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-rw-r--r--passes/opt/wreduce.cc23
1 files changed, 23 insertions, 0 deletions
diff --git a/passes/opt/wreduce.cc b/passes/opt/wreduce.cc
index 1fbc41082..e8c2cb726 100644
--- a/passes/opt/wreduce.cc
+++ b/passes/opt/wreduce.cc
@@ -365,6 +365,29 @@ struct WreduceWorker
}
}
+ if (cell->type.in("$add", "$sub")) {
+ SigSpec A = cell->getPort("\\A");
+ SigSpec B = cell->getPort("\\B");
+ bool sub = cell->type == "$sub";
+
+ int i;
+ for (i = 0; i < GetSize(sig); i++) {
+ if (B[i] != S0 && (sub || A[i] != S0))
+ break;
+ if (B[i] == S0)
+ module->connect(sig[i], A[i]);
+ else if (A[i] == S0)
+ module->connect(sig[i], B[i]);
+ else log_abort();
+ }
+ if (i > 0) {
+ cell->setPort("\\A", A.extract(i, -1));
+ cell->setPort("\\B", B.extract(i, -1));
+ sig.remove(0, i);
+ bits_removed += i;
+ }
+ }
+
if (GetSize(sig) == 0) {
log("Removed cell %s.%s (%s).\n", log_id(module), log_id(cell), log_id(cell->type));
module->remove(cell);