https://github.com/agontarek created
https://github.com/llvm/llvm-project/pull/158350
- Introduced a new helper function `IsCIEMarker` to determine if a given
`cie_id` indicates a CIE (Common Information Entry) or FDE (Frame Description
Entry).
- New helper function can now correctly identify both 32-bit and 64-bit CIE
based on the DWARF specifications.
- Updated the `ParseCIE` and `GetFDEIndex` methods to utilize the new helper
function for improved clarity and correctness in identifying CIE and FDE
entries.
- Replaced direct comparisons with `UINT32_MAX` and `UINT64_MAX` with
`std::numeric_limits` for better readability.
I do not know the proper way to test this change and am open to recommendations
on how to add a test.
>From a5db208cd21b45ba0c2dc7816fcab6b85bc9cc41 Mon Sep 17 00:00:00 2001
From: Andrew Gontarek <agonta...@nvidia.com>
Date: Wed, 10 Sep 2025 12:53:21 -0500
Subject: [PATCH] [LLDB] Refactor CIE and FDE handling in DWARFCallFrameInfo
- Introduced a new helper function `IsCIEMarker` to determine if a given
`cie_id` indicates a CIE (Common Information Entry) or FDE (Frame Description
Entry).
- New helper function can now correctly identify both 32-bit and 64-bit CIE
based on the DWARF specifications.
- Updated the `ParseCIE` and `GetFDEIndex` methods to utilize the new helper
function for improved clarity and correctness in identifying CIE and FDE
entries.
- Replaced direct comparisons with `UINT32_MAX` and `UINT64_MAX` with
`std::numeric_limits` for better readability.
---
lldb/source/Symbol/DWARFCallFrameInfo.cpp | 44 +++++++++++++++++------
1 file changed, 33 insertions(+), 11 deletions(-)
diff --git a/lldb/source/Symbol/DWARFCallFrameInfo.cpp
b/lldb/source/Symbol/DWARFCallFrameInfo.cpp
index 2f8f9e9182fb2..6ba5c6660140b 100644
--- a/lldb/source/Symbol/DWARFCallFrameInfo.cpp
+++ b/lldb/source/Symbol/DWARFCallFrameInfo.cpp
@@ -20,7 +20,9 @@
#include "lldb/Utility/LLDBLog.h"
#include "lldb/Utility/Log.h"
#include "lldb/Utility/Timer.h"
+#include <cstdint>
#include <cstring>
+#include <limits>
#include <list>
#include <optional>
@@ -147,6 +149,27 @@ GetGNUEHPointer(const DataExtractor &DE, lldb::offset_t
*offset_ptr,
return baseAddress + addressValue;
}
+// Check if the given cie_id value indicates a CIE (Common Information Entry)
+// as opposed to an FDE (Frame Description Entry).
+//
+// For eh_frame sections: CIE is marked with cie_id == 0
+// For debug_frame sections:
+// - DWARF32: CIE is marked with cie_id ==
+// std::numeric_limits<uint32_t>::max()
+// - DWARF64: CIE is marked with cie_id ==
+// std::numeric_limits<uint64_t>::max()
+static bool IsCIEMarker(uint64_t cie_id, bool is_64bit,
+ DWARFCallFrameInfo::Type type) {
+ if (type == DWARFCallFrameInfo::EH)
+ return cie_id == 0;
+
+ // DWARF type
+ if (is_64bit)
+ return cie_id == std::numeric_limits<uint64_t>::max();
+
+ return cie_id == std::numeric_limits<uint32_t>::max();
+}
+
DWARFCallFrameInfo::DWARFCallFrameInfo(ObjectFile &objfile,
SectionSP §ion_sp, Type type)
: m_objfile(objfile), m_section_sp(section_sp), m_type(type) {}
@@ -283,7 +306,7 @@ DWARFCallFrameInfo::ParseCIE(const dw_offset_t cie_offset) {
GetCFIData();
uint32_t length = m_cfi_data.GetU32(&offset);
dw_offset_t cie_id, end_offset;
- bool is_64bit = (length == UINT32_MAX);
+ bool is_64bit = (length == std::numeric_limits<uint32_t>::max());
if (is_64bit) {
length = m_cfi_data.GetU64(&offset);
cie_id = m_cfi_data.GetU64(&offset);
@@ -292,8 +315,9 @@ DWARFCallFrameInfo::ParseCIE(const dw_offset_t cie_offset) {
cie_id = m_cfi_data.GetU32(&offset);
end_offset = cie_offset + length + 4;
}
- if (length > 0 && ((m_type == DWARF && cie_id == UINT32_MAX) ||
- (m_type == EH && cie_id == 0ul))) {
+
+ // Check if this is a CIE or FDE based on the CIE ID marker
+ if (length > 0 && IsCIEMarker(cie_id, is_64bit, m_type)) {
size_t i;
// cie.offset = cie_offset;
// cie.length = length;
@@ -470,7 +494,7 @@ void DWARFCallFrameInfo::GetFDEIndex() {
const dw_offset_t current_entry = offset;
dw_offset_t cie_id, next_entry, cie_offset;
uint32_t len = m_cfi_data.GetU32(&offset);
- bool is_64bit = (len == UINT32_MAX);
+ bool is_64bit = (len == std::numeric_limits<uint32_t>::max());
if (is_64bit) {
len = m_cfi_data.GetU64(&offset);
cie_id = m_cfi_data.GetU64(&offset);
@@ -493,11 +517,8 @@ void DWARFCallFrameInfo::GetFDEIndex() {
return;
}
- // An FDE entry contains CIE_pointer in debug_frame in same place as cie_id
- // in eh_frame. CIE_pointer is an offset into the .debug_frame section. So,
- // variable cie_offset should be equal to cie_id for debug_frame.
- // FDE entries with cie_id == 0 shouldn't be ignored for it.
- if ((cie_id == 0 && m_type == EH) || cie_id == UINT32_MAX || len == 0) {
+ // Check if this is a CIE or FDE based on the CIE ID marker
+ if (IsCIEMarker(cie_id, is_64bit, m_type) || len == 0) {
auto cie_sp = ParseCIE(current_entry);
if (!cie_sp) {
// Cannot parse, the reason is already logged
@@ -568,7 +589,7 @@ DWARFCallFrameInfo::ParseFDE(dw_offset_t dwarf_offset,
uint32_t length = m_cfi_data.GetU32(&offset);
dw_offset_t cie_offset;
- bool is_64bit = (length == UINT32_MAX);
+ bool is_64bit = (length == std::numeric_limits<uint32_t>::max());
if (is_64bit) {
length = m_cfi_data.GetU64(&offset);
cie_offset = m_cfi_data.GetU64(&offset);
@@ -577,7 +598,8 @@ DWARFCallFrameInfo::ParseFDE(dw_offset_t dwarf_offset,
}
// FDE entries with zeroth cie_offset may occur for debug_frame.
- assert(!(m_type == EH && 0 == cie_offset) && cie_offset != UINT32_MAX);
+ assert(!(m_type == EH && 0 == cie_offset) &&
+ cie_offset != std::numeric_limits<uint32_t>::max());
// Translate the CIE_id from the eh_frame format, which is relative to the
// FDE offset, into a __eh_frame section offset
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