[Lldb-commits] [lldb] [lldb-server] Add type info for qMemoryinfo reponse (PR #209235)

[Felipe de Azevedo Piovezan via lldb-commits]

https://github.com/felipepiovezan updated https://github.com/llvm/llvm-project/pull/209235

>From e399cf7e6aba2ef2999addffc5401099f543bc9a Mon Sep 17 00:00:00 2001
From: Felipe de Azevedo Piovezan <fpiovezan at apple.com>
Date: Mon, 13 Jul 2026 11:45:42 +0100
Subject: [PATCH 1/2] [lldb-server] Add type info for qMemoryinfo reponse

Use the name of the memory region to report the known cases of where an
address points to stack/heap: "[stack]" or "[heap"].

According to [1], the "[stack]" name is only available for the main
thread. So we can only set "isStack" to Yes in some cases, and to "No"
when the name is "[heap]". If there is no name, or the name is something
else, we keep the "don't know" answer.

> [stack:tid] (from Linux 3.4 to Linux 4.4)
>        A thread's stack (where the tid is a thread ID).  It
>        corresponds to the /proc/pid/task/tid/ path.  This
>        field was removed in Linux 4.5, since providing this
>        information for a process with large numbers of
>        threads is expensive.

https://man7.org/linux/man-pages/man5/proc_pid_maps.5.html
---
 lldb/include/lldb/Target/MemoryRegionInfo.h         |  5 ++++-
 .../Plugins/Process/Utility/LinuxProcMaps.cpp       |  9 ++++++++-
 .../gdb-remote/GDBRemoteCommunicationServerLLGS.cpp |  7 +++++++
 .../unittests/Process/Utility/LinuxProcMapsTest.cpp | 13 ++++++++++++-
 4 files changed, 31 insertions(+), 3 deletions(-)

diff --git a/lldb/include/lldb/Target/MemoryRegionInfo.h b/lldb/include/lldb/Target/MemoryRegionInfo.h
index 16faf6ed9d64b..e8a16a3ab9757 100644
--- a/lldb/include/lldb/Target/MemoryRegionInfo.h
+++ b/lldb/include/lldb/Target/MemoryRegionInfo.h
@@ -142,7 +142,10 @@ class MemoryRegionInfo {
 
   LazyBool IsStackMemory() const { return m_is_stack_memory; }
 
-  void SetIsStackMemory(LazyBool val) { m_is_stack_memory = val; }
+  MemoryRegionInfo &SetIsStackMemory(LazyBool val) {
+    m_is_stack_memory = val;
+    return *this;
+  }
 
   void SetPageSize(int pagesize) { m_pagesize = pagesize; }
 
diff --git a/lldb/source/Plugins/Process/Utility/LinuxProcMaps.cpp b/lldb/source/Plugins/Process/Utility/LinuxProcMaps.cpp
index d952b7dbdb816..bdb340332851a 100644
--- a/lldb/source/Plugins/Process/Utility/LinuxProcMaps.cpp
+++ b/lldb/source/Plugins/Process/Utility/LinuxProcMaps.cpp
@@ -114,8 +114,15 @@ ParseMemoryRegionInfoFromProcMapsLine(llvm::StringRef maps_line,
 
   line_extractor.SkipSpaces();
   const char *name = line_extractor.Peek();
-  if (name)
+  if (name) {
     region.SetName(name);
+    // /proc/maps labels only the main thread's stack; thread stacks are
+    // anonymous and the default MemoryRegionInfo::eDontKnow is kept.
+    if (llvm::StringRef(name) == "[stack]")
+      region.SetIsStackMemory(eLazyBoolYes);
+    else if (llvm::StringRef(name) == "[heap]")
+      region.SetIsStackMemory(eLazyBoolNo);
+  }
 
   return region;
 }
diff --git a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.cpp b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.cpp
index 769705588fbdf..451855ef80e75 100644
--- a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.cpp
+++ b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.cpp
@@ -2971,6 +2971,13 @@ GDBRemoteCommunicationServerLLGS::Handle_qMemoryRegionInfo(
 
     if (std::optional<unsigned> protection_key = region_info.GetProtectionKey())
       response.Printf("protection-key:%" PRIu32 ";", *protection_key);
+
+    // Type: stack/heap classification, when known.
+    LazyBool is_stack = region_info.IsStackMemory();
+    if (is_stack == eLazyBoolYes)
+      response.PutCString("type:stack;");
+    else if (is_stack == eLazyBoolNo)
+      response.PutCString("type:heap;");
   }
 
   return SendPacketNoLock(response.GetString());
diff --git a/lldb/unittests/Process/Utility/LinuxProcMapsTest.cpp b/lldb/unittests/Process/Utility/LinuxProcMapsTest.cpp
index fcfd76cc67960..84aa206b4e50a 100644
--- a/lldb/unittests/Process/Utility/LinuxProcMapsTest.cpp
+++ b/lldb/unittests/Process/Utility/LinuxProcMapsTest.cpp
@@ -99,7 +99,18 @@ INSTANTIATE_TEST_SUITE_P(
                 MemoryRegionInfo(make_range(0x55a4512f7000, 0x55a451b68000),
                                  eLazyBoolYes, eLazyBoolYes, eLazyBoolNo,
                                  eLazyBoolNo, eLazyBoolYes,
-                                 ConstString("[heap]")),
+                                 ConstString("[heap]"))
+                    .SetIsStackMemory(eLazyBoolNo),
+            },
+            ""),
+        std::make_tuple(
+            "7ffcad8f7000-7ffcad918000 rw-p 00000000 00:00 0    [stack]",
+            MemoryRegionInfos{
+                MemoryRegionInfo(make_range(0x7ffcad8f7000, 0x7ffcad918000),
+                                 eLazyBoolYes, eLazyBoolYes, eLazyBoolNo,
+                                 eLazyBoolNo, eLazyBoolYes,
+                                 ConstString("[stack]"))
+                    .SetIsStackMemory(eLazyBoolYes),
             },
             ""),
         // Multiple entries

>From c1909ed9d19571988a0137d3837806e9af1f0c88 Mon Sep 17 00:00:00 2001
From: Felipe de Azevedo Piovezan <fpiovezan at apple.com>
Date: Tue, 14 Jul 2026 10:18:24 +0100
Subject: [PATCH 2/2] fixup! Address review comments

---
 lldb/source/Plugins/Process/Utility/LinuxProcMaps.cpp      | 2 ++
 .../gdb-remote/GDBRemoteCommunicationServerLLGS.cpp        | 7 ++-----
 2 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/lldb/source/Plugins/Process/Utility/LinuxProcMaps.cpp b/lldb/source/Plugins/Process/Utility/LinuxProcMaps.cpp
index bdb340332851a..e922f3edeb550 100644
--- a/lldb/source/Plugins/Process/Utility/LinuxProcMaps.cpp
+++ b/lldb/source/Plugins/Process/Utility/LinuxProcMaps.cpp
@@ -122,6 +122,8 @@ ParseMemoryRegionInfoFromProcMapsLine(llvm::StringRef maps_line,
       region.SetIsStackMemory(eLazyBoolYes);
     else if (llvm::StringRef(name) == "[heap]")
       region.SetIsStackMemory(eLazyBoolNo);
+    else
+     region.SetIsStackMemory(eLazyBoolDontKnow);
   }
 
   return region;
diff --git a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.cpp b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.cpp
index 451855ef80e75..4f11cf8c5475e 100644
--- a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.cpp
+++ b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.cpp
@@ -2972,12 +2972,9 @@ GDBRemoteCommunicationServerLLGS::Handle_qMemoryRegionInfo(
     if (std::optional<unsigned> protection_key = region_info.GetProtectionKey())
       response.Printf("protection-key:%" PRIu32 ";", *protection_key);
 
-    // Type: stack/heap classification, when known.
     LazyBool is_stack = region_info.IsStackMemory();
-    if (is_stack == eLazyBoolYes)
-      response.PutCString("type:stack;");
-    else if (is_stack == eLazyBoolNo)
-      response.PutCString("type:heap;");
+    if (is_stack != eLazyBoolDontKnow)
+      response.Printf("type: %s", is_stack ? "stack" : "heap");
   }
 
   return SendPacketNoLock(response.GetString());