[PATCH] D159468: [AsmPrinter][DwarfDebug] Skip vars with fragments in different location kinds

[Felipe de Azevedo Piovezan via Phabricator via llvm-commits]

fdeazeve updated this revision to Diff 556575.
fdeazeve added a comment.

Rebased


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D159468/new/

https://reviews.llvm.org/D159468

Files:
  llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
  llvm/test/DebugInfo/AArch64/dbg-entry-value-swiftasync.mir


Index: llvm/test/DebugInfo/AArch64/dbg-entry-value-swiftasync.mir
===================================================================
--- llvm/test/DebugInfo/AArch64/dbg-entry-value-swiftasync.mir
+++ llvm/test/DebugInfo/AArch64/dbg-entry-value-swiftasync.mir
@@ -8,16 +8,23 @@
 # CHECK-SAME:     DW_OP_GNU_entry_value(DW_OP_reg22 W22), DW_OP_piece 0x8,
 # CHECK-SAME:     DW_OP_GNU_entry_value(DW_OP_reg22 W22), DW_OP_plus_uconst 0x2a, DW_OP_piece 0x8)
 # CHECK-NEXT:   DW_AT_name    ("fragmented_var")
+# CHECK:      DW_TAG_variable
+# CHECK-NEXT:   DW_AT_location       (DW_OP_piece 0x8, DW_OP_GNU_entry_value(DW_OP_reg22 W22), DW_OP_piece 0x8)
+# CHECK-NEXT:   DW_AT_name    ("multi_type_fragmented_var")
 
 
 --- |
   target triple = "aarch64--"
   define void @foo(ptr %unused_arg, ptr swiftasync %async_arg) !dbg !4 {
+    %storage = alloca i64
     call void @llvm.dbg.declare(metadata ptr %async_arg, metadata !10, metadata !DIExpression(DW_OP_LLVM_entry_value, 1)), !dbg !12
     ; A two fragment variable.
     ; Fragments intentionally out of order to ensure the code can handle this.
     call void @llvm.dbg.declare(metadata ptr %async_arg, metadata !10, metadata !DIExpression(DW_OP_LLVM_entry_value, 1, DW_OP_plus_uconst, 42, DW_OP_LLVM_fragment, 64, 64)), !dbg !12
     call void @llvm.dbg.declare(metadata ptr %async_arg, metadata !11, metadata !DIExpression(DW_OP_LLVM_entry_value, 1, DW_OP_LLVM_fragment, 0, 64)), !dbg !12
+    ; A fragmented variable mixing entry values and stack slot locations.
+    call void @llvm.dbg.declare(metadata ptr %async_arg, metadata !13, metadata !DIExpression(DW_OP_LLVM_entry_value, 1, DW_OP_LLVM_fragment, 64, 64)), !dbg !12
+    call void @llvm.dbg.declare(metadata ptr %storage, metadata !13, metadata !DIExpression(DW_OP_LLVM_fragment, 0, 64)), !dbg !12
     ret void, !dbg !12
   }
   declare void @llvm.dbg.declare(metadata, metadata, metadata)
@@ -36,6 +43,7 @@
   !10 = !DILocalVariable(name: "a", scope: !4, file: !1, line: 1, type: !7)
   !11 = !DILocalVariable(name: "fragmented_var", scope: !4, file: !1, line: 1, type: !7)
   !12 = !DILocation(line: 1, column: 37, scope: !4)
+  !13 = !DILocalVariable(name: "multi_type_fragmented_var", scope: !4, file: !1, line: 1, type: !7)
 ...
 ---
 name:            foo
@@ -45,6 +53,11 @@
 stack:
   - { id: 0, name: '', type: spill-slot, offset: -16, size: 8, alignment: 16,
       stack-id: default, callee-saved-register: '$lr', callee-saved-restored: true }
+  - { id: 1, name: '', type: default, offset: 0, size: 1, alignment: 8,
+      stack-id: default, callee-saved-register: '', callee-saved-restored: true,
+      debug-info-variable: '!13', debug-info-expression: '!DIExpression(DW_OP_LLVM_fragment, 0, 64)',
+      debug-info-location: '!12' }
+
 entry_values:
   - { entry-value-register: '$x22', debug-info-variable: '!10', debug-info-expression: '!DIExpression(DW_OP_LLVM_entry_value, 1, DW_OP_deref)',
       debug-info-location: '!12' }
@@ -52,6 +65,8 @@
       debug-info-location: '!12' }
   - { entry-value-register: '$x22', debug-info-variable: '!11', debug-info-expression: '!DIExpression(DW_OP_LLVM_entry_value, 1,  DW_OP_deref, DW_OP_LLVM_fragment, 0, 64)',
       debug-info-location: '!12' }
+  - { entry-value-register: '$x22', debug-info-variable: '!13', debug-info-expression: '!DIExpression(DW_OP_LLVM_entry_value, 1, DW_OP_deref, DW_OP_LLVM_fragment, 64, 64)',
+      debug-info-location: '!12' }
 body:             |
   bb.0 (%ir-block.0):
     liveins: $x0, $x22, $lr
Index: llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
===================================================================
--- llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -1546,12 +1546,27 @@
 
     ensureAbstractEntityIsCreatedIfScoped(TheCU, Var.first, Scope->getScopeNode());
 
-    if (DbgVariable *DbgVar = MFVars.lookup(Var)) {
-      if (auto *MMI = std::get_if<Loc::MMI>(DbgVar))
-        MMI->addFrameIndexExpr(VI.Expr, VI.getStackSlot());
-      else
-        DbgVar->get<Loc::EntryValue>().addExpr(VI.getEntryValueRegister(),
-                                               *VI.Expr);
+    // If we have already seen information for this variable, add to what we
+    // already know.
+    if (DbgVariable *PreviousLoc = MFVars.lookup(Var)) {
+      auto *PreviousMMI = std::get_if<Loc::MMI>(PreviousLoc);
+      auto *PreviousEntryValue = std::get_if<Loc::EntryValue>(PreviousLoc);
+      // Previous and new locations are both stack slots (MMI).
+      if (PreviousMMI && VI.inStackSlot())
+        PreviousMMI->addFrameIndexExpr(VI.Expr, VI.getStackSlot());
+      // Previous and new locations are both entry values.
+      else if (PreviousEntryValue && VI.inEntryValueRegister())
+        PreviousEntryValue->addExpr(VI.getEntryValueRegister(), *VI.Expr);
+      else {
+        // Locations differ, this should (rarely) happen in optimized async
+        // coroutines.
+        // Prefer whichever location has an EntryValue.
+        if (PreviousLoc->holds<Loc::MMI>())
+          PreviousLoc->emplace<Loc::EntryValue>(VI.getEntryValueRegister(),
+                                                *VI.Expr);
+        LLVM_DEBUG(dbgs() << "Dropping debug info for " << VI.Var->getName()
+                          << ", conflicting fragment location types\n");
+      }
       continue;
     }
 


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D159468.556575.patch
Type: text/x-patch
Size: 5365 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20230912/62075498/attachment.bin>