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-rw-r--r--common/place_sa.cc61
-rw-r--r--ice40/cells.cc4
-rw-r--r--ice40/pack.cc21
3 files changed, 34 insertions, 52 deletions
diff --git a/common/place_sa.cc b/common/place_sa.cc
index f5f2858a..2a56b177 100644
--- a/common/place_sa.cc
+++ b/common/place_sa.cc
@@ -42,42 +42,15 @@
NEXTPNR_NAMESPACE_BEGIN
-struct rnd_state
-{
- uint32_t state;
-};
-
-/* The state word must be initialized to non-zero */
-static uint32_t xorshift32(rnd_state &rnd)
-{
- /* Algorithm "xor" from p. 4 of Marsaglia, "Xorshift RNGs" */
- uint32_t x = rnd.state;
- x ^= x << 13;
- x ^= x >> 17;
- x ^= x << 5;
- rnd.state = x;
- return x;
-}
-
-static float random_float_upto(rnd_state &rnd, float limit)
-{
- return xorshift32(rnd) / (4294967296 / limit);
-}
-
-static int random_int_between(rnd_state &rnd, int a, int b)
-{
- return a + int(random_float_upto(rnd, b - a) - 0.00001);
-}
-
// Initial random placement
-static void place_initial(Context *ctx, CellInfo *cell, rnd_state &rnd)
+static void place_initial(Context *ctx, CellInfo *cell)
{
bool all_placed = false;
int iters = 25;
while (!all_placed) {
BelId best_bel = BelId();
- float best_score = std::numeric_limits<float>::infinity(),
- best_ripup_score = std::numeric_limits<float>::infinity();
+ uint64_t best_score = std::numeric_limits<uint64_t>::max(),
+ best_ripup_score = std::numeric_limits<uint64_t>::max();
CellInfo *ripup_target = nullptr;
BelId ripup_bel = BelId();
if (cell->bel != BelId()) {
@@ -89,13 +62,13 @@ static void place_initial(Context *ctx, CellInfo *cell, rnd_state &rnd)
if (ctx->getBelType(bel) == targetType &&
isValidBelForCell(ctx, cell, bel)) {
if (ctx->checkBelAvail(bel)) {
- float score = random_float_upto(rnd, 1.0);
+ uint64_t score = ctx->rng64();
if (score <= best_score) {
best_score = score;
best_bel = bel;
}
} else {
- float score = random_float_upto(rnd, 1.0);
+ uint64_t score = ctx->rng64();
if (score <= best_ripup_score) {
best_ripup_score = score;
ripup_target =
@@ -173,8 +146,7 @@ static float get_wirelength(Context *ctx, NetInfo *net)
}
// Attempt a SA position swap, return true on success or false on failure
-static bool try_swap_position(Context *ctx, CellInfo *cell, BelId newBel,
- rnd_state &rnd, SAState &state)
+static bool try_swap_position(Context *ctx, CellInfo *cell, BelId newBel, SAState &state)
{
static std::unordered_set<NetInfo *> update;
static std::vector<std::pair<NetInfo *, float>> new_lengths;
@@ -232,7 +204,7 @@ static bool try_swap_position(Context *ctx, CellInfo *cell, BelId newBel,
// SA acceptance criterea
if (delta < 0 ||
(state.temp > 1e-6 &&
- random_float_upto(rnd, 1.0) <= std::exp(-delta / state.temp))) {
+ (ctx->rng() / float(0x3fffffff)) <= std::exp(-delta / state.temp))) {
state.n_accept++;
if (delta < 0)
state.improved = true;
@@ -259,17 +231,14 @@ swap_fail:
// Find a random Bel of the correct type for a cell, within the specified
// diameter
-BelId random_bel_for_cell(Context *ctx, CellInfo *cell, SAState &state,
- rnd_state &rnd)
+BelId random_bel_for_cell(Context *ctx, CellInfo *cell, SAState &state)
{
BelType targetType = ctx->belTypeFromId(cell->type);
int x = 0, y = 0;
ctx->estimatePosition(cell->bel, x, y);
while (true) {
- int nx = random_int_between(rnd, std::max(int(x) - state.diameter, 0),
- int(x) + state.diameter + 1);
- int ny = random_int_between(rnd, std::max(int(y) - state.diameter, 0),
- int(y) + state.diameter + 1);
+ int nx = ctx->rng(2 * state.diameter + 1) + std::max(x - state.diameter, 0);
+ int ny = ctx->rng(2 * state.diameter + 1) + std::max(y - state.diameter, 0);
int beltype_idx = state.bel_types.at(targetType);
if (nx >= int(state.fast_bels.at(beltype_idx).size()))
continue;
@@ -278,7 +247,7 @@ BelId random_bel_for_cell(Context *ctx, CellInfo *cell, SAState &state,
const auto &fb = state.fast_bels.at(beltype_idx).at(nx).at(ny);
if (fb.size() == 0)
continue;
- BelId bel = fb.at(random_int_between(rnd, 0, fb.size()));
+ BelId bel = fb.at(ctx->rng(int(fb.size())));
if (state.locked_bels.find(bel) != state.locked_bels.end())
continue;
return bel;
@@ -321,8 +290,6 @@ bool place_design_sa(Context *ctx)
}
}
log_info("place_constraints placed %d\n", int(placed_cells));
- rnd_state rnd;
- rnd.state = ctx->rng();
std::vector<CellInfo *> autoplaced;
// Sort to-place cells for deterministic initial placement
for (auto cell : ctx->cells) {
@@ -335,7 +302,7 @@ bool place_design_sa(Context *ctx)
[](CellInfo *a, CellInfo *b) { return a->name < b->name; });
// Place cells randomly initially
for (auto cell : autoplaced) {
- place_initial(ctx, cell, rnd);
+ place_initial(ctx, cell);
placed_cells++;
}
// Build up a fast position/type to Bel lookup table
@@ -388,11 +355,11 @@ bool place_design_sa(Context *ctx)
// Loop through all automatically placed cells
for (auto cell : autoplaced) {
// Find another random Bel for this cell
- BelId try_bel = random_bel_for_cell(ctx, cell, state, rnd);
+ BelId try_bel = random_bel_for_cell(ctx, cell, state);
// If valid, try and swap to a new position and see if
// the new position is valid/worthwhile
if (try_bel != BelId() && try_bel != cell->bel)
- try_swap_position(ctx, cell, try_bel, rnd, state);
+ try_swap_position(ctx, cell, try_bel, state);
}
}
// Heuristic to improve placement on the 8k
diff --git a/ice40/cells.cc b/ice40/cells.cc
index b6f10f7b..582e5c14 100644
--- a/ice40/cells.cc
+++ b/ice40/cells.cc
@@ -210,6 +210,10 @@ void nxio_to_sb(Context *ctx, CellInfo *nxio, CellInfo *sbio)
replace_port(tbuf, "A", sbio, "D_OUT_0");
replace_port(tbuf, "E", sbio, "OUTPUT_ENABLE");
ctx->nets.erase(donet->name);
+ if (!donet->users.empty())
+ log_error("unsupported tristate IO pattern for IO buffer '%s', "
+ "instantiate SB_IO manually to ensure correct behaviour\n",
+ nxio->name.c_str(ctx));
ctx->cells.erase(tbuf->name);
}
}
diff --git a/ice40/pack.cc b/ice40/pack.cc
index 92f9a369..d3f07118 100644
--- a/ice40/pack.cc
+++ b/ice40/pack.cc
@@ -203,23 +203,33 @@ static void pack_constants(Context *ctx)
std::vector<IdString> dead_nets;
+ bool gnd_used = false, vcc_used = false;
+
for (auto net : ctx->nets) {
NetInfo *ni = net.second;
if (ni->driver.cell != nullptr &&
ni->driver.cell->type == ctx->id("GND")) {
set_net_constant(ctx, ni, gnd_net, false);
- ctx->cells[gnd_cell->name] = gnd_cell;
- ctx->nets[gnd_net->name] = gnd_net;
+ gnd_used = true;
dead_nets.push_back(net.first);
} else if (ni->driver.cell != nullptr &&
ni->driver.cell->type == ctx->id("VCC")) {
set_net_constant(ctx, ni, vcc_net, true);
- ctx->cells[vcc_cell->name] = vcc_cell;
- ctx->nets[vcc_net->name] = vcc_net;
+ vcc_used = true;
dead_nets.push_back(net.first);
}
}
+ if (gnd_used) {
+ ctx->cells[gnd_cell->name] = gnd_cell;
+ ctx->nets[gnd_net->name] = gnd_net;
+ }
+
+ if (vcc_used) {
+ ctx->cells[vcc_cell->name] = vcc_cell;
+ ctx->nets[vcc_net->name] = vcc_net;
+ }
+
for (auto dn : dead_nets)
ctx->nets.erase(dn);
}
@@ -265,7 +275,8 @@ static void pack_io(Context *ctx)
}
} else {
// Create a SB_IO buffer
- sb = create_ice_cell(ctx, "SB_IO");
+ sb = create_ice_cell(ctx, "SB_IO",
+ ci->name.str(ctx) + "$sb_io");
nxio_to_sb(ctx, ci, sb);
new_cells.push_back(sb);
}
generated by cgit v1.2.3 (git 2.25.1) at 2025-11-04 03:24:46 +0000