| //===-- llvm/CodeGen/GlobalISel/CSEMIRBuilder.h --*- C++ -*-==// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| /// \file |
| /// This file implements a version of MachineIRBuilder which CSEs insts within |
| /// a MachineBasicBlock. |
| //===----------------------------------------------------------------------===// |
| #ifndef LLVM_CODEGEN_GLOBALISEL_CSEMIRBUILDER_H |
| #define LLVM_CODEGEN_GLOBALISEL_CSEMIRBUILDER_H |
| |
| #include "llvm/CodeGen/GlobalISel/MachineIRBuilder.h" |
| #include "llvm/CodeGen/GlobalISel/Utils.h" |
| |
| namespace llvm { |
| |
| /// Defines a builder that does CSE of MachineInstructions using GISelCSEInfo. |
| /// Eg usage. |
| /// |
| /// |
| /// GISelCSEInfo *Info = |
| /// &getAnalysis<GISelCSEAnalysisWrapperPass>().getCSEInfo(); CSEMIRBuilder |
| /// CB(Builder.getState()); CB.setCSEInfo(Info); auto A = CB.buildConstant(s32, |
| /// 42); auto B = CB.buildConstant(s32, 42); assert(A == B); unsigned CReg = |
| /// MRI.createGenericVirtualRegister(s32); auto C = CB.buildConstant(CReg, 42); |
| /// assert(C->getOpcode() == TargetOpcode::COPY); |
| /// Explicitly passing in a register would materialize a copy if possible. |
| /// CSEMIRBuilder also does trivial constant folding for binary ops. |
| class CSEMIRBuilder : public MachineIRBuilder { |
| |
| /// Returns true if A dominates B (within the same basic block). |
| /// Both iterators must be in the same basic block. |
| // |
| // TODO: Another approach for checking dominance is having two iterators and |
| // making them go towards each other until they meet or reach begin/end. Which |
| // approach is better? Should this even change dynamically? For G_CONSTANTS |
| // most of which will be at the top of the BB, the top down approach would be |
| // a better choice. Does IRTranslator placing constants at the beginning still |
| // make sense? Should this change based on Opcode? |
| bool dominates(MachineBasicBlock::const_iterator A, |
| MachineBasicBlock::const_iterator B) const; |
| |
| /// For given ID, find a machineinstr in the CSE Map. If found, check if it |
| /// dominates the current insertion point and if not, move it just before the |
| /// current insertion point and return it. If not found, return Null |
| /// MachineInstrBuilder. |
| MachineInstrBuilder getDominatingInstrForID(FoldingSetNodeID &ID, |
| void *&NodeInsertPos); |
| /// Simple check if we can CSE (we have the CSEInfo) or if this Opcode is |
| /// safe to CSE. |
| bool canPerformCSEForOpc(unsigned Opc) const; |
| |
| void profileDstOp(const DstOp &Op, GISelInstProfileBuilder &B) const; |
| |
| void profileDstOps(ArrayRef<DstOp> Ops, GISelInstProfileBuilder &B) const { |
| for (const DstOp &Op : Ops) |
| profileDstOp(Op, B); |
| } |
| |
| void profileSrcOp(const SrcOp &Op, GISelInstProfileBuilder &B) const; |
| |
| void profileSrcOps(ArrayRef<SrcOp> Ops, GISelInstProfileBuilder &B) const { |
| for (const SrcOp &Op : Ops) |
| profileSrcOp(Op, B); |
| } |
| |
| void profileMBBOpcode(GISelInstProfileBuilder &B, unsigned Opc) const; |
| |
| void profileEverything(unsigned Opc, ArrayRef<DstOp> DstOps, |
| ArrayRef<SrcOp> SrcOps, Optional<unsigned> Flags, |
| GISelInstProfileBuilder &B) const; |
| |
| // Takes a MachineInstrBuilder and inserts it into the CSEMap using the |
| // NodeInsertPos. |
| MachineInstrBuilder memoizeMI(MachineInstrBuilder MIB, void *NodeInsertPos); |
| |
| // If we have can CSE an instruction, but still need to materialize to a VReg, |
| // we emit a copy from the CSE'd inst to the VReg. |
| MachineInstrBuilder generateCopiesIfRequired(ArrayRef<DstOp> DstOps, |
| MachineInstrBuilder &MIB); |
| |
| // If we have can CSE an instruction, but still need to materialize to a VReg, |
| // check if we can generate copies. It's not possible to return a single MIB, |
| // while emitting copies to multiple vregs. |
| bool checkCopyToDefsPossible(ArrayRef<DstOp> DstOps); |
| |
| public: |
| // Pull in base class constructors. |
| using MachineIRBuilder::MachineIRBuilder; |
| // Unhide buildInstr |
| MachineInstrBuilder buildInstr(unsigned Opc, ArrayRef<DstOp> DstOps, |
| ArrayRef<SrcOp> SrcOps, |
| Optional<unsigned> Flag = None) override; |
| // Bring in the other overload from the base class. |
| using MachineIRBuilder::buildConstant; |
| |
| MachineInstrBuilder buildConstant(const DstOp &Res, |
| const ConstantInt &Val) override; |
| |
| // Bring in the other overload from the base class. |
| using MachineIRBuilder::buildFConstant; |
| MachineInstrBuilder buildFConstant(const DstOp &Res, |
| const ConstantFP &Val) override; |
| }; |
| } // namespace llvm |
| #endif |