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🐛 The code modifications in this commit remediate a null pointer dere…
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…ference bug within the fiction library. The layout is now checked to ensure that it implements the clocking scheme before asserting that it is an obstruction layout in the `improve_gate_location` function, guarding against null reference errors.

This change enhances code safety, preventing potential runtime issues that could arise from null pointer dereferencing. The changes also include an addition in reporting total runtime for post layout optimization.

Additional minor code refactoring was performed for better readability and to explicitly state the layout type requirements in the template typename declarations.

Lastly, code to handle optional return of stats from post layout optmization function has been added.
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@marcelwa
marcelwa committed Sep 19, 2023
1 parent 5bc7ede commit dcfdaaa
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Showing 4 changed files with 106 additions and 92 deletions.
55 changes: 32 additions & 23 deletions include/fiction/algorithms/physical_design/hexagonalization.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -32,19 +32,20 @@ namespace detail
* @return coordinate on the hexagonal grid.
*/
template <typename CartLyt, typename HexLyt>
[[nodiscard]] fiction::coordinate<HexLyt> to_hex(fiction::coordinate<CartLyt> cartesian_coordinate,
int64_t cartesian_layout_height) noexcept
[[nodiscard]] coordinate<HexLyt> to_hex(coordinate<CartLyt> cartesian_coordinate,
int64_t cartesian_layout_height) noexcept
{
static_assert(is_cartesian_layout_v<CartLyt>, "Old coordinate is not Cartesian");
static_assert(is_hexagonal_layout_v<HexLyt>, "New coordinate is not hexagonal");

const auto y = cartesian_coordinate.x + cartesian_coordinate.y;
const auto x = static_cast<int64_t>(
cartesian_coordinate.x +
static_cast<int64_t>(
std::ceil(std::floor(static_cast<double>(cartesian_layout_height) / 2) - static_cast<double>(y) / 2)));
const auto z = cartesian_coordinate.z;

return fiction::coordinate<HexLyt>{x, y, z};
return coordinate<HexLyt>{x, y, z};
}
} // namespace detail

Expand All @@ -54,18 +55,21 @@ template <typename CartLyt, typename HexLyt>
* How a 45° Turn Prevents the Reinvention of the Wheel\" by S. Hofmann, M. Walter, and R. Wille in IEEE NANO 2023
* (https://ieeexplore.ieee.org/document/10231278).
*
* @param Lyt Gate-level layout that is 2DDWave-clocked.
*
* @tparam HexLyt Even-row hexagonal gate-level layout return type.
* @tparam CartLyt Input Cartesian gate-level layout type.
* @param lyt 2DDWave-clocked Cartesian gate-level layout to hexagonalize.
* @return Hexagonal representation of the Cartesian layout.
*/
template <typename Lyt>
[[nodiscard]] hex_even_row_gate_clk_lyt hexagonalization(const Lyt& lyt) noexcept
template <typename HexLyt, typename CartLyt>
[[nodiscard]] HexLyt hexagonalization(const CartLyt& lyt) noexcept
{
static_assert(is_gate_level_layout_v<Lyt>, "Lyt is not a gate level layout");
static_assert(is_cartesian_layout_v<Lyt>, "Lyt is not a Cartesian layout");
assert(lyt.is_clocking_scheme(clock_name::TWODDWAVE));
static_assert(is_gate_level_layout_v<HexLyt>, "HexLyt is not a gate-level layout");
static_assert(is_hexagonal_layout_v<HexLyt>, "HexLyt is not a hexagonal layout");
static_assert(has_even_row_hex_arrangement_v<HexLyt>, "HexLyt does not have an even row hexagon arrangement");

using hex_lyt = hex_even_row_gate_clk_lyt;
static_assert(is_gate_level_layout_v<CartLyt>, "Lyt is not a gate-level layout");
static_assert(is_cartesian_layout_v<CartLyt>, "Lyt is not a Cartesian layout");
assert(lyt.is_clocking_scheme(clock_name::TWODDWAVE));

// get width, height and depth of Cartesian layout
const auto layout_width = static_cast<int64_t>(lyt.x()) + 1;
Expand All @@ -74,12 +78,13 @@ template <typename Lyt>

// calculate max width, height and depth of hexagonal layout
const auto hex_height =
detail::to_hex<Lyt, hex_lyt>(coordinate<Lyt>(layout_width - 1, layout_height - 1, 0), layout_height).y;
const auto hex_width = detail::to_hex<Lyt, hex_lyt>(coordinate<Lyt>(layout_width - 1, 0, 0), layout_height).x;
detail::to_hex<CartLyt, HexLyt>(coordinate<CartLyt>(layout_width - 1, layout_height - 1, 0), layout_height).y;
const auto hex_width =
detail::to_hex<CartLyt, HexLyt>(coordinate<CartLyt>(layout_width - 1, 0, 0), layout_height).x;
const auto hex_depth = layout_depth;

// instantiate hexagonal layout
hex_lyt hex_layout{{hex_width, hex_height, hex_depth}, fiction::row_clocking<hex_lyt>()};
HexLyt hex_layout{{hex_width, hex_height, hex_depth}, row_clocking<HexLyt>()};

// iterate through cartesian layout diagonally
for (int64_t k = 0; k < layout_width + layout_height - 1; ++k)
Expand All @@ -92,9 +97,9 @@ template <typename Lyt>
for (int64_t z = 0; z <= hex_depth; ++z)
{
// old coordinate
const coordinate<Lyt> old_coord{x, y, z};
const coordinate<CartLyt> old_coord{x, y, z};
// new coordinate
const coordinate<Lyt> hex{detail::to_hex<Lyt, hex_lyt>(old_coord, layout_height)};
const coordinate<CartLyt> hex{detail::to_hex<CartLyt, HexLyt>(old_coord, layout_height)};

if (lyt.is_empty_tile(old_coord))
{
Expand All @@ -109,9 +114,10 @@ template <typename Lyt>

if (const auto signals = lyt.incoming_data_flow(old_coord); signals.size() == 1)
{
const auto signal = signals[0];
const auto signal = signals[0];

const auto hex_signal = hex_layout.make_signal(
hex_layout.get_node(detail::to_hex<Lyt, hex_lyt>(signal, layout_height)));
hex_layout.get_node(detail::to_hex<CartLyt, HexLyt>(signal, layout_height)));

if (lyt.is_po(node))
{
Expand All @@ -129,12 +135,13 @@ template <typename Lyt>

else if (signals.size() == 2)
{
const auto signal_a = signals[0];
const auto signal_b = signals[1];
const auto signal_a = signals[0];
const auto signal_b = signals[1];

const auto hex_signal_a = hex_layout.make_signal(
hex_layout.get_node(detail::to_hex<Lyt, hex_lyt>(signal_a, layout_height)));
hex_layout.get_node(detail::to_hex<CartLyt, HexLyt>(signal_a, layout_height)));
const auto hex_signal_b = hex_layout.make_signal(
hex_layout.get_node(detail::to_hex<Lyt, hex_lyt>(signal_b, layout_height)));
hex_layout.get_node(detail::to_hex<CartLyt, HexLyt>(signal_b, layout_height)));

if (lyt.is_and(node))
{
Expand Down Expand Up @@ -171,7 +178,9 @@ template <typename Lyt>
}
}
}
restore_names<Lyt, hex_lyt>(lyt, hex_layout);

restore_names<CartLyt, HexLyt>(lyt, hex_layout);

return hex_layout;
}

Expand Down
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