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[lldb] Call FixUpPointer in WritePointerToMemory (try 2) #153585

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[lldb] Call FixUpPointer in WritePointerToMemory (try 2) #153585

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ce9c2cc
[lldb] Call FixUpPointer in WritePointerToMemory (try 2)
felipepiovezan Aug 14, 2025
36dcebb
fixup! Improve comment
felipepiovezan Aug 14, 2025
579c985
fixup! Add {} to if statement
felipepiovezan Aug 14, 2025
d098df3
fixup! Fix address confusion
felipepiovezan Aug 27, 2025
e96470a
fixup! Add test
felipepiovezan Sep 2, 2025
293e1dd
fixup! Clang-format test
felipepiovezan Sep 2, 2025
7f02dbd
fixup! Address test feedback
felipepiovezan Sep 3, 2025
1431f5e
fixup! Fix python formatting
felipepiovezan Sep 3, 2025
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9 changes: 9 additions & 0 deletions lldb/source/Expression/IRMemoryMap.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -640,6 +640,15 @@ 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. An address belongs to the process if the Allocation contains a
/// non-empty m_data member.
if (auto it = FindAllocation(process_address, 1);
it != m_allocations.end() && it->second.m_data.GetByteSize() == 0) {
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Looking at IRMemoryMap::WriteMemory() (I haven't read these methods in years, needed to refresh my memory), it has different behavior based on the Allocation m_policy which can be one of eAllocationPolicyHostOnly, eAllocationPolicyMirror, or eAllocationPolicyProcessOnly. The goal is to run any pointer that is written into actual process memory through Fix, because it will be used by a jitted expression running in native code, and cannot refer to the host-side-only fake addresses that IRMemoryMap may hand out. Maybe the m_data.GetByteSize() test is sufficient, but I think it's maybe clearer to test for m_policy != eAllocationPolicyHostOnly? I'm not sure what Mirror is used for, possibly expression results where we might want to take the address of them in inferior-memory, but for efficiency of display/use in lldb, also stored in lldb.

if (auto process_sp = GetProcessWP().lock())
address = process_sp->FixAnyAddress(address);
}

Scalar scalar(address);

WriteScalarToMemory(process_address, scalar, GetAddressByteSize(), error);
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