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xilinx: Fix packing of weird mux trees 

Signed-off-by: gatecat <gatecat@ds0.me>
This commit is contained in:
gatecat 2025-06-25 12:38:11 +02:00
parent 23cf1d3b92
commit 1cd1e4a8d9
2 changed files with 10 additions and 7 deletions
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15
himbaechel/uarch/xilinx/pack.cc
View File

@ -250,7 +250,7 @@ void XilinxPacker::pack_lutffs()
bool XilinxPacker::is_constrained(const CellInfo *cell) { return cell->cluster != ClusterId(); }
void XilinxPacker::legalise_muxf_tree(CellInfo *curr, std::vector<CellInfo *> &mux_roots)
void XilinxPacker::legalise_muxf_tree(CellInfo *curr, std::vector<CellInfo *> &mux_roots, pool<IdString> &seen_leaves)
{
if (curr->type.str(ctx).substr(0, 3) == "LUT")
return;
@ -259,13 +259,15 @@ void XilinxPacker::legalise_muxf_tree(CellInfo *curr, std::vector<CellInfo *> &m
if (pn == nullptr || pn->driver.cell == nullptr)
continue;
if (curr->type == id_MUXF7) {
if (pn->driver.cell->type.str(ctx).substr(0, 3) != "LUT" || is_constrained(pn->driver.cell)) {
if (pn->driver.cell->type.str(ctx).substr(0, 3) != "LUT" || is_constrained(pn->driver.cell) ||
seen_leaves.count(pn->driver.cell->name)) {
PortRef pr;
pr.cell = curr;
pr.port = p;
feed_through_lut(pn, {pr});
continue;
}
seen_leaves.insert(pn->driver.cell->name);
} else {
IdString next_type;
if (curr->type == id_MUXF9)
@ -275,21 +277,21 @@ void XilinxPacker::legalise_muxf_tree(CellInfo *curr, std::vector<CellInfo *> &m
else
NPNR_ASSERT_FALSE("bad mux type");
if (pn->driver.cell->type != next_type || is_constrained(pn->driver.cell) ||
bool_or_default(pn->driver.cell->attrs, id_MUX_TREE_ROOT)) {
seen_leaves.count(pn->driver.cell->name) || bool_or_default(pn->driver.cell->attrs, id_MUX_TREE_ROOT)) {
PortRef pr;
pr.cell = curr;
pr.port = p;
feed_through_muxf(pn, next_type, {pr});
continue;
}
seen_leaves.insert(pn->driver.cell->name);
}
legalise_muxf_tree(pn->driver.cell, mux_roots);
legalise_muxf_tree(pn->driver.cell, mux_roots, seen_leaves);
}
}
void XilinxPacker::constrain_muxf_tree(CellInfo *curr, CellInfo *base, int zoffset)
{
if (curr->type == id_SLICE_LUTX && (curr->constr_abs_z || curr->cluster != ClusterId()))
return;
@ -357,8 +359,9 @@ void XilinxPacker::pack_muxfs()
}
for (auto root : mux_roots)
root->attrs[id_MUX_TREE_ROOT] = 1;
pool<IdString> seen_leaves;
for (auto root : mux_roots)
legalise_muxf_tree(root, mux_roots);
legalise_muxf_tree(root, mux_roots, seen_leaves);
for (auto root : mux_roots) {
root->cluster = root->name;
constrain_muxf_tree(root, root, 0);

2
himbaechel/uarch/xilinx/pack.h
View File

@ -125,7 +125,7 @@ struct XilinxPacker
bool is_constrained(const CellInfo *cell);
void pack_muxfs();
void finalise_muxfs();
void legalise_muxf_tree(CellInfo *curr, std::vector<CellInfo *> &mux_roots);
void legalise_muxf_tree(CellInfo *curr, std::vector<CellInfo *> &mux_roots, pool<IdString> &seen_leaves);
void constrain_muxf_tree(CellInfo *curr, CellInfo *base, int zoffset);
void create_muxf_tree(CellInfo *base, const std::string &name_base, const std::vector<NetInfo *> &data,
const std::vector<NetInfo *> &select, NetInfo *out, int zoffset);