldbsuite/test/tools/lldb-dap/lldbdap_testcase.py
index a0a009ae6cc9a..882eec9971a73 100644
--- a/lldb/packages/Python/lldbsuite/test/tools/lldb-dap/lldbdap_testcase.py
+++ b/lldb/packages/Python/lldbsuite/test/tools/lldb-dap/lldbdap_testcase.py
@@ -248,6 +248,14 @@ def verify_invalidated_event(self, expected_areas):
areas = event["body"].get("areas", [])
self.assertEqual(set(expected_areas), set(areas))
+ def verify_memory_event(self, memoryReference):
+ if memoryReference is None:
+ self.assertIsNone(self.dap_server.memory_event)
+ event = self.dap_server.memory_event
+ self.dap_server.memory_event = None
+ self.assertIsNotNone(event)
+ self.assertEqual(memoryReference, event["body"].get("memoryReference"))
+
def get_dict_value(self, d: dict, key_path: list[str]) -> Any:
"""Verify each key in the key_path array is in contained in each
dictionary within "d". Assert if any key isn't in the
@@ -364,6 +372,7 @@ def set_variable(self, varRef, name, value, id=None):
response = self.dap_server.request_setVariable(varRef, name, str(value), id=id)
if response["success"]:
self.verify_invalidated_event(["variables"])
+ self.verify_memory_event(response["body"].get("memoryReference"))
return response
def set_local(self, name, value, id=None):
diff --git a/lldb/tools/lldb-dap/EventHelper.cpp b/lldb/tools/lldb-dap/EventHelper.cpp
index 6eb468e76b16c..9c2c1f846d11e 100644
--- a/lldb/tools/lldb-dap/EventHelper.cpp
+++ b/lldb/tools/lldb-dap/EventHelper.cpp
@@ -284,4 +284,17 @@ void SendInvalidatedEvent(
dap.Send(protocol::Event{"invalidated", std::move(body)});
}
+void SendMemoryEvent(DAP &dap, lldb::SBValue variable) {
+ if (!dap.clientFeatures.contains(protocol::eClientFeatureMemoryEvent))
+ return;
+ const lldb::addr_t addr = variable.GetLoadAddress();
+ if (addr == LLDB_INVALID_ADDRESS)
+ return;
+ protocol::MemoryEventBody body;
+ body.memoryReference = addr;
+ body.offset = 0;
+ body.count = variable.GetByteSize();
+ dap.Send(protocol::Event{"memory", std::move(body)});
+}
+
} // namespace lldb_dap
diff --git a/lldb/tools/lldb-dap/EventHelper.h b/lldb/tools/lldb-dap/EventHelper.h
index 0c57afbaf1f33..48eb5af6bd0b9 100644
--- a/lldb/tools/lldb-dap/EventHelper.h
+++ b/lldb/tools/lldb-dap/EventHelper.h
@@ -37,6 +37,8 @@ void SendProcessExitedEvent(DAP &dap, lldb::SBProcess &process);
void SendInvalidatedEvent(
DAP &dap, llvm::ArrayRef<protocol::InvalidatedEventBody::Area> areas);
+void SendMemoryEvent(DAP &dap, lldb::SBValue variable);
+
} // namespace lldb_dap
#endif
diff --git a/lldb/tools/lldb-dap/Handler/SetVariableRequestHandler.cpp b/lldb/tools/lldb-dap/Handler/SetVariableRequestHandler.cpp
index 2a50dea0b4ada..b9ae28d6772ac 100644
--- a/lldb/tools/lldb-dap/Handler/SetVariableRequestHandler.cpp
+++ b/lldb/tools/lldb-dap/Handler/SetVariableRequestHandler.cpp
@@ -82,6 +82,9 @@ SetVariableRequestHandler::Run(const SetVariableArguments &args) const {
// (e.g. references) can be changed.
SendInvalidatedEvent(dap, {InvalidatedEventBody::eAreaVariables});
+ // Also send memory event to signal client that variable memory was changed.
+ SendMemoryEvent(dap, variable);
+
return body;
}
diff --git a/lldb/tools/lldb-dap/Protocol/ProtocolEvents.cpp b/lldb/tools/lldb-dap/Protocol/ProtocolEvents.cpp
index 9598c69878d66..98bc18f880aa8 100644
--- a/lldb/tools/lldb-dap/Protocol/ProtocolEvents.cpp
+++ b/lldb/tools/lldb-dap/Protocol/ProtocolEvents.cpp
@@ -7,6 +7,7 @@
//===----------------------------------------------------------------------===//
#include "Protocol/ProtocolEvents.h"
+#include "JSONUtils.h"
#include "llvm/Support/JSON.h"
using namespace llvm;
@@ -56,4 +57,11 @@ llvm::json::Value toJSON(const InvalidatedEventBody &IEB) {
return Result;
}
+llvm::json::Value toJSON(const MemoryEventBody &MEB) {
+ return json::Object{
+ {"memoryReference", EncodeMemoryReference(MEB.memoryReference)},
+ {"offset", MEB.offset},
+ {"count", MEB.count}};
+}
+
} // namespace lldb_dap::protocol
diff --git a/lldb/tools/lldb-dap/Protocol/ProtocolEvents.h b/lldb/tools/lldb-dap/Protocol/ProtocolEvents.h
index 138b622e01210..045b2ac7d8ea8 100644
--- a/lldb/tools/lldb-dap/Protocol/ProtocolEvents.h
+++ b/lldb/tools/lldb-dap/Protocol/ProtocolEvents.h
@@ -88,6 +88,34 @@ struct InvalidatedEventBody {
llvm::json::Value toJSON(const InvalidatedEventBody::Area &);
llvm::json::Value toJSON(const InvalidatedEventBody &);
+/// This event indicates that some memory range has been updated. It should only
+/// be sent if the corresponding capability supportsMemoryEvent is true.
+///
+/// Clients typically react to the event by re-issuing a readMemory request if
+/// they show the memory identified by the memoryReference and if the updated
+/// memory range overlaps the displayed range. Clients should not make
+/// assumptions how individual memory references relate to each other, so they
+/// should not assume that they are part of a single continuous address range
+/// and might overlap.
+///
+/// Debug adapters can use this event to indicate that the contents of a memory
+/// range has changed due to some other request like setVariable or
+/// setExpression. Debug adapters are not expected to emit this event for each
+/// and every memory change of a running program, because that information is
+/// typically not available from debuggers and it would flood clients with too
+/// many events.
+struct MemoryEventBody {
+ /// Memory reference of a memory range that has been updated.
+ lldb::addr_t memoryReference;
+
+ /// Starting offset in bytes where memory has been updated. Can be negative.
+ int64_t offset;
+
+ /// Number of bytes updated.
+ uint64_t count;
+};
+llvm::json::Value toJSON(const MemoryEventBody &);
+
} // end namespace lldb_dap::protocol
#endif
diff --git a/lldb/unittests/DAP/ProtocolTypesTest.cpp b/lldb/unittests/DAP/ProtocolTypesTest.cpp
index a964592495347..be1e6a1470252 100644
--- a/lldb/unittests/DAP/ProtocolTypesTest.cpp
+++ b/lldb/unittests/DAP/ProtocolTypesTest.cpp
@@ -1088,3 +1088,16 @@ TEST(ProtocolTypesTest, InvalidatedEventBody) {
})";
EXPECT_EQ(json, pp(body));
}
+
+TEST(ProtocolTypesTest, MemoryEventBody) {
+ MemoryEventBody body;
+ body.memoryReference = 12345;
+ body.offset = 0;
+ body.count = 4;
+ StringRef json = R"({
+ "count": 4,
+ "memoryReference": "0x3039",
+ "offset": 0
+})";
+ EXPECT_EQ(json, pp(body));
+}
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