[llvm] r205360 - DebugInfo: Split DebugLocEntry into its own file.

David Blaikie dblaikie at gmail.com
Tue Apr 1 15:14:53 PDT 2014


On Tue, Apr 1, 2014 at 3:12 PM, Adrian Prantl <aprantl at apple.com> wrote:
>
> On Apr 1, 2014, at 2:49 PM, David Blaikie <dblaikie at gmail.com> wrote:
>
>> Author: dblaikie
>> Date: Tue Apr  1 16:49:04 2014
>> New Revision: 205360
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=205360&view=rev
>> Log:
>> DebugInfo: Split DebugLocEntry into its own file.
>>
>> It seems big enough that it deserves its own file - but it is header
>> only, so there's no need for another cpp file, etc.
>>
>> Added:
>>    llvm/trunk/lib/CodeGen/AsmPrinter/DebugLocEntry.h
>> Modified:
>>    llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.h
>>
>> Added: llvm/trunk/lib/CodeGen/AsmPrinter/DebugLocEntry.h
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DebugLocEntry.h?rev=205360&view=auto
>> ==============================================================================
>> --- llvm/trunk/lib/CodeGen/AsmPrinter/DebugLocEntry.h (added)
>> +++ llvm/trunk/lib/CodeGen/AsmPrinter/DebugLocEntry.h Tue Apr  1 16:49:04 2014
>> @@ -0,0 +1,112 @@
>> +//===-- llvm/CodeGen/DebugLocEntry.h - Entry in debug_loc list -*- C++ -*--===//
>> +//
>> +//                     The LLVM Compiler Infrastructure
>> +//
>> +// This file is distributed under the University of Illinois Open Source
>> +// License. See LICENSE.TXT for details.
>> +//
>> +//===----------------------------------------------------------------------===//
>> +
>> +#ifndef CODEGEN_ASMPRINTER_DEBUGLOCENTRY_H__
>> +#define CODEGEN_ASMPRINTER_DEBUGLOCENTRY_H__
>> +#include "llvm/IR/Constants.h"
>> +#include "llvm/MC/MachineLocation.h"
>> +#include "llvm/MC/MCSymbol.h"
>> +
>> +namespace llvm {
>> +class DwarfCompileUnit;
>> +class MDNode;
>> +/// \brief This struct describes location entries emitted in the .debug_loc
>> +/// section.
>> +class DebugLocEntry {
>> +  // Begin and end symbols for the address range that this location is valid.
>> +  const MCSymbol *Begin;
>> +  const MCSymbol *End;
>> +
>> +  // Type of entry that this represents.
>> +  enum EntryType { E_Location, E_Integer, E_ConstantFP, E_ConstantInt };
>> +  enum EntryType EntryKind;
>> +
>> +  union {
>> +    int64_t Int;
>> +    const ConstantFP *CFP;
>> +    const ConstantInt *CIP;
>> +  } Constants;
>> +
>> +  // The location in the machine frame.
>> +  MachineLocation Loc;
>> +
>> +  // The variable to which this location entry corresponds.
>> +  const MDNode *Variable;
>> +
>> +  // The compile unit to which this location entry is referenced by.
>> +  const DwarfCompileUnit *Unit;
>> +
>> +public:
>> +  DebugLocEntry() : Begin(0), End(0), Variable(0), Unit(0) {
>> +    Constants.Int = 0;
>> +  }
>> +  DebugLocEntry(const MCSymbol *B, const MCSymbol *E, MachineLocation &L,
>> +                const MDNode *V, const DwarfCompileUnit *U)
>> +      : Begin(B), End(E), Loc(L), Variable(V), Unit(U) {
>> +    Constants.Int = 0;
>> +    EntryKind = E_Location;
>> +  }
>> +  DebugLocEntry(const MCSymbol *B, const MCSymbol *E, int64_t i,
>> +                const DwarfCompileUnit *U)
>> +      : Begin(B), End(E), Variable(0), Unit(U) {
>> +    Constants.Int = i;
>> +    EntryKind = E_Integer;
>> +  }
>> +  DebugLocEntry(const MCSymbol *B, const MCSymbol *E, const ConstantFP *FPtr,
>> +                const DwarfCompileUnit *U)
>> +      : Begin(B), End(E), Variable(0), Unit(U) {
>> +    Constants.CFP = FPtr;
>> +    EntryKind = E_ConstantFP;
>> +  }
>> +  DebugLocEntry(const MCSymbol *B, const MCSymbol *E, const ConstantInt *IPtr,
>> +                const DwarfCompileUnit *U)
>> +      : Begin(B), End(E), Variable(0), Unit(U) {
>> +    Constants.CIP = IPtr;
>> +    EntryKind = E_ConstantInt;
>> +  }
>> +
>> +  /// \brief 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() const { return Begin == 0 && End == 0; }
>> +  bool Merge(const DebugLocEntry &Next) {
>> +    if (End != Next.Begin)
>> +      return false;
>> +
>> +    if (EntryKind != Next.EntryKind)
>> +      return false;
>> +
>> +    switch (EntryKind) {
>> +    case E_Location:
>> +      if (Loc != Next.Loc) return false;
>> +    case E_Integer:
>> +      if (Constants.Int != Next.Constants.Int) return false;
>> +    case E_ConstantFP:
>> +      if (Constants.CFP != Next.Constants.CFP) return false;
>> +    case E_ConstantInt:
>> +      if (Constants.CIP != Next.Constants.CIP) return false;
>> +    }
>> +
>> +    return true;
>> +  }
>
>
> I know this is a union, but this still feels wrong without a break.. What about:

We early return from switches pretty regularly - I kind of prefer it
over adding extra variables and more non-linear control flow (at least
"leaving the function" is simpler than "jump to the end of the switch
and continue" maybe?)

>
>   /// \brief Attempt to merge this DebugLocEntry with Next and return
>   /// true if the merge was successful. Entries can be merged if they
>   /// share the same Loc/Constant and their ranges are adjacent.
>   bool Merge(const DebugLocEntry &Next) {
>     if (!Begin || End != Next.Begin)
>       return false;
>     if (EntryKind != Next.EntryKind)
>       return false;
>     bool CanMerge;
>     switch (EntryKind) {
>     case E_Location:    CanMerge =           Loc == Next.Loc;           break;
>     case E_Integer:     CanMerge = Constants.Int == Next.Constants.Int; break;
>     case E_ConstantFP:  CanMerge = Constants.CFP == Next.Constants.CFP; break;
>     case E_ConstantInt: CanMerge = Constants.CIP == Next.Constants.CIP; break;
>     }
>     // Merge the entries by adjusting End.
>     if (CanMerge)
>       End = Next.End;

OK, so the fact that I completely dropped the "End = Next.End" and
didn't cause any tests to fail is... bad.

I'll see what test coverage we're missing here.

>
>     return CanMerge;
>
>> +  bool isLocation() const { return EntryKind == E_Location; }
>> +  bool isInt() const { return EntryKind == E_Integer; }
>> +  bool isConstantFP() const { return EntryKind == E_ConstantFP; }
>> +  bool isConstantInt() const { return EntryKind == E_ConstantInt; }
>> +  int64_t getInt() const { return Constants.Int; }
>> +  const ConstantFP *getConstantFP() const { return Constants.CFP; }
>> +  const ConstantInt *getConstantInt() const { return Constants.CIP; }
>> +  const MDNode *getVariable() const { return Variable; }
>> +  const MCSymbol *getBeginSym() const { return Begin; }
>> +  const MCSymbol *getEndSym() const { return End; }
>> +  const DwarfCompileUnit *getCU() const { return Unit; }
>> +  MachineLocation getLoc() const { return Loc; }
>> +};
>> +
>> +}
>> +#endif
>>
>> Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.h
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.h?rev=205360&r1=205359&r2=205360&view=diff
>> ==============================================================================
>> --- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.h (original)
>> +++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.h Tue Apr  1 16:49:04 2014
>> @@ -16,6 +16,7 @@
>>
>> #include "AsmPrinterHandler.h"
>> #include "DIE.h"
>> +#include "DebugLocEntry.h"
>> #include "llvm/ADT/DenseMap.h"
>> #include "llvm/ADT/MapVector.h"
>> #include "llvm/ADT/SmallPtrSet.h"
>> @@ -58,91 +59,6 @@ public:
>>   MCSymbol *getLabel() const { return Label; }
>> };
>>
>> -/// \brief This struct describes location entries emitted in the .debug_loc
>> -/// section.
>> -class DebugLocEntry {
>> -  // Begin and end symbols for the address range that this location is valid.
>> -  const MCSymbol *Begin;
>> -  const MCSymbol *End;
>> -
>> -  // Type of entry that this represents.
>> -  enum EntryType { E_Location, E_Integer, E_ConstantFP, E_ConstantInt };
>> -  enum EntryType EntryKind;
>> -
>> -  union {
>> -    int64_t Int;
>> -    const ConstantFP *CFP;
>> -    const ConstantInt *CIP;
>> -  } Constants;
>> -
>> -  // The location in the machine frame.
>> -  MachineLocation Loc;
>> -
>> -  // The variable to which this location entry corresponds.
>> -  const MDNode *Variable;
>> -
>> -  // The compile unit to which this location entry is referenced by.
>> -  const DwarfCompileUnit *Unit;
>> -
>> -public:
>> -  DebugLocEntry() : Begin(0), End(0), Variable(0), Unit(0) {
>> -    Constants.Int = 0;
>> -  }
>> -  DebugLocEntry(const MCSymbol *B, const MCSymbol *E, MachineLocation &L,
>> -                const MDNode *V, const DwarfCompileUnit *U)
>> -      : Begin(B), End(E), Loc(L), Variable(V), Unit(U) {
>> -    Constants.Int = 0;
>> -    EntryKind = E_Location;
>> -  }
>> -  DebugLocEntry(const MCSymbol *B, const MCSymbol *E, int64_t i,
>> -                const DwarfCompileUnit *U)
>> -      : Begin(B), End(E), Variable(0), Unit(U) {
>> -    Constants.Int = i;
>> -    EntryKind = E_Integer;
>> -  }
>> -  DebugLocEntry(const MCSymbol *B, const MCSymbol *E, const ConstantFP *FPtr,
>> -                const DwarfCompileUnit *U)
>> -      : Begin(B), End(E), Variable(0), Unit(U) {
>> -    Constants.CFP = FPtr;
>> -    EntryKind = E_ConstantFP;
>> -  }
>> -  DebugLocEntry(const MCSymbol *B, const MCSymbol *E, const ConstantInt *IPtr,
>> -                const DwarfCompileUnit *U)
>> -      : Begin(B), End(E), Variable(0), Unit(U) {
>> -    Constants.CIP = IPtr;
>> -    EntryKind = E_ConstantInt;
>> -  }
>> -
>> -  /// \brief 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() const { return Begin == 0 && End == 0; }
>> -  bool Merge(const DebugLocEntry &Next) {
>> -    if (Begin &&
>> -     Loc == Next.Loc &&
>> -     EntryKind == Next.EntryKind &&
>> -     (!isInt() || getInt() == Next.getInt()) &&
>> -     (!isConstantInt() || getConstantInt() == Next.getConstantInt()) &&
>> -     (!isConstantFP() || getConstantFP() == Next.getConstantFP()) &&
>> -     End == Next.Begin) {
>> -    End = Next.End;
>> -    return true;
>> -  }
>> -  return false;
>> -  }
>> -  bool isLocation() const { return EntryKind == E_Location; }
>> -  bool isInt() const { return EntryKind == E_Integer; }
>> -  bool isConstantFP() const { return EntryKind == E_ConstantFP; }
>> -  bool isConstantInt() const { return EntryKind == E_ConstantInt; }
>> -  int64_t getInt() const { return Constants.Int; }
>> -  const ConstantFP *getConstantFP() const { return Constants.CFP; }
>> -  const ConstantInt *getConstantInt() const { return Constants.CIP; }
>> -  const MDNode *getVariable() const { return Variable; }
>> -  const MCSymbol *getBeginSym() const { return Begin; }
>> -  const MCSymbol *getEndSym() const { return End; }
>> -  const DwarfCompileUnit *getCU() const { return Unit; }
>> -  MachineLocation getLoc() const { return Loc; }
>> -};
>> -
>> //===----------------------------------------------------------------------===//
>> /// \brief This class is used to track local variable information.
>> class DbgVariable {
>>
>>
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