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authorDavid Shah <davey1576@gmail.com>2018-10-14 13:22:47 +0100
committerDavid Shah <davey1576@gmail.com>2018-10-14 13:22:47 +0100
commit1fc2318c530f85e6c3fe93d7459646b4cfdff68f (patch)
tree2290d3a9d84a5137f161288f1be503841088708a
parentbda94aa5a563bc16e4ed437fbc5443467c5a8db4 (diff)
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ecp5: Optimise DCC placement
Signed-off-by: David Shah <davey1576@gmail.com>
-rw-r--r--ecp5/globals.cc15
1 files changed, 12 insertions, 3 deletions
diff --git a/ecp5/globals.cc b/ecp5/globals.cc
index 364e4bca..5e5a2a01 100644
--- a/ecp5/globals.cc
+++ b/ecp5/globals.cc
@@ -24,7 +24,7 @@
#include "cells.h"
#include "log.h"
#include "nextpnr.h"
-
+#include "place_common.h"
#define fmt_str(x) (static_cast<const std::ostringstream &>(std::ostringstream() << x).str())
NEXTPNR_NAMESPACE_BEGIN
@@ -260,15 +260,24 @@ class Ecp5GlobalRouter
// Attempt to place a DCC
void place_dcc(CellInfo *dcc)
{
+ BelId best_bel;
+ wirelen_t best_wirelen = 9999999;
for (auto bel : ctx->getBels()) {
if (ctx->getBelType(bel) == id_DCCA && ctx->checkBelAvail(bel)) {
if (ctx->isValidBelForCell(dcc, bel)) {
ctx->bindBel(bel, dcc, STRENGTH_LOCKED);
- return;
+ float tns;
+ wirelen_t wirelen = get_net_metric(ctx, dcc->ports.at(id_CLKI).net, MetricType::WIRELENGTH, tns);
+ if (wirelen < best_wirelen) {
+ best_bel = bel;
+ best_wirelen = wirelen;
+ }
+ ctx->unbindBel(bel);
}
}
}
- NPNR_ASSERT_FALSE("failed to place dcca");
+ NPNR_ASSERT(best_bel != BelId());
+ ctx->bindBel(best_bel, dcc, STRENGTH_LOCKED);
}
// Insert a DCC into a net to promote it to a global