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Fix #1267: Allow wire logic connected to uwire port to have multiple drivers 

TODO: Decide how resolved net types (tri0/tri1/triand/trior) should interact with uwire in a shared nexus.
This commit is contained in:
Andrew Pullin 2026-01-23 11:28:58 -08:00
parent d540260a20
commit a03033e743
3 changed files with 43 additions and 2 deletions
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23
ivtest/ivltests/br_gh1267.v Normal file
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@ -0,0 +1,23 @@
// Test for GitHub issue #1267
// Wire logic connected to uwire port should not trigger multi-driver error
// The uwire semantics apply only to the uwire signal, not to wires connected to it.
module a(input uwire logic a1);
endmodule
module b();
wire logic b1;
a b_inst(.a1(b1));
not not_inst(b1, b1);
assign b1 = 'b0;
initial begin
#1;
// b1 has multiple drivers, which is allowed for wire types
// The value will be X due to conflicting drivers
$display("b1 = %b (expected X due to conflicting drivers)", b1);
$display("PASSED");
end
endmodule

1
ivtest/regress-sv.list
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@ -991,3 +991,4 @@ ipsupsel_real_idx CE,-g2012 ivltests gold=ipsupsel_real_idx.gold
real_edges CE,-g2012 ivltests gold=real_edges.gold
br_gh1112 CE,-g2009 ivltests gold=br_gh1112.gold
br_gh670 normal,-g2009 ivltests
br_gh1267 normal,-g2012 ivltests

21
tgt-vvp/draw_net_input.c
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@ -30,6 +30,8 @@ static ivl_signal_type_t signal_type_of_nexus(ivl_nexus_t nex)
{
unsigned idx;
ivl_signal_type_t out = IVL_SIT_TRI;
int has_tri = 0;
int has_uwire = 0;
for (idx = 0 ; idx < ivl_nexus_ptrs(nex) ; idx += 1) {
ivl_signal_type_t stype;
@ -41,14 +43,29 @@ static ivl_signal_type_t signal_type_of_nexus(ivl_nexus_t nex)
stype = ivl_signal_type(sig);
if (stype == IVL_SIT_REG)
continue;
if (stype == IVL_SIT_TRI)
if (stype == IVL_SIT_TRI) {
has_tri = 1;
continue;
}
if (stype == IVL_SIT_NONE)
continue;
if (stype == IVL_SIT_UWIRE) return IVL_SIT_UWIRE;
if (stype == IVL_SIT_UWIRE) {
has_uwire = 1;
continue;
}
out = stype;
}
/* If both TRI (wire) and UWIRE are in the nexus, return TRI
because wire semantics allow multiple drivers. Only return
UWIRE if no TRI signals are present. This fixes GitHub #1267
where wire logic connected to uwire ports was incorrectly
treated as requiring single-driver semantics.
TODO: Decide how resolved net types (tri0/tri1/triand/trior)
should interact with uwire in a shared nexus. */
if (has_uwire && !has_tri)
return IVL_SIT_UWIRE;
return out;
}