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More aggressive $macc merging in alumacc

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This commit is contained in:
Clifford Wolf 2014-09-15 12:42:11 +02:00
parent b470c480e9
commit b86410b2ab
1 changed files with 37 additions and 1 deletions
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38
passes/techmap/alumacc.cc
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@ -172,6 +172,42 @@ struct AlumaccWorker
} }
} }
static bool macc_may_overflow(Macc &macc, int width, bool is_signed)
{
std::vector<int> port_sizes;
for (auto &port : macc.ports) {
if (port.is_signed != is_signed)
return true;
if (!port.is_signed && port.do_subtract)
return true;
if (SIZE(port.in_b))
port_sizes.push_back(SIZE(port.in_a) + SIZE(port.in_b));
else
port_sizes.push_back(SIZE(port.in_a));
}
std::sort(port_sizes.begin(), port_sizes.end());
int acc_sum = 0, acc_shift = 0;
for (int sz : port_sizes) {
while ((sz - acc_shift) > 20) {
if (acc_sum & 1)
acc_sum++;
acc_sum = acc_sum >> 1;
acc_shift++;
}
acc_sum += (1 << (sz - acc_shift)) - 1;
}
while (acc_sum) {
acc_sum = acc_sum >> 1;
acc_shift++;
}
return acc_shift > width;
}
void merge_macc() void merge_macc()
{ {
while (1) while (1)
@ -197,7 +233,7 @@ struct AlumaccWorker
if (other_n->users > 1) if (other_n->users > 1)
continue; continue;
if (SIZE(other_n->y) != SIZE(n->y)) if (SIZE(other_n->y) != SIZE(n->y) && macc_may_overflow(other_n->macc, SIZE(other_n->y), port.is_signed))
continue; continue;
log(" merging $macc model for %s into %s.\n", log_id(other_n->cell), log_id(n->cell)); log(" merging $macc model for %s into %s.\n", log_id(other_n->cell), log_id(n->cell));