[Lldb-commits] [lldb] 71ccd0d - [IRInterpreter] Return zero address for missing weak function (#93548)

[via lldb-commits]

Author: Nikita Popov
Date: 2024-05-31T08:18:35+02:00
New Revision: 71ccd0d8ccf876e32e21514839195f159642fe4c

URL: https://github.com/llvm/llvm-project/commit/71ccd0d8ccf876e32e21514839195f159642fe4c
DIFF: https://github.com/llvm/llvm-project/commit/71ccd0d8ccf876e32e21514839195f159642fe4c.diff

LOG: [IRInterpreter] Return zero address for missing weak function (#93548)

If a weak function is missing, still return it's address (zero) rather
than failing interpretation. Otherwise we have a mismatch between
Interpret() and CanInterpret() resulting in failures that would not
occur with JIT execution.

Alternatively, we could try to look for weak symbols in CanInterpret()
and generally reject them there.

This is the root cause for the issue exposed by
https://github.com/llvm/llvm-project/pull/92885. Previously, the case
affected by that always fell back to JIT because an icmp constant
expression was used, which is not supported by the interpreter. Now a
normal icmp instruction is used, which is supported. However, we fail to
interpret due to incorrect handling of weak function addresses.

Added: 
    

Modified: 
    lldb/source/Expression/IRInterpreter.cpp

Removed: 
    


################################################################################
diff  --git a/lldb/source/Expression/IRInterpreter.cpp b/lldb/source/Expression/IRInterpreter.cpp
index df02922708663..5b670067b5c43 100644
--- a/lldb/source/Expression/IRInterpreter.cpp
+++ b/lldb/source/Expression/IRInterpreter.cpp
@@ -264,7 +264,7 @@ class InterpreterStackFrame {
         lldb_private::ConstString name(constant_func->getName());
         bool missing_weak = false;
         lldb::addr_t addr = m_execution_unit.FindSymbol(name, missing_weak);
-        if (addr == LLDB_INVALID_ADDRESS || missing_weak)
+        if (addr == LLDB_INVALID_ADDRESS)
           return false;
         value = APInt(m_target_data.getPointerSizeInBits(), addr);
         return true;