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Evaluate constant negated reductions. 

This patch adds support for calculating the negated reductions
(~&, ~| and ~^) in the compiler when given a constant argument.
This commit is contained in:
Cary R 2008-11-17 15:39:53 -08:00 committed by Stephen Williams
parent e191fcdd28
commit 95065819f1
1 changed files with 12 additions and 5 deletions
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17
eval_tree.cc
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@ -1604,6 +1604,7 @@ NetEConst* NetEUReduce::eval_tree(int prune_to_width)
verinum val = rval->value();
verinum::V res;
bool invert = false;
switch (op_) {
@ -1632,6 +1633,8 @@ NetEConst* NetEUReduce::eval_tree(int prune_to_width)
break;
}
case 'A':
invert = true;
case '&': {
res = verinum::V1;
for (unsigned idx = 0 ; idx < val.len() ; idx += 1)
@ -1639,6 +1642,8 @@ NetEConst* NetEUReduce::eval_tree(int prune_to_width)
break;
}
case 'N':
invert = true;
case '|': {
res = verinum::V0;
for (unsigned idx = 0 ; idx < val.len() ; idx += 1)
@ -1646,6 +1651,8 @@ NetEConst* NetEUReduce::eval_tree(int prune_to_width)
break;
}
case 'X':
invert = true;
case '^': {
/* Reduction XOR. */
unsigned ones = 0, unknown = 0;
@ -1661,17 +1668,17 @@ NetEConst* NetEUReduce::eval_tree(int prune_to_width)
break;
}
if (unknown)
return new NetEConst(verinum(verinum::Vx,1,true));
if (ones%2)
return new NetEConst(verinum(verinum::V1,1,true));
return new NetEConst(verinum(verinum::V0,1,true));
if (unknown) res = verinum::Vx;
else if (ones%2) res = verinum::V1;
else res = verinum::V0;
break;
}
default:
return 0;
}
if (invert) res = ~res;
return new NetEConst(verinum(res, 1));
}