[PATCH] D133925: [DebugInfo] Fix: Variables that have no non-empty values being emitted when they have a DBG_VALUE_LIST

[Stephen Tozer via Phabricator via llvm-commits]

StephenTozer created this revision.
StephenTozer added reviewers: jmorse, Orlando.
StephenTozer added a project: debug-info.
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This patch fixes a simple bug where `DbgValueHistoryMap::hasNonEmptyLocation` was incorrectly handling DBG_VALUE_LIST instructions, treating empty values as non-empty, causing empty variables to be emitted into DWARF.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D133925

Files:
  llvm/lib/CodeGen/AsmPrinter/DbgEntityHistoryCalculator.cpp
  llvm/test/DebugInfo/X86/dbg_value_list_emission.mir


Index: llvm/test/DebugInfo/X86/dbg_value_list_emission.mir
===================================================================
--- llvm/test/DebugInfo/X86/dbg_value_list_emission.mir
+++ llvm/test/DebugInfo/X86/dbg_value_list_emission.mir
@@ -93,9 +93,7 @@
     
     ; (8) Check that a single $noreg location invalidates the entire entry.
     DBG_VALUE_LIST !30, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 1, DW_OP_plus, DW_OP_stack_value), $eax, $noreg, debug-location !15
-    ; CHECK:      DW_TAG_variable
-    ; CHECK-NEXT:   DW_AT_name ("localh")
-    ; CHECK-NOT:   DW_AT_location
+    ; CHECK-NOT:   DW_AT_name ("localh")
 
     RET64 debug-location !15
 ...
Index: llvm/lib/CodeGen/AsmPrinter/DbgEntityHistoryCalculator.cpp
===================================================================
--- llvm/lib/CodeGen/AsmPrinter/DbgEntityHistoryCalculator.cpp
+++ llvm/lib/CodeGen/AsmPrinter/DbgEntityHistoryCalculator.cpp
@@ -264,7 +264,7 @@
     const MachineInstr *MI = Entry.getInstr();
     assert(MI->isDebugValue());
     // A DBG_VALUE $noreg is an empty variable location
-    if (MI->getOperand(0).isReg() && MI->getOperand(0).getReg() == 0)
+    if (MI->isUndefDebugValue())
       continue;
 
     return true;


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