Debug Info: Move support for constants into DwarfExpression.

Move the declaration of DebugLocDwarfExpression into DwarfExpression.h
because it needs to be accessed from AsmPrinterDwarf.cpp and DwarfDebug.cpp

NFC.

llvm-svn: 225734

llvm/lib/CodeGen/AsmPrinter/AsmPrinterDwarf.cpp

@@ -32,32 +32,24 @@ using namespace llvm;
 
 #define DEBUG_TYPE "asm-printer"
 
-/// DwarfExpression implementation for .debug_loc entries.
-class DebugLocDwarfExpression : public DwarfExpression {
-  ByteStreamer &BS;
-
-public:
-  DebugLocDwarfExpression(const AsmPrinter &AP, ByteStreamer &BS)
-      : DwarfExpression(AP), BS(BS) {}
-
-  void EmitOp(uint8_t Op, const char *Comment) override;
-  void EmitSigned(int Value) override;
-  void EmitUnsigned(unsigned Value) override;
-  unsigned getFrameRegister() override { llvm_unreachable("not available"); };
-};
-
 void DebugLocDwarfExpression::EmitOp(uint8_t Op, const char *Comment) {
   BS.EmitInt8(
       Op, Comment ? Twine(Comment) + " " + dwarf::OperationEncodingString(Op)
                   : dwarf::OperationEncodingString(Op));
 }
+
 void DebugLocDwarfExpression::EmitSigned(int Value) {
   BS.EmitSLEB128(Value, Twine(Value));
 }
+
 void DebugLocDwarfExpression::EmitUnsigned(unsigned Value) {
   BS.EmitULEB128(Value, Twine(Value));
 }
 
+unsigned DebugLocDwarfExpression::getFrameRegister() {
+ llvm_unreachable("not available");
+}
+
 //===----------------------------------------------------------------------===//
 // Dwarf Emission Helper Routines
 //===----------------------------------------------------------------------===//

llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp

@@ -14,6 +14,7 @@
 #include "DwarfDebug.h"
 
 #include "ByteStreamer.h"
+#include "DwarfExpression.h"
 #include "DwarfCompileUnit.h"
 #include "DIEHash.h"
 #include "DwarfUnit.h"
@@ -1717,29 +1718,15 @@ void DwarfDebug::emitDebugLocEntry(ByteStreamer &Streamer,
 void DwarfDebug::emitDebugLocValue(ByteStreamer &Streamer,
                                    const DebugLocEntry::Value &Value) {
   DIVariable DV = Value.getVariable();
+  DebugLocDwarfExpression Expr(*Asm, Streamer);
   // Regular entry.
   if (Value.isInt()) {
     DIBasicType BTy(resolve(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(Value.getInt());
-    } else {
-      Streamer.EmitInt8(dwarf::DW_OP_constu, "DW_OP_constu");
-      Streamer.EmitULEB128(Value.getInt());
-    }
-    // The proper way to describe a constant value is 
-    // DW_OP_constu <const>, DW_OP_stack_value. 
-    // Unfortunately, DW_OP_stack_value was not available until DWARF-4,
-    // so we will continue to generate DW_OP_constu <const> for DWARF-2
-    // and DWARF-3. Technically, this is incorrect since DW_OP_const <const>
-    // actually describes a value at a constant addess, not a constant value. 
-    // However, in the past there was no better way  to describe a constant 
-    // value, so the producers and consumers started to rely on heuristics 
-    // to disambiguate the value vs. location status of the expression. 
-    // See PR21176 for more details.
-    if (getDwarfVersion() >= 4)
-      Streamer.EmitInt8(dwarf::DW_OP_stack_value, "DW_OP_stack_value");
+                         BTy.getEncoding() == dwarf::DW_ATE_signed_char))
+      Expr.AddSignedConstant(Value.getInt());
+    else
+      Expr.AddUnsignedConstant(Value.getInt());
   } else if (Value.isLocation()) {
     MachineLocation Loc = Value.getLoc();
     DIExpression Expr = Value.getExpression();

llvm/lib/CodeGen/AsmPrinter/DwarfExpression.cpp

@@ -21,14 +21,17 @@
 #include "llvm/Target/TargetRegisterInfo.h"
 #include "llvm/Target/TargetSubtargetInfo.h"
 
-
 using namespace llvm;
 
 const TargetRegisterInfo *DwarfExpression::getTRI() const {
   return AP.TM.getSubtargetImpl()->getRegisterInfo();
 }
 
-void DwarfExpression::AddReg(int DwarfReg, const char* Comment) {
+unsigned DwarfExpression::getDwarfVersion() const {
+  return AP.getDwarfDebug()->getDwarfVersion();
+}
+
+void DwarfExpression::AddReg(int DwarfReg, const char *Comment) {
   assert(DwarfReg >= 0 && "invalid negative dwarf register number");
   if (DwarfReg < 32) {
     EmitOp(dwarf::DW_OP_reg0 + DwarfReg, Comment);
@@ -51,8 +54,7 @@ void DwarfExpression::AddRegIndirect(int DwarfReg, int Offset, bool Deref) {
     EmitOp(dwarf::DW_OP_deref);
 }
 
-void DwarfExpression::AddOpPiece(unsigned SizeInBits,
-                                 unsigned OffsetInBits) {
+void DwarfExpression::AddOpPiece(unsigned SizeInBits, unsigned OffsetInBits) {
   assert(SizeInBits > 0 && "piece has size zero");
   const unsigned SizeOfByte = 8;
   if (OffsetInBits > 0 || SizeInBits % SizeOfByte) {
@@ -164,3 +166,28 @@ void DwarfExpression::AddMachineRegPiece(unsigned MachineReg,
     // FIXME: We have no reasonable way of handling errors in here.
     EmitOp(dwarf::DW_OP_nop, "nop (could not find a dwarf register number)");
 }
+
+void DwarfExpression::AddSignedConstant(int Value) {
+  EmitOp(dwarf::DW_OP_consts);
+  EmitSigned(Value);
+  // The proper way to describe a constant value is
+  // DW_OP_constu <const>, DW_OP_stack_value.
+  // Unfortunately, DW_OP_stack_value was not available until DWARF-4,
+  // so we will continue to generate DW_OP_constu <const> for DWARF-2
+  // and DWARF-3. Technically, this is incorrect since DW_OP_const <const>
+  // actually describes a value at a constant addess, not a constant value.
+  // However, in the past there was no better way  to describe a constant
+  // value, so the producers and consumers started to rely on heuristics
+  // to disambiguate the value vs. location status of the expression.
+  // See PR21176 for more details.
+  if (getDwarfVersion() >= 4)
+    EmitOp(dwarf::DW_OP_stack_value);
+}
+
+void DwarfExpression::AddUnsignedConstant(unsigned Value) {
+  EmitOp(dwarf::DW_OP_constu);
+  EmitUnsigned(Value);
+  // cf. comment in DwarfExpression::AddSignedConstant().
+  if (getDwarfVersion() >= 4)
+    EmitOp(dwarf::DW_OP_stack_value);
+}

llvm/lib/CodeGen/AsmPrinter/DwarfExpression.h

@@ -19,6 +19,7 @@
 namespace llvm {
 
 class AsmPrinter;
+class ByteStreamer;
 class TargetRegisterInfo;
 
 /// Base class containing the logic for constructing DWARF expressions
@@ -29,6 +30,7 @@ protected:
   const AsmPrinter ≈
   // Various convenience accessors that extract things out of AsmPrinter.
   const TargetRegisterInfo *getTRI() const;
+  unsigned getDwarfVersion() const;
 
 public:
   DwarfExpression(const AsmPrinter &AP) : AP(AP) {}
@@ -71,6 +73,26 @@ public:
   void AddMachineRegPiece(unsigned MachineReg,
                           unsigned PieceSizeInBits = 0,
                           unsigned PieceOffsetInBits = 0);
+
+  /// Emit a signed constant.
+  void AddSignedConstant(int Value);
+  /// Emit an unsigned constant.
+  void AddUnsignedConstant(unsigned Value);
+};
+
+
+/// DwarfExpression implementation for .debug_loc entries.
+class DebugLocDwarfExpression : public DwarfExpression {
+  ByteStreamer &BS;
+
+public:
+  DebugLocDwarfExpression(const AsmPrinter &AP, ByteStreamer &BS)
+      : DwarfExpression(AP), BS(BS) {}
+
+  void EmitOp(uint8_t Op, const char *Comment) override;
+  void EmitSigned(int Value) override;
+  void EmitUnsigned(unsigned Value) override;
+  unsigned getFrameRegister() override;
 };
 
 }