The lowerDistConstraints() function was not recursing into ConstraintIf
nodes, causing dist operators inside if-else blocks to remain unlowered
and trigger an internal error when ConstraintExprVisitor encountered them.
Fix by adding recursive handling of ConstraintIf nodes in lowerDistConstraints:
- Check for AstConstraintIf nodes before AstConstraintExpr
- Recursively process thensp() and elsesp() branches
- This ensures all dist operators are lowered regardless of nesting
Test case: t_randomize_dist_conditional.v demonstrates conditional dist:
constraint c {
if (randd) {
x dist { 8'd0 := 1, 8'd255 := 3 }; // 25% / 75%
} else {
x dist { 8'd0 := 3, 8'd255 := 1 }; // 75% / 25%
}
}
Fixes#7221
Rahul Behl