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

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

Exceptions

This instruction may result in the following synchronous exceptions:

  • IllegalInstruction

  • LoadAccessFault

  • LoadPageFault