| //===- X86InstrInfo.cpp - X86 Instruction Information -----------*- C++ -*-===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file was developed by the LLVM research group and is distributed under |
| // the University of Illinois Open Source License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file contains the X86 implementation of the TargetInstrInfo class. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "X86InstrInfo.h" |
| #include "X86.h" |
| #include "X86GenInstrInfo.inc" |
| #include "X86InstrBuilder.h" |
| #include "X86Subtarget.h" |
| #include "X86TargetMachine.h" |
| #include "llvm/ADT/STLExtras.h" |
| #include "llvm/CodeGen/MachineInstrBuilder.h" |
| #include "llvm/CodeGen/LiveVariables.h" |
| #include "llvm/CodeGen/SSARegMap.h" |
| #include "llvm/Target/TargetOptions.h" |
| #include "llvm/Support/CommandLine.h" |
| using namespace llvm; |
| |
| namespace { |
| cl::opt<bool> |
| EnableConvert3Addr("enable-x86-conv-3-addr", |
| cl::desc("Enable convertToThreeAddress for X86")); |
| } |
| |
| X86InstrInfo::X86InstrInfo(X86TargetMachine &tm) |
| : TargetInstrInfo(X86Insts, array_lengthof(X86Insts)), |
| TM(tm), RI(tm, *this) { |
| } |
| |
| bool X86InstrInfo::isMoveInstr(const MachineInstr& MI, |
| unsigned& sourceReg, |
| unsigned& destReg) const { |
| MachineOpCode oc = MI.getOpcode(); |
| if (oc == X86::MOV8rr || oc == X86::MOV16rr || |
| oc == X86::MOV32rr || oc == X86::MOV64rr || |
| oc == X86::MOV16to16_ || oc == X86::MOV32to32_ || |
| oc == X86::MOV_Fp3232 || oc == X86::MOVSSrr || oc == X86::MOVSDrr || |
| oc == X86::MOV_Fp3264 || oc == X86::MOV_Fp6432 || oc == X86::MOV_Fp6464 || |
| oc == X86::FsMOVAPSrr || oc == X86::FsMOVAPDrr || |
| oc == X86::MOVAPSrr || oc == X86::MOVAPDrr || |
| oc == X86::MOVSS2PSrr || oc == X86::MOVSD2PDrr || |
| oc == X86::MOVPS2SSrr || oc == X86::MOVPD2SDrr || |
| oc == X86::MMX_MOVD64rr || oc == X86::MMX_MOVQ64rr) { |
| assert(MI.getNumOperands() >= 2 && |
| MI.getOperand(0).isRegister() && |
| MI.getOperand(1).isRegister() && |
| "invalid register-register move instruction"); |
| sourceReg = MI.getOperand(1).getReg(); |
| destReg = MI.getOperand(0).getReg(); |
| return true; |
| } |
| return false; |
| } |
| |
| unsigned X86InstrInfo::isLoadFromStackSlot(MachineInstr *MI, |
| int &FrameIndex) const { |
| switch (MI->getOpcode()) { |
| default: break; |
| case X86::MOV8rm: |
| case X86::MOV16rm: |
| case X86::MOV16_rm: |
| case X86::MOV32rm: |
| case X86::MOV32_rm: |
| case X86::MOV64rm: |
| case X86::LD_Fp64m: |
| case X86::MOVSSrm: |
| case X86::MOVSDrm: |
| case X86::MOVAPSrm: |
| case X86::MOVAPDrm: |
| case X86::MMX_MOVD64rm: |
| case X86::MMX_MOVQ64rm: |
| if (MI->getOperand(1).isFrameIndex() && MI->getOperand(2).isImmediate() && |
| MI->getOperand(3).isRegister() && MI->getOperand(4).isImmediate() && |
| MI->getOperand(2).getImmedValue() == 1 && |
| MI->getOperand(3).getReg() == 0 && |
| MI->getOperand(4).getImmedValue() == 0) { |
| FrameIndex = MI->getOperand(1).getFrameIndex(); |
| return MI->getOperand(0).getReg(); |
| } |
| break; |
| } |
| return 0; |
| } |
| |
| unsigned X86InstrInfo::isStoreToStackSlot(MachineInstr *MI, |
| int &FrameIndex) const { |
| switch (MI->getOpcode()) { |
| default: break; |
| case X86::MOV8mr: |
| case X86::MOV16mr: |
| case X86::MOV16_mr: |
| case X86::MOV32mr: |
| case X86::MOV32_mr: |
| case X86::MOV64mr: |
| case X86::ST_FpP64m: |
| case X86::MOVSSmr: |
| case X86::MOVSDmr: |
| case X86::MOVAPSmr: |
| case X86::MOVAPDmr: |
| case X86::MMX_MOVD64mr: |
| case X86::MMX_MOVQ64mr: |
| case X86::MMX_MOVNTQmr: |
| if (MI->getOperand(0).isFrameIndex() && MI->getOperand(1).isImmediate() && |
| MI->getOperand(2).isRegister() && MI->getOperand(3).isImmediate() && |
| MI->getOperand(1).getImmedValue() == 1 && |
| MI->getOperand(2).getReg() == 0 && |
| MI->getOperand(3).getImmedValue() == 0) { |
| FrameIndex = MI->getOperand(0).getFrameIndex(); |
| return MI->getOperand(4).getReg(); |
| } |
| break; |
| } |
| return 0; |
| } |
| |
| |
| bool X86InstrInfo::isReallyTriviallyReMaterializable(MachineInstr *MI) const { |
| switch (MI->getOpcode()) { |
| default: break; |
| case X86::MOV8rm: |
| case X86::MOV16rm: |
| case X86::MOV16_rm: |
| case X86::MOV32rm: |
| case X86::MOV32_rm: |
| case X86::MOV64rm: |
| case X86::LD_Fp64m: |
| case X86::MOVSSrm: |
| case X86::MOVSDrm: |
| case X86::MOVAPSrm: |
| case X86::MOVAPDrm: |
| case X86::MMX_MOVD64rm: |
| case X86::MMX_MOVQ64rm: |
| // Loads from constant pools are trivially rematerializable. |
| return MI->getOperand(1).isRegister() && MI->getOperand(2).isImmediate() && |
| MI->getOperand(3).isRegister() && MI->getOperand(4).isConstantPoolIndex() && |
| MI->getOperand(1).getReg() == 0 && |
| MI->getOperand(2).getImmedValue() == 1 && |
| MI->getOperand(3).getReg() == 0; |
| } |
| // All other instructions marked M_REMATERIALIZABLE are always trivially |
| // rematerializable. |
| return true; |
| } |
| |
| /// hasLiveCondCodeDef - True if MI has a condition code def, e.g. EFLAGS, that |
| /// is not marked dead. |
| static bool hasLiveCondCodeDef(MachineInstr *MI) { |
| if (!EnableConvert3Addr) |
| return true; |
| for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) { |
| MachineOperand &MO = MI->getOperand(i); |
| if (MO.isRegister() && MO.isDef() && |
| MO.getReg() == X86::EFLAGS && !MO.isDead()) { |
| return true; |
| } |
| } |
| return false; |
| } |
| |
| /// convertToThreeAddress - This method must be implemented by targets that |
| /// set the M_CONVERTIBLE_TO_3_ADDR flag. When this flag is set, the target |
| /// may be able to convert a two-address instruction into a true |
| /// three-address instruction on demand. This allows the X86 target (for |
| /// example) to convert ADD and SHL instructions into LEA instructions if they |
| /// would require register copies due to two-addressness. |
| /// |
| /// This method returns a null pointer if the transformation cannot be |
| /// performed, otherwise it returns the new instruction. |
| /// |
| MachineInstr * |
| X86InstrInfo::convertToThreeAddress(MachineFunction::iterator &MFI, |
| MachineBasicBlock::iterator &MBBI, |
| LiveVariables &LV) const { |
| MachineInstr *MI = MBBI; |
| // All instructions input are two-addr instructions. Get the known operands. |
| unsigned Dest = MI->getOperand(0).getReg(); |
| unsigned Src = MI->getOperand(1).getReg(); |
| |
| MachineInstr *NewMI = NULL; |
| // FIXME: 16-bit LEA's are really slow on Athlons, but not bad on P4's. When |
| // we have better subtarget support, enable the 16-bit LEA generation here. |
| bool DisableLEA16 = true; |
| |
| unsigned MIOpc = MI->getOpcode(); |
| switch (MIOpc) { |
| case X86::SHUFPSrri: { |
| assert(MI->getNumOperands() == 4 && "Unknown shufps instruction!"); |
| if (!TM.getSubtarget<X86Subtarget>().hasSSE2()) return 0; |
| |
| unsigned A = MI->getOperand(0).getReg(); |
| unsigned B = MI->getOperand(1).getReg(); |
| unsigned C = MI->getOperand(2).getReg(); |
| unsigned M = MI->getOperand(3).getImm(); |
| if (B != C) return 0; |
| NewMI = BuildMI(get(X86::PSHUFDri), A).addReg(B).addImm(M); |
| break; |
| } |
| case X86::SHL64ri: { |
| assert(MI->getNumOperands() >= 3 && "Unknown shift instruction!"); |
| // NOTE: LEA doesn't produce flags like shift does, but LLVM never uses |
| // the flags produced by a shift yet, so this is safe. |
| unsigned Dest = MI->getOperand(0).getReg(); |
| unsigned Src = MI->getOperand(1).getReg(); |
| unsigned ShAmt = MI->getOperand(2).getImm(); |
| if (ShAmt == 0 || ShAmt >= 4) return 0; |
| |
| NewMI = BuildMI(get(X86::LEA64r), Dest) |
| .addReg(0).addImm(1 << ShAmt).addReg(Src).addImm(0); |
| break; |
| } |
| case X86::SHL32ri: { |
| assert(MI->getNumOperands() >= 3 && "Unknown shift instruction!"); |
| // NOTE: LEA doesn't produce flags like shift does, but LLVM never uses |
| // the flags produced by a shift yet, so this is safe. |
| unsigned Dest = MI->getOperand(0).getReg(); |
| unsigned Src = MI->getOperand(1).getReg(); |
| unsigned ShAmt = MI->getOperand(2).getImm(); |
| if (ShAmt == 0 || ShAmt >= 4) return 0; |
| |
| unsigned Opc = TM.getSubtarget<X86Subtarget>().is64Bit() ? |
| X86::LEA64_32r : X86::LEA32r; |
| NewMI = BuildMI(get(Opc), Dest) |
| .addReg(0).addImm(1 << ShAmt).addReg(Src).addImm(0); |
| break; |
| } |
| case X86::SHL16ri: { |
| assert(MI->getNumOperands() >= 3 && "Unknown shift instruction!"); |
| // NOTE: LEA doesn't produce flags like shift does, but LLVM never uses |
| // the flags produced by a shift yet, so this is safe. |
| unsigned Dest = MI->getOperand(0).getReg(); |
| unsigned Src = MI->getOperand(1).getReg(); |
| unsigned ShAmt = MI->getOperand(2).getImm(); |
| if (ShAmt == 0 || ShAmt >= 4) return 0; |
| |
| if (DisableLEA16) { |
| // If 16-bit LEA is disabled, use 32-bit LEA via subregisters. |
| SSARegMap *RegMap = MFI->getParent()->getSSARegMap(); |
| unsigned Opc = TM.getSubtarget<X86Subtarget>().is64Bit() |
| ? X86::LEA64_32r : X86::LEA32r; |
| unsigned leaInReg = RegMap->createVirtualRegister(&X86::GR32RegClass); |
| unsigned leaOutReg = RegMap->createVirtualRegister(&X86::GR32RegClass); |
| |
| MachineInstr *Ins = |
| BuildMI(get(X86::INSERT_SUBREG), leaInReg).addReg(Src).addImm(2); |
| Ins->copyKillDeadInfo(MI); |
| |
| NewMI = BuildMI(get(Opc), leaOutReg) |
| .addReg(0).addImm(1 << ShAmt).addReg(leaInReg).addImm(0); |
| |
| MachineInstr *Ext = |
| BuildMI(get(X86::EXTRACT_SUBREG), Dest).addReg(leaOutReg).addImm(2); |
| Ext->copyKillDeadInfo(MI); |
| |
| MFI->insert(MBBI, Ins); // Insert the insert_subreg |
| LV.instructionChanged(MI, NewMI); // Update live variables |
| LV.addVirtualRegisterKilled(leaInReg, NewMI); |
| MFI->insert(MBBI, NewMI); // Insert the new inst |
| LV.addVirtualRegisterKilled(leaOutReg, Ext); |
| MFI->insert(MBBI, Ext); // Insert the extract_subreg |
| return Ext; |
| } else { |
| NewMI = BuildMI(get(X86::LEA16r), Dest) |
| .addReg(0).addImm(1 << ShAmt).addReg(Src).addImm(0); |
| } |
| break; |
| } |
| default: { |
| // The following opcodes also sets the condition code register(s). Only |
| // convert them to equivalent lea if the condition code register def's |
| // are dead! |
| if (hasLiveCondCodeDef(MI)) |
| return 0; |
| |
| switch (MIOpc) { |
| default: return 0; |
| case X86::INC64r: |
| case X86::INC32r: { |
| assert(MI->getNumOperands() >= 2 && "Unknown inc instruction!"); |
| unsigned Opc = MIOpc == X86::INC64r ? X86::LEA64r : X86::LEA32r; |
| NewMI = addRegOffset(BuildMI(get(Opc), Dest), Src, 1); |
| break; |
| } |
| case X86::INC16r: |
| case X86::INC64_16r: |
| if (DisableLEA16) return 0; |
| assert(MI->getNumOperands() >= 2 && "Unknown inc instruction!"); |
| NewMI = addRegOffset(BuildMI(get(X86::LEA16r), Dest), Src, 1); |
| break; |
| case X86::DEC64r: |
| case X86::DEC32r: { |
| assert(MI->getNumOperands() >= 2 && "Unknown dec instruction!"); |
| unsigned Opc = MIOpc == X86::DEC64r ? X86::LEA64r : X86::LEA32r; |
| NewMI = addRegOffset(BuildMI(get(Opc), Dest), Src, -1); |
| break; |
| } |
| case X86::DEC16r: |
| case X86::DEC64_16r: |
| if (DisableLEA16) return 0; |
| assert(MI->getNumOperands() >= 2 && "Unknown dec instruction!"); |
| NewMI = addRegOffset(BuildMI(get(X86::LEA16r), Dest), Src, -1); |
| break; |
| case X86::ADD64rr: |
| case X86::ADD32rr: { |
| assert(MI->getNumOperands() >= 3 && "Unknown add instruction!"); |
| unsigned Opc = MIOpc == X86::ADD64rr ? X86::LEA64r : X86::LEA32r; |
| NewMI = addRegReg(BuildMI(get(Opc), Dest), Src, |
| MI->getOperand(2).getReg()); |
| break; |
| } |
| case X86::ADD16rr: |
| if (DisableLEA16) return 0; |
| assert(MI->getNumOperands() >= 3 && "Unknown add instruction!"); |
| NewMI = addRegReg(BuildMI(get(X86::LEA16r), Dest), Src, |
| MI->getOperand(2).getReg()); |
| break; |
| case X86::ADD64ri32: |
| case X86::ADD64ri8: |
| assert(MI->getNumOperands() >= 3 && "Unknown add instruction!"); |
| if (MI->getOperand(2).isImmediate()) |
| NewMI = addRegOffset(BuildMI(get(X86::LEA64r), Dest), Src, |
| MI->getOperand(2).getImmedValue()); |
| break; |
| case X86::ADD32ri: |
| case X86::ADD32ri8: |
| assert(MI->getNumOperands() >= 3 && "Unknown add instruction!"); |
| if (MI->getOperand(2).isImmediate()) |
| NewMI = addRegOffset(BuildMI(get(X86::LEA32r), Dest), Src, |
| MI->getOperand(2).getImmedValue()); |
| break; |
| case X86::ADD16ri: |
| case X86::ADD16ri8: |
| if (DisableLEA16) return 0; |
| assert(MI->getNumOperands() >= 3 && "Unknown add instruction!"); |
| if (MI->getOperand(2).isImmediate()) |
| NewMI = addRegOffset(BuildMI(get(X86::LEA16r), Dest), Src, |
| MI->getOperand(2).getImmedValue()); |
| break; |
| case X86::SHL16ri: |
| if (DisableLEA16) return 0; |
| case X86::SHL32ri: |
| case X86::SHL64ri: { |
| assert(MI->getNumOperands() >= 3 && MI->getOperand(2).isImmediate() && |
| "Unknown shl instruction!"); |
| unsigned ShAmt = MI->getOperand(2).getImmedValue(); |
| if (ShAmt == 1 || ShAmt == 2 || ShAmt == 3) { |
| X86AddressMode AM; |
| AM.Scale = 1 << ShAmt; |
| AM.IndexReg = Src; |
| unsigned Opc = MIOpc == X86::SHL64ri ? X86::LEA64r |
| : (MIOpc == X86::SHL32ri ? X86::LEA32r : X86::LEA16r); |
| NewMI = addFullAddress(BuildMI(get(Opc), Dest), AM); |
| } |
| break; |
| } |
| } |
| } |
| } |
| |
| NewMI->copyKillDeadInfo(MI); |
| LV.instructionChanged(MI, NewMI); // Update live variables |
| MFI->insert(MBBI, NewMI); // Insert the new inst |
| return NewMI; |
| } |
| |
| /// commuteInstruction - We have a few instructions that must be hacked on to |
| /// commute them. |
| /// |
| MachineInstr *X86InstrInfo::commuteInstruction(MachineInstr *MI) const { |
| // FIXME: Can commute cmoves by changing the condition! |
| switch (MI->getOpcode()) { |
| case X86::SHRD16rri8: // A = SHRD16rri8 B, C, I -> A = SHLD16rri8 C, B, (16-I) |
| case X86::SHLD16rri8: // A = SHLD16rri8 B, C, I -> A = SHRD16rri8 C, B, (16-I) |
| case X86::SHRD32rri8: // A = SHRD32rri8 B, C, I -> A = SHLD32rri8 C, B, (32-I) |
| case X86::SHLD32rri8: // A = SHLD32rri8 B, C, I -> A = SHRD32rri8 C, B, (32-I) |
| case X86::SHRD64rri8: // A = SHRD64rri8 B, C, I -> A = SHLD64rri8 C, B, (64-I) |
| case X86::SHLD64rri8:{// A = SHLD64rri8 B, C, I -> A = SHRD64rri8 C, B, (64-I) |
| unsigned Opc; |
| unsigned Size; |
| switch (MI->getOpcode()) { |
| default: assert(0 && "Unreachable!"); |
| case X86::SHRD16rri8: Size = 16; Opc = X86::SHLD16rri8; break; |
| case X86::SHLD16rri8: Size = 16; Opc = X86::SHRD16rri8; break; |
| case X86::SHRD32rri8: Size = 32; Opc = X86::SHLD32rri8; break; |
| case X86::SHLD32rri8: Size = 32; Opc = X86::SHRD32rri8; break; |
| case X86::SHRD64rri8: Size = 64; Opc = X86::SHLD64rri8; break; |
| case X86::SHLD64rri8: Size = 64; Opc = X86::SHRD64rri8; break; |
| } |
| unsigned Amt = MI->getOperand(3).getImmedValue(); |
| unsigned A = MI->getOperand(0).getReg(); |
| unsigned B = MI->getOperand(1).getReg(); |
| unsigned C = MI->getOperand(2).getReg(); |
| bool BisKill = MI->getOperand(1).isKill(); |
| bool CisKill = MI->getOperand(2).isKill(); |
| return BuildMI(get(Opc), A).addReg(C, false, false, CisKill) |
| .addReg(B, false, false, BisKill).addImm(Size-Amt); |
| } |
| default: |
| return TargetInstrInfo::commuteInstruction(MI); |
| } |
| } |
| |
| static X86::CondCode GetCondFromBranchOpc(unsigned BrOpc) { |
| switch (BrOpc) { |
| default: return X86::COND_INVALID; |
| case X86::JE: return X86::COND_E; |
| case X86::JNE: return X86::COND_NE; |
| case X86::JL: return X86::COND_L; |
| case X86::JLE: return X86::COND_LE; |
| case X86::JG: return X86::COND_G; |
| case X86::JGE: return X86::COND_GE; |
| case X86::JB: return X86::COND_B; |
| case X86::JBE: return X86::COND_BE; |
| case X86::JA: return X86::COND_A; |
| case X86::JAE: return X86::COND_AE; |
| case X86::JS: return X86::COND_S; |
| case X86::JNS: return X86::COND_NS; |
| case X86::JP: return X86::COND_P; |
| case X86::JNP: return X86::COND_NP; |
| case X86::JO: return X86::COND_O; |
| case X86::JNO: return X86::COND_NO; |
| } |
| } |
| |
| unsigned X86::GetCondBranchFromCond(X86::CondCode CC) { |
| switch (CC) { |
| default: assert(0 && "Illegal condition code!"); |
| case X86::COND_E: return X86::JE; |
| case X86::COND_NE: return X86::JNE; |
| case X86::COND_L: return X86::JL; |
| case X86::COND_LE: return X86::JLE; |
| case X86::COND_G: return X86::JG; |
| case X86::COND_GE: return X86::JGE; |
| case X86::COND_B: return X86::JB; |
| case X86::COND_BE: return X86::JBE; |
| case X86::COND_A: return X86::JA; |
| case X86::COND_AE: return X86::JAE; |
| case X86::COND_S: return X86::JS; |
| case X86::COND_NS: return X86::JNS; |
| case X86::COND_P: return X86::JP; |
| case X86::COND_NP: return X86::JNP; |
| case X86::COND_O: return X86::JO; |
| case X86::COND_NO: return X86::JNO; |
| } |
| } |
| |
| /// GetOppositeBranchCondition - Return the inverse of the specified condition, |
| /// e.g. turning COND_E to COND_NE. |
| X86::CondCode X86::GetOppositeBranchCondition(X86::CondCode CC) { |
| switch (CC) { |
| default: assert(0 && "Illegal condition code!"); |
| case X86::COND_E: return X86::COND_NE; |
| case X86::COND_NE: return X86::COND_E; |
| case X86::COND_L: return X86::COND_GE; |
| case X86::COND_LE: return X86::COND_G; |
| case X86::COND_G: return X86::COND_LE; |
| case X86::COND_GE: return X86::COND_L; |
| case X86::COND_B: return X86::COND_AE; |
| case X86::COND_BE: return X86::COND_A; |
| case X86::COND_A: return X86::COND_BE; |
| case X86::COND_AE: return X86::COND_B; |
| case X86::COND_S: return X86::COND_NS; |
| case X86::COND_NS: return X86::COND_S; |
| case X86::COND_P: return X86::COND_NP; |
| case X86::COND_NP: return X86::COND_P; |
| case X86::COND_O: return X86::COND_NO; |
| case X86::COND_NO: return X86::COND_O; |
| } |
| } |
| |
| bool X86InstrInfo::isUnpredicatedTerminator(const MachineInstr *MI) const { |
| const TargetInstrDescriptor *TID = MI->getInstrDescriptor(); |
| if (TID->Flags & M_TERMINATOR_FLAG) { |
| // Conditional branch is a special case. |
| if ((TID->Flags & M_BRANCH_FLAG) != 0 && (TID->Flags & M_BARRIER_FLAG) == 0) |
| return true; |
| if ((TID->Flags & M_PREDICABLE) == 0) |
| return true; |
| return !isPredicated(MI); |
| } |
| return false; |
| } |
| |
| // For purposes of branch analysis do not count FP_REG_KILL as a terminator. |
| static bool isBrAnalysisUnpredicatedTerminator(const MachineInstr *MI, |
| const X86InstrInfo &TII) { |
| if (MI->getOpcode() == X86::FP_REG_KILL) |
| return false; |
| return TII.isUnpredicatedTerminator(MI); |
| } |
| |
| bool X86InstrInfo::AnalyzeBranch(MachineBasicBlock &MBB, |
| MachineBasicBlock *&TBB, |
| MachineBasicBlock *&FBB, |
| std::vector<MachineOperand> &Cond) const { |
| // If the block has no terminators, it just falls into the block after it. |
| MachineBasicBlock::iterator I = MBB.end(); |
| if (I == MBB.begin() || !isBrAnalysisUnpredicatedTerminator(--I, *this)) |
| return false; |
| |
| // Get the last instruction in the block. |
| MachineInstr *LastInst = I; |
| |
| // If there is only one terminator instruction, process it. |
| if (I == MBB.begin() || !isBrAnalysisUnpredicatedTerminator(--I, *this)) { |
| if (!isBranch(LastInst->getOpcode())) |
| return true; |
| |
| // If the block ends with a branch there are 3 possibilities: |
| // it's an unconditional, conditional, or indirect branch. |
| |
| if (LastInst->getOpcode() == X86::JMP) { |
| TBB = LastInst->getOperand(0).getMachineBasicBlock(); |
| return false; |
| } |
| X86::CondCode BranchCode = GetCondFromBranchOpc(LastInst->getOpcode()); |
| if (BranchCode == X86::COND_INVALID) |
| return true; // Can't handle indirect branch. |
| |
| // Otherwise, block ends with fall-through condbranch. |
| TBB = LastInst->getOperand(0).getMachineBasicBlock(); |
| Cond.push_back(MachineOperand::CreateImm(BranchCode)); |
| return false; |
| } |
| |
| // Get the instruction before it if it's a terminator. |
| MachineInstr *SecondLastInst = I; |
| |
| // If there are three terminators, we don't know what sort of block this is. |
| if (SecondLastInst && I != MBB.begin() && |
| isBrAnalysisUnpredicatedTerminator(--I, *this)) |
| return true; |
| |
| // If the block ends with X86::JMP and a conditional branch, handle it. |
| X86::CondCode BranchCode = GetCondFromBranchOpc(SecondLastInst->getOpcode()); |
| if (BranchCode != X86::COND_INVALID && LastInst->getOpcode() == X86::JMP) { |
| TBB = SecondLastInst->getOperand(0).getMachineBasicBlock(); |
| Cond.push_back(MachineOperand::CreateImm(BranchCode)); |
| FBB = LastInst->getOperand(0).getMachineBasicBlock(); |
| return false; |
| } |
| |
| // If the block ends with two X86::JMPs, handle it. The second one is not |
| // executed, so remove it. |
| if (SecondLastInst->getOpcode() == X86::JMP && |
| LastInst->getOpcode() == X86::JMP) { |
| TBB = SecondLastInst->getOperand(0).getMachineBasicBlock(); |
| I = LastInst; |
| I->eraseFromParent(); |
| return false; |
| } |
| |
| // Otherwise, can't handle this. |
| return true; |
| } |
| |
| unsigned X86InstrInfo::RemoveBranch(MachineBasicBlock &MBB) const { |
| MachineBasicBlock::iterator I = MBB.end(); |
| if (I == MBB.begin()) return 0; |
| --I; |
| if (I->getOpcode() != X86::JMP && |
| GetCondFromBranchOpc(I->getOpcode()) == X86::COND_INVALID) |
| return 0; |
| |
| // Remove the branch. |
| I->eraseFromParent(); |
| |
| I = MBB.end(); |
| |
| if (I == MBB.begin()) return 1; |
| --I; |
| if (GetCondFromBranchOpc(I->getOpcode()) == X86::COND_INVALID) |
| return 1; |
| |
| // Remove the branch. |
| I->eraseFromParent(); |
| return 2; |
| } |
| |
| unsigned |
| X86InstrInfo::InsertBranch(MachineBasicBlock &MBB, MachineBasicBlock *TBB, |
| MachineBasicBlock *FBB, |
| const std::vector<MachineOperand> &Cond) const { |
| // Shouldn't be a fall through. |
| assert(TBB && "InsertBranch must not be told to insert a fallthrough"); |
| assert((Cond.size() == 1 || Cond.size() == 0) && |
| "X86 branch conditions have one component!"); |
| |
| if (FBB == 0) { // One way branch. |
| if (Cond.empty()) { |
| // Unconditional branch? |
| BuildMI(&MBB, get(X86::JMP)).addMBB(TBB); |
| } else { |
| // Conditional branch. |
| unsigned Opc = GetCondBranchFromCond((X86::CondCode)Cond[0].getImm()); |
| BuildMI(&MBB, get(Opc)).addMBB(TBB); |
| } |
| return 1; |
| } |
| |
| // Two-way Conditional branch. |
| unsigned Opc = GetCondBranchFromCond((X86::CondCode)Cond[0].getImm()); |
| BuildMI(&MBB, get(Opc)).addMBB(TBB); |
| BuildMI(&MBB, get(X86::JMP)).addMBB(FBB); |
| return 2; |
| } |
| |
| bool X86InstrInfo::BlockHasNoFallThrough(MachineBasicBlock &MBB) const { |
| if (MBB.empty()) return false; |
| |
| switch (MBB.back().getOpcode()) { |
| case X86::RET: // Return. |
| case X86::RETI: |
| case X86::TAILJMPd: |
| case X86::TAILJMPr: |
| case X86::TAILJMPm: |
| case X86::JMP: // Uncond branch. |
| case X86::JMP32r: // Indirect branch. |
| case X86::JMP64r: // Indirect branch (64-bit). |
| case X86::JMP32m: // Indirect branch through mem. |
| case X86::JMP64m: // Indirect branch through mem (64-bit). |
| return true; |
| default: return false; |
| } |
| } |
| |
| bool X86InstrInfo:: |
| ReverseBranchCondition(std::vector<MachineOperand> &Cond) const { |
| assert(Cond.size() == 1 && "Invalid X86 branch condition!"); |
| Cond[0].setImm(GetOppositeBranchCondition((X86::CondCode)Cond[0].getImm())); |
| return false; |
| } |
| |
| const TargetRegisterClass *X86InstrInfo::getPointerRegClass() const { |
| const X86Subtarget *Subtarget = &TM.getSubtarget<X86Subtarget>(); |
| if (Subtarget->is64Bit()) |
| return &X86::GR64RegClass; |
| else |
| return &X86::GR32RegClass; |
| } |