Add meta definitions for floating point operations.

Rename the Select instruction format to Ternary since it is also used by the fma
instruction.

src/libcretonne/instructions.rs

@@ -159,7 +159,7 @@ pub enum InstructionData {
         second_result: Value,
         args: [Value; 2],
     },
-    Select {
+    Ternary {
         opcode: Opcode,
         ty: Type,
         args: [Value; 3],

src/libcretonne/write.rs

@@ -194,7 +194,7 @@ pub fn write_instruction(w: &mut Write, func: &Function, inst: Inst) -> Result {
         BinaryImm { arg, imm, .. } => writeln!(w, " {}, {}", arg, imm),
         BinaryImmRev { imm, arg, .. } => writeln!(w, " {}, {}", imm, arg),
         BinaryOverflow { args, .. } => writeln!(w, " {}, {}", args[0], args[1]),
-        Select { args, .. } => writeln!(w, " {}, {}, {}", args[0], args[1], args[2]),
+        Ternary { args, .. } => writeln!(w, " {}, {}, {}", args[0], args[1], args[2]),
         InsertLane { lane, args, .. } => writeln!(w, " {}, {}, {}", args[0], lane, args[1]),
         ExtractLane { lane, arg, .. } => writeln!(w, " {}, {}", arg, lane),
         IntCompare { cond, args, .. } => writeln!(w, " {}, {}, {}", cond, args[0], args[1]),