Fix bug that caused DwarfExpression to drop DW_OP_deref from FI locations

- introduced in r300522 and found via the Swift LLDB testsuite.

The fix is to set the location kind to memory whenever an FrameIndex
location is emitted.

rdar://problem/31707602

llvm-svn: 300793

lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp

@@ -556,9 +556,9 @@ DIE *DwarfCompileUnit::constructVariableDIEImpl(const DbgVariable &DV,
     Ops.push_back(Offset);
     Ops.append(Expr->elements_begin(), Expr->elements_end());
     DIExpressionCursor Cursor(Ops);
-    DwarfExpr.addMachineLocExpression(
-        *Asm->MF->getSubtarget().getRegisterInfo(), Cursor,
-        MachineLocation(FrameReg));
+    DwarfExpr.setMemoryLocationKind();
+    DwarfExpr.addMachineRegExpression(
+        *Asm->MF->getSubtarget().getRegisterInfo(), Cursor, FrameReg);
     DwarfExpr.addExpression(std::move(Cursor));
   }
   addBlock(*VariableDie, dwarf::DW_AT_location, DwarfExpr.finalize());
@@ -780,6 +780,8 @@ void DwarfCompileUnit::addAddress(DIE &Die, dwarf::Attribute Attribute,
                                   const MachineLocation &Location) {
   DIELoc *Loc = new (DIEValueAllocator) DIELoc;
   DIEDwarfExpression DwarfExpr(*Asm, *this, *Loc);
+  if (Location.isIndirect())
+    DwarfExpr.setMemoryLocationKind();
 
   SmallVector<uint64_t, 8> Ops;
   if (Location.isIndirect() && Location.getOffset()) {
@@ -788,7 +790,7 @@ void DwarfCompileUnit::addAddress(DIE &Die, dwarf::Attribute Attribute,
   }
   DIExpressionCursor Cursor(Ops);
   const TargetRegisterInfo &TRI = *Asm->MF->getSubtarget().getRegisterInfo();
-  if (!DwarfExpr.addMachineLocExpression(TRI, Cursor, Location))
+  if (!DwarfExpr.addMachineRegExpression(TRI, Cursor, Location.getReg()))
     return;
   DwarfExpr.addExpression(std::move(Cursor));
 
@@ -807,6 +809,8 @@ void DwarfCompileUnit::addComplexAddress(const DbgVariable &DV, DIE &Die,
   DIEDwarfExpression DwarfExpr(*Asm, *this, *Loc);
   const DIExpression *DIExpr = DV.getSingleExpression();
   DwarfExpr.addFragmentOffset(DIExpr);
+  if (Location.isIndirect())
+    DwarfExpr.setMemoryLocationKind();
 
   SmallVector<uint64_t, 8> Ops;
   if (Location.isIndirect() && Location.getOffset()) {
@@ -816,7 +820,7 @@ void DwarfCompileUnit::addComplexAddress(const DbgVariable &DV, DIE &Die,
   Ops.append(DIExpr->elements_begin(), DIExpr->elements_end());
   DIExpressionCursor Cursor(Ops);
   const TargetRegisterInfo &TRI = *Asm->MF->getSubtarget().getRegisterInfo();
-  if (!DwarfExpr.addMachineLocExpression(TRI, Cursor, Location))
+  if (!DwarfExpr.addMachineRegExpression(TRI, Cursor, Location.getReg()))
     return;
   DwarfExpr.addExpression(std::move(Cursor));
 

lib/CodeGen/AsmPrinter/DwarfDebug.cpp

@@ -1517,6 +1517,8 @@ static void emitDebugLocValue(const AsmPrinter &AP, const DIBasicType *BT,
       DwarfExpr.addUnsignedConstant(Value.getInt());
   } else if (Value.isLocation()) {
     MachineLocation Location = Value.getLoc();
+    if (Location.isIndirect())
+      DwarfExpr.setMemoryLocationKind();
     SmallVector<uint64_t, 8> Ops;
     if (Location.isIndirect() && Location.getOffset()) {
       Ops.push_back(dwarf::DW_OP_plus);
@@ -1525,7 +1527,7 @@ static void emitDebugLocValue(const AsmPrinter &AP, const DIBasicType *BT,
     Ops.append(DIExpr->elements_begin(), DIExpr->elements_end());
     DIExpressionCursor Cursor(Ops);
     const TargetRegisterInfo &TRI = *AP.MF->getSubtarget().getRegisterInfo();
-    if (!DwarfExpr.addMachineLocExpression(TRI, Cursor, Location))
+    if (!DwarfExpr.addMachineRegExpression(TRI, Cursor, Location.getReg()))
       return;
     return DwarfExpr.addExpression(std::move(Cursor));
   } else if (Value.isConstantFP()) {

lib/CodeGen/AsmPrinter/DwarfExpression.cpp

@@ -193,14 +193,10 @@ void DwarfExpression::addUnsignedConstant(const APInt &Value) {
   }
 }
 
-bool DwarfExpression::addMachineLocExpression(const TargetRegisterInfo &TRI,
+bool DwarfExpression::addMachineRegExpression(const TargetRegisterInfo &TRI,
                                               DIExpressionCursor &ExprCursor,
-                                              MachineLocation Loc,
+                                              unsigned MachineReg,
                                               unsigned FragmentOffsetInBits) {
-  if (Loc.isIndirect())
-    LocationKind = Memory;
-
-  unsigned MachineReg = Loc.getReg();
   auto Fragment = ExprCursor.getFragmentInfo();
   if (!addMachineReg(TRI, MachineReg, Fragment ? Fragment->SizeInBits : ~1U))
     return false;

lib/CodeGen/AsmPrinter/DwarfExpression.h

@@ -16,7 +16,6 @@
 
 #include "llvm/IR/DebugInfo.h"
 #include "llvm/Support/DataTypes.h"
-#include "llvm/MC/MachineLocation.h"
 
 namespace llvm {
 
@@ -113,8 +112,6 @@ protected:
     SubRegisterOffsetInBits = OffsetInBits;
   }
 
-  void setMemoryLocationKind();
-
   /// Add masking operations to stencil out a subregister.
   void maskSubRegister();
 
@@ -192,17 +189,24 @@ public:
   /// Emit an unsigned constant.
   void addUnsignedConstant(const APInt &Value);
 
+  /// Lock this down to become a memory location description.
+  void setMemoryLocationKind() {
+    assert(LocationKind == Unknown);
+    LocationKind = Memory;
+  }
+
   /// Emit a machine register location. As an optimization this may also consume
   /// the prefix of a DwarfExpression if a more efficient representation for
   /// combining the register location and the first operation exists.
   ///
-  /// \param FragmentOffsetInBits     If this is one fragment out of a fragmented
+  /// \param FragmentOffsetInBits     If this is one fragment out of a
+  /// fragmented
   ///                                 location, this is the offset of the
   ///                                 fragment inside the entire variable.
   /// \return                         false if no DWARF register exists
   ///                                 for MachineReg.
-  bool addMachineLocExpression(const TargetRegisterInfo &TRI,
-                               DIExpressionCursor &Expr, MachineLocation Loc,
+  bool addMachineRegExpression(const TargetRegisterInfo &TRI,
+                               DIExpressionCursor &Expr, unsigned MachineReg,
                                unsigned FragmentOffsetInBits = 0);
   /// Emit all remaining operations in the DIExpressionCursor.
   ///

lib/CodeGen/AsmPrinter/DwarfUnit.cpp

@@ -472,6 +472,8 @@ void DwarfUnit::addBlockByrefAddress(const DbgVariable &DV, DIE &Die,
   // variable's location.
   DIELoc *Loc = new (DIEValueAllocator) DIELoc;
   DIEDwarfExpression DwarfExpr(*Asm, *this, *Loc);
+  if (Location.isIndirect())
+    DwarfExpr.setMemoryLocationKind();
 
   SmallVector<uint64_t, 9> Ops;
   if (Location.isIndirect() && Location.getOffset()) {
@@ -505,7 +507,7 @@ void DwarfUnit::addBlockByrefAddress(const DbgVariable &DV, DIE &Die,
 
   DIExpressionCursor Cursor(Ops);
   const TargetRegisterInfo &TRI = *Asm->MF->getSubtarget().getRegisterInfo();
-  if (!DwarfExpr.addMachineLocExpression(TRI, Cursor, Location))
+  if (!DwarfExpr.addMachineRegExpression(TRI, Cursor, Location.getReg()))
     return;
   DwarfExpr.addExpression(std::move(Cursor));
 

test/DebugInfo/X86/fi-expr.ll

@@ -0,0 +1,35 @@
+; RUN: llc -mtriple=x86_64-apple-darwin -o - %s -filetype=obj \
+; RUN:   | llvm-dwarfdump -debug-dump=info - | FileCheck %s
+; A hand-crafted FrameIndex location with a DW_OP_deref.
+; CHECK: DW_TAG_formal_parameter
+;                                          fbreg -8, deref
+; CHECK-NEXT: DW_AT_location {{.*}} (<0x3> 91 78 06 )
+; CHECK-NEXT: DW_AT_name {{.*}} "foo"
+define void @f(i8* %bar) !dbg !6 {
+entry:
+  %foo.addr = alloca i8*
+  store i8* %bar, i8** %foo.addr
+  call void @llvm.dbg.declare(metadata i8** %foo.addr, metadata !12, metadata !13), !dbg !14
+  ret void, !dbg !15
+}
+
+declare void @llvm.dbg.declare(metadata, metadata, metadata)
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2)
+!1 = !DIFile(filename: "t.c", directory: "/")
+!2 = !{}
+!3 = !{i32 2, !"Dwarf Version", i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!6 = distinct !DISubprogram(name: "f", scope: !1, file: !1, line: 1, type: !7, isLocal: false, isDefinition: true, scopeLine: 1, flags: DIFlagPrototyped, isOptimized: false, unit: !0, variables: !2)
+!7 = !DISubroutineType(types: !8)
+!8 = !{null, !9}
+!9 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !10, size: 64)
+!10 = !DIDerivedType(tag: DW_TAG_const_type, baseType: !11)
+!11 = !DIBasicType(name: "char", size: 8, encoding: DW_ATE_signed_char)
+!12 = !DILocalVariable(name: "foo", arg: 1, scope: !6, file: !1, line: 1, type: !10)
+!13 = !DIExpression(DW_OP_deref)
+!14 = !DILocation(line: 1, scope: !6)
+!15 = !DILocation(line: 1, scope: !6)