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Self-determined ternary expressions use better width tester. 

When ternary expressions are self-determined, use the test_width
method to get a proper reading of the expression width. Also improve
the test_width method to handle unsized operands.
This commit is contained in:
Stephen Williams 2008-09-20 18:17:17 -07:00
parent 46bf03bba4
commit dc313436c1
1 changed files with 27 additions and 14 deletions
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41
elab_expr.cc
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@ -2166,7 +2166,20 @@ unsigned PETernary::test_width(Design*des, NetScope*scope,
bool&flag) const
{
unsigned tru_wid = tru_->test_width(des, scope, min, lval, flag);
bool initial_flag = flag;
unsigned fal_wid = fal_->test_width(des, scope, min, lval, flag);
// If the false clause is unsized, then try again with the
// true clause, because it might choose a different width if
// it is in an unsized context.
if (initial_flag == false && flag == true) {
if (debug_elaborate)
cerr << get_fileline() << ": debug: "
<< "False clause is unsized, so retest width of true clause."
<< endl;
tru_wid = tru_->test_width(des, scope, max(min,fal_wid), lval, flag);
}
return max(tru_wid,fal_wid);
}
@ -2201,16 +2214,16 @@ NetExpr*PETernary::elaborate_expr(Design*des, NetScope*scope,
assert(tru_);
assert(fal_);
int use_wid = expr_wid >= 0? expr_wid : 0;
if (expr_wid < 0) {
bool flag = false;
unsigned tru_wid = tru_->test_width(des, scope, 0, 0, flag);
unsigned fal_wid = fal_->test_width(des, scope, 0, 0, flag);
expr_wid = max(tru_wid, fal_wid);
bool flag = expr_wid == -2;
use_wid = this->test_width(des, scope, 0, 0, flag);
if (debug_elaborate)
cerr << get_fileline() << ": debug: "
<< "Self-sized ternary chooses wid="<< expr_wid
<< " from " <<tru_wid
<< " and " << fal_wid << endl;
<< "Self-sized ternary chooses wid="<< use_wid
<< endl;
ivl_assert(*this, use_wid > 0);
}
// Elaborate and evaluate the condition expression. Note that
@ -2237,8 +2250,8 @@ NetExpr*PETernary::elaborate_expr(Design*des, NetScope*scope,
cerr << get_fileline() << ": debug: Short-circuit "
"elaborate TRUE clause of ternary."
<< endl;
NetExpr*tru = elab_and_eval(des, scope, tru_, expr_wid);
return pad_to_width(tru, expr_wid);
NetExpr*tru = elab_and_eval(des, scope, tru_, use_wid);
return pad_to_width(tru, use_wid);
}
// Condition is constant FALSE, so we only need the
@ -2248,7 +2261,7 @@ NetExpr*PETernary::elaborate_expr(Design*des, NetScope*scope,
cerr << get_fileline() << ": debug: Short-circuit "
"elaborate FALSE clause of ternary."
<< endl;
NetExpr*fal = elab_and_eval(des, scope, fal_, expr_wid);
NetExpr*fal = elab_and_eval(des, scope, fal_, use_wid);
return pad_to_width(fal, expr_wid);
}
@ -2256,13 +2269,13 @@ NetExpr*PETernary::elaborate_expr(Design*des, NetScope*scope,
// can't short-circuit.
}
NetExpr*tru = elab_and_eval(des, scope, tru_, expr_wid);
NetExpr*tru = elab_and_eval(des, scope, tru_, use_wid);
if (tru == 0) {
delete con;
return 0;
}
NetExpr*fal = elab_and_eval(des, scope, fal_, expr_wid);
NetExpr*fal = elab_and_eval(des, scope, fal_, use_wid);
if (fal == 0) {
delete con;
delete tru;
@ -2280,8 +2293,8 @@ NetExpr*PETernary::elaborate_expr(Design*des, NetScope*scope,
/* Whatever the width we choose for the ternary operator, we
need to make sure the operands match. */
tru = pad_to_width(tru, expr_wid);
fal = pad_to_width(fal, expr_wid);
tru = pad_to_width(tru, use_wid);
fal = pad_to_width(fal, use_wid);
NetETernary*res = new NetETernary(con, tru, fal);
res->set_line(*this);