llvm/lib/Target/RISCV/RISCVInstrInfoM.td

//===-- RISCVInstrInfoM.td - RISC-V 'M' instructions -------*- tablegen -*-===//
//
// 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 file describes the RISC-V instructions from the standard 'M', Integer
// Multiplication and Division instruction set extension.
//
//===----------------------------------------------------------------------===//

//===----------------------------------------------------------------------===//
// RISC-V specific DAG Nodes.
//===----------------------------------------------------------------------===//

def riscv_mulhsu : SDNode<"RISCVISD::MULHSU", SDTIntBinOp>;
def riscv_divw  : SDNode<"RISCVISD::DIVW",  SDT_RISCVIntBinOpW>;
def riscv_divuw : SDNode<"RISCVISD::DIVUW", SDT_RISCVIntBinOpW>;
def riscv_remuw : SDNode<"RISCVISD::REMUW", SDT_RISCVIntBinOpW>;

//===----------------------------------------------------------------------===//
// Instructions
//===----------------------------------------------------------------------===//

let Predicates = [HasStdExtM] in {
def MUL     : ALU_rr<0b0000001, 0b000, "mul">,
              Sched<[WriteIMul, ReadIMul, ReadIMul]>;
def MULH    : ALU_rr<0b0000001, 0b001, "mulh">,
              Sched<[WriteIMul, ReadIMul, ReadIMul]>;
def MULHSU  : ALU_rr<0b0000001, 0b010, "mulhsu">,
              Sched<[WriteIMul, ReadIMul, ReadIMul]>;
def MULHU   : ALU_rr<0b0000001, 0b011, "mulhu">,
              Sched<[WriteIMul, ReadIMul, ReadIMul]>;
def DIV     : ALU_rr<0b0000001, 0b100, "div">,
              Sched<[WriteIDiv, ReadIDiv, ReadIDiv]>;
def DIVU    : ALU_rr<0b0000001, 0b101, "divu">,
              Sched<[WriteIDiv, ReadIDiv, ReadIDiv]>;
def REM     : ALU_rr<0b0000001, 0b110, "rem">,
              Sched<[WriteIDiv, ReadIDiv, ReadIDiv]>;
def REMU    : ALU_rr<0b0000001, 0b111, "remu">,
              Sched<[WriteIDiv, ReadIDiv, ReadIDiv]>;
} // Predicates = [HasStdExtM]

let Predicates = [HasStdExtM, IsRV64] in {
def MULW    : ALUW_rr<0b0000001, 0b000, "mulw">,
              Sched<[WriteIMul32, ReadIMul32, ReadIMul32]>;
def DIVW    : ALUW_rr<0b0000001, 0b100, "divw">,
              Sched<[WriteIDiv32, ReadIDiv32, ReadIDiv32]>;
def DIVUW   : ALUW_rr<0b0000001, 0b101, "divuw">,
              Sched<[WriteIDiv32, ReadIDiv32, ReadIDiv32]>;
def REMW    : ALUW_rr<0b0000001, 0b110, "remw">,
              Sched<[WriteIDiv32, ReadIDiv32, ReadIDiv32]>;
def REMUW   : ALUW_rr<0b0000001, 0b111, "remuw">,
              Sched<[WriteIDiv32, ReadIDiv32, ReadIDiv32]>;
} // Predicates = [HasStdExtM, IsRV64]

//===----------------------------------------------------------------------===//
// Pseudo-instructions and codegen patterns
//===----------------------------------------------------------------------===//

let Predicates = [HasStdExtM] in {
def : PatGprGpr<mul, MUL>;
def : PatGprGpr<mulhs, MULH>;
def : PatGprGpr<mulhu, MULHU>;
def : PatGprGpr<riscv_mulhsu, MULHSU>;
def : PatGprGpr<sdiv, DIV>;
def : PatGprGpr<udiv, DIVU>;
def : PatGprGpr<srem, REM>;
def : PatGprGpr<urem, REMU>;
} // Predicates = [HasStdExtM]

let Predicates = [HasStdExtM, IsRV64] in {
// Select W instructions if only the lower 32-bits of the result are used.
def : PatGprGpr<binop_allwusers<mul>, MULW>;

def : PatGprGpr<riscv_divw, DIVW>;
def : PatGprGpr<riscv_divuw, DIVUW>;
def : PatGprGpr<riscv_remuw, REMUW>;

// Handle the specific cases where using DIVU/REMU would be correct and result
// in fewer instructions than emitting DIVUW/REMUW then zero-extending the
// result.
def : Pat<(and (riscv_divuw (assertzexti32 GPR:$rs1),
                            (assertzexti32 GPR:$rs2)), 0xffffffff),
          (DIVU GPR:$rs1, GPR:$rs2)>;
def : Pat<(and (riscv_remuw (assertzexti32 GPR:$rs1),
                            (assertzexti32 GPR:$rs2)), 0xffffffff),
          (REMU GPR:$rs1, GPR:$rs2)>;

// Although the sexti32 operands may not have originated from an i32 srem,
// this pattern is safe as it is impossible for two sign extended inputs to
// produce a result where res[63:32]=0 and res[31]=1.
def : Pat<(srem (sexti32 (i64 GPR:$rs1)), (sexti32 (i64 GPR:$rs2))),
          (REMW GPR:$rs1, GPR:$rs2)>;
} // Predicates = [HasStdExtM, IsRV64]

// Pattern to detect constants with no more than 32 active bits that can't
// be materialized with lui+addiw.
def uimm32_not_simm32 : PatLeaf<(XLenVT GPR:$a), [{
  auto *C = dyn_cast<ConstantSDNode>(N);
  return C && C->hasOneUse() && isUInt<32>(C->getZExtValue()) &&
         !isInt<32>(C->getSExtValue());
}]>;

let Predicates = [HasStdExtM, IsRV64, NotHasStdExtZba] in {
// Special case for calculating the full 64-bit product of a 32x32 unsigned
// multiply where the inputs aren't known to be zero extended. We can shift the
// inputs left by 32 and use a MULHU. This saves two SRLIs needed to finish
// zeroing the upper 32 bits.
def : Pat<(i64 (mul (and GPR:$rs1, 0xffffffff), (and GPR:$rs2, 0xffffffff))),
          (MULHU (SLLI GPR:$rs1, 32), (SLLI GPR:$rs2, 32))>;
// The RHS could also be a constant that is hard to materialize. By shifting
// left we can allow constant materialization to use LUI+ADDIW via
// hasAllWUsers.
def : Pat<(i64 (mul (and GPR:$rs1, 0xffffffff), uimm32_not_simm32:$rs2)),
          (MULHU (SLLI GPR:$rs1, 32), (SLLI GPR:$rs2, 32))>;
} // Predicates = [HasStdExtM, IsRV64, NotHasStdExtZba]