cm.pop
Destroy function call stack frame
This instruction is defined by:
-
anyOf:
-
Zcmp, version >= 0
-
This instruction is included in the following profiles:
Synopsis
Destroy stack frame: load ra and 0 to 12 saved registers from the stack frame, deallocate the stack frame.
This instruction pops (loads) the registers in reg_list from stack memory, and then adjusts the stack pointer by stack_adj.
Restrictions on stack_adj:
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it must be enough to store all of the listed registers
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it must be a multiple of 16 (bytes):
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for RV32 the allowed values are: 16, 32, 48, 64, 80, 96, 112
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for RV64 the allowed values are: 16, 32, 48, 64, 80, 96, 112, 128, 144, 160
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Execution
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IDL
if (implemented?(ExtensionName::Zcmp) && (CSR[misa].C == 1'b0)) {
raise(ExceptionCode::IllegalInstruction, mode(), $encoding);
}
XReg size = xlen();
XReg nreg = (rlist == 15) ? 13 : (rlist - 3);
XReg stack_aligned_adj = (nreg * 4 + 15) & ~0xF;
XReg virtual_address_sp = X[2];
XReg virtual_address_new_sp = virtual_address_sp + stack_aligned_adj + spimm;
XReg virtual_address_base = virtual_address_new_sp - (nreg * size);
X[1] = read_memory_xlen(virtual_address_base + 0 * size, $encoding);
if (nreg > 1) {
X[8] = read_memory_xlen(virtual_address_base + 1 * size, $encoding);
}
if (nreg > 2) {
X[9] = read_memory_xlen(virtual_address_base + 2 * size, $encoding);
}
if (nreg > 3) {
X[18] = read_memory_xlen(virtual_address_base + 3 * size, $encoding);
}
if (nreg > 4) {
X[19] = read_memory_xlen(virtual_address_base + 4 * size, $encoding);
}
if (nreg > 5) {
X[20] = read_memory_xlen(virtual_address_base + 5 * size, $encoding);
}
if (nreg > 6) {
X[21] = read_memory_xlen(virtual_address_base + 6 * size, $encoding);
}
if (nreg > 7) {
X[22] = read_memory_xlen(virtual_address_base + 7 * size, $encoding);
}
if (nreg > 8) {
X[23] = read_memory_xlen(virtual_address_base + 8 * size, $encoding);
}
if (nreg > 9) {
X[24] = read_memory_xlen(virtual_address_base + 9 * size, $encoding);
}
if (nreg > 10) {
X[25] = read_memory_xlen(virtual_address_base + 10 * size, $encoding);
}
if (nreg > 11) {
X[26] = read_memory_xlen(virtual_address_base + 11 * size, $encoding);
X[27] = read_memory_xlen(virtual_address_base + 12 * size, $encoding);
}
X[2] = virtual_address_new_sp;