llvm/CodeGen/SwiftErrorValueTracking.h

0001 //===- SwiftErrorValueTracking.h - Track swifterror VReg vals --*- C++ -*--===//
0002 //
0003 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
0004 // See https://llvm.org/LICENSE.txt for license information.
0005 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
0006 //
0007 //===----------------------------------------------------------------------===//
0008 //
0009 // This implements a limited mem2reg-like analysis to promote uses of function
0010 // arguments and allocas marked with swiftalloc from memory into virtual
0011 // registers tracked by this class.
0012 //
0013 //===----------------------------------------------------------------------===//
0014
0015 #ifndef LLVM_CODEGEN_SWIFTERRORVALUETRACKING_H
0016 #define LLVM_CODEGEN_SWIFTERRORVALUETRACKING_H
0017
0018 #include "llvm/ADT/DenseMap.h"
0019 #include "llvm/ADT/SmallVector.h"
0020 #include "llvm/CodeGen/Register.h"
0021 #include "llvm/IR/BasicBlock.h"
0022 #include "llvm/IR/DebugLoc.h"
0023 #include <utility>
0024
0025
0026 namespace llvm {
0027   class Function;
0028   class MachineBasicBlock;
0029   class MachineFunction;
0030   class MachineInstr;
0031   class TargetInstrInfo;
0032   class TargetLowering;
0033
0034 class SwiftErrorValueTracking {
0035   // Some useful objects to reduce the number of function arguments needed.
0036   MachineFunction *MF;
0037   const Function *Fn;
0038   const TargetLowering *TLI;
0039   const TargetInstrInfo *TII;
0040
0041   /// A map from swifterror value in a basic block to the virtual register it is
0042   /// currently represented by.
0043   DenseMap<std::pair<const MachineBasicBlock *, const Value *>, Register>
0044       VRegDefMap;
0045
0046   /// A list of upward exposed vreg uses that need to be satisfied by either a
0047   /// copy def or a phi node at the beginning of the basic block representing
0048   /// the predecessor(s) swifterror value.
0049   DenseMap<std::pair<const MachineBasicBlock *, const Value *>, Register>
0050       VRegUpwardsUse;
0051
0052   /// A map from instructions that define/use a swifterror value to the virtual
0053   /// register that represents that def/use.
0054   llvm::DenseMap<PointerIntPair<const Instruction *, 1, bool>, Register>
0055       VRegDefUses;
0056
0057   /// The swifterror argument of the current function.
0058   const Value *SwiftErrorArg;
0059
0060   using SwiftErrorValues = SmallVector<const Value*, 1>;
0061   /// A function can only have a single swifterror argument. And if it does
0062   /// have a swifterror argument, it must be the first entry in
0063   /// SwiftErrorVals.
0064   SwiftErrorValues SwiftErrorVals;
0065
0066 public:
0067   /// Initialize data structures for specified new function.
0068   void setFunction(MachineFunction &MF);
0069
0070   /// Get the (unique) function argument that was marked swifterror, or nullptr
0071   /// if this function has no swifterror args.
0072   const Value *getFunctionArg() const {
0073     return SwiftErrorArg;
0074   }
0075
0076   /// Get or create the swifterror value virtual register in
0077   /// VRegDefMap for this basic block.
0078   Register getOrCreateVReg(const MachineBasicBlock *, const Value *);
0079
0080   /// Set the swifterror virtual register in the VRegDefMap for this
0081   /// basic block.
0082   void setCurrentVReg(const MachineBasicBlock *MBB, const Value *, Register);
0083
0084   /// Get or create the swifterror value virtual register for a def of a
0085   /// swifterror by an instruction.
0086   Register getOrCreateVRegDefAt(const Instruction *, const MachineBasicBlock *,
0087                                 const Value *);
0088
0089   /// Get or create the swifterror value virtual register for a use of a
0090   /// swifterror by an instruction.
0091   Register getOrCreateVRegUseAt(const Instruction *, const MachineBasicBlock *,
0092                                 const Value *);
0093
0094   /// Create initial definitions of swifterror values in the entry block of the
0095   /// current function.
0096   bool createEntriesInEntryBlock(DebugLoc DbgLoc);
0097
0098   /// Propagate assigned swifterror vregs through a function, synthesizing PHI
0099   /// nodes when needed to maintain consistency.
0100   void propagateVRegs();
0101
0102   void preassignVRegs(MachineBasicBlock *MBB, BasicBlock::const_iterator Begin,
0103                       BasicBlock::const_iterator End);
0104 };
0105
0106 }
0107
0108 #endif