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Get padding of signed comparison operands. 

The results of comparisons are unsigned, but the arguments may be signed
and the calculation performed may be signed. Handle the padding properly
for comparisons so that the math is properly signed.
This commit is contained in:
Stephen Williams 2008-10-11 09:20:49 -07:00
parent bd71b7fbb2
commit 995fc380e8
1 changed files with 15 additions and 0 deletions
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15
elab_expr.cc
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@ -224,6 +224,13 @@ NetExpr* PEBinary::elaborate_expr(Design*des, NetScope*scope,
void PEBinary::suppress_operand_sign_if_needed_(NetExpr*lp, NetExpr*rp)
{
// If an argument is a non-vector type, then this type
// suppression does not apply.
if (! type_is_vectorable(lp->expr_type()))
return;
if (! type_is_vectorable(rp->expr_type()))
return;
// If either operand is unsigned, then treat the whole
// expression as unsigned. This test needs to be done here
// instead of in *_expr_base_ because it needs to be done
@ -759,6 +766,14 @@ NetExpr* PEBComp::elaborate_expr(Design*des, NetScope*scope,
suppress_operand_sign_if_needed_(lp, rp);
// The arguments of a compare need to have matching widths, so
// pad the width here. This matters because if the arguments
// are signed, then this padding will do sign extension.
if (type_is_vectorable(lp->expr_type()))
lp = pad_to_width(lp, use_wid);
if (type_is_vectorable(rp->expr_type()))
rp = pad_to_width(rp, use_wid);
return elaborate_eval_expr_base_(des, lp, rp, use_wid);
}