495 lines
22 KiB
C++
495 lines
22 KiB
C++
//===-- llvm/Target/TargetInstrInfo.h - Instruction Info --------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file describes the target machine instruction set to the code generator.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_TARGET_TARGETINSTRINFO_H
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#define LLVM_TARGET_TARGETINSTRINFO_H
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#include "llvm/Target/TargetInstrDesc.h"
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#include "llvm/CodeGen/MachineFunction.h"
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namespace llvm {
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class MCAsmInfo;
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class TargetRegisterClass;
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class TargetRegisterInfo;
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class LiveVariables;
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class CalleeSavedInfo;
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class SDNode;
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class SelectionDAG;
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template<class T> class SmallVectorImpl;
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//---------------------------------------------------------------------------
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///
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/// TargetInstrInfo - Interface to description of machine instruction set
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///
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class TargetInstrInfo {
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const TargetInstrDesc *Descriptors; // Raw array to allow static init'n
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unsigned NumOpcodes; // Number of entries in the desc array
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TargetInstrInfo(const TargetInstrInfo &); // DO NOT IMPLEMENT
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void operator=(const TargetInstrInfo &); // DO NOT IMPLEMENT
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public:
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TargetInstrInfo(const TargetInstrDesc *desc, unsigned NumOpcodes);
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virtual ~TargetInstrInfo();
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// Invariant opcodes: All instruction sets have these as their low opcodes.
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enum {
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PHI = 0,
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INLINEASM = 1,
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DBG_LABEL = 2,
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EH_LABEL = 3,
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GC_LABEL = 4,
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/// KILL - This instruction is a noop that is used only to adjust the liveness
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/// of registers. This can be useful when dealing with sub-registers.
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KILL = 5,
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/// EXTRACT_SUBREG - This instruction takes two operands: a register
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/// that has subregisters, and a subregister index. It returns the
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/// extracted subregister value. This is commonly used to implement
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/// truncation operations on target architectures which support it.
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EXTRACT_SUBREG = 6,
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/// INSERT_SUBREG - This instruction takes three operands: a register
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/// that has subregisters, a register providing an insert value, and a
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/// subregister index. It returns the value of the first register with
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/// the value of the second register inserted. The first register is
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/// often defined by an IMPLICIT_DEF, as is commonly used to implement
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/// anyext operations on target architectures which support it.
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INSERT_SUBREG = 7,
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/// IMPLICIT_DEF - This is the MachineInstr-level equivalent of undef.
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IMPLICIT_DEF = 8,
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/// SUBREG_TO_REG - This instruction is similar to INSERT_SUBREG except
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/// that the first operand is an immediate integer constant. This constant
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/// is often zero, as is commonly used to implement zext operations on
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/// target architectures which support it, such as with x86-64 (with
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/// zext from i32 to i64 via implicit zero-extension).
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SUBREG_TO_REG = 9,
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/// COPY_TO_REGCLASS - This instruction is a placeholder for a plain
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/// register-to-register copy into a specific register class. This is only
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/// used between instruction selection and MachineInstr creation, before
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/// virtual registers have been created for all the instructions, and it's
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/// only needed in cases where the register classes implied by the
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/// instructions are insufficient. The actual MachineInstrs to perform
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/// the copy are emitted with the TargetInstrInfo::copyRegToReg hook.
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COPY_TO_REGCLASS = 10
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};
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unsigned getNumOpcodes() const { return NumOpcodes; }
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/// get - Return the machine instruction descriptor that corresponds to the
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/// specified instruction opcode.
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///
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const TargetInstrDesc &get(unsigned Opcode) const {
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assert(Opcode < NumOpcodes && "Invalid opcode!");
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return Descriptors[Opcode];
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}
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/// isTriviallyReMaterializable - Return true if the instruction is trivially
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/// rematerializable, meaning it has no side effects and requires no operands
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/// that aren't always available.
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bool isTriviallyReMaterializable(const MachineInstr *MI,
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AliasAnalysis *AA = 0) const {
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return MI->getOpcode() == IMPLICIT_DEF ||
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(MI->getDesc().isRematerializable() &&
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(isReallyTriviallyReMaterializable(MI, AA) ||
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isReallyTriviallyReMaterializableGeneric(MI, AA)));
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}
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protected:
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/// isReallyTriviallyReMaterializable - For instructions with opcodes for
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/// which the M_REMATERIALIZABLE flag is set, this hook lets the target
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/// specify whether the instruction is actually trivially rematerializable,
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/// taking into consideration its operands. This predicate must return false
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/// if the instruction has any side effects other than producing a value, or
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/// if it requres any address registers that are not always available.
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virtual bool isReallyTriviallyReMaterializable(const MachineInstr *MI,
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AliasAnalysis *AA) const {
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return false;
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}
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private:
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/// isReallyTriviallyReMaterializableGeneric - For instructions with opcodes
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/// for which the M_REMATERIALIZABLE flag is set and the target hook
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/// isReallyTriviallyReMaterializable returns false, this function does
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/// target-independent tests to determine if the instruction is really
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/// trivially rematerializable.
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bool isReallyTriviallyReMaterializableGeneric(const MachineInstr *MI,
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AliasAnalysis *AA) const;
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public:
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/// Return true if the instruction is a register to register move and return
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/// the source and dest operands and their sub-register indices by reference.
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virtual bool isMoveInstr(const MachineInstr& MI,
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unsigned& SrcReg, unsigned& DstReg,
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unsigned& SrcSubIdx, unsigned& DstSubIdx) const {
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return false;
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}
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/// isLoadFromStackSlot - If the specified machine instruction is a direct
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/// load from a stack slot, return the virtual or physical register number of
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/// the destination along with the FrameIndex of the loaded stack slot. If
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/// not, return 0. This predicate must return 0 if the instruction has
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/// any side effects other than loading from the stack slot.
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virtual unsigned isLoadFromStackSlot(const MachineInstr *MI,
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int &FrameIndex) const {
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return 0;
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}
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/// isStoreToStackSlot - If the specified machine instruction is a direct
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/// store to a stack slot, return the virtual or physical register number of
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/// the source reg along with the FrameIndex of the loaded stack slot. If
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/// not, return 0. This predicate must return 0 if the instruction has
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/// any side effects other than storing to the stack slot.
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virtual unsigned isStoreToStackSlot(const MachineInstr *MI,
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int &FrameIndex) const {
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return 0;
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}
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/// reMaterialize - Re-issue the specified 'original' instruction at the
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/// specific location targeting a new destination register.
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virtual void reMaterialize(MachineBasicBlock &MBB,
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MachineBasicBlock::iterator MI,
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unsigned DestReg, unsigned SubIdx,
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const MachineInstr *Orig) const = 0;
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/// convertToThreeAddress - This method must be implemented by targets that
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/// set the M_CONVERTIBLE_TO_3_ADDR flag. When this flag is set, the target
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/// may be able to convert a two-address instruction into one or more true
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/// three-address instructions on demand. This allows the X86 target (for
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/// example) to convert ADD and SHL instructions into LEA instructions if they
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/// would require register copies due to two-addressness.
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///
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/// This method returns a null pointer if the transformation cannot be
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/// performed, otherwise it returns the last new instruction.
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///
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virtual MachineInstr *
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convertToThreeAddress(MachineFunction::iterator &MFI,
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MachineBasicBlock::iterator &MBBI, LiveVariables *LV) const {
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return 0;
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}
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/// commuteInstruction - If a target has any instructions that are commutable,
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/// but require converting to a different instruction or making non-trivial
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/// changes to commute them, this method can overloaded to do this. The
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/// default implementation of this method simply swaps the first two operands
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/// of MI and returns it.
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///
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/// If a target wants to make more aggressive changes, they can construct and
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/// return a new machine instruction. If an instruction cannot commute, it
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/// can also return null.
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///
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/// If NewMI is true, then a new machine instruction must be created.
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///
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virtual MachineInstr *commuteInstruction(MachineInstr *MI,
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bool NewMI = false) const = 0;
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/// findCommutedOpIndices - If specified MI is commutable, return the two
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/// operand indices that would swap value. Return true if the instruction
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/// is not in a form which this routine understands.
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virtual bool findCommutedOpIndices(MachineInstr *MI, unsigned &SrcOpIdx1,
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unsigned &SrcOpIdx2) const = 0;
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/// AnalyzeBranch - Analyze the branching code at the end of MBB, returning
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/// true if it cannot be understood (e.g. it's a switch dispatch or isn't
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/// implemented for a target). Upon success, this returns false and returns
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/// with the following information in various cases:
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///
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/// 1. If this block ends with no branches (it just falls through to its succ)
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/// just return false, leaving TBB/FBB null.
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/// 2. If this block ends with only an unconditional branch, it sets TBB to be
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/// the destination block.
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/// 3. If this block ends with an conditional branch and it falls through to
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/// a successor block, it sets TBB to be the branch destination block and
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/// a list of operands that evaluate the condition. These
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/// operands can be passed to other TargetInstrInfo methods to create new
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/// branches.
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/// 4. If this block ends with a conditional branch followed by an
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/// unconditional branch, it returns the 'true' destination in TBB, the
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/// 'false' destination in FBB, and a list of operands that evaluate the
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/// condition. These operands can be passed to other TargetInstrInfo
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/// methods to create new branches.
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///
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/// Note that RemoveBranch and InsertBranch must be implemented to support
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/// cases where this method returns success.
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///
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/// If AllowModify is true, then this routine is allowed to modify the basic
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/// block (e.g. delete instructions after the unconditional branch).
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///
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virtual bool AnalyzeBranch(MachineBasicBlock &MBB, MachineBasicBlock *&TBB,
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MachineBasicBlock *&FBB,
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SmallVectorImpl<MachineOperand> &Cond,
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bool AllowModify = false) const {
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return true;
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}
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/// RemoveBranch - Remove the branching code at the end of the specific MBB.
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/// This is only invoked in cases where AnalyzeBranch returns success. It
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/// returns the number of instructions that were removed.
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virtual unsigned RemoveBranch(MachineBasicBlock &MBB) const {
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assert(0 && "Target didn't implement TargetInstrInfo::RemoveBranch!");
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return 0;
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}
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/// InsertBranch - Insert branch code into the end of the specified
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/// MachineBasicBlock. The operands to this method are the same as those
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/// returned by AnalyzeBranch. This is only invoked in cases where
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/// AnalyzeBranch returns success. It returns the number of instructions
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/// inserted.
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///
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/// It is also invoked by tail merging to add unconditional branches in
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/// cases where AnalyzeBranch doesn't apply because there was no original
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/// branch to analyze. At least this much must be implemented, else tail
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/// merging needs to be disabled.
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virtual unsigned InsertBranch(MachineBasicBlock &MBB, MachineBasicBlock *TBB,
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MachineBasicBlock *FBB,
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const SmallVectorImpl<MachineOperand> &Cond) const {
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assert(0 && "Target didn't implement TargetInstrInfo::InsertBranch!");
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return 0;
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}
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/// copyRegToReg - Emit instructions to copy between a pair of registers. It
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/// returns false if the target does not how to copy between the specified
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/// registers.
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virtual bool copyRegToReg(MachineBasicBlock &MBB,
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MachineBasicBlock::iterator MI,
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unsigned DestReg, unsigned SrcReg,
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const TargetRegisterClass *DestRC,
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const TargetRegisterClass *SrcRC) const {
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assert(0 && "Target didn't implement TargetInstrInfo::copyRegToReg!");
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return false;
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}
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/// storeRegToStackSlot - Store the specified register of the given register
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/// class to the specified stack frame index. The store instruction is to be
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/// added to the given machine basic block before the specified machine
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/// instruction. If isKill is true, the register operand is the last use and
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/// must be marked kill.
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virtual void storeRegToStackSlot(MachineBasicBlock &MBB,
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MachineBasicBlock::iterator MI,
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unsigned SrcReg, bool isKill, int FrameIndex,
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const TargetRegisterClass *RC) const {
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assert(0 && "Target didn't implement TargetInstrInfo::storeRegToStackSlot!");
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}
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/// loadRegFromStackSlot - Load the specified register of the given register
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/// class from the specified stack frame index. The load instruction is to be
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/// added to the given machine basic block before the specified machine
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/// instruction.
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virtual void loadRegFromStackSlot(MachineBasicBlock &MBB,
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MachineBasicBlock::iterator MI,
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unsigned DestReg, int FrameIndex,
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const TargetRegisterClass *RC) const {
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assert(0 && "Target didn't implement TargetInstrInfo::loadRegFromStackSlot!");
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}
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/// spillCalleeSavedRegisters - Issues instruction(s) to spill all callee
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/// saved registers and returns true if it isn't possible / profitable to do
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/// so by issuing a series of store instructions via
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/// storeRegToStackSlot(). Returns false otherwise.
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virtual bool spillCalleeSavedRegisters(MachineBasicBlock &MBB,
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MachineBasicBlock::iterator MI,
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const std::vector<CalleeSavedInfo> &CSI) const {
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return false;
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}
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/// restoreCalleeSavedRegisters - Issues instruction(s) to restore all callee
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/// saved registers and returns true if it isn't possible / profitable to do
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/// so by issuing a series of load instructions via loadRegToStackSlot().
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/// Returns false otherwise.
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virtual bool restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
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MachineBasicBlock::iterator MI,
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const std::vector<CalleeSavedInfo> &CSI) const {
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return false;
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}
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/// foldMemoryOperand - Attempt to fold a load or store of the specified stack
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/// slot into the specified machine instruction for the specified operand(s).
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/// If this is possible, a new instruction is returned with the specified
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/// operand folded, otherwise NULL is returned. The client is responsible for
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/// removing the old instruction and adding the new one in the instruction
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/// stream.
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MachineInstr* foldMemoryOperand(MachineFunction &MF,
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MachineInstr* MI,
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const SmallVectorImpl<unsigned> &Ops,
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int FrameIndex) const;
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/// foldMemoryOperand - Same as the previous version except it allows folding
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/// of any load and store from / to any address, not just from a specific
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/// stack slot.
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MachineInstr* foldMemoryOperand(MachineFunction &MF,
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MachineInstr* MI,
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const SmallVectorImpl<unsigned> &Ops,
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MachineInstr* LoadMI) const;
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protected:
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/// foldMemoryOperandImpl - Target-dependent implementation for
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/// foldMemoryOperand. Target-independent code in foldMemoryOperand will
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/// take care of adding a MachineMemOperand to the newly created instruction.
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virtual MachineInstr* foldMemoryOperandImpl(MachineFunction &MF,
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MachineInstr* MI,
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const SmallVectorImpl<unsigned> &Ops,
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int FrameIndex) const {
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return 0;
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}
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/// foldMemoryOperandImpl - Target-dependent implementation for
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/// foldMemoryOperand. Target-independent code in foldMemoryOperand will
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/// take care of adding a MachineMemOperand to the newly created instruction.
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virtual MachineInstr* foldMemoryOperandImpl(MachineFunction &MF,
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MachineInstr* MI,
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const SmallVectorImpl<unsigned> &Ops,
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MachineInstr* LoadMI) const {
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return 0;
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}
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public:
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/// canFoldMemoryOperand - Returns true for the specified load / store if
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/// folding is possible.
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virtual
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bool canFoldMemoryOperand(const MachineInstr *MI,
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const SmallVectorImpl<unsigned> &Ops) const {
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return false;
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}
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/// unfoldMemoryOperand - Separate a single instruction which folded a load or
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/// a store or a load and a store into two or more instruction. If this is
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/// possible, returns true as well as the new instructions by reference.
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virtual bool unfoldMemoryOperand(MachineFunction &MF, MachineInstr *MI,
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unsigned Reg, bool UnfoldLoad, bool UnfoldStore,
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SmallVectorImpl<MachineInstr*> &NewMIs) const{
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return false;
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}
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virtual bool unfoldMemoryOperand(SelectionDAG &DAG, SDNode *N,
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SmallVectorImpl<SDNode*> &NewNodes) const {
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return false;
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}
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/// getOpcodeAfterMemoryUnfold - Returns the opcode of the would be new
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/// instruction after load / store are unfolded from an instruction of the
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/// specified opcode. It returns zero if the specified unfolding is not
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/// possible.
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virtual unsigned getOpcodeAfterMemoryUnfold(unsigned Opc,
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bool UnfoldLoad, bool UnfoldStore) const {
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return 0;
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}
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/// BlockHasNoFallThrough - Return true if the specified block does not
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/// fall-through into its successor block. This is primarily used when a
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/// branch is unanalyzable. It is useful for things like unconditional
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/// indirect branches (jump tables).
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virtual bool BlockHasNoFallThrough(const MachineBasicBlock &MBB) const {
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return false;
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}
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/// ReverseBranchCondition - Reverses the branch condition of the specified
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/// condition list, returning false on success and true if it cannot be
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/// reversed.
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virtual
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bool ReverseBranchCondition(SmallVectorImpl<MachineOperand> &Cond) const {
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return true;
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}
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/// insertNoop - Insert a noop into the instruction stream at the specified
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/// point.
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virtual void insertNoop(MachineBasicBlock &MBB,
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MachineBasicBlock::iterator MI) const;
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/// isPredicated - Returns true if the instruction is already predicated.
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///
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virtual bool isPredicated(const MachineInstr *MI) const {
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return false;
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}
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/// isUnpredicatedTerminator - Returns true if the instruction is a
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/// terminator instruction that has not been predicated.
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virtual bool isUnpredicatedTerminator(const MachineInstr *MI) const;
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/// PredicateInstruction - Convert the instruction into a predicated
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/// instruction. It returns true if the operation was successful.
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virtual
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bool PredicateInstruction(MachineInstr *MI,
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const SmallVectorImpl<MachineOperand> &Pred) const = 0;
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/// SubsumesPredicate - Returns true if the first specified predicate
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/// subsumes the second, e.g. GE subsumes GT.
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virtual
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bool SubsumesPredicate(const SmallVectorImpl<MachineOperand> &Pred1,
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const SmallVectorImpl<MachineOperand> &Pred2) const {
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return false;
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}
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/// DefinesPredicate - If the specified instruction defines any predicate
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/// or condition code register(s) used for predication, returns true as well
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/// as the definition predicate(s) by reference.
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virtual bool DefinesPredicate(MachineInstr *MI,
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std::vector<MachineOperand> &Pred) const {
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return false;
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}
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/// isSafeToMoveRegClassDefs - Return true if it's safe to move a machine
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/// instruction that defines the specified register class.
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virtual bool isSafeToMoveRegClassDefs(const TargetRegisterClass *RC) const {
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return true;
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}
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/// GetInstSize - Returns the size of the specified Instruction.
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///
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virtual unsigned GetInstSizeInBytes(const MachineInstr *MI) const {
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assert(0 && "Target didn't implement TargetInstrInfo::GetInstSize!");
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return 0;
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}
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/// GetFunctionSizeInBytes - Returns the size of the specified
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/// MachineFunction.
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///
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virtual unsigned GetFunctionSizeInBytes(const MachineFunction &MF) const = 0;
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/// Measure the specified inline asm to determine an approximation of its
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/// length.
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virtual unsigned getInlineAsmLength(const char *Str,
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const MCAsmInfo &MAI) const;
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};
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/// TargetInstrInfoImpl - This is the default implementation of
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/// TargetInstrInfo, which just provides a couple of default implementations
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/// for various methods. This separated out because it is implemented in
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/// libcodegen, not in libtarget.
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class TargetInstrInfoImpl : public TargetInstrInfo {
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protected:
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TargetInstrInfoImpl(const TargetInstrDesc *desc, unsigned NumOpcodes)
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: TargetInstrInfo(desc, NumOpcodes) {}
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public:
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virtual MachineInstr *commuteInstruction(MachineInstr *MI,
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bool NewMI = false) const;
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virtual bool findCommutedOpIndices(MachineInstr *MI, unsigned &SrcOpIdx1,
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unsigned &SrcOpIdx2) const;
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virtual bool PredicateInstruction(MachineInstr *MI,
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const SmallVectorImpl<MachineOperand> &Pred) const;
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virtual void reMaterialize(MachineBasicBlock &MBB,
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MachineBasicBlock::iterator MI,
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unsigned DestReg, unsigned SubReg,
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const MachineInstr *Orig) const;
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virtual unsigned GetFunctionSizeInBytes(const MachineFunction &MF) const;
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};
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} // End llvm namespace
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#endif
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