Generate code to precompute predicates.

Each ISA predicate is assigned a bit the the Flags struct, and a corresponding
method is generated.

cranelift/src/libcretonne/isa/riscv/mod.rs

@@ -25,8 +25,8 @@ fn isa_constructor(shared_flags: shared_settings::Flags,
                    builder: shared_settings::Builder)
                    -> Box<TargetIsa> {
     Box::new(Isa {
+        isa_flags: settings::Flags::new(&shared_flags, builder),
         shared_flags: shared_flags,
-        isa_flags: settings::Flags::new(builder),
     })
 }
 

cranelift/src/libcretonne/isa/riscv/settings.rs

@@ -1,6 +1,6 @@
 //! RISC-V Settings.
 
-use settings::{detail, Builder};
+use settings::{self, detail, Builder};
 use std::fmt;
 
 // Include code generated by `meta/gen_settings.py`. This file contains a public `Flags` struct
@@ -10,16 +10,39 @@ include!(concat!(env!("OUT_DIR"), "/settings-riscv.rs"));
 #[cfg(test)]
 mod tests {
     use super::{builder, Flags};
+    use settings::{self, Configurable};
 
     #[test]
     fn display_default() {
+        let shared = settings::Flags::new(settings::builder());
         let b = builder();
-        let f = Flags::new(b);
+        let f = Flags::new(&shared, b);
         assert_eq!(f.to_string(),
                    "[riscv]\n\
                     supports_m = false\n\
                     supports_a = false\n\
                     supports_f = false\n\
                     supports_d = false\n");
+        // Predicates are not part of the Display output.
+        assert_eq!(f.full_float(), false);
+    }
+
+    #[test]
+    fn predicates() {
+        let shared = settings::Flags::new(settings::builder());
+        let mut b = builder();
+        b.set_bool("supports_f", true).unwrap();
+        b.set_bool("supports_d", true).unwrap();
+        let f = Flags::new(&shared, b);
+        assert_eq!(f.full_float(), true);
+
+        let mut sb = settings::builder();
+        sb.set_bool("enable_simd", false).unwrap();
+        let shared = settings::Flags::new(sb);
+        let mut b = builder();
+        b.set_bool("supports_f", true).unwrap();
+        b.set_bool("supports_d", true).unwrap();
+        let f = Flags::new(&shared, b);
+        assert_eq!(f.full_float(), false);
     }
 }