+bool X86FastISel::X86SelectDivRem(const Instruction *I) {
+ const static unsigned NumTypes = 4; // i8, i16, i32, i64
+ const static unsigned NumOps = 4; // SDiv, SRem, UDiv, URem
+ const static bool S = true; // IsSigned
+ const static bool U = false; // !IsSigned
+ const static unsigned Copy = TargetOpcode::COPY;
+ // For the X86 DIV/IDIV instruction, in most cases the dividend
+ // (numerator) must be in a specific register pair highreg:lowreg,
+ // producing the quotient in lowreg and the remainder in highreg.
+ // For most data types, to set up the instruction, the dividend is
+ // copied into lowreg, and lowreg is sign-extended or zero-extended
+ // into highreg. The exception is i8, where the dividend is defined
+ // as a single register rather than a register pair, and we
+ // therefore directly sign-extend or zero-extend the dividend into
+ // lowreg, instead of copying, and ignore the highreg.
+ const static struct DivRemEntry {
+ // The following portion depends only on the data type.
+ const TargetRegisterClass *RC;
+ unsigned LowInReg; // low part of the register pair
+ unsigned HighInReg; // high part of the register pair
+ // The following portion depends on both the data type and the operation.
+ struct DivRemResult {
+ unsigned OpDivRem; // The specific DIV/IDIV opcode to use.
+ unsigned OpSignExtend; // Opcode for sign-extending lowreg into
+ // highreg, or copying a zero into highreg.
+ unsigned OpCopy; // Opcode for copying dividend into lowreg, or
+ // zero/sign-extending into lowreg for i8.
+ unsigned DivRemResultReg; // Register containing the desired result.
+ bool IsOpSigned; // Whether to use signed or unsigned form.
+ } ResultTable[NumOps];
+ } OpTable[NumTypes] = {
+ { &X86::GR8RegClass, X86::AX, 0, {
+ { X86::IDIV8r, 0, X86::MOVSX16rr8, X86::AL, S }, // SDiv
+ { X86::IDIV8r, 0, X86::MOVSX16rr8, X86::AH, S }, // SRem
+ { X86::DIV8r, 0, X86::MOVZX16rr8, X86::AL, U }, // UDiv
+ { X86::DIV8r, 0, X86::MOVZX16rr8, X86::AH, U }, // URem
+ }
+ }, // i8
+ { &X86::GR16RegClass, X86::AX, X86::DX, {
+ { X86::IDIV16r, X86::CWD, Copy, X86::AX, S }, // SDiv
+ { X86::IDIV16r, X86::CWD, Copy, X86::DX, S }, // SRem
+ { X86::DIV16r, X86::MOV32r0, Copy, X86::AX, U }, // UDiv
+ { X86::DIV16r, X86::MOV32r0, Copy, X86::DX, U }, // URem
+ }
+ }, // i16
+ { &X86::GR32RegClass, X86::EAX, X86::EDX, {
+ { X86::IDIV32r, X86::CDQ, Copy, X86::EAX, S }, // SDiv
+ { X86::IDIV32r, X86::CDQ, Copy, X86::EDX, S }, // SRem
+ { X86::DIV32r, X86::MOV32r0, Copy, X86::EAX, U }, // UDiv
+ { X86::DIV32r, X86::MOV32r0, Copy, X86::EDX, U }, // URem
+ }
+ }, // i32
+ { &X86::GR64RegClass, X86::RAX, X86::RDX, {
+ { X86::IDIV64r, X86::CQO, Copy, X86::RAX, S }, // SDiv
+ { X86::IDIV64r, X86::CQO, Copy, X86::RDX, S }, // SRem
+ { X86::DIV64r, X86::MOV32r0, Copy, X86::RAX, U }, // UDiv
+ { X86::DIV64r, X86::MOV32r0, Copy, X86::RDX, U }, // URem
+ }
+ }, // i64
+ };
+
+ MVT VT;
+ if (!isTypeLegal(I->getType(), VT))
+ return false;
+
+ unsigned TypeIndex, OpIndex;
+ switch (VT.SimpleTy) {
+ default: return false;
+ case MVT::i8: TypeIndex = 0; break;
+ case MVT::i16: TypeIndex = 1; break;
+ case MVT::i32: TypeIndex = 2; break;
+ case MVT::i64: TypeIndex = 3;
+ if (!Subtarget->is64Bit())
+ return false;
+ break;
+ }
+
+ switch (I->getOpcode()) {
+ default: llvm_unreachable("Unexpected div/rem opcode");
+ case Instruction::SDiv: OpIndex = 0; break;
+ case Instruction::SRem: OpIndex = 1; break;
+ case Instruction::UDiv: OpIndex = 2; break;
+ case Instruction::URem: OpIndex = 3; break;
+ }
+
+ const DivRemEntry &TypeEntry = OpTable[TypeIndex];
+ const DivRemEntry::DivRemResult &OpEntry = TypeEntry.ResultTable[OpIndex];
+ unsigned Op0Reg = getRegForValue(I->getOperand(0));
+ if (Op0Reg == 0)
+ return false;
+ unsigned Op1Reg = getRegForValue(I->getOperand(1));
+ if (Op1Reg == 0)
+ return false;
+
+ // Move op0 into low-order input register.
+ BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL,
+ TII.get(OpEntry.OpCopy), TypeEntry.LowInReg).addReg(Op0Reg);
+ // Zero-extend or sign-extend into high-order input register.
+ if (OpEntry.OpSignExtend) {
+ if (OpEntry.IsOpSigned)
+ BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL,
+ TII.get(OpEntry.OpSignExtend));
+ else {
+ unsigned Zero32 = createResultReg(&X86::GR32RegClass);
+ BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL,
+ TII.get(X86::MOV32r0), Zero32);
+
+ // Copy the zero into the appropriate sub/super/identical physical
+ // register. Unfortunately the operations needed are not uniform enough to
+ // fit neatly into the table above.
+ if (VT.SimpleTy == MVT::i16) {
+ BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL,
+ TII.get(Copy), TypeEntry.HighInReg)
+ .addReg(Zero32, 0, X86::sub_16bit);
+ } else if (VT.SimpleTy == MVT::i32) {
+ BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL,
+ TII.get(Copy), TypeEntry.HighInReg)
+ .addReg(Zero32);
+ } else if (VT.SimpleTy == MVT::i64) {
+ BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL,
+ TII.get(TargetOpcode::SUBREG_TO_REG), TypeEntry.HighInReg)
+ .addImm(0).addReg(Zero32).addImm(X86::sub_32bit);
+ }
+ }
+ }
+ // Generate the DIV/IDIV instruction.
+ BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL,
+ TII.get(OpEntry.OpDivRem)).addReg(Op1Reg);
+ // For i8 remainder, we can't reference AH directly, as we'll end
+ // up with bogus copies like %R9B = COPY %AH. Reference AX
+ // instead to prevent AH references in a REX instruction.
+ //
+ // The current assumption of the fast register allocator is that isel
+ // won't generate explicit references to the GPR8_NOREX registers. If
+ // the allocator and/or the backend get enhanced to be more robust in
+ // that regard, this can be, and should be, removed.
+ unsigned ResultReg = 0;
+ if ((I->getOpcode() == Instruction::SRem ||
+ I->getOpcode() == Instruction::URem) &&
+ OpEntry.DivRemResultReg == X86::AH && Subtarget->is64Bit()) {
+ unsigned SourceSuperReg = createResultReg(&X86::GR16RegClass);
+ unsigned ResultSuperReg = createResultReg(&X86::GR16RegClass);
+ BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL,
+ TII.get(Copy), SourceSuperReg).addReg(X86::AX);
+
+ // Shift AX right by 8 bits instead of using AH.
+ BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, TII.get(X86::SHR16ri),
+ ResultSuperReg).addReg(SourceSuperReg).addImm(8);
+
+ // Now reference the 8-bit subreg of the result.
+ ResultReg = FastEmitInst_extractsubreg(MVT::i8, ResultSuperReg,
+ /*Kill=*/true, X86::sub_8bit);
+ }
+ // Copy the result out of the physreg if we haven't already.
+ if (!ResultReg) {
+ ResultReg = createResultReg(TypeEntry.RC);
+ BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, TII.get(Copy), ResultReg)
+ .addReg(OpEntry.DivRemResultReg);
+ }
+ UpdateValueMap(I, ResultReg);
+
+ return true;
+}
+