[llvm] [DWARFLinker] Use different addresses to distinguish invalid DW_AT_LLVM_stmt_sequence offset (PR #149376)

[Peter Rong via llvm-commits]

https://github.com/DataCorrupted created https://github.com/llvm/llvm-project/pull/149376

None

>From 00f11a4abb7d266a51204660c0d0b55c03d87931 Mon Sep 17 00:00:00 2001
From: Peter Rong <PeterRong at meta.com>
Date: Thu, 17 Jul 2025 11:21:50 -0700
Subject: [PATCH 1/2] [DWARFLinker] Use different invalid addresses to
 distinguish reasons why DW_AT_LLVM_stmt_sequence is invalid.

---
 llvm/lib/DWARFLinker/Classic/DWARFLinker.cpp | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/llvm/lib/DWARFLinker/Classic/DWARFLinker.cpp b/llvm/lib/DWARFLinker/Classic/DWARFLinker.cpp
index 222dc88098102..4ed3a90d386c8 100644
--- a/llvm/lib/DWARFLinker/Classic/DWARFLinker.cpp
+++ b/llvm/lib/DWARFLinker/Classic/DWARFLinker.cpp
@@ -23,10 +23,10 @@
 #include "llvm/DebugInfo/DWARF/DWARFDebugMacro.h"
 #include "llvm/DebugInfo/DWARF/DWARFDebugRangeList.h"
 #include "llvm/DebugInfo/DWARF/DWARFDie.h"
+#include "llvm/DebugInfo/DWARF/DWARFExpression.h"
 #include "llvm/DebugInfo/DWARF/DWARFFormValue.h"
 #include "llvm/DebugInfo/DWARF/DWARFSection.h"
 #include "llvm/DebugInfo/DWARF/DWARFUnit.h"
-#include "llvm/DebugInfo/DWARF/LowLevel/DWARFExpression.h"
 #include "llvm/MC/MCDwarf.h"
 #include "llvm/Support/DataExtractor.h"
 #include "llvm/Support/Error.h"
@@ -43,6 +43,12 @@ namespace llvm {
 using namespace dwarf_linker;
 using namespace dwarf_linker::classic;
 
+enum InvalidStmtSeqOffset {
+  MaxStmtSeqOffset = UINT64_MAX,
+  OrigOffsetMissing = MaxStmtSeqOffset - 1,
+  NewOffsetMissing = MaxStmtSeqOffset - 2,
+};
+
 /// Hold the input and output of the debug info size in bytes.
 struct DebugInfoSize {
   uint64_t Input;
@@ -2315,7 +2321,7 @@ void DWARFLinker::DIECloner::generateLineTableForUnit(CompileUnit &Unit) {
           // Some sequences are discarded by the DWARFLinker if they are invalid
           // (empty).
           if (OrigRowIter == SeqOffToOrigRow.end()) {
-            StmtSeq.set(UINT64_MAX);
+            StmtSeq.set(OrigOffsetMissing);
             continue;
           }
           size_t OrigRowIndex = OrigRowIter->second;
@@ -2325,7 +2331,7 @@ void DWARFLinker::DIECloner::generateLineTableForUnit(CompileUnit &Unit) {
           if (NewRowIter == OrigRowToNewRow.end()) {
             // If the original row index is not found in the map, update the
             // stmt_sequence attribute to the 'invalid offset' magic value.
-            StmtSeq.set(UINT64_MAX);
+            StmtSeq.set(NewOffsetMissing);
             continue;
           }
 

>From f3a0b8c429a116bb8d78ad6b27c0e8098a4d5e20 Mon Sep 17 00:00:00 2001
From: Peter Rong <PeterRong at meta.com>
Date: Thu, 17 Jul 2025 11:25:43 -0700
Subject: [PATCH 2/2] resolve header

---
 llvm/lib/DWARFLinker/Classic/DWARFLinker.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/llvm/lib/DWARFLinker/Classic/DWARFLinker.cpp b/llvm/lib/DWARFLinker/Classic/DWARFLinker.cpp
index 4ed3a90d386c8..2760bc169ff36 100644
--- a/llvm/lib/DWARFLinker/Classic/DWARFLinker.cpp
+++ b/llvm/lib/DWARFLinker/Classic/DWARFLinker.cpp
@@ -23,7 +23,7 @@
 #include "llvm/DebugInfo/DWARF/DWARFDebugMacro.h"
 #include "llvm/DebugInfo/DWARF/DWARFDebugRangeList.h"
 #include "llvm/DebugInfo/DWARF/DWARFDie.h"
-#include "llvm/DebugInfo/DWARF/DWARFExpression.h"
+#include "llvm/DebugInfo/DWARF/LowLevel/DWARFExpression.h"
 #include "llvm/DebugInfo/DWARF/DWARFFormValue.h"
 #include "llvm/DebugInfo/DWARF/DWARFSection.h"
 #include "llvm/DebugInfo/DWARF/DWARFUnit.h"