flw

Single-precision floating-point load

This instruction is defined by:

Encoding

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Synopsis

The flw instruction loads a single-precision floating-point value from memory at address rs1 + imm into floating-point register fd.

flw does not modify the bits being transferred; in particular, the payloads of non-canonical NaNs are preserved.

Access

M

HS

U

VS

VU

Always

Always

Always

Always

Always

Decode Variables

Bits<12> imm = $encoding[31:20];
Bits<5> rs1 = $encoding[19:15];
Bits<5> fd = $encoding[11:7];

Execution

  • Pruned, XLEN == 64

  • Original

check_f_ok($encoding);
XReg virtual_address = X[rs1] + $signed(imm);
Bits<32> sp_value = read_memory<32>(virtual_address, $encoding);
f[fd] = nan_box<32, 64>(sp_value);
mark_f_state_dirty();
check_f_ok($encoding);
XReg virtual_address = X[rs1] + $signed(imm);
Bits<32> sp_value = read_memory<32>(virtual_address, $encoding);
if (implemented?(ExtensionName::D)) {
  f[fd] = nan_box<32, 64>(sp_value);
} else {
  f[fd] = sp_value;
}
mark_f_state_dirty();

Exceptions

This instruction may result in the following synchronous exceptions:

  • IllegalInstruction

  • LoadAccessFault

  • LoadPageFault