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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 val = rval->value();
verinum::V res; verinum::V res;
bool invert = false;
switch (op_) { switch (op_) {
@ -1632,6 +1633,8 @@ NetEConst* NetEUReduce::eval_tree(int prune_to_width)
break; break;
} }
case 'A':
invert = true;
case '&': { case '&': {
res = verinum::V1; res = verinum::V1;
for (unsigned idx = 0 ; idx < val.len() ; idx += 1) for (unsigned idx = 0 ; idx < val.len() ; idx += 1)
@ -1639,6 +1642,8 @@ NetEConst* NetEUReduce::eval_tree(int prune_to_width)
break; break;
} }
case 'N':
invert = true;
case '|': { case '|': {
res = verinum::V0; res = verinum::V0;
for (unsigned idx = 0 ; idx < val.len() ; idx += 1) for (unsigned idx = 0 ; idx < val.len() ; idx += 1)
@ -1646,6 +1651,8 @@ NetEConst* NetEUReduce::eval_tree(int prune_to_width)
break; break;
} }
case 'X':
invert = true;
case '^': { case '^': {
/* Reduction XOR. */ /* Reduction XOR. */
unsigned ones = 0, unknown = 0; unsigned ones = 0, unknown = 0;
@ -1661,17 +1668,17 @@ NetEConst* NetEUReduce::eval_tree(int prune_to_width)
break; break;
} }
if (unknown) if (unknown) res = verinum::Vx;
return new NetEConst(verinum(verinum::Vx,1,true)); else if (ones%2) res = verinum::V1;
if (ones%2) else res = verinum::V0;
return new NetEConst(verinum(verinum::V1,1,true)); break;
return new NetEConst(verinum(verinum::V0,1,true));
} }
default: default:
return 0; return 0;
} }
if (invert) res = ~res;
return new NetEConst(verinum(res, 1)); return new NetEConst(verinum(res, 1));
} }