[Lldb-commits] [lldb] [lldb] Reimplement LineTable::FindLineEntryByAddress on top of lower_bound (PR #127799)

[Pavel Labath via lldb-commits]

https://github.com/labath created https://github.com/llvm/llvm-project/pull/127799

I *think* this should be equivalent to the original implementation for all line tables occurring in practice. One difference I'm aware of is that the original implementation tried to return the first line entry out of multiple ones for the same address. However, this is not possible (anymore?) because of the check in LineTable::AppendLineEntryToSequence.

>From 1c24ddb7f3ec385c01bb056551e080ea4b38800d Mon Sep 17 00:00:00 2001
From: Pavel Labath <pavel at labath.sk>
Date: Wed, 19 Feb 2025 13:57:56 +0100
Subject: [PATCH] [lldb] Reimplement LineTable::FindLineEntryByAddress on top
 of lower_bound

I *think* this should be equivalent to the original implementation for
all line tables occuring in practice. One difference I'm aware of is
that the original implementation tried to return the first line entry
out of multiple ones for the same address. However, this is not possible
(anymore?) because of the check in LineTable::AppendLineEntryToSequence.
---
 lldb/source/Symbol/LineTable.cpp | 72 +++++---------------------------
 1 file changed, 10 insertions(+), 62 deletions(-)

diff --git a/lldb/source/Symbol/LineTable.cpp b/lldb/source/Symbol/LineTable.cpp
index aae4ab59ff156..c199398f31a4c 100644
--- a/lldb/source/Symbol/LineTable.cpp
+++ b/lldb/source/Symbol/LineTable.cpp
@@ -233,69 +233,17 @@ bool LineTable::FindLineEntryByAddress(const Address &so_addr,
   if (index_ptr != nullptr)
     *index_ptr = UINT32_MAX;
 
-  bool success = false;
-
-  if (so_addr.GetModule().get() == m_comp_unit->GetModule().get()) {
-    Entry search_entry;
-    search_entry.file_addr = so_addr.GetFileAddress();
-    if (search_entry.file_addr != LLDB_INVALID_ADDRESS) {
-      entry_collection::const_iterator begin_pos = m_entries.begin();
-      entry_collection::const_iterator end_pos = m_entries.end();
-      entry_collection::const_iterator pos = std::lower_bound(
-          begin_pos, end_pos, search_entry, Entry::EntryAddressLessThan);
-      if (pos != end_pos) {
-        if (pos != begin_pos) {
-          if (pos->file_addr != search_entry.file_addr)
-            --pos;
-          else if (pos->file_addr == search_entry.file_addr) {
-            // If this is a termination entry, it shouldn't match since entries
-            // with the "is_terminal_entry" member set to true are termination
-            // entries that define the range for the previous entry.
-            if (pos->is_terminal_entry) {
-              // The matching entry is a terminal entry, so we skip ahead to
-              // the next entry to see if there is another entry following this
-              // one whose section/offset matches.
-              ++pos;
-              if (pos != end_pos) {
-                if (pos->file_addr != search_entry.file_addr)
-                  pos = end_pos;
-              }
-            }
-
-            if (pos != end_pos) {
-              // While in the same section/offset backup to find the first line
-              // entry that matches the address in case there are multiple
-              while (pos != begin_pos) {
-                entry_collection::const_iterator prev_pos = pos - 1;
-                if (prev_pos->file_addr == search_entry.file_addr &&
-                    prev_pos->is_terminal_entry == false)
-                  --pos;
-                else
-                  break;
-              }
-            }
-          }
-        }
-        else
-        {
-          // There might be code in the containing objfile before the first
-          // line table entry.  Make sure that does not get considered part of
-          // the first line table entry.
-          if (pos->file_addr > so_addr.GetFileAddress())
-            return false;
-        }
+  uint32_t idx = lower_bound(so_addr);
+  if (idx >= GetSize())
+    return false;
 
-        // Make sure we have a valid match and that the match isn't a
-        // terminating entry for a previous line...
-        if (pos != end_pos && pos->is_terminal_entry == false) {
-          uint32_t match_idx = std::distance(begin_pos, pos);
-          success = ConvertEntryAtIndexToLineEntry(match_idx, line_entry);
-          if (index_ptr != nullptr && success)
-            *index_ptr = match_idx;
-        }
-      }
-    }
-  }
+  addr_t file_addr = so_addr.GetFileAddress();
+  if (m_entries[idx].file_addr > file_addr)
+    return false;
+
+  bool success = ConvertEntryAtIndexToLineEntry(idx, line_entry);
+  if (index_ptr != nullptr && success)
+    *index_ptr = idx;
   return success;
 }