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Fix width calculation for packed array bounds 

Variable select base normalization extends the base expression to cover
the packed array bounds. The current code compared min_wid against
num_bits() of each bound, but then assigned the bound value itself to
min_wid.

For positive bounds this can make the generated index expression much
wider than required. For negative bounds the effect is much worse since
min_wid is unsigned. Assigning a negative bound converts it to a huge
width, causing elaboration to try to pad the expression to that size and
abort or run out of memory for otherwise valid variable selects.

Use the bit width of the bound instead of the bound value.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
This commit is contained in:
Lars-Peter Clausen 2026-06-19 21:43:33 -07:00
parent de415b2f03
commit 128c621e85
1 changed files with 4 additions and 2 deletions
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6
netmisc.cc
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@ -423,8 +423,10 @@ NetExpr *normalize_variable_slice_base(const list<long>&indices, NetExpr*base,
unsigned min_wid = base->expr_width();
if ((sb < 0) && !base->has_sign()) min_wid += 1;
if (min_wid < num_bits(pcur->get_lsb())) min_wid = pcur->get_lsb();
if (min_wid < num_bits(pcur->get_msb())) min_wid = pcur->get_msb();
if (min_wid < num_bits(pcur->get_lsb()))
min_wid = num_bits(pcur->get_lsb());
if (min_wid < num_bits(pcur->get_msb()))
min_wid = num_bits(pcur->get_msb());
base = pad_to_width(base, min_wid, *base);
if ((sb < 0) && !base->has_sign()) {
NetESelect *tmp = new NetESelect(base, 0 , min_wid);