jwnhy created this revision.
jwnhy added reviewers: clayborg, jingham.
Herald added a project: All.
jwnhy requested review of this revision.
Herald added a project: LLDB.
Herald added a subscriber: lldb-commits.
As described in #61706 <https://github.com/llvm/llvm-project/issues/61706>, the
`ValueObjectChild::UpdateValue(...)` may underflow the unsigned
`m_bitfield_bit_offset`.
This is due to that in `ValueObjectChild::UpdateValue(...)`, the moved
`overhang_bytes` only considers the `bitfield_end - *type_bit_size`. However,
under certain cases, the `m_bitfield_bit_offset` may not strictly aligned to
`*type_bit_size`, e.g. 27 < 32.
This results 27 - 32 = -5 underflows the unsigned `uint8_t
m_bitfield_bit_offset`.
This patch fixes this issue by setting the `overhang_bytes` to the smaller
value between `bitfield_end - *type_bit_size` and `m_bitfield_bit_offset` to
avoid underflow.
I am quite new to this community, any helps/guidance are much appreciated.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D146919
Files:
lldb/source/Core/ValueObjectChild.cpp
Index: lldb/source/Core/ValueObjectChild.cpp
===================================================================
--- lldb/source/Core/ValueObjectChild.cpp
+++ lldb/source/Core/ValueObjectChild.cpp
@@ -170,6 +170,8 @@
if (bitfield_end > *type_bit_size) {
uint64_t overhang_bytes =
(bitfield_end - *type_bit_size + 7) / 8;
+ if (overhang_bytes > m_bitfield_bit_offset / 8)
+ overhang_bytes = m_bitfield_bit_offset / 8;
m_byte_offset += overhang_bytes;
m_bitfield_bit_offset -= overhang_bytes * 8;
}
Index: lldb/source/Core/ValueObjectChild.cpp
===================================================================
--- lldb/source/Core/ValueObjectChild.cpp
+++ lldb/source/Core/ValueObjectChild.cpp
@@ -170,6 +170,8 @@
if (bitfield_end > *type_bit_size) {
uint64_t overhang_bytes =
(bitfield_end - *type_bit_size + 7) / 8;
+ if (overhang_bytes > m_bitfield_bit_offset / 8)
+ overhang_bytes = m_bitfield_bit_offset / 8;
m_byte_offset += overhang_bytes;
m_bitfield_bit_offset -= overhang_bytes * 8;
}
_______________________________________________
lldb-commits mailing list
lldb-commits@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits
