| //===-- llvm/CodeGen/GlobalISel/CombinerHelper.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 |
| // |
| //===--------------------------------------------------------------------===// |
| // |
| /// This contains common combine transformations that may be used in a combine |
| /// pass,or by the target elsewhere. |
| /// Targets can pick individual opcode transformations from the helper or use |
| /// tryCombine which invokes all transformations. All of the transformations |
| /// return true if the MachineInstruction changed and false otherwise. |
| // |
| //===--------------------------------------------------------------------===// |
| |
| #ifndef LLVM_CODEGEN_GLOBALISEL_COMBINER_HELPER_H |
| #define LLVM_CODEGEN_GLOBALISEL_COMBINER_HELPER_H |
| |
| #include "llvm/CodeGen/LowLevelType.h" |
| #include "llvm/CodeGen/Register.h" |
| |
| namespace llvm { |
| |
| class GISelChangeObserver; |
| class MachineIRBuilder; |
| class MachineRegisterInfo; |
| class MachineInstr; |
| class MachineOperand; |
| class GISelKnownBits; |
| class MachineDominatorTree; |
| |
| struct PreferredTuple { |
| LLT Ty; // The result type of the extend. |
| unsigned ExtendOpcode; // G_ANYEXT/G_SEXT/G_ZEXT |
| MachineInstr *MI; |
| }; |
| |
| class CombinerHelper { |
| protected: |
| MachineIRBuilder &Builder; |
| MachineRegisterInfo &MRI; |
| GISelChangeObserver &Observer; |
| GISelKnownBits *KB; |
| MachineDominatorTree *MDT; |
| |
| public: |
| CombinerHelper(GISelChangeObserver &Observer, MachineIRBuilder &B, |
| GISelKnownBits *KB = nullptr, |
| MachineDominatorTree *MDT = nullptr); |
| |
| /// MachineRegisterInfo::replaceRegWith() and inform the observer of the changes |
| void replaceRegWith(MachineRegisterInfo &MRI, Register FromReg, Register ToReg) const; |
| |
| /// Replace a single register operand with a new register and inform the |
| /// observer of the changes. |
| void replaceRegOpWith(MachineRegisterInfo &MRI, MachineOperand &FromRegOp, |
| Register ToReg) const; |
| |
| /// If \p MI is COPY, try to combine it. |
| /// Returns true if MI changed. |
| bool tryCombineCopy(MachineInstr &MI); |
| bool matchCombineCopy(MachineInstr &MI); |
| void applyCombineCopy(MachineInstr &MI); |
| |
| /// Returns true if \p DefMI precedes \p UseMI or they are the same |
| /// instruction. Both must be in the same basic block. |
| bool isPredecessor(MachineInstr &DefMI, MachineInstr &UseMI); |
| |
| /// Returns true if \p DefMI dominates \p UseMI. By definition an |
| /// instruction dominates itself. |
| /// |
| /// If we haven't been provided with a MachineDominatorTree during |
| /// construction, this function returns a conservative result that tracks just |
| /// a single basic block. |
| bool dominates(MachineInstr &DefMI, MachineInstr &UseMI); |
| |
| /// If \p MI is extend that consumes the result of a load, try to combine it. |
| /// Returns true if MI changed. |
| bool tryCombineExtendingLoads(MachineInstr &MI); |
| bool matchCombineExtendingLoads(MachineInstr &MI, PreferredTuple &MatchInfo); |
| void applyCombineExtendingLoads(MachineInstr &MI, PreferredTuple &MatchInfo); |
| |
| /// Combine \p MI into a pre-indexed or post-indexed load/store operation if |
| /// legal and the surrounding code makes it useful. |
| bool tryCombineIndexedLoadStore(MachineInstr &MI); |
| |
| bool matchElideBrByInvertingCond(MachineInstr &MI); |
| void applyElideBrByInvertingCond(MachineInstr &MI); |
| bool tryElideBrByInvertingCond(MachineInstr &MI); |
| |
| /// If \p MI is G_CONCAT_VECTORS, try to combine it. |
| /// Returns true if MI changed. |
| /// Right now, we support: |
| /// - concat_vector(undef, undef) => undef |
| /// - concat_vector(build_vector(A, B), build_vector(C, D)) => |
| /// build_vector(A, B, C, D) |
| /// |
| /// \pre MI.getOpcode() == G_CONCAT_VECTORS. |
| bool tryCombineConcatVectors(MachineInstr &MI); |
| /// Check if the G_CONCAT_VECTORS \p MI is undef or if it |
| /// can be flattened into a build_vector. |
| /// In the first case \p IsUndef will be true. |
| /// In the second case \p Ops will contain the operands needed |
| /// to produce the flattened build_vector. |
| /// |
| /// \pre MI.getOpcode() == G_CONCAT_VECTORS. |
| bool matchCombineConcatVectors(MachineInstr &MI, bool &IsUndef, |
| SmallVectorImpl<Register> &Ops); |
| /// Replace \p MI with a flattened build_vector with \p Ops or an |
| /// implicit_def if IsUndef is true. |
| void applyCombineConcatVectors(MachineInstr &MI, bool IsUndef, |
| const ArrayRef<Register> Ops); |
| |
| /// Optimize memcpy intrinsics et al, e.g. constant len calls. |
| /// /p MaxLen if non-zero specifies the max length of a mem libcall to inline. |
| /// |
| /// For example (pre-indexed): |
| /// |
| /// $addr = G_GEP $base, $offset |
| /// [...] |
| /// $val = G_LOAD $addr |
| /// [...] |
| /// $whatever = COPY $addr |
| /// |
| /// --> |
| /// |
| /// $val, $addr = G_INDEXED_LOAD $base, $offset, 1 (IsPre) |
| /// [...] |
| /// $whatever = COPY $addr |
| /// |
| /// or (post-indexed): |
| /// |
| /// G_STORE $val, $base |
| /// [...] |
| /// $addr = G_GEP $base, $offset |
| /// [...] |
| /// $whatever = COPY $addr |
| /// |
| /// --> |
| /// |
| /// $addr = G_INDEXED_STORE $val, $base, $offset |
| /// [...] |
| /// $whatever = COPY $addr |
| bool tryCombineMemCpyFamily(MachineInstr &MI, unsigned MaxLen = 0); |
| |
| /// Try to transform \p MI by using all of the above |
| /// combine functions. Returns true if changed. |
| bool tryCombine(MachineInstr &MI); |
| |
| private: |
| // Memcpy family optimization helpers. |
| bool optimizeMemcpy(MachineInstr &MI, Register Dst, Register Src, |
| unsigned KnownLen, unsigned DstAlign, unsigned SrcAlign, |
| bool IsVolatile); |
| bool optimizeMemmove(MachineInstr &MI, Register Dst, Register Src, |
| unsigned KnownLen, unsigned DstAlign, unsigned SrcAlign, |
| bool IsVolatile); |
| bool optimizeMemset(MachineInstr &MI, Register Dst, Register Val, |
| unsigned KnownLen, unsigned DstAlign, bool IsVolatile); |
| |
| /// Given a non-indexed load or store instruction \p MI, find an offset that |
| /// can be usefully and legally folded into it as a post-indexing operation. |
| /// |
| /// \returns true if a candidate is found. |
| bool findPostIndexCandidate(MachineInstr &MI, Register &Addr, Register &Base, |
| Register &Offset); |
| |
| /// Given a non-indexed load or store instruction \p MI, find an offset that |
| /// can be usefully and legally folded into it as a pre-indexing operation. |
| /// |
| /// \returns true if a candidate is found. |
| bool findPreIndexCandidate(MachineInstr &MI, Register &Addr, Register &Base, |
| Register &Offset); |
| }; |
| } // namespace llvm |
| |
| #endif |