Teach dwarf writer to handle complex address expression for .debug_loc entries.

This fixes clang generated blocks' variables' debug info.
Radar 9279956.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@130373 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/CodeGen/AsmPrinter.h

@@ -379,6 +379,10 @@ namespace llvm {
     /// operands.
     virtual MachineLocation getDebugValueLocation(const MachineInstr *MI) const;
 
+    /// getDwarfRegOpSize - get size required to emit given machine location
+    /// using dwarf encoding.
+    virtual unsigned getDwarfRegOpSize(const MachineLocation &MLoc) const;
+
     /// getISAEncoding - Get the value for DW_AT_APPLE_isa. Zero if no isa
     /// encoding specified.
     virtual unsigned getISAEncoding() { return 0; }

lib/CodeGen/AsmPrinter/AsmPrinter.cpp

@@ -749,33 +749,49 @@ getDebugValueLocation(const MachineInstr *MI) const {
   return MachineLocation();
 }
 
+/// getDwarfRegOpSize - get size required to emit given machine location using
+/// dwarf encoding.
+unsigned AsmPrinter::getDwarfRegOpSize(const MachineLocation &MLoc) const {
+  const TargetRegisterInfo *RI = TM.getRegisterInfo();
+  unsigned DWReg = RI->getDwarfRegNum(MLoc.getReg(), false);
+  if (int Offset = MLoc.getOffset()) {
+    // If the value is at a certain offset from frame register then
+    // use DW_OP_breg.
+    if (DWReg < 32)
+      return 1 + MCAsmInfo::getSLEB128Size(Offset);
+    else
+      return 1 + MCAsmInfo::getULEB128Size(MLoc.getReg()) 
+        + MCAsmInfo::getSLEB128Size(Offset);
+  }
+  if (DWReg < 32)
+    return 1;
+
+  return 1 + MCAsmInfo::getULEB128Size(DWReg);
+}
+
 /// EmitDwarfRegOp - Emit dwarf register operation.
 void AsmPrinter::EmitDwarfRegOp(const MachineLocation &MLoc) const {
-  const TargetRegisterInfo *RI = TM.getRegisterInfo();
-  unsigned Reg = RI->getDwarfRegNum(MLoc.getReg(), false);
+  const TargetRegisterInfo *TRI = TM.getRegisterInfo();
+  unsigned Reg = TRI->getDwarfRegNum(MLoc.getReg(), false);
   if (int Offset =  MLoc.getOffset()) {
-    // If the value is at a certain offset from frame register then
-    // use DW_OP_fbreg.
-    unsigned OffsetSize = Offset ? MCAsmInfo::getSLEB128Size(Offset) : 1;
-    OutStreamer.AddComment("Loc expr size");
-    EmitInt16(1 + OffsetSize);
-    OutStreamer.AddComment(
-      dwarf::OperationEncodingString(dwarf::DW_OP_fbreg));
-    EmitInt8(dwarf::DW_OP_fbreg);
-    OutStreamer.AddComment("Offset");
+    if (Reg < 32) {
+      OutStreamer.AddComment(
+        dwarf::OperationEncodingString(dwarf::DW_OP_breg0 + Reg));
+      EmitInt8(dwarf::DW_OP_breg0 + Reg);
+    } else {
+      OutStreamer.AddComment("DW_OP_bregx");
+      EmitInt8(dwarf::DW_OP_bregx);
+      OutStreamer.AddComment(Twine(Reg));
+      EmitULEB128(Reg);
+    }
     EmitSLEB128(Offset);
   } else {
     if (Reg < 32) {
-      OutStreamer.AddComment("Loc expr size");
-      EmitInt16(1);
       OutStreamer.AddComment(
         dwarf::OperationEncodingString(dwarf::DW_OP_reg0 + Reg));
       EmitInt8(dwarf::DW_OP_reg0 + Reg);
     } else {
-      OutStreamer.AddComment("Loc expr size");
-      EmitInt16(1 + MCAsmInfo::getULEB128Size(Reg));
-      OutStreamer.AddComment(
-        dwarf::OperationEncodingString(dwarf::DW_OP_regx));
+      OutStreamer.AddComment("DW_OP_regx");
       EmitInt8(dwarf::DW_OP_regx);
       OutStreamer.AddComment(Twine(Reg));
       EmitULEB128(Reg);

lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp

@@ -258,15 +258,22 @@ void CompileUnit::addComplexAddress(DbgVariable *&DV, DIE *Die,
                                     unsigned Attribute,
                                     const MachineLocation &Location) {
   DIEBlock *Block = new (DIEValueAllocator) DIEBlock();
-
-  if (Location.isReg())
-    addRegisterOp(Block, Location.getReg());
+  unsigned N = DV->getNumAddrElements();
+  unsigned i = 0;
+  if (Location.isReg()) {
+    if (N >= 2 && DV->getAddrElement(0) == DIBuilder::OpPlus) {
+      // If first address element is OpPlus then emit
+      // DW_OP_breg + Offset instead of DW_OP_reg + Offset.
+      addRegisterOffset(Block, Location.getReg(), DV->getAddrElement(1));
+      i = 2;
+    } else
+      addRegisterOp(Block, Location.getReg());
+  }
   else
     addRegisterOffset(Block, Location.getReg(), Location.getOffset());
 
-  for (unsigned i = 0, N = DV->getNumAddrElements(); i < N; ++i) {
+  for (;i < N; ++i) {
     uint64_t Element = DV->getAddrElement(i);
-
     if (Element == DIBuilder::OpPlus) {
       addUInt(Block, 0, dwarf::DW_FORM_data1, dwarf::DW_OP_plus_uconst);
       addUInt(Block, 0, dwarf::DW_FORM_udata, DV->getAddrElement(++i));

lib/CodeGen/AsmPrinter/DwarfDebug.cpp

@@ -1466,7 +1466,7 @@ DwarfDebug::collectVariableInfo(const MachineFunction *MF,
       }
 
       // The value is valid until the next DBG_VALUE or clobber.
-      DotDebugLocEntries.push_back(DotDebugLocEntry(FLabel, SLabel, MLoc));
+      DotDebugLocEntries.push_back(DotDebugLocEntry(FLabel, SLabel, MLoc, Var));
     }
     DotDebugLocEntries.push_back(DotDebugLocEntry());
   }
@@ -2721,7 +2721,39 @@ void DwarfDebug::emitDebugLoc() {
     } else {
       Asm->OutStreamer.EmitSymbolValue(Entry.Begin, Size, 0);
       Asm->OutStreamer.EmitSymbolValue(Entry.End, Size, 0);
-      Asm->EmitDwarfRegOp(Entry.Loc);
+      DIVariable DV(Entry.Variable);
+      if (DV.hasComplexAddress()) {
+        unsigned N = DV.getNumAddrElements();
+        unsigned i = 0;
+        Asm->OutStreamer.AddComment("Loc expr size");
+        if (N >= 2 && DV.getAddrElement(0) == DIBuilder::OpPlus) {
+          // If first address element is OpPlus then emit
+          // DW_OP_breg + Offset instead of DW_OP_reg + Offset.
+          MachineLocation Loc(Entry.Loc.getReg(), DV.getAddrElement(1));
+          Asm->EmitInt16(Asm->getDwarfRegOpSize(Loc) + N - 2);
+          Asm->EmitDwarfRegOp(Loc);
+//          Asm->EmitULEB128(DV.getAddrElement(1));
+          i = 2;
+        } else {
+          Asm->EmitInt16(Asm->getDwarfRegOpSize(Entry.Loc) + N);
+          Asm->EmitDwarfRegOp(Entry.Loc);
+        }
+
+        // Emit remaining complex address elements.
+        for (; i < N; ++i) {
+          uint64_t Element = DV.getAddrElement(i);
+          if (Element == DIBuilder::OpPlus) {
+            Asm->EmitInt8(dwarf::DW_OP_plus_uconst);
+            Asm->EmitULEB128(DV.getAddrElement(++i));
+          } else if (Element == DIBuilder::OpDeref)
+            Asm->EmitInt8(dwarf::DW_OP_deref);
+          else llvm_unreachable("unknown Opcode found in complex address");
+        }
+      } else {
+        Asm->OutStreamer.AddComment("Loc expr size");
+        Asm->EmitInt16(Asm->getDwarfRegOpSize(Entry.Loc));
+        Asm->EmitDwarfRegOp(Entry.Loc);
+      }
     }
   }
 }

lib/CodeGen/AsmPrinter/DwarfDebug.h

@@ -66,10 +66,12 @@ typedef struct DotDebugLocEntry {
   const MCSymbol *Begin;
   const MCSymbol *End;
   MachineLocation Loc;
+  const MDNode *Variable;
   bool Merged;
-  DotDebugLocEntry() : Begin(0), End(0), Merged(false) {}
-  DotDebugLocEntry(const MCSymbol *B, const MCSymbol *E, MachineLocation &L) 
-    : Begin(B), End(E), Loc(L), Merged(false) {}
+  DotDebugLocEntry() : Begin(0), End(0), Variable(0), Merged(false) {}
+  DotDebugLocEntry(const MCSymbol *B, const MCSymbol *E, MachineLocation &L,
+                   const MDNode *V) 
+    : Begin(B), End(E), Loc(L), Variable(V), Merged(false) {}
   /// Empty entries are also used as a trigger to emit temp label. Such
   /// labels are referenced is used to find debug_loc offset for a given DIE.
   bool isEmpty() { return Begin == 0 && End == 0; }

lib/Target/ARM/ARMAsmPrinter.cpp

@@ -172,6 +172,47 @@ getDebugValueLocation(const MachineInstr *MI) const {
   return Location;
 }
 
+/// getDwarfRegOpSize - get size required to emit given machine location using
+/// dwarf encoding.
+unsigned ARMAsmPrinter::getDwarfRegOpSize(const MachineLocation &MLoc) const {
+ const TargetRegisterInfo *RI = TM.getRegisterInfo();
+  if (RI->getDwarfRegNum(MLoc.getReg(), false) != -1)
+    return AsmPrinter::getDwarfRegOpSize(MLoc);
+  else {
+    unsigned Reg = MLoc.getReg();
+    if (Reg >= ARM::S0 && Reg <= ARM::S31) {
+      assert(ARM::S0 + 31 == ARM::S31 && "Unexpected ARM S register numbering");
+      // S registers are described as bit-pieces of a register
+      // S[2x] = DW_OP_regx(256 + (x>>1)) DW_OP_bit_piece(32, 0)
+      // S[2x+1] = DW_OP_regx(256 + (x>>1)) DW_OP_bit_piece(32, 32)
+      
+      unsigned SReg = Reg - ARM::S0;
+      unsigned Rx = 256 + (SReg >> 1);
+      OutStreamer.AddComment("Loc expr size");
+      // DW_OP_regx + ULEB + DW_OP_bit_piece + ULEB + ULEB
+      //   1 + ULEB(Rx) + 1 + 1 + 1
+      return 4 + MCAsmInfo::getULEB128Size(Rx);
+    } 
+    
+    if (Reg >= ARM::Q0 && Reg <= ARM::Q15) {
+      assert(ARM::Q0 + 15 == ARM::Q15 && "Unexpected ARM Q register numbering");
+      // Q registers Q0-Q15 are described by composing two D registers together.
+      // Qx = DW_OP_regx(256+2x) DW_OP_piece(8) DW_OP_regx(256+2x+1) DW_OP_piece(8)
+
+      unsigned QReg = Reg - ARM::Q0;
+      unsigned D1 = 256 + 2 * QReg;
+      unsigned D2 = D1 + 1;
+      
+      OutStreamer.AddComment("Loc expr size");
+      // DW_OP_regx + ULEB + DW_OP_piece + ULEB(8) +
+      // DW_OP_regx + ULEB + DW_OP_piece + ULEB(8);
+      //   6 + ULEB(D1) + ULEB(D2)
+      return 6 + MCAsmInfo::getULEB128Size(D1) + MCAsmInfo::getULEB128Size(D2);
+    }
+  }
+  return 0;
+}
+
 /// EmitDwarfRegOp - Emit dwarf register operation.
 void ARMAsmPrinter::EmitDwarfRegOp(const MachineLocation &MLoc) const {
   const TargetRegisterInfo *RI = TM.getRegisterInfo();

lib/Target/ARM/ARMAsmPrinter.h

@@ -89,6 +89,10 @@ public:
 
   MachineLocation getDebugValueLocation(const MachineInstr *MI) const;
 
+  /// getDwarfRegOpSize - get size required to emit given machine location
+  /// using dwarf encoding.
+  virtual unsigned getDwarfRegOpSize(const MachineLocation &MLoc) const;
+
   /// EmitDwarfRegOp - Emit dwarf register operation.
   virtual void EmitDwarfRegOp(const MachineLocation &MLoc) const;
 

test/CodeGen/ARM/2010-08-04-StackVariable.ll

@@ -1,5 +1,5 @@
-; RUN: llc -O0 -mtriple=arm-apple-darwin < %s | grep DW_OP_fbreg
-; Use DW_OP_fbreg in variable's location expression if the variable is in a stack slot.
+; RUN: llc -O0 -mtriple=arm-apple-darwin < %s | grep DW_OP_breg
+; Use DW_OP_breg in variable's location expression if the variable is in a stack slot.
 
 %struct.SVal = type { i8*, i32 }
 

test/CodeGen/X86/2010-08-04-StackVariable.ll

@@ -1,5 +1,5 @@
-; RUN: llc -O0 -mtriple=x86_64-apple-darwin < %s | grep DW_OP_fbreg
-; Use DW_OP_fbreg in variable's location expression if the variable is in a stack slot.
+; RUN: llc -O0 -mtriple=x86_64-apple-darwin < %s | grep DW_OP_breg7
+; Use DW_OP_breg7 in variable's location expression if the variable is in a stack slot.
 
 %struct.SVal = type { i8*, i32 }