Fix ADCE to mark scope and inlined_at of line instructions as live. (#4910)

2 files changed, 15 insertions, 10 deletions

diff --git a/source/opt/aggressive_dead_code_elim_pass.cpp b/source/opt/aggressive_dead_code_elim_pass.cpp
index 116ab69ae..7fa5c8a95 100644
--- a/source/opt/aggressive_dead_code_elim_pass.cpp
+++ b/source/opt/aggressive_dead_code_elim_pass.cpp
@@ -338,23 +338,25 @@ void AggressiveDCEPass::ProcessWorkList(Function* func) {
   }
 }
 
+void AggressiveDCEPass::AddDebugScopeToWorkList(const Instruction* inst) {
+  auto scope = inst->GetDebugScope();
+  auto lex_scope_id = scope.GetLexicalScope();
+  if (lex_scope_id != kNoDebugScope)
+    AddToWorklist(get_def_use_mgr()->GetDef(lex_scope_id));
+  auto inlined_at_id = scope.GetInlinedAt();
+  if (inlined_at_id != kNoInlinedAt)
+    AddToWorklist(get_def_use_mgr()->GetDef(inlined_at_id));
+}
+
 void AggressiveDCEPass::AddDebugInstructionsToWorkList(
     const Instruction* inst) {
   for (auto& line_inst : inst->dbg_line_insts()) {
     if (line_inst.IsDebugLineInst()) {
       AddOperandsToWorkList(&line_inst);
     }
+    AddDebugScopeToWorkList(&line_inst);
   }
-
-  if (inst->GetDebugScope().GetLexicalScope() != kNoDebugScope) {
-    auto* scope =
-        get_def_use_mgr()->GetDef(inst->GetDebugScope().GetLexicalScope());
-    AddToWorklist(scope);
-  }
-  if (inst->GetDebugInlinedAt() != kNoInlinedAt) {
-    auto* inlined_at = get_def_use_mgr()->GetDef(inst->GetDebugInlinedAt());
-    AddToWorklist(inlined_at);
-  }
+  AddDebugScopeToWorkList(inst);
 }
 
 void AggressiveDCEPass::AddDecorationsToWorkList(const Instruction* inst) {
diff --git a/source/opt/aggressive_dead_code_elim_pass.h b/source/opt/aggressive_dead_code_elim_pass.h
index 1b3fd1e85..c1291dc47 100644
--- a/source/opt/aggressive_dead_code_elim_pass.h
+++ b/source/opt/aggressive_dead_code_elim_pass.h
@@ -178,6 +178,9 @@ class AggressiveDCEPass : public MemPass {
   // Adds all decorations of |inst| to the work list.
   void AddDecorationsToWorkList(const Instruction* inst);
 
+  // Adds DebugScope instruction associated with |inst| to the work list.
+  void AddDebugScopeToWorkList(const Instruction* inst);
+
   // Adds all debug instruction associated with |inst| to the work list.
   void AddDebugInstructionsToWorkList(const Instruction* inst);