[AsmPrinter] Use EntryValue object info to emit Dwarf

This patch consumes the EntryValueObjects in a MachineFunction's table, using
them to emit the appropriate debug information for these variables.

Depends on D149880

Differential Revision: https://reviews.llvm.org/D149881

llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp

@@ -1529,7 +1529,7 @@ void DwarfDebug::collectVariableInfoFromMFTable(
     DwarfCompileUnit &TheCU, DenseSet<InlinedEntity> &Processed) {
   SmallDenseMap<InlinedEntity, DbgVariable *> MFVars;
   LLVM_DEBUG(dbgs() << "DwarfDebug: collecting variables from MF side table\n");
-  for (const auto &VI : Asm->MF->getInStackSlotVariableDbgInfo()) {
+  for (const auto &VI : Asm->MF->getVariableDbgInfo()) {
     if (!VI.Var)
       continue;
     assert(VI.Var->isValidLocationForIntrinsic(VI.Loc) &&
@@ -1549,13 +1549,24 @@ void DwarfDebug::collectVariableInfoFromMFTable(
     ensureAbstractEntityIsCreatedIfScoped(TheCU, Var.first, Scope->getScopeNode());
     auto RegVar = std::make_unique<DbgVariable>(
                     cast<DILocalVariable>(Var.first), Var.second);
-    RegVar->initializeMMI(VI.Expr, VI.getStackSlot());
+    if (VI.inStackSlot())
+      RegVar->initializeMMI(VI.Expr, VI.getStackSlot());
+    else {
+      MachineLocation MLoc(VI.getEntryValueRegister(), /*IsIndirect*/ true);
+      auto LocEntry = DbgValueLocEntry(MLoc);
+      RegVar->initializeDbgValue(DbgValueLoc(VI.Expr, LocEntry));
+    }
     LLVM_DEBUG(dbgs() << "Created DbgVariable for " << VI.Var->getName()
                       << "\n");
 
-    if (DbgVariable *DbgVar = MFVars.lookup(Var))
-      DbgVar->addMMIEntry(*RegVar);
-    else if (InfoHolder.addScopeVariable(Scope, RegVar.get())) {
+    if (DbgVariable *DbgVar = MFVars.lookup(Var)) {
+      if (DbgVar->getValueLoc())
+        LLVM_DEBUG(dbgs() << "Dropping repeated entry value debug info for "
+                             "variable "
+                          << VI.Var->getName() << "\n");
+      else
+        DbgVar->addMMIEntry(*RegVar);
+    } else if (InfoHolder.addScopeVariable(Scope, RegVar.get())) {
       MFVars.insert({Var, RegVar.get()});
       ConcreteEntities.push_back(std::move(RegVar));
     }

llvm/test/DebugInfo/AArch64/dbg-entry-value-swiftasync.mir

@@ -0,0 +1,45 @@
+# RUN: llc -start-after=machineverifier -O0 %s -filetype=obj -o - | llvm-dwarfdump - | FileCheck %s
+
+# CHECK:      DW_TAG_variable
+# CHECK-NEXT:   DW_AT_location        (DW_OP_GNU_entry_value(DW_OP_reg22 W22))
+# CHECK-NEXT:   DW_AT_name    ("a")
+
+
+--- |
+  target triple = "aarch64--"
+  define void @foo(ptr %unused_arg, ptr swiftasync %async_arg) !dbg !4 {
+    call void @llvm.dbg.declare(metadata ptr %async_arg, metadata !10, metadata !DIExpression(DW_OP_LLVM_entry_value, 1)), !dbg !12
+    ret void, !dbg !12
+  }
+  declare void @llvm.dbg.declare(metadata, metadata, metadata)
+  declare void @consume(ptr)
+  !llvm.dbg.cu = !{!0}
+  !llvm.module.flags = !{!2, !3}
+  !0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug)
+  !1 = !DIFile(filename: "x.c", directory: "/")
+  !2 = !{i32 2, !"Dwarf Version", i32 4}
+  !3 = !{i32 2, !"Debug Info Version", i32 3}
+  !4 = distinct !DISubprogram(name: "f", scope: !1, file: !1, line: 1, type: !5, scopeLine: 1, spFlags: DISPFlagDefinition, unit: !0)
+  !5 = !DISubroutineType(types: !6)
+  !6 = !{null, !7, !7, !7}
+  !7 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !9, size: 64)
+  !9 = !DIBasicType(name: "char", size: 8, encoding: DW_ATE_signed_char)
+  !10 = !DILocalVariable(name: "a", scope: !4, file: !1, line: 1, type: !7)
+  !12 = !DILocation(line: 1, column: 37, scope: !4)
+...
+---
+name:            foo
+liveins:
+  - { reg: '$x0', virtual-reg: '' }
+  - { reg: '$x22', virtual-reg: '' }
+stack:
+  - { id: 0, name: '', type: spill-slot, offset: -16, size: 8, alignment: 16,
+      stack-id: default, callee-saved-register: '$lr', callee-saved-restored: true }
+entry_values:
+  - { entry-value-register: '$x22', debug-info-variable: '!10', debug-info-expression: '!DIExpression(DW_OP_LLVM_entry_value, 1)',
+      debug-info-location: '!12' }
+body:             |
+  bb.0 (%ir-block.0):
+    liveins: $x0, $x22, $lr
+    RET undef $lr, debug-location !12
+...