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| //===-- 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);
/// Try to combine G_SHUFFLE_VECTOR into G_CONCAT_VECTORS.
/// Returns true if MI changed.
///
/// \pre MI.getOpcode() == G_SHUFFLE_VECTOR.
bool tryCombineShuffleVector(MachineInstr &MI);
/// Check if the G_SHUFFLE_VECTOR \p MI can be replaced by a
/// concat_vectors.
/// \p Ops will contain the operands needed to produce the flattened
/// concat_vectors.
///
/// \pre MI.getOpcode() == G_SHUFFLE_VECTOR.
bool matchCombineShuffleVector(MachineInstr &MI,
SmallVectorImpl<Register> &Ops);
/// Replace \p MI with a concat_vectors with \p Ops.
void applyCombineShuffleVector(MachineInstr &MI,
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
|