[Lldb-commits] [lldb] [lldb] Call FixUpPointer in WritePointerToMemory (try 2) (PR #153585)

[Felipe de Azevedo Piovezan via lldb-commits]

https://github.com/felipepiovezan created https://github.com/llvm/llvm-project/pull/153585

In architectures where pointers may contain metadata, such as arm64e, the metadata may need to be cleaned prior to sending this pointer to be used in expression evaluation generated code.

This patch is a step towards allowing consumers of pointers to decide whether they want to keep or remove metadata, as opposed to discarding metadata at the moment pointers are created. See #150537.

This was tested running the LLDB test suite on arm64e.

(The first attempt at this patch caused a failure in TestScriptedProcessEmptyMemoryRegion.py. This test exercises a case where IRMemoryMap uses host memory in its allocations; pointers to such allocations should not be fixed, which is what the original patch failed to account for).

>From ce9c2cc6748c22ce4b0f5178b66668f5e877d430 Mon Sep 17 00:00:00 2001
From: Felipe de Azevedo Piovezan <fpiovezan at apple.com>
Date: Wed, 13 Aug 2025 18:38:23 -0700
Subject: [PATCH] [lldb] Call FixUpPointer in WritePointerToMemory (try 2)

In architectures where pointers may contain metadata, such as arm64e,
the metadata may need to be cleaned prior to sending this pointer to be
used in expression evaluation generated code.

This patch is a step towards allowing consumers of pointers to decide
whether they want to keep or remove metadata, as opposed to discarding
metadata at the moment pointers are created. See #150537.

This was tested running the LLDB test suite on arm64e.

(The first attempt at this patch caused a failure in
TestScriptedProcessEmptyMemoryRegion.py. This test exercises a case
where IRMemoryMap uses host memory in its allocations; pointers to such
allocations should not be fixed, which is what the original patch failed
to account for).
---
 lldb/source/Expression/IRMemoryMap.cpp | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/lldb/source/Expression/IRMemoryMap.cpp b/lldb/source/Expression/IRMemoryMap.cpp
index 150699352a2e3..3ac42649d0834 100644
--- a/lldb/source/Expression/IRMemoryMap.cpp
+++ b/lldb/source/Expression/IRMemoryMap.cpp
@@ -640,6 +640,13 @@ void IRMemoryMap::WritePointerToMemory(lldb::addr_t process_address,
                                        lldb::addr_t address, Status &error) {
   error.Clear();
 
+  /// Only ask the Process to fix the address if this address belongs to the
+  /// process (host allocations are stored in m_data).
+  if (auto it = FindAllocation(process_address, 1);
+      it != m_allocations.end() && it->second.m_data.GetByteSize() == 0)
+    if (auto process_sp = GetProcessWP().lock())
+      address = process_sp->FixAnyAddress(address);
+
   Scalar scalar(address);
 
   WriteScalarToMemory(process_address, scalar, GetAddressByteSize(), error);