include/llvm/CodeGen/SwiftErrorValueTracking.h

   1 //===- SwiftErrorValueTracking.h - Track swifterror VReg vals --*- 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 // This implements a limited mem2reg-like analysis to promote uses of function
  10 // arguments and allocas marked with swiftalloc from memory into virtual
  11 // registers tracked by this class.
  12 //
  13 //===----------------------------------------------------------------------===//
  14
  15 #ifndef SWIFTERRORVALUETRACKING_H
  16 #define SWIFTERRORVALUETRACKING_H
  17
  18 #include "llvm/ADT/DenseMap.h"
  19 #include "llvm/ADT/SmallVector.h"
  20 #include "llvm/CodeGen/Register.h"
  21 #include "llvm/IR/BasicBlock.h"
  22 #include "llvm/IR/DebugLoc.h"
  23 #include <functional>
  24 #include <type_traits>
  25 #include <utility>
  26
  27
  28 namespace llvm {
  29   class Function;
  30   class MachineBasicBlock;
  31   class MachineFunction;
  32   class MachineInstr;
  33   class TargetInstrInfo;
  34   class TargetLowering;
  35
  36 class SwiftErrorValueTracking {
  37   // Some useful objects to reduce the number of function arguments needed.
  38   MachineFunction *MF;
  39   const Function *Fn;
  40   const TargetLowering *TLI;
  41   const TargetInstrInfo *TII;
  42
  43   /// A map from swifterror value in a basic block to the virtual register it is
  44   /// currently represented by.
  45   DenseMap<std::pair<const MachineBasicBlock *, const Value *>, Register>
  46       VRegDefMap;
  47
  48   /// A list of upward exposed vreg uses that need to be satisfied by either a
  49   /// copy def or a phi node at the beginning of the basic block representing
  50   /// the predecessor(s) swifterror value.
  51   DenseMap<std::pair<const MachineBasicBlock *, const Value *>, Register>
  52       VRegUpwardsUse;
  53
  54   /// A map from instructions that define/use a swifterror value to the virtual
  55   /// register that represents that def/use.
  56   llvm::DenseMap<PointerIntPair<const Instruction *, 1, bool>, Register>
  57       VRegDefUses;
  58
  59   /// The swifterror argument of the current function.
  60   const Value *SwiftErrorArg;
  61
  62   using SwiftErrorValues = SmallVector<const Value*, 1>;
  63   /// A function can only have a single swifterror argument. And if it does
  64   /// have a swifterror argument, it must be the first entry in
  65   /// SwiftErrorVals.
  66   SwiftErrorValues SwiftErrorVals;
  67
  68 public:
  69   /// Initialize data structures for specified new function.
  70   void setFunction(MachineFunction &MF);
  71
  72   /// Get the (unique) function argument that was marked swifterror, or nullptr
  73   /// if this function has no swifterror args.
  74   const Value *getFunctionArg() const {
  75     return SwiftErrorArg;
  76   }
  77
  78   /// Get or create the swifterror value virtual register in
  79   /// VRegDefMap for this basic block.
  80   Register getOrCreateVReg(const MachineBasicBlock *, const Value *);
  81
  82   /// Set the swifterror virtual register in the VRegDefMap for this
  83   /// basic block.
  84   void setCurrentVReg(const MachineBasicBlock *MBB, const Value *, Register);
  85
  86   /// Get or create the swifterror value virtual register for a def of a
  87   /// swifterror by an instruction.
  88   Register getOrCreateVRegDefAt(const Instruction *, const MachineBasicBlock *,
  89                                 const Value *);
  90
  91   /// Get or create the swifterror value virtual register for a use of a
  92   /// swifterror by an instruction.
  93   Register getOrCreateVRegUseAt(const Instruction *, const MachineBasicBlock *,
  94                                 const Value *);
  95
  96   /// Create initial definitions of swifterror values in the entry block of the
  97   /// current function.
  98   bool createEntriesInEntryBlock(DebugLoc DbgLoc);
  99
 100   /// Propagate assigned swifterror vregs through a function, synthesizing PHI
 101   /// nodes when needed to maintain consistency.
 102   void propagateVRegs();
 103
 104   void preassignVRegs(MachineBasicBlock *MBB, BasicBlock::const_iterator Begin,
 105                       BasicBlock::const_iterator End);
 106 };
 107
 108 }
 109
 110 #endif