[llvm] [DebugInfo][DWARF] Utilize DW_AT_LLVM_stmt_sequence attr in line table lookups (PR #123391)

[David Blaikie via llvm-commits]

================
@@ -1401,6 +1409,14 @@ bool DWARFDebugLine::LineTable::lookupAddressRangeImpl(
 
   while (SeqPos != LastSeq && SeqPos->LowPC < EndAddr) {
     const DWARFDebugLine::Sequence &CurSeq = *SeqPos;
+
+    // Skip sequences that don't match our stmt_sequence offset if one was
+    // provided
+    if (StmtSequenceOffset && CurSeq.StmtSeqOffset != *StmtSequenceOffset) {
+      ++SeqPos;
----------------
dwblaikie wrote:

Might help if the `while` turned into a for loop (`for (; SeqPos != LastSeq && SeqPos->LowPC < EndAddr; ++SeqPos)`) so that the increment doesn't have to appear in two places/risk getting out of sync.

Though more generally - since the entries will be ordered by StmtSeqOffset - you could do a binary search (`llvm::binary_search`) to find the sequence, if the StmtSequenceOffset is specified.

https://github.com/llvm/llvm-project/pull/123391