sh3add

Shift left by 3 and add

This instruction is defined by:

  • anyOf:

    • B, version >= 0

    • Zba, version >= 0

This instruction is included in the following profiles:

  • RVA22S64 (Mandatory)

  • RVA22U64 (Mandatory)

Encoding

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Assembly format

sh3add rd, rs1, rs2

Synopsis

This instruction shifts rs1 to the left by 3 places and adds it to rs2.

Access

M HS U VS VU

Always

Always

Always

Always

Always

Decode Variables

Bits<5> rs2 = $encoding[24:20];
Bits<5> rs1 = $encoding[19:15];
Bits<5> rd = $encoding[11:7];

Execution

  • IDL

  • Sail

if (implemented?(ExtensionName::B) && (CSR[misa].B == 1'b0)) {
  raise(ExceptionCode::IllegalInstruction, mode(), $encoding);
}
X[rd] = X[rs2] + (X[rs1] << 3);
{
  let rs1_val = X(rs1);
  let rs2_val = X(rs2);
  let shamt : bits(2) = match op {
    RISCV_SH1ADD => 0b01,
    RISCV_SH2ADD => 0b10,
    RISCV_SH3ADD => 0b11
  };
  let result : xlenbits = (rs1_val << shamt) + rs2_val;
  X(rd) = result;
  RETIRE_SUCCESS
}

Exceptions

This instruction may result in the following synchronous exceptions:

  • IllegalInstruction