lib/CodeGen/AsmPrinter/DebugLocEntry.h

   1 //===-- llvm/CodeGen/DebugLocEntry.h - Entry in debug_loc list -*- C++ -*--===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #ifndef LLVM_LIB_CODEGEN_ASMPRINTER_DEBUGLOCENTRY_H
  10 #define LLVM_LIB_CODEGEN_ASMPRINTER_DEBUGLOCENTRY_H
  11
  12 #include "DebugLocStream.h"
  13 #include "llvm/Config/llvm-config.h"
  14 #include "llvm/IR/Constants.h"
  15 #include "llvm/IR/DebugInfo.h"
  16 #include "llvm/MC/MCSymbol.h"
  17 #include "llvm/MC/MachineLocation.h"
  18 #include "llvm/Support/Debug.h"
  19
  20 namespace llvm {
  21 class AsmPrinter;
  22
  23 /// This struct describes location entries emitted in the .debug_loc
  24 /// section.
  25 class DebugLocEntry {
  26   /// Begin and end symbols for the address range that this location is valid.
  27   const MCSymbol *Begin;
  28   const MCSymbol *End;
  29
  30 public:
  31   /// A single location or constant.
  32   struct Value {
  33     Value(const DIExpression *Expr, int64_t i)
  34         : Expression(Expr), EntryKind(E_Integer) {
  35       Constant.Int = i;
  36     }
  37     Value(const DIExpression *Expr, const ConstantFP *CFP)
  38         : Expression(Expr), EntryKind(E_ConstantFP) {
  39       Constant.CFP = CFP;
  40     }
  41     Value(const DIExpression *Expr, const ConstantInt *CIP)
  42         : Expression(Expr), EntryKind(E_ConstantInt) {
  43       Constant.CIP = CIP;
  44     }
  45     Value(const DIExpression *Expr, MachineLocation Loc)
  46         : Expression(Expr), EntryKind(E_Location), Loc(Loc) {
  47       assert(cast<DIExpression>(Expr)->isValid());
  48     }
  49
  50     /// Any complex address location expression for this Value.
  51     const DIExpression *Expression;
  52
  53     /// Type of entry that this represents.
  54     enum EntryType { E_Location, E_Integer, E_ConstantFP, E_ConstantInt };
  55     enum EntryType EntryKind;
  56
  57     /// Either a constant,
  58     union {
  59       int64_t Int;
  60       const ConstantFP *CFP;
  61       const ConstantInt *CIP;
  62     } Constant;
  63
  64     // Or a location in the machine frame.
  65     MachineLocation Loc;
  66
  67     bool isLocation() const { return EntryKind == E_Location; }
  68     bool isInt() const { return EntryKind == E_Integer; }
  69     bool isConstantFP() const { return EntryKind == E_ConstantFP; }
  70     bool isConstantInt() const { return EntryKind == E_ConstantInt; }
  71     int64_t getInt() const { return Constant.Int; }
  72     const ConstantFP *getConstantFP() const { return Constant.CFP; }
  73     const ConstantInt *getConstantInt() const { return Constant.CIP; }
  74     MachineLocation getLoc() const { return Loc; }
  75     bool isFragment() const { return getExpression()->isFragment(); }
  76     const DIExpression *getExpression() const { return Expression; }
  77     friend bool operator==(const Value &, const Value &);
  78     friend bool operator<(const Value &, const Value &);
  79 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
  80     LLVM_DUMP_METHOD void dump() const {
  81       if (isLocation()) {
  82         llvm::dbgs() << "Loc = { reg=" << Loc.getReg() << " ";
  83         if (Loc.isIndirect())
  84           llvm::dbgs() << "+0";
  85         llvm::dbgs() << "} ";
  86       }
  87       else if (isConstantInt())
  88         Constant.CIP->dump();
  89       else if (isConstantFP())
  90         Constant.CFP->dump();
  91       if (Expression)
  92         Expression->dump();
  93     }
  94 #endif
  95   };
  96
  97 private:
  98   /// A nonempty list of locations/constants belonging to this entry,
  99   /// sorted by offset.
 100   SmallVector<Value, 1> Values;
 101
 102 public:
 103   DebugLocEntry(const MCSymbol *B, const MCSymbol *E, Value Val)
 104       : Begin(B), End(E) {
 105     Values.push_back(std::move(Val));
 106   }
 107
 108   /// If this and Next are describing different pieces of the same
 109   /// variable, merge them by appending Next's values to the current
 110   /// list of values.
 111   /// Return true if the merge was successful.
 112   bool MergeValues(const DebugLocEntry &Next);
 113
 114   /// Attempt to merge this DebugLocEntry with Next and return
 115   /// true if the merge was successful. Entries can be merged if they
 116   /// share the same Loc/Constant and if Next immediately follows this
 117   /// Entry.
 118   bool MergeRanges(const DebugLocEntry &Next) {
 119     // If this and Next are describing the same variable, merge them.
 120     if ((End == Next.Begin && Values == Next.Values)) {
 121       End = Next.End;
 122       return true;
 123     }
 124     return false;
 125   }
 126
 127   const MCSymbol *getBeginSym() const { return Begin; }
 128   const MCSymbol *getEndSym() const { return End; }
 129   ArrayRef<Value> getValues() const { return Values; }
 130   void addValues(ArrayRef<DebugLocEntry::Value> Vals) {
 131     Values.append(Vals.begin(), Vals.end());
 132     sortUniqueValues();
 133     assert(all_of(Values, [](DebugLocEntry::Value V) {
 134           return V.isFragment();
 135         }) && "value must be a piece");
 136   }
 137
 138   // Sort the pieces by offset.
 139   // Remove any duplicate entries by dropping all but the first.
 140   void sortUniqueValues() {
 141     llvm::sort(Values);
 142     Values.erase(
 143         std::unique(
 144             Values.begin(), Values.end(), [](const Value &A, const Value &B) {
 145               return A.getExpression() == B.getExpression();
 146             }),
 147         Values.end());
 148   }
 149
 150   /// Lower this entry into a DWARF expression.
 151   void finalize(const AsmPrinter &AP, DebugLocStream::ListBuilder &List,
 152                 const DIBasicType *BT);
 153 };
 154
 155 /// Compare two Values for equality.
 156 inline bool operator==(const DebugLocEntry::Value &A,
 157                        const DebugLocEntry::Value &B) {
 158   if (A.EntryKind != B.EntryKind)
 159     return false;
 160
 161   if (A.Expression != B.Expression)
 162     return false;
 163
 164   switch (A.EntryKind) {
 165   case DebugLocEntry::Value::E_Location:
 166     return A.Loc == B.Loc;
 167   case DebugLocEntry::Value::E_Integer:
 168     return A.Constant.Int == B.Constant.Int;
 169   case DebugLocEntry::Value::E_ConstantFP:
 170     return A.Constant.CFP == B.Constant.CFP;
 171   case DebugLocEntry::Value::E_ConstantInt:
 172     return A.Constant.CIP == B.Constant.CIP;
 173   }
 174   llvm_unreachable("unhandled EntryKind");
 175 }
 176
 177 /// Compare two fragments based on their offset.
 178 inline bool operator<(const DebugLocEntry::Value &A,
 179                       const DebugLocEntry::Value &B) {
 180   return A.getExpression()->getFragmentInfo()->OffsetInBits <
 181          B.getExpression()->getFragmentInfo()->OffsetInBits;
 182 }
 183
 184 }
 185
 186 #endif