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sign extended expressions are signed. 

Fix when sign extending an expression that the result is also signed.
This bug caused some arithmetic operations (with extended arguments)
to not notice that they are signed.

Also be more robust in noticing that comparisons are signed and should
generate the right code.
This commit is contained in:
Stephen Williams 2008-05-06 13:27:04 -07:00
parent 34e90bb3a6
commit 3e591f730e
1 changed files with 7 additions and 0 deletions
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7
expr_synth.cc
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@ -235,6 +235,8 @@ NetNet* NetEBComp::synthesize(Design*des)
osig->local_flag(true);
osig->data_type(IVL_VT_LOGIC);
bool signed_compare = lsig->get_signed() && rsig->get_signed();
/* Handle the special case of a single bit equality
operation. Make an XNOR gate instead of a comparator. */
if ((width == 1) && ((op_ == 'e') || (op_ == 'E')) && !real_args) {
@ -274,9 +276,11 @@ NetNet* NetEBComp::synthesize(Design*des)
switch (op_) {
case '<':
connect(dev->pin_ALB(), osig->pin(0));
dev->set_signed(signed_compare);
break;
case '>':
connect(dev->pin_AGB(), osig->pin(0));
dev->set_signed(signed_compare);
break;
case 'E': // === ?
if (real_args) {
@ -290,9 +294,11 @@ NetNet* NetEBComp::synthesize(Design*des)
break;
case 'G': // >=
connect(dev->pin_AGEB(), osig->pin(0));
dev->set_signed(signed_compare);
break;
case 'L': // <=
connect(dev->pin_ALEB(), osig->pin(0));
dev->set_signed(signed_compare);
break;
case 'N': // !==
if (real_args) {
@ -923,6 +929,7 @@ NetNet* NetESelect::synthesize(Design *des)
connect(pad->pin(1), sub->pin(0));
connect(pad->pin(0), net->pin(0));
net->set_signed(true);
} else {