Define icmp and fcmp comparison instructions.

Add new intcc and floatcc operand types for the immediate condition codes on
these instructions.

Add new IntCompare and FloatCompare instruction formats.

Add a generic match_enum() parser function that can match any identifier-like
enumerated operand kind that implements FromStr.

Define the icmp and fcmp instructions in case.py. Include documentation for the
condition codes with these two instructions.

src/libcretonne/instructions.rs

@@ -11,6 +11,7 @@ use std::str::FromStr;
 
 use entities::*;
 use immediates::*;
+use condcodes::*;
 use types::{self, Type};
 
 // Include code generated by `meta/gen_instr.py`. This file contains:
@@ -175,6 +176,18 @@ pub enum InstructionData {
         lane: u8,
         arg: Value,
     },
+    IntCompare {
+        opcode: Opcode,
+        ty: Type,
+        cond: IntCC,
+        args: [Value; 2],
+    },
+    FloatCompare {
+        opcode: Opcode,
+        ty: Type,
+        cond: FloatCC,
+        args: [Value; 2],
+    },
     Jump {
         opcode: Opcode,
         ty: Type,

src/libcretonne/write.rs

@@ -197,6 +197,8 @@ pub fn write_instruction(w: &mut Write, func: &Function, inst: Inst) -> Result {
         Select { 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]),
+        FloatCompare { cond, args, .. } => writeln!(w, " {}, {}, {}", cond, args[0], args[1]),
         Jump { ref data, .. } => writeln!(w, " {}", data),
         Branch { ref data, .. } => writeln!(w, " {}", data),
         BranchTable { arg, table, .. } => writeln!(w, " {}, {}", arg, table),