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fix handling right shifts

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This commit is contained in:
N. Engelhardt 2023-10-02 18:32:53 +02:00
parent 2d6d6a8da1
commit 6c562c76bc
2 changed files with 53 additions and 12 deletions
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61
kernel/celledges.cc
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@ -174,26 +174,67 @@ void demux_op(AbstractCellEdgesDatabase *db, RTLIL::Cell *cell)
void shift_op(AbstractCellEdgesDatabase *db, RTLIL::Cell *cell)
{
bool is_signed = cell->getParam(ID::A_SIGNED).as_bool();
int a_width = GetSize(cell->getPort(ID::A));
int b_width = GetSize(cell->getPort(ID::B));
int y_width = GetSize(cell->getPort(ID::Y));
for (int i = 0; i < y_width; i++){
for (int k = 0; k < b_width; k++)
db->add_edge(cell, ID::B, k, ID::Y, i, -1);
// how far the maximum value of B is able to shift
int b_range = (1<<b_width) - 1;
// highest position of Y that can change with the value of B
int b_range_upper;
// 1 + highest position of A that can be moved to Y[i]
int a_range_upper;
// lowest position of A that can be moved to Y[i]
int a_range_lower;
for (int i = 0; i < y_width; i++){
if (cell->type.in(ID($shl), ID($sshl))) {
for (int k = min(i, a_width); k >= 0; k--)
db->add_edge(cell, ID::A, k, ID::Y, i, -1);
// << and <<<
b_range_upper = a_width + b_range;
if (is_signed) b_range_upper -= 1;
a_range_lower = max(0, i - b_range);
a_range_upper = min(i+1, a_width);
} else if (cell->type.in(ID($shr), ID($sshr))){
// >> and >>>
b_range_upper = a_width;
a_range_lower = min(i, a_width - 1); // technically the min is unneccessary as b_range_upper check already skips any i >= a_width, but let's leave the logic in since this is hard enough
a_range_upper = min(i+1 + b_range, a_width);
} else if (cell->type.in(ID($shift), ID($shiftx))) {
// can go both ways depending on sign of B
// 2's complement range is different depending on direction
int b_range_left = (1<<(b_width - 1));
int b_range_right = (1<<(b_width - 1)) - 1;
b_range_upper = a_width + b_range_left;
a_range_lower = max(0, i - b_range_left);
a_range_upper = min(i+1 + b_range_right, a_width);
}
if (cell->type.in(ID($shr), ID($sshr)))
for (int k = i; k < a_width; k++)
if (i < b_range_upper) {
for (int k = a_range_lower; k < a_range_upper; k++)
db->add_edge(cell, ID::A, k, ID::Y, i, -1);
} else {
// the only possible influence value is sign extension
if (is_signed)
db->add_edge(cell, ID::A, a_width - 1, ID::Y, i, -1);
}
for (int k = 0; k < b_width; k++) {
if (cell->type.in(ID($shl), ID($sshl)) && a_width == 1 && is_signed) {
int skip = (1<<(k+1));
int base = skip -1;
if (i % skip != base)
db->add_edge(cell, ID::B, k, ID::Y, i, -1);
} else if (cell->type.in(ID($shr), ID($sshr)) && is_signed) {
int skip = (1<<(k+1));
int base = 0;
if (i % skip != base || i < a_width - 1)
db->add_edge(cell, ID::B, k, ID::Y, i, -1);
} else {
db->add_edge(cell, ID::B, k, ID::Y, i, -1);
}
}
if (cell->type.in(ID($shift), ID($shiftx)))
for (int k = 0; k < a_width; k++)
db->add_edge(cell, ID::A, k, ID::Y, i, -1);
}
}

4
passes/sat/eval.cc
View file

@ -543,13 +543,13 @@ struct EvalPass : public Pass {
int pos = 0;
for (auto &c : tabsigs.chunks()) {
tab_line.push_back(log_signal(RTLIL::SigSpec(tabvals).extract(pos, c.width)));
tab_line.push_back(log_signal(RTLIL::SigSpec(tabvals).extract(pos, c.width), false));
pos += c.width;
}
pos = 0;
for (auto &c : signal.chunks()) {
tab_line.push_back(log_signal(value.extract(pos, c.width)));
tab_line.push_back(log_signal(value.extract(pos, c.width), false));
pos += c.width;
}