mirrors/yosys
3
0
Fork 0
mirror of https://github.com/YosysHQ/yosys synced 2025-10-31 11:42:30 +00:00
Code Activity

Do not use b.as_int() in calculation of bit set

Browse source
This commit is contained in:
C-Elegans 2017-01-21 12:58:26 -05:00
parent 84f9cd0025
commit 2fa0fd4a37
1 changed files with 29 additions and 8 deletions
Download patch file Download diff file Expand all files Collapse all files

37
passes/opt/opt_expr.cc
View file

@ -258,7 +258,27 @@ bool is_one_or_minus_one(const Const &value, bool is_signed, bool &is_negative)
return last_bit_one;
}
int get_onehot_bit_index(RTLIL::SigSpec signal){
if(!signal.is_fully_const())
return -1;
bool bit_set = false;
int bit_index = 0;
int i = 0;
for(auto bit: signal.bits()){
if(bit == RTLIL::State::S1){
if(bit_set)
return -1;
bit_index = i;
bit_set = true;
}
i++;
}
if(bit_set){
return bit_index;
}else{
return -1;
}
}
void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bool consume_x, bool mux_undef, bool mux_bool, bool do_fine, bool keepdc, bool clkinv)
{
if (!design->selected(module))
@ -1190,9 +1210,9 @@ void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bool cons
did_something = true;
goto next_cell;
}
else if(b.is_fully_const() && b.is_fully_def() && cell->parameters["\\A_SIGNED"].as_bool() == false){
int b_value = b.as_int(false);
if(b_value == 0){
else if(b.is_fully_const() && b.is_fully_def() && cell->parameters["\\A_SIGNED"].as_bool() == false){
int b_bit_set = get_onehot_bit_index(b);
if(b.is_fully_zero()){
RTLIL::SigSpec a_prime(RTLIL::State::S0,1);
if(is_lt){
log("replacing a(unsigned) < 0 with constant false\n");
@ -1207,18 +1227,19 @@ void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bool cons
did_something = true;
goto next_cell;
}
else if((b_value & -b_value) == b_value){ //if b has only 1 bit set
int bit_set = ceil_log2(b_value);
else if(b_bit_set >= 0){ //if b has only 1 bit set
int bit_set = b_bit_set;
RTLIL::SigSpec a_prime(RTLIL::State::S0,a_width-bit_set);
for(int i = bit_set; i < a_width; i++){
a_prime[i-bit_set] = a[i];
}
if(is_lt){
log("replacing a < %d with !a[%d:%d]\n",b_value,a_width-1,bit_set);
log("replacing a < %d with !a[%d:%d]\n",b.as_int(false),a_width-1,bit_set);
module->addLogicNot("$logic_not", a_prime,cell->getPort("\\Y"));
}
else{
log("replacing a >= %d with |a[%d:%d]\n",b_value,a_width-1,bit_set);
log("replacing a >= %d with |a[%d:%d]\n",b.as_int(false),a_width-1,bit_set);
module->addReduceOr("$reduce_or", a_prime,cell->getPort("\\Y"));
}
module->remove(cell);