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booth: Rewrite the main cell selection loop

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This commit is contained in:
Martin Povišer 2023-09-19 16:25:10 +02:00
parent 986507f95f
commit 30f8387b75
1 changed files with 77 additions and 93 deletions
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170
passes/techmap/booth.cc
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@ -225,108 +225,92 @@ struct BoothPassWorker {
void run()
{
for (auto cell : module->selected_cells()) {
if (cell->type.in(ID($mul))) {
RTLIL::SigSpec A = sigmap(cell->getPort(ID::A));
RTLIL::SigSpec B = sigmap(cell->getPort(ID::B));
RTLIL::SigSpec Y = sigmap(cell->getPort(ID::Y));
if (GetSize(A) >= 4 && GetSize(B) >= 4 && GetSize(Y) >= 8 &&
((cell->getParam(ID::A_SIGNED).as_bool() && cell->getParam(ID::B_SIGNED).as_bool()) ||
(!cell->getParam(ID::A_SIGNED).as_bool() && !cell->getParam(ID::B_SIGNED).as_bool()))) {
bool is_signed = false;
if (cell->getParam(ID::A_SIGNED).as_bool()) {
log(" By passing macc inferencing for signed multiplier -- generating booth\n");
is_signed = true;
} else
log(" By passing macc inferencing for unsigned multiplier -- generating booth\n");
if (cell->type != ID($mul))
continue;
int x_sz = GetSize(A);
int y_sz = GetSize(B);
int z_sz = GetSize(Y);
SigSpec A = cell->getPort(ID::A);
SigSpec B = cell->getPort(ID::B);
SigSpec Y = cell->getPort(ID::Y);
int x_sz = GetSize(A), y_sz = GetSize(B), z_sz = GetSize(Y);
// To simplify the generator size the arguments
// to be the same. Then allow logic synthesis to
// clean things up. Size to biggest
if (x_sz < 4 || y_sz < 4 || z_sz < 8) {
log_debug("Not mapping cell %s sized at %dx%x, %x: size below threshold\n",
log_id(cell), x_sz, y_sz, z_sz);
continue;
}
int x_sz_revised = x_sz;
int y_sz_revised = y_sz;
log_assert(cell->getParam(ID::A_SIGNED).as_bool() == cell->getParam(ID::B_SIGNED).as_bool());
bool is_signed = cell->getParam(ID::A_SIGNED).as_bool();
if (x_sz != y_sz) {
if (x_sz < y_sz) {
if (y_sz % 2 != 0) {
x_sz_revised = y_sz + 1;
y_sz_revised = y_sz + 1;
} else
x_sz_revised = y_sz;
log("Mapping cell %s to %s Booth multiplier\n", log_id(cell), is_signed ? "signed" : "unsigned");
} else {
if (x_sz % 2 != 0) {
y_sz_revised = x_sz + 1;
x_sz_revised = x_sz + 1;
} else
y_sz_revised = x_sz;
}
// To simplify the generator size the arguments
// to be the same. Then allow logic synthesis to
// clean things up. Size to biggest
int x_sz_revised = x_sz;
int y_sz_revised = y_sz;
if (x_sz != y_sz) {
if (x_sz < y_sz) {
if (y_sz % 2 != 0) {
x_sz_revised = y_sz + 1;
y_sz_revised = y_sz + 1;
} else {
if (x_sz % 2 != 0) {
y_sz_revised = y_sz + 1;
x_sz_revised = x_sz + 1;
}
x_sz_revised = y_sz;
}
} else {
if (x_sz % 2 != 0) {
y_sz_revised = x_sz + 1;
x_sz_revised = x_sz + 1;
} else {
y_sz_revised = x_sz;
}
log_assert((x_sz_revised == y_sz_revised) && (x_sz_revised % 2 == 0) && (y_sz_revised % 2 == 0));
Wire *expanded_A = module->addWire(NEW_ID, x_sz_revised);
Wire *expanded_B = module->addWire(NEW_ID, y_sz_revised);
std::string buf_name = "expand_a_buf_";
auto buf = module->addCell(new_id(buf_name, __LINE__, ""), ID($pos));
buf->setParam(ID::A_WIDTH, x_sz);
buf->setParam(ID::Y_WIDTH, x_sz_revised);
buf->setPort(ID::A, SigSpec(A));
buf->setParam(ID::A_SIGNED, is_signed ? true : false);
buf->setPort(ID::Y, SigSpec(expanded_A));
buf_name = "expand_b_buf_";
buf = module->addCell(new_id(buf_name, __LINE__, ""), ID($pos));
buf->setPort(ID::A, SigSpec(B));
buf->setParam(ID::A_WIDTH, y_sz);
buf->setParam(ID::Y_WIDTH, y_sz_revised);
buf->setParam(ID::A_SIGNED, is_signed ? true : false);
buf->setPort(ID::Y, SigSpec(expanded_B));
// Make sure output domain is big enough to take
// all combinations.
// Later logic synthesis will kill unused
// portions of the output domain.
unsigned required_op_size = x_sz_revised + y_sz_revised;
Wire *expanded_Y = module->addWire(NEW_ID, required_op_size);
// now connect the expanded_Y with a tap to fill out sig Spec Y
buf_name = "reducer_buf_";
buf = module->addCell(new_id(buf_name, __LINE__, ""), ID($pos));
buf->setPort(ID::A, expanded_Y);
buf->setParam(ID::A_WIDTH, required_op_size);
buf->setParam(ID::Y_WIDTH, z_sz); // The real user width
buf->setParam(ID::A_SIGNED, is_signed ? true : false);
// wire in output Y
buf->setPort(ID::Y, SigSpec(Y));
if (is_signed == false) /* unsigned multiplier */
CreateBoothUMult(module,
expanded_A, // multiplicand
expanded_B, // multiplier(scanned)
expanded_Y // result
);
else /*signed multiplier */
CreateBoothSMult(module,
expanded_A, // multiplicand
expanded_B, // multiplier(scanned)
expanded_Y // result (sized)
);
module->remove(cell);
booth_counter++;
continue;
}
} else {
if (x_sz % 2 != 0) {
y_sz_revised = y_sz + 1;
x_sz_revised = x_sz + 1;
}
}
log_assert((x_sz_revised == y_sz_revised) && (x_sz_revised % 2 == 0) && (y_sz_revised % 2 == 0));
A.extend_u0(x_sz_revised, is_signed);
B.extend_u0(y_sz_revised, is_signed);
// Make sure output domain is big enough to take
// all combinations.
// Later logic synthesis will kill unused
// portions of the output domain.
int required_op_size = x_sz_revised + y_sz_revised;
if (required_op_size != z_sz) {
SigSpec expanded_Y = module->addWire(NEW_ID, required_op_size);
SigSpec Y_driver = expanded_Y;
Y_driver.extend_u0(Y.size(), is_signed);
module->connect(Y, Y_driver);
Y = expanded_Y;
}
log_assert(GetSize(Y) == required_op_size);
if (!is_signed) /* unsigned multiplier */
CreateBoothUMult(module,
A, // multiplicand
B, // multiplier(scanned)
Y // result
);
else /* signed multiplier */
CreateBoothSMult(module,
A, // multiplicand
B, // multiplier(scanned)
Y // result (sized)
);
module->remove(cell);
booth_counter++;
}
}