[llvm] c290a8b - [DebugInfo] Fix: Variables that have no non-empty values being emitted when they have a DBG_VALUE_LIST

[Vitaly Buka via llvm-commits]

Author: Stephen Tozer
Date: 2022-12-25T13:28:27-08:00
New Revision: c290a8b7a4aa0fefd2c9f3f13a1bb507d8608d7d

URL: https://github.com/llvm/llvm-project/commit/c290a8b7a4aa0fefd2c9f3f13a1bb507d8608d7d
DIFF: https://github.com/llvm/llvm-project/commit/c290a8b7a4aa0fefd2c9f3f13a1bb507d8608d7d.diff

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

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.

Reviewed By: Orlando

Differential Revision: https://reviews.llvm.org/D133925

Added: 
    

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

Removed: 
    


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diff  --git a/llvm/lib/CodeGen/AsmPrinter/DbgEntityHistoryCalculator.cpp b/llvm/lib/CodeGen/AsmPrinter/DbgEntityHistoryCalculator.cpp
index 42715efbee09d..2c90b9c150098 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DbgEntityHistoryCalculator.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DbgEntityHistoryCalculator.cpp
@@ -264,7 +264,7 @@ bool DbgValueHistoryMap::hasNonEmptyLocation(const Entries &Entries) const {
     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;

diff  --git a/llvm/test/DebugInfo/X86/dbg_value_list_emission.mir b/llvm/test/DebugInfo/X86/dbg_value_list_emission.mir
index e447fa82f95b3..b96582473cd0b 100644
--- a/llvm/test/DebugInfo/X86/dbg_value_list_emission.mir
+++ b/llvm/test/DebugInfo/X86/dbg_value_list_emission.mir
@@ -93,9 +93,7 @@ body:             |
     
     ; (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
 ...