c.ldsp

Load doubleword from stack pointer

This instruction is defined by:

Encoding

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Synopsis

C.LDSP is an RV64C/RV128C-only instruction that loads a 64-bit value from memory into register rd. It computes its effective address by adding the zero-extended offset, scaled by 8, to the stack pointer, x2. It expands to ld rd, offset(x2). C.LDSP is only valid when rd ≠ x0 the code points with rd=x0 are reserved.

Access

M

HS

U

VS

VU

Always

Always

Always

Always

Always

Decode Variables

Bits<9> imm = {$encoding[4:2], $encoding[12], $encoding[6:5], 3'd0};
Bits<5> rd = $encoding[11:7];

Execution

  • Pruned, XLEN == 64

  • Original

XReg virtual_address = X[2] + imm;
X[rd] = read_memory<64>(virtual_address, $encoding);
if (implemented?(ExtensionName::C) && (CSR[misa].C == 1'b0)) {
  raise(ExceptionCode::IllegalInstruction, mode(), $encoding);
}
XReg virtual_address = X[2] + imm;
X[rd] = read_memory<64>(virtual_address, $encoding);

Exceptions

This instruction may result in the following synchronous exceptions:

  • LoadAccessFault

  • LoadPageFault