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Fix tininess when rounding to ebmin

This commit is contained in:
Krystine Sherwin 2026-02-04 17:16:32 +13:00
parent f430908512
commit a464c2ae6a
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2 changed files with 16 additions and 2 deletions
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2
libs/symfpu

@ -1 +1 @@
Subproject commit f5eccd09323fba1a7ee78df2e7bb43dc5509dfe5
Subproject commit 7fce38f94fa0730b3010443eb9a1390c91e5fba0

16
tests/symfpu/edges.sv
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@ -249,13 +249,27 @@ module edges();
assert (UF || o_zero);
end
end
// an unrounded result between +-e^bmin is still an underflow when rounded to ebmin
if (a_unsigned == 31'h0031b7be && b_unsigned == 31'h3ec6def9)
assert (UF);
`endif
`ifdef MUL
assume (c_zero);
// an unrounded result between +-e^bmin is still an underflow when rounded to ebmin
if (a_unsigned == 31'h0ffffffd && b_unsigned == 31'h30000001) begin
assert (UF);
// but it's only ebmin when rounded towards the nearest infinity
assert (o_ebmin ^~ (o_sign ? rm_RTN : rm_RTP));
end
`endif
`ifdef MULS
if (a_unsigned == 31'h0ffffffd && b_unsigned == 31'h30000001 && c_subnorm)
if (!c_sign ^ b_sign ^ a_sign)
assert (!UF);
else
assert (UF);
// 0/inf or inf/0
if ((a_inf && b_zero) || (a_zero && b_inf))
assert (NV);
@ -263,7 +277,7 @@ module edges();
if (a_unsigned == 31'h7f400000 && b_unsigned == a_unsigned && !c_special)
assert (OF);
// multiplying a small number by an even smaller number will underflow
if (a_norm && a_exp < 8'h60 && b_subnorm && !c_special) begin
if (a_norm && a_exp < 8'h68 && b_subnorm && !c_special) begin
assert (NX);
`ifdef MULADD
// within rounding