cranelift: Remove is_pic predicate from x86 backend (#5548)

This is still present as shared flags and we don't use the predicate anywhere.

cranelift/codegen/meta/src/cdsl/settings.rs

@@ -181,7 +181,6 @@ struct ProtoSetting {
 pub(crate) enum PredicateNode {
     OwnedBool(BoolSettingIndex),
     SharedBool(&'static str, &'static str),
-    Not(Box<PredicateNode>),
     And(Box<PredicateNode>, Box<PredicateNode>),
 }
 
@@ -211,7 +210,6 @@ impl PredicateNode {
             PredicateNode::And(ref lhs, ref rhs) => {
                 format!("{} && {}", lhs.render(group), rhs.render(group))
             }
-            PredicateNode::Not(ref node) => format!("!({})", node.render(group)),
         }
     }
 }

cranelift/codegen/meta/src/isa/x86.rs

@@ -164,15 +164,6 @@ fn define_settings(shared: &SettingGroup) -> SettingGroup {
     settings.add_predicate("use_bmi1", predicate!(has_bmi1));
     settings.add_predicate("use_lzcnt", predicate!(has_lzcnt));
 
-    // Some shared boolean values are used in x86 instruction predicates, so we need to group them
-    // in the same TargetIsa, for compatibility with code generated by meta-python.
-    // TODO Once all the meta generation code has been migrated from Python to Rust, we can put it
-    // back in the shared SettingGroup, and use it in x86 instruction predicates.
-
-    let is_pic = shared.get_bool("is_pic");
-    settings.add_predicate("is_pic", predicate!(is_pic));
-    settings.add_predicate("not_is_pic", predicate!(!is_pic));
-
     // Presets corresponding to x86 CPUs.
 
     settings.add_preset(