Two part patch:

First: refactor out the emission of entries into the .debug_loc section
into its own routine.

Second: add a new class ByteStreamer that can be used to either emit
using an AsmPrinter or hash using DIEHash the series of bytes that
would be emitted. Use this in all of the location emission routines
for the .debug_loc section.

No functional change intended outside of a few additional comments
in verbose assembly.

llvm-svn: 203304

include/llvm/CodeGen/AsmPrinter.h

@@ -24,6 +24,7 @@
 namespace llvm {
   class AsmPrinterHandler;
   class BlockAddress;
+  class ByteStreamer;
   class GCStrategy;
   class Constant;
   class ConstantArray;
@@ -429,7 +430,7 @@ namespace llvm {
     virtual unsigned getISAEncoding() { return 0; }
 
     /// EmitDwarfRegOp - Emit dwarf register operation.
-    virtual void EmitDwarfRegOp(const MachineLocation &MLoc,
+    virtual void EmitDwarfRegOp(ByteStreamer &BS, const MachineLocation &MLoc,
                                 bool Indirect) const;
 
     //===------------------------------------------------------------------===//

lib/CodeGen/AsmPrinter/AsmPrinterDwarf.cpp

@@ -12,6 +12,7 @@
 //===----------------------------------------------------------------------===//
 
 #define DEBUG_TYPE "asm-printer"
+#include "ByteStreamer.h"
 #include "llvm/CodeGen/AsmPrinter.h"
 #include "llvm/ADT/SmallBitVector.h"
 #include "llvm/ADT/Twine.h"
@@ -185,58 +186,47 @@ void AsmPrinter::EmitSectionOffset(const MCSymbol *Label,
 }
 
 /// Emit a dwarf register operation.
-static void emitDwarfRegOp(const AsmPrinter &AP, int Reg) {
+static void emitDwarfRegOp(ByteStreamer &Streamer, int Reg) {
   assert(Reg >= 0);
   if (Reg < 32) {
-    AP.OutStreamer.AddComment(
-        dwarf::OperationEncodingString(dwarf::DW_OP_reg0 + Reg));
-    AP.EmitInt8(dwarf::DW_OP_reg0 + Reg);
+    Streamer.EmitInt8(dwarf::DW_OP_reg0 + Reg,
+                      dwarf::OperationEncodingString(dwarf::DW_OP_reg0 + Reg));
   } else {
-    AP.OutStreamer.AddComment("DW_OP_regx");
-    AP.EmitInt8(dwarf::DW_OP_regx);
-    AP.OutStreamer.AddComment(Twine(Reg));
-    AP.EmitULEB128(Reg);
+    Streamer.EmitInt8(dwarf::DW_OP_regx, "DW_OP_regx");
+    Streamer.EmitULEB128(Reg, Twine(Reg));
   }
 }
 
 /// Emit an (double-)indirect dwarf register operation.
-static void emitDwarfRegOpIndirect(const AsmPrinter &AP, int Reg, int Offset,
+static void emitDwarfRegOpIndirect(ByteStreamer &Streamer, int Reg, int Offset,
                                    bool Deref) {
   assert(Reg >= 0);
   if (Reg < 32) {
-    AP.OutStreamer.AddComment(
-        dwarf::OperationEncodingString(dwarf::DW_OP_breg0 + Reg));
-    AP.EmitInt8(dwarf::DW_OP_breg0 + Reg);
+    Streamer.EmitInt8(dwarf::DW_OP_breg0 + Reg,
+                      dwarf::OperationEncodingString(dwarf::DW_OP_breg0 + Reg));
   } else {
-    AP.OutStreamer.AddComment("DW_OP_bregx");
-    AP.EmitInt8(dwarf::DW_OP_bregx);
-    AP.OutStreamer.AddComment(Twine(Reg));
-    AP.EmitULEB128(Reg);
+    Streamer.EmitInt8(dwarf::DW_OP_bregx, "DW_OP_bregx");
+    Streamer.EmitULEB128(Reg, Twine(Reg));
   }
-  AP.EmitSLEB128(Offset);
+  Streamer.EmitSLEB128(Offset);
   if (Deref)
-    AP.EmitInt8(dwarf::DW_OP_deref);
+    Streamer.EmitInt8(dwarf::DW_OP_deref, "DW_OP_deref");
 }
 
 /// Emit a dwarf register operation for describing
 /// - a small value occupying only part of a register or
 /// - a small register representing only part of a value.
-static void emitDwarfOpPiece(const AsmPrinter &AP, unsigned Size,
+static void emitDwarfOpPiece(ByteStreamer &Streamer, unsigned Size,
                              unsigned Offset) {
   assert(Size > 0);
   if (Offset > 0) {
-    AP.OutStreamer.AddComment("DW_OP_bit_piece");
-    AP.EmitInt8(dwarf::DW_OP_bit_piece);
-    AP.OutStreamer.AddComment(Twine(Size));
-    AP.EmitULEB128(Size);
-    AP.OutStreamer.AddComment(Twine(Offset));
-    AP.EmitULEB128(Offset);
+    Streamer.EmitInt8(dwarf::DW_OP_bit_piece, "DW_OP_bit_piece");
+    Streamer.EmitULEB128(Size, Twine(Size));
+    Streamer.EmitULEB128(Offset, Twine(Offset));
   } else {
-    AP.OutStreamer.AddComment("DW_OP_piece");
-    AP.EmitInt8(dwarf::DW_OP_piece);
+    Streamer.EmitInt8(dwarf::DW_OP_piece, "DW_OP_piece");
     unsigned ByteSize = Size / 8; // Assuming 8 bits per byte.
-    AP.OutStreamer.AddComment(Twine(ByteSize));
-    AP.EmitULEB128(ByteSize);
+    Streamer.EmitULEB128(ByteSize, Twine(ByteSize));
   }
 }
 
@@ -244,7 +234,7 @@ static void emitDwarfOpPiece(const AsmPrinter &AP, unsigned Size,
 /// register.  This function attempts to emit a dwarf register by
 /// emitting a piece of a super-register or by piecing together
 /// multiple subregisters that alias the register.
-static void EmitDwarfRegOpPiece(const AsmPrinter &AP,
+static void EmitDwarfRegOpPiece(ByteStreamer &Streamer, const AsmPrinter &AP,
                                 const MachineLocation &MLoc) {
   assert(!MLoc.isIndirect());
   const TargetRegisterInfo *TRI = AP.TM.getRegisterInfo();
@@ -259,8 +249,8 @@ static void EmitDwarfRegOpPiece(const AsmPrinter &AP,
       unsigned Size = TRI->getSubRegIdxSize(Idx);
       unsigned Offset = TRI->getSubRegIdxOffset(Idx);
       AP.OutStreamer.AddComment("super-register");
-      emitDwarfRegOp(AP, Reg);
-      emitDwarfOpPiece(AP, Size, Offset);
+      emitDwarfRegOp(Streamer, Reg);
+      emitDwarfOpPiece(Streamer, Size, Offset);
       return;
     }
   }
@@ -292,8 +282,8 @@ static void EmitDwarfRegOpPiece(const AsmPrinter &AP,
     // its range, emit a DWARF piece for it.
     if (Reg >= 0 && Intersection.any()) {
       AP.OutStreamer.AddComment("sub-register");
-      emitDwarfRegOp(AP, Reg);
-      emitDwarfOpPiece(AP, Size, Offset == CurPos ? 0 : Offset);
+      emitDwarfRegOp(Streamer, Reg);
+      emitDwarfOpPiece(Streamer, Size, Offset == CurPos ? 0 : Offset);
       CurPos = Offset + Size;
 
       // Mark it as emitted.
@@ -303,13 +293,14 @@ static void EmitDwarfRegOpPiece(const AsmPrinter &AP,
 
   if (CurPos == 0) {
     // FIXME: We have no reasonable way of handling errors in here.
-    AP.OutStreamer.AddComment("nop (could not find a dwarf register number)");
-    AP.EmitInt8(dwarf::DW_OP_nop);
+    Streamer.EmitInt8(dwarf::DW_OP_nop,
+                      "nop (could not find a dwarf register number)");
   }
 }
 
 /// EmitDwarfRegOp - Emit dwarf register operation.
-void AsmPrinter::EmitDwarfRegOp(const MachineLocation &MLoc,
+void AsmPrinter::EmitDwarfRegOp(ByteStreamer &Streamer,
+                                const MachineLocation &MLoc,
                                 bool Indirect) const {
   const TargetRegisterInfo *TRI = TM.getRegisterInfo();
   int Reg = TRI->getDwarfRegNum(MLoc.getReg(), false);
@@ -320,23 +311,22 @@ void AsmPrinter::EmitDwarfRegOp(const MachineLocation &MLoc,
       // caller might be in the middle of a dwarf expression. We should
       // probably assert that Reg >= 0 once debug info generation is more
       // mature.
-      OutStreamer.AddComment(
-          "nop (invalid dwarf register number for indirect loc)");
-      EmitInt8(dwarf::DW_OP_nop);
+      Streamer.EmitInt8(dwarf::DW_OP_nop,
+                        "nop (invalid dwarf register number for indirect loc)");
       return;
     }
 
     // Attempt to find a valid super- or sub-register.
     if (!Indirect && !MLoc.isIndirect())
-      return EmitDwarfRegOpPiece(*this, MLoc);
+      return EmitDwarfRegOpPiece(Streamer, *this, MLoc);
   }
 
   if (MLoc.isIndirect())
-    emitDwarfRegOpIndirect(*this, Reg, MLoc.getOffset(), Indirect);
+    emitDwarfRegOpIndirect(Streamer, Reg, MLoc.getOffset(), Indirect);
   else if (Indirect)
-    emitDwarfRegOpIndirect(*this, Reg, 0, false);
+    emitDwarfRegOpIndirect(Streamer, Reg, 0, false);
   else
-    emitDwarfRegOp(*this, Reg);
+    emitDwarfRegOp(Streamer, Reg);
 }
 
 //===----------------------------------------------------------------------===//

lib/CodeGen/AsmPrinter/DwarfDebug.cpp

@@ -12,6 +12,7 @@
 //===----------------------------------------------------------------------===//
 
 #define DEBUG_TYPE "dwarfdebug"
+#include "ByteStreamer.h"
 #include "DwarfDebug.h"
 #include "DIE.h"
 #include "DIEHash.h"
@@ -2395,6 +2396,65 @@ void DwarfDebug::emitDebugStr() {
   Holder.emitStrings(Asm->getObjFileLowering().getDwarfStrSection());
 }
 
+void DwarfDebug::emitDebugLocEntry(ByteStreamer &Streamer,
+                                   const DotDebugLocEntry &Entry) {
+  DIVariable DV(Entry.getVariable());
+  if (Entry.isInt()) {
+    DIBasicType BTy(DV.getType());
+    if (BTy.Verify() && (BTy.getEncoding() == dwarf::DW_ATE_signed ||
+                         BTy.getEncoding() == dwarf::DW_ATE_signed_char)) {
+      Streamer.EmitInt8(dwarf::DW_OP_consts, "DW_OP_consts");
+      Streamer.EmitSLEB128(Entry.getInt());
+    } else {
+      Streamer.EmitInt8(dwarf::DW_OP_constu, "DW_OP_constu");
+      Streamer.EmitULEB128(Entry.getInt());
+    }
+  } else if (Entry.isLocation()) {
+    MachineLocation Loc = Entry.getLoc();
+    if (!DV.hasComplexAddress())
+      // Regular entry.
+      Asm->EmitDwarfRegOp(Streamer, Loc, DV.isIndirect());
+    else {
+      // Complex address entry.
+      unsigned N = DV.getNumAddrElements();
+      unsigned i = 0;
+      if (N >= 2 && DV.getAddrElement(0) == DIBuilder::OpPlus) {
+        if (Loc.getOffset()) {
+          i = 2;
+          Asm->EmitDwarfRegOp(Streamer, Loc, DV.isIndirect());
+          Streamer.EmitInt8(dwarf::DW_OP_deref, "DW_OP_deref");
+          Streamer.EmitInt8(dwarf::DW_OP_plus_uconst, "DW_OP_plus_uconst");
+          Streamer.EmitSLEB128(DV.getAddrElement(1));
+        } else {
+          // If first address element is OpPlus then emit
+          // DW_OP_breg + Offset instead of DW_OP_reg + Offset.
+          MachineLocation TLoc(Loc.getReg(), DV.getAddrElement(1));
+          Asm->EmitDwarfRegOp(Streamer, TLoc, DV.isIndirect());
+          i = 2;
+        }
+      } else {
+        Asm->EmitDwarfRegOp(Streamer, Loc, DV.isIndirect());
+      }
+
+      // Emit remaining complex address elements.
+      for (; i < N; ++i) {
+        uint64_t Element = DV.getAddrElement(i);
+        if (Element == DIBuilder::OpPlus) {
+          Streamer.EmitInt8(dwarf::DW_OP_plus_uconst, "DW_OP_plus_uconst");
+          Streamer.EmitULEB128(DV.getAddrElement(++i));
+        } else if (Element == DIBuilder::OpDeref) {
+          if (!Loc.isReg())
+            Streamer.EmitInt8(dwarf::DW_OP_deref, "DW_OP_deref");
+        } else
+          llvm_unreachable("unknown Opcode found in complex address");
+      }
+    }
+  }
+  // else ... ignore constant fp. There is not any good way to
+  // to represent them here in dwarf.
+  // FIXME: ^
+}
+
 // Emit locations into the debug loc section.
 void DwarfDebug::emitDebugLoc() {
   if (DotDebugLocEntries.empty())
@@ -2422,76 +2482,24 @@ void DwarfDebug::emitDebugLoc() {
     const DotDebugLocEntry &Entry = *I;
     if (Entry.isMerged())
       continue;
+
     if (Entry.isEmpty()) {
       Asm->OutStreamer.EmitIntValue(0, Size);
       Asm->OutStreamer.EmitIntValue(0, Size);
       Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("debug_loc", index));
     } else {
+      // Set up the range.
       Asm->OutStreamer.EmitSymbolValue(Entry.getBeginSym(), Size);
       Asm->OutStreamer.EmitSymbolValue(Entry.getEndSym(), Size);
-      DIVariable DV(Entry.getVariable());
       Asm->OutStreamer.AddComment("Loc expr size");
       MCSymbol *begin = Asm->OutStreamer.getContext().CreateTempSymbol();
       MCSymbol *end = Asm->OutStreamer.getContext().CreateTempSymbol();
       Asm->EmitLabelDifference(end, begin, 2);
       Asm->OutStreamer.EmitLabel(begin);
-      if (Entry.isInt()) {
-        DIBasicType BTy(DV.getType());
-        if (BTy.Verify() && (BTy.getEncoding() == dwarf::DW_ATE_signed ||
-                             BTy.getEncoding() == dwarf::DW_ATE_signed_char)) {
-          Asm->OutStreamer.AddComment("DW_OP_consts");
-          Asm->EmitInt8(dwarf::DW_OP_consts);
-          Asm->EmitSLEB128(Entry.getInt());
-        } else {
-          Asm->OutStreamer.AddComment("DW_OP_constu");
-          Asm->EmitInt8(dwarf::DW_OP_constu);
-          Asm->EmitULEB128(Entry.getInt());
-        }
-      } else if (Entry.isLocation()) {
-        MachineLocation Loc = Entry.getLoc();
-        if (!DV.hasComplexAddress())
-          // Regular entry.
-          Asm->EmitDwarfRegOp(Loc, DV.isIndirect());
-        else {
-          // Complex address entry.
-          unsigned N = DV.getNumAddrElements();
-          unsigned i = 0;
-          if (N >= 2 && DV.getAddrElement(0) == DIBuilder::OpPlus) {
-            if (Loc.getOffset()) {
-              i = 2;
-              Asm->EmitDwarfRegOp(Loc, DV.isIndirect());
-              Asm->OutStreamer.AddComment("DW_OP_deref");
-              Asm->EmitInt8(dwarf::DW_OP_deref);
-              Asm->OutStreamer.AddComment("DW_OP_plus_uconst");
-              Asm->EmitInt8(dwarf::DW_OP_plus_uconst);
-              Asm->EmitSLEB128(DV.getAddrElement(1));
-            } else {
-              // If first address element is OpPlus then emit
-              // DW_OP_breg + Offset instead of DW_OP_reg + Offset.
-              MachineLocation TLoc(Loc.getReg(), DV.getAddrElement(1));
-              Asm->EmitDwarfRegOp(TLoc, DV.isIndirect());
-              i = 2;
-            }
-          } else {
-            Asm->EmitDwarfRegOp(Loc, DV.isIndirect());
-          }
-
-          // 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) {
-              if (!Loc.isReg())
-                Asm->EmitInt8(dwarf::DW_OP_deref);
-            } else
-              llvm_unreachable("unknown Opcode found in complex address");
-          }
-        }
-      }
-      // else ... ignore constant fp. There is not any good way to
-      // to represent them here in dwarf.
+      // Emit the entry.
+      APByteStreamer Streamer(*Asm);
+      emitDebugLocEntry(Streamer, Entry);
+      // Close the range.
       Asm->OutStreamer.EmitLabel(end);
     }
   }

lib/CodeGen/AsmPrinter/DwarfDebug.h

@@ -31,6 +31,7 @@
 
 namespace llvm {
 
+class ByteStreamer;
 class DwarfUnit;
 class DwarfCompileUnit;
 class ConstantInt;
@@ -587,6 +588,9 @@ class DwarfDebug : public AsmPrinterHandler {
   /// \brief Emit visible names into a debug str section.
   void emitDebugStr();
 
+  /// \brief Emit an entry for the debug loc section.
+  void emitDebugLocEntry(ByteStreamer &Streamer, const DotDebugLocEntry &Entry);
+
   /// \brief Emit visible names into a debug loc section.
   void emitDebugLoc();