Add a trapif instruction.

This is a conditional trap controlled by integer CPU flags.
Compare to brif.

lib/cretonne/src/ir/instructions.rs

@@ -264,6 +264,12 @@ pub enum InstructionData {
         arg: Value,
         code: ir::TrapCode,
     },
+    IntCondTrap {
+        opcode: Opcode,
+        cond: IntCC,
+        arg: Value,
+        code: ir::TrapCode,
+    },
 }
 
 /// A variable list of `Value` operands used for function call arguments and passing arguments to

lib/cretonne/src/verifier/mod.rs

@@ -365,6 +365,7 @@ impl<'a> Verifier<'a> {
             CopySpecial { .. } |
             Trap { .. } |
             CondTrap { .. } |
+            IntCondTrap { .. } |
             NullAry { .. } => {}
         }
 

lib/cretonne/src/write.rs

@@ -428,6 +428,7 @@ pub fn write_operands(
         }
         Trap { code, .. } => write!(w, " {}", code),
         CondTrap { arg, code, .. } => write!(w, " {}, {}", arg, code),
+        IntCondTrap { cond, arg, code, .. } => write!(w, " {} {}, {}", cond, arg, code),
     }
 }