Add enums for condition codes.

The icmp and fmp instructions use different kinds of condition codes because integers and floating point values behave differently. Add a CondCode trait implementing shared behavior.
2016-07-06 15:02:12 -07:00
parent 7f8479e097
commit 70507a3be0
2 changed files with 326 additions and 0 deletions
--- a/cranelift/src/libcretonne/condcodes.rs
+++ b/cranelift/src/libcretonne/condcodes.rs
@@ -0,0 +1,325 @@
+//! Condition codes for the Cretonne code generator.
+//!
+//! A condition code here is an enumerated type that determined how to compare two numbers. There
+//! are different rules for comparing integers and floating point numbers, so they use different
+//! condition codes.
+
+use std::fmt::{self, Display, Formatter};
+use std::str::FromStr;
+
+/// Common traits of condition codes.
+pub trait CondCode: Copy {
+    /// Get the inverse condition code of `self`.
+    ///
+    /// The inverse condition code produces the opposite result for all comparisons.
+    /// That is, `cmp CC, x, y` is true if and only if `cmp CC.inverse(), x, y` is false.
+    fn inverse(self) -> Self;
+
+    /// Get the reversed condition code for `self`.
+    ///
+    /// The reversed condition code produces the same result as swapping `x` and `y` in the
+    /// comparison. That is, `cmp CC, x, y` is the same as `cmp CC.reverse(), y, x`.
+    fn reverse(self) -> Self;
+}
+
+/// Condition code for comparing integers.
+///
+/// This condition code is used by the `icmp` instruction to compare integer values. There are
+/// separate codes for comparing the integers as signed or unsigned numbers where it makes a
+/// difference.
+#[derive(Clone, Copy, PartialEq, Eq, Debug)]
+pub enum IntCC {
+    Equal,
+    NotEqual,
+    SignedLessThan,
+    SignedGreaterThanOrEqual,
+    SignedGreaterThan,
+    SignedLessThanOrEqual,
+    UnsignedLessThan,
+    UnsignedGreaterThanOrEqual,
+    UnsignedGreaterThan,
+    UnsignedLessThanOrEqual,
+}
+
+impl CondCode for IntCC {
+    fn inverse(self) -> Self {
+        use self::IntCC::*;
+        match self {
+            Equal => NotEqual,
+            NotEqual => Equal,
+            SignedLessThan => SignedGreaterThanOrEqual,
+            SignedGreaterThanOrEqual => SignedLessThan,
+            SignedGreaterThan => SignedLessThanOrEqual,
+            SignedLessThanOrEqual => SignedGreaterThan,
+            UnsignedLessThan => UnsignedGreaterThanOrEqual,
+            UnsignedGreaterThanOrEqual => UnsignedLessThan,
+            UnsignedGreaterThan => UnsignedLessThanOrEqual,
+            UnsignedLessThanOrEqual => UnsignedGreaterThan,
+        }
+    }
+
+    fn reverse(self) -> Self {
+        use self::IntCC::*;
+        match self {
+            Equal => Equal,
+            NotEqual => NotEqual,
+            SignedGreaterThan => SignedLessThan,
+            SignedGreaterThanOrEqual => SignedLessThanOrEqual,
+            SignedLessThan => SignedGreaterThan,
+            SignedLessThanOrEqual => SignedGreaterThanOrEqual,
+            UnsignedGreaterThan => UnsignedLessThan,
+            UnsignedGreaterThanOrEqual => UnsignedLessThanOrEqual,
+            UnsignedLessThan => UnsignedGreaterThan,
+            UnsignedLessThanOrEqual => UnsignedGreaterThanOrEqual,
+        }
+    }
+}
+
+impl Display for IntCC {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        use self::IntCC::*;
+        f.write_str(match self {
+            &Equal => "eq",
+            &NotEqual => "ne",
+            &SignedGreaterThan => "sgt",
+            &SignedGreaterThanOrEqual => "sge",
+            &SignedLessThan => "slt",
+            &SignedLessThanOrEqual => "sle",
+            &UnsignedGreaterThan => "ugt",
+            &UnsignedGreaterThanOrEqual => "uge",
+            &UnsignedLessThan => "ult",
+            &UnsignedLessThanOrEqual => "ule",
+        })
+    }
+}
+
+impl FromStr for IntCC {
+    type Err = ();
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        use self::IntCC::*;
+        match s {
+            "eq" => Ok(Equal),
+            "ne" => Ok(NotEqual),
+            "sge" => Ok(SignedGreaterThanOrEqual),
+            "sgt" => Ok(SignedGreaterThan),
+            "sle" => Ok(SignedLessThanOrEqual),
+            "slt" => Ok(SignedLessThan),
+            "uge" => Ok(UnsignedGreaterThanOrEqual),
+            "ugt" => Ok(UnsignedGreaterThan),
+            "ule" => Ok(UnsignedLessThanOrEqual),
+            "ult" => Ok(UnsignedLessThan),
+            _ => Err(()),
+        }
+    }
+}
+
+/// Condition code for comparing floating point numbers.
+///
+/// This condition code is used by the `fcmp` instruction to compare floating point values. Two
+/// IEEE floating point values relate in exactly one of four ways:
+///
+/// 1. `UN` - unordered when either value is NaN.
+/// 2. `EQ` - equal numerical value.
+/// 3. `LT` - `x` is less than `y`.
+/// 4. `GT` - `x` is greater than `y`.
+///
+/// Note that `0.0` and `-0.0` relate as `EQ` because they both represent the number 0.
+///
+/// The condition codes described here are used to produce a single boolean value from the
+/// comparison. The 14 condition codes here cover every possible combination of the relation above
+/// except the impossible `!UN & !EQ & !LT & !GT` and the always true `UN | EQ | LT | GT`.
+#[derive(Clone, Copy, PartialEq, Eq, Debug)]
+pub enum FloatCC {
+    Ordered, // EQ | LT | GT
+    Unordered, // UN
+
+    Equal, // EQ
+    // The C '!=' operator is the inverse of '==': NotEqual.
+    NotEqual, // UN | LT | GT
+    OrderedNotEqual, // LT | GT
+    UnorderedOrEqual, // UN | EQ
+
+    LessThan, // LT
+    LessThanOrEqual, // LT | EQ
+    GreaterThan, // GT
+    GreaterThanOrEqual, // GT | EQ
+
+    UnorderedOrLessThan, // UN | LT
+    UnorderedOrLessThanOrEqual, // UN | LT | EQ
+    UnorderedOrGreaterThan, // UN | GT
+    UnorderedOrGreaterThanOrEqual, // UN | GT | EQ
+}
+
+impl CondCode for FloatCC {
+    fn inverse(self) -> Self {
+        use self::FloatCC::*;
+        match self {
+            Ordered => Unordered,
+            Unordered => Ordered,
+            Equal => NotEqual,
+            NotEqual => Equal,
+            OrderedNotEqual => UnorderedOrEqual,
+            UnorderedOrEqual => OrderedNotEqual,
+            LessThan => UnorderedOrGreaterThanOrEqual,
+            LessThanOrEqual => UnorderedOrGreaterThan,
+            GreaterThan => UnorderedOrLessThanOrEqual,
+            GreaterThanOrEqual => UnorderedOrLessThan,
+            UnorderedOrLessThan => GreaterThanOrEqual,
+            UnorderedOrLessThanOrEqual => GreaterThan,
+            UnorderedOrGreaterThan => LessThanOrEqual,
+            UnorderedOrGreaterThanOrEqual => LessThan,
+        }
+    }
+    fn reverse(self) -> Self {
+        use self::FloatCC::*;
+        match self {
+            Ordered => Ordered,
+            Unordered => Unordered,
+            Equal => Equal,
+            NotEqual => NotEqual,
+            OrderedNotEqual => OrderedNotEqual,
+            UnorderedOrEqual => UnorderedOrEqual,
+            LessThan => GreaterThan,
+            LessThanOrEqual => GreaterThanOrEqual,
+            GreaterThan => LessThan,
+            GreaterThanOrEqual => LessThanOrEqual,
+            UnorderedOrLessThan => UnorderedOrGreaterThan,
+            UnorderedOrLessThanOrEqual => UnorderedOrGreaterThanOrEqual,
+            UnorderedOrGreaterThan => UnorderedOrLessThan,
+            UnorderedOrGreaterThanOrEqual => UnorderedOrLessThanOrEqual,
+        }
+    }
+}
+
+impl Display for FloatCC {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        use self::FloatCC::*;
+        f.write_str(match self {
+            &Ordered => "ord",
+            &Unordered => "uno",
+            &Equal => "eq",
+            &NotEqual => "ne",
+            &OrderedNotEqual => "one",
+            &UnorderedOrEqual => "ueq",
+            &LessThan => "lt",
+            &LessThanOrEqual => "le",
+            &GreaterThan => "gt",
+            &GreaterThanOrEqual => "ge",
+            &UnorderedOrLessThan => "ult",
+            &UnorderedOrLessThanOrEqual => "ule",
+            &UnorderedOrGreaterThan => "ugt",
+            &UnorderedOrGreaterThanOrEqual => "uge",
+        })
+    }
+}
+
+impl FromStr for FloatCC {
+    type Err = ();
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        use self::FloatCC::*;
+        match s {
+            "ord" => Ok(Ordered),
+            "uno" => Ok(Unordered),
+            "eq" => Ok(Equal),
+            "ne" => Ok(NotEqual),
+            "one" => Ok(OrderedNotEqual),
+            "ueq" => Ok(UnorderedOrEqual),
+            "lt" => Ok(LessThan),
+            "le" => Ok(LessThanOrEqual),
+            "gt" => Ok(GreaterThan),
+            "ge" => Ok(GreaterThanOrEqual),
+            "ult" => Ok(UnorderedOrLessThan),
+            "ule" => Ok(UnorderedOrLessThanOrEqual),
+            "ugt" => Ok(UnorderedOrGreaterThan),
+            "uge" => Ok(UnorderedOrGreaterThanOrEqual),
+            _ => Err(()),
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    static INT_ALL: [IntCC; 10] = [IntCC::Equal,
+                                   IntCC::NotEqual,
+                                   IntCC::SignedLessThan,
+                                   IntCC::SignedGreaterThanOrEqual,
+                                   IntCC::SignedGreaterThan,
+                                   IntCC::SignedLessThanOrEqual,
+                                   IntCC::UnsignedLessThan,
+                                   IntCC::UnsignedGreaterThanOrEqual,
+                                   IntCC::UnsignedGreaterThan,
+                                   IntCC::UnsignedLessThanOrEqual];
+
+    #[test]
+    fn int_inverse() {
+        for r in &INT_ALL {
+            let cc = *r;
+            let inv = cc.inverse();
+            assert!(cc != inv);
+            assert_eq!(inv.inverse(), cc);
+        }
+    }
+
+    #[test]
+    fn int_reverse() {
+        for r in &INT_ALL {
+            let cc = *r;
+            let rev = cc.reverse();
+            assert_eq!(rev.reverse(), cc);
+        }
+    }
+
+    #[test]
+    fn int_display() {
+        for r in &INT_ALL {
+            let cc = *r;
+            assert_eq!(cc.to_string().parse(), Ok(cc));
+        }
+    }
+
+    static FLOAT_ALL: [FloatCC; 14] = [FloatCC::Ordered,
+                                       FloatCC::Unordered,
+                                       FloatCC::Equal,
+                                       FloatCC::NotEqual,
+                                       FloatCC::OrderedNotEqual,
+                                       FloatCC::UnorderedOrEqual,
+                                       FloatCC::LessThan,
+                                       FloatCC::LessThanOrEqual,
+                                       FloatCC::GreaterThan,
+                                       FloatCC::GreaterThanOrEqual,
+                                       FloatCC::UnorderedOrLessThan,
+                                       FloatCC::UnorderedOrLessThanOrEqual,
+                                       FloatCC::UnorderedOrGreaterThan,
+                                       FloatCC::UnorderedOrGreaterThanOrEqual];
+
+    #[test]
+    fn float_inverse() {
+        for r in &FLOAT_ALL {
+            let cc = *r;
+            let inv = cc.inverse();
+            assert!(cc != inv);
+            assert_eq!(inv.inverse(), cc);
+        }
+    }
+
+    #[test]
+    fn float_reverse() {
+        for r in &FLOAT_ALL {
+            let cc = *r;
+            let rev = cc.reverse();
+            assert_eq!(rev.reverse(), cc);
+        }
+    }
+
+    #[test]
+    fn float_display() {
+        for r in &FLOAT_ALL {
+            let cc = *r;
+            assert_eq!(cc.to_string().parse(), Ok(cc));
+        }
+    }
+}
--- a/cranelift/src/libcretonne/lib.rs
+++ b/cranelift/src/libcretonne/lib.rs
@@ -8,6 +8,7 @@
 pub const VERSION: &'static str = env!("CARGO_PKG_VERSION");

 pub mod types;
+pub mod condcodes;
 pub mod immediates;
 pub mod entities;
 pub mod instructions;