cranelift: Add f16const and f128const instructions (#8893)

* cranelift: Add `f16const` and `f128const` instructions

* cranelift: Add constant propagation for `f16` and `f128`

cranelift/codegen/meta/src/shared/formats.rs

@@ -36,6 +36,7 @@ pub(crate) struct Formats {
     pub(crate) unary: Rc<InstructionFormat>,
     pub(crate) unary_const: Rc<InstructionFormat>,
     pub(crate) unary_global_value: Rc<InstructionFormat>,
+    pub(crate) unary_ieee16: Rc<InstructionFormat>,
     pub(crate) unary_ieee32: Rc<InstructionFormat>,
     pub(crate) unary_ieee64: Rc<InstructionFormat>,
     pub(crate) unary_imm: Rc<InstructionFormat>,
@@ -48,6 +49,8 @@ impl Formats {
 
             unary_imm: Builder::new("UnaryImm").imm(&imm.imm64).build(),
 
+            unary_ieee16: Builder::new("UnaryIeee16").imm(&imm.ieee16).build(),
+
             unary_ieee32: Builder::new("UnaryIeee32").imm(&imm.ieee32).build(),
 
             unary_ieee64: Builder::new("UnaryIeee64").imm(&imm.ieee64).build(),

cranelift/codegen/meta/src/shared/immediates.rs

@@ -31,6 +31,11 @@ pub(crate) struct Immediates {
     /// This is used to represent an immediate address offset in load/store instructions.
     pub offset32: OperandKind,
 
+    /// A 16-bit immediate floating point operand.
+    ///
+    /// IEEE 754-2008 binary16 interchange format.
+    pub ieee16: OperandKind,
+
     /// A 32-bit immediate floating point operand.
     ///
     /// IEEE 754-2008 binary32 interchange format.
@@ -119,6 +124,11 @@ impl Immediates {
                 "ir::immediates::Offset32",
                 "A 32-bit immediate signed offset.",
             ),
+            ieee16: new_imm(
+                "imm",
+                "ir::immediates::Ieee16",
+                "A 16-bit immediate floating point number.",
+            ),
             ieee32: new_imm(
                 "imm",
                 "ir::immediates::Ieee32",

cranelift/codegen/meta/src/shared/instructions.rs

@@ -599,8 +599,10 @@ pub(crate) fn define(
 
     // Operand kind shorthands.
     let i8: &TypeVar = &ValueType::from(LaneType::from(types::Int::I8)).into();
+    let f16_: &TypeVar = &ValueType::from(LaneType::from(types::Float::F16)).into();
     let f32_: &TypeVar = &ValueType::from(LaneType::from(types::Float::F32)).into();
     let f64_: &TypeVar = &ValueType::from(LaneType::from(types::Float::F64)).into();
+    let f128_: &TypeVar = &ValueType::from(LaneType::from(types::Float::F128)).into();
 
     // Starting definitions.
     let Int = &TypeVar::new(
@@ -1285,6 +1287,22 @@ pub(crate) fn define(
         ]),
     );
 
+    ig.push(
+        Inst::new(
+            "f16const",
+            r#"
+        Floating point constant.
+
+        Create a `f16` SSA value with an immediate constant value.
+        "#,
+            &formats.unary_ieee16,
+        )
+        .operands_in(vec![Operand::new("N", &imm.ieee16)])
+        .operands_out(vec![
+            Operand::new("a", f16_).with_doc("A constant f16 scalar value")
+        ]),
+    );
+
     ig.push(
         Inst::new(
             "f32const",
@@ -1317,6 +1335,22 @@ pub(crate) fn define(
         ]),
     );
 
+    ig.push(
+        Inst::new(
+            "f128const",
+            r#"
+        Floating point constant.
+
+        Create a `f128` SSA value with an immediate constant value.
+        "#,
+            &formats.unary_const,
+        )
+        .operands_in(vec![Operand::new("N", &imm.pool_constant)])
+        .operands_out(vec![
+            Operand::new("a", f128_).with_doc("A constant f128 scalar value")
+        ]),
+    );
+
     ig.push(
         Inst::new(
             "vconst",

cranelift/codegen/src/inst_predicates.rs

@@ -121,6 +121,7 @@ pub fn is_constant_64bit(func: &Function, inst: Inst) -> Option<u64> {
     }
     match data {
         &InstructionData::UnaryImm { imm, .. } => Some(imm.bits() as u64),
+        &InstructionData::UnaryIeee16 { imm, .. } => Some(imm.bits() as u64),
         &InstructionData::UnaryIeee32 { imm, .. } => Some(imm.bits() as u64),
         &InstructionData::UnaryIeee64 { imm, .. } => Some(imm.bits()),
         _ => None,

cranelift/codegen/src/ir/constant.rs

@@ -8,7 +8,7 @@
 //! - ensuring alignment of constants within the pool,
 //! - bucketing constants by size.
 
-use crate::ir::immediates::{IntoBytes, V128Imm};
+use crate::ir::immediates::{Ieee128, IntoBytes, V128Imm};
 use crate::ir::Constant;
 use alloc::collections::BTreeMap;
 use alloc::vec::Vec;
@@ -54,6 +54,22 @@ impl From<V128Imm> for ConstantData {
     }
 }
 
+impl From<Ieee128> for ConstantData {
+    fn from(v: Ieee128) -> Self {
+        Self(v.into_bytes())
+    }
+}
+
+impl TryFrom<&ConstantData> for Ieee128 {
+    type Error = <[u8; 16] as TryFrom<&'static [u8]>>::Error;
+
+    fn try_from(value: &ConstantData) -> Result<Self, Self::Error> {
+        Ok(Ieee128::with_bits(u128::from_le_bytes(
+            value.as_slice().try_into()?,
+        )))
+    }
+}
+
 impl ConstantData {
     /// Return the number of bytes in the constant.
     pub fn len(&self) -> usize {
@@ -459,4 +475,15 @@ mod tests {
             [0x78, 0x56, 0x34, 0x12, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
         );
     }
+
+    #[test]
+    fn constant_ieee128() {
+        let value = Ieee128::with_bits(0x000102030405060708090a0b0c0d0e0f);
+        let constant = ConstantData::from(value);
+        assert_eq!(
+            constant.as_slice(),
+            &[0xf, 0xe, 0xd, 0xc, 0xb, 0xa, 0x9, 0x8, 0x7, 0x6, 0x5, 0x4, 0x3, 0x2, 0x1, 0x0]
+        );
+        assert_eq!(Ieee128::try_from(&constant).unwrap().bits(), value.bits());
+    }
 }

cranelift/codegen/src/ir/entities.rs

@@ -56,8 +56,10 @@ impl Block {
 /// [`InstBuilder`](super::InstBuilder) instructions:
 ///
 /// - [`iconst`](super::InstBuilder::iconst) for integer constants
+/// - [`f16const`](super::InstBuilder::f16const) for 16-bit float constants
 /// - [`f32const`](super::InstBuilder::f32const) for 32-bit float constants
 /// - [`f64const`](super::InstBuilder::f64const) for 64-bit float constants
+/// - [`f128const`](super::InstBuilder::f128const) for 128-bit float constants
 /// - [`vconst`](super::InstBuilder::vconst) for vector constants
 /// - [`null`](super::InstBuilder::null) for null reference constants
 ///

cranelift/codegen/src/ir/immediates.rs

@@ -768,6 +768,9 @@ fn parse_float(s: &str, w: u8, t: u8) -> Result<u128, &'static str> {
 impl Ieee16 {
     const SIGNIFICAND_BITS: u8 = 10;
     const EXPONENT_BITS: u8 = 5;
+    const SIGN_MASK: u16 = 1 << (Self::EXPONENT_BITS + Self::SIGNIFICAND_BITS);
+    const SIGNIFICAND_MASK: u16 = u16::MAX >> (Self::EXPONENT_BITS + 1);
+    const EXPONENT_MASK: u16 = !Self::SIGN_MASK & !Self::SIGNIFICAND_MASK;
 
     /// Create a new `Ieee16` containing the bits of `x`.
     pub fn with_bits(x: u16) -> Self {
@@ -779,6 +782,16 @@ impl Ieee16 {
         self.0
     }
 
+    /// Computes the absolute value of self.
+    pub fn abs(self) -> Self {
+        Self::with_bits(self.bits() & !Self::SIGN_MASK)
+    }
+
+    /// Returns a number composed of the magnitude of self and the sign of sign.
+    pub fn copysign(self, sign: Self) -> Self {
+        Self::with_bits((self.bits() & !Self::SIGN_MASK) | (sign.bits() & Self::SIGN_MASK))
+    }
+
     /// Returns true if self is positive or negative zero
     pub fn is_zero(&self) -> bool {
         self.partial_cmp(&Self::with_bits(0)) == Some(Ordering::Equal)
@@ -788,14 +801,12 @@ impl Ieee16 {
 impl PartialOrd for Ieee16 {
     fn partial_cmp(&self, rhs: &Self) -> Option<Ordering> {
         // FIXME(#8312): Use Rust `f16` comparisons once `f16` support is stabalised.
-        let significand_mask = u16::MAX >> (Self::EXPONENT_BITS + 1);
-        let sign_mask = 1 << (Self::EXPONENT_BITS + Self::SIGNIFICAND_BITS);
-        let exponent_mask = !sign_mask & !significand_mask;
-
-        let lhs_abs = self.bits() & !sign_mask;
-        let rhs_abs = rhs.bits() & !sign_mask;
-        if (lhs_abs & exponent_mask == exponent_mask && lhs_abs & significand_mask != 0)
-            && (rhs_abs & exponent_mask == exponent_mask && rhs_abs & significand_mask != 0)
+        let lhs_abs = self.bits() & !Self::SIGN_MASK;
+        let rhs_abs = rhs.bits() & !Self::SIGN_MASK;
+        if (lhs_abs & Self::EXPONENT_MASK == Self::EXPONENT_MASK
+            && lhs_abs & Self::SIGNIFICAND_MASK != 0)
+            && (rhs_abs & Self::EXPONENT_MASK == Self::EXPONENT_MASK
+                && rhs_abs & Self::SIGNIFICAND_MASK != 0)
         {
             // One of the floats is a NaN.
             return None;
@@ -804,8 +815,8 @@ impl PartialOrd for Ieee16 {
             // Zeros are always equal regardless of sign.
             return Some(Ordering::Equal);
         }
-        let lhs_positive = self.bits() & sign_mask == 0;
-        let rhs_positive = rhs.bits() & sign_mask == 0;
+        let lhs_positive = self.bits() & Self::SIGN_MASK == 0;
+        let rhs_positive = rhs.bits() & Self::SIGN_MASK == 0;
         if lhs_positive != rhs_positive {
             // Different signs: negative < positive
             return lhs_positive.partial_cmp(&rhs_positive);
@@ -843,6 +854,20 @@ impl FromStr for Ieee16 {
     }
 }
 
+impl IntoBytes for Ieee16 {
+    fn into_bytes(self) -> Vec<u8> {
+        self.bits().to_le_bytes().to_vec()
+    }
+}
+
+impl Neg for Ieee16 {
+    type Output = Self;
+
+    fn neg(self) -> Self {
+        Self::with_bits(self.bits() ^ Self::SIGN_MASK)
+    }
+}
+
 impl Ieee32 {
     /// Create a new `Ieee32` containing the bits of `x`.
     pub fn with_bits(x: u32) -> Self {
@@ -1287,6 +1312,9 @@ impl Not for Ieee64 {
 impl Ieee128 {
     const SIGNIFICAND_BITS: u8 = 112;
     const EXPONENT_BITS: u8 = 15;
+    const SIGN_MASK: u128 = 1 << (Self::EXPONENT_BITS + Self::SIGNIFICAND_BITS);
+    const SIGNIFICAND_MASK: u128 = u128::MAX >> (Self::EXPONENT_BITS + 1);
+    const EXPONENT_MASK: u128 = !Self::SIGN_MASK & !Self::SIGNIFICAND_MASK;
 
     /// Create a new `Ieee128` containing the bits of `x`.
     pub fn with_bits(x: u128) -> Self {
@@ -1298,6 +1326,16 @@ impl Ieee128 {
         self.0
     }
 
+    /// Computes the absolute value of self.
+    pub fn abs(self) -> Self {
+        Self::with_bits(self.bits() & !Self::SIGN_MASK)
+    }
+
+    /// Returns a number composed of the magnitude of self and the sign of sign.
+    pub fn copysign(self, sign: Self) -> Self {
+        Self::with_bits((self.bits() & !Self::SIGN_MASK) | (sign.bits() & Self::SIGN_MASK))
+    }
+
     /// Returns true if self is positive or negative zero
     pub fn is_zero(&self) -> bool {
         self.partial_cmp(&Self::with_bits(0)) == Some(Ordering::Equal)
@@ -1307,14 +1345,12 @@ impl Ieee128 {
 impl PartialOrd for Ieee128 {
     fn partial_cmp(&self, rhs: &Self) -> Option<Ordering> {
         // FIXME(#8312): Use Rust `f128` comparisons once `f128` support is stabalised.
-        let significand_mask = u128::MAX >> (Self::EXPONENT_BITS + 1);
-        let sign_mask = 1 << (Self::EXPONENT_BITS + Self::SIGNIFICAND_BITS);
-        let exponent_mask = !sign_mask & !significand_mask;
-
-        let lhs_abs = self.bits() & !sign_mask;
-        let rhs_abs = rhs.bits() & !sign_mask;
-        if (lhs_abs & exponent_mask == exponent_mask && lhs_abs & significand_mask != 0)
-            && (rhs_abs & exponent_mask == exponent_mask && rhs_abs & significand_mask != 0)
+        let lhs_abs = self.bits() & !Self::SIGN_MASK;
+        let rhs_abs = rhs.bits() & !Self::SIGN_MASK;
+        if (lhs_abs & Self::EXPONENT_MASK == Self::EXPONENT_MASK
+            && lhs_abs & Self::SIGNIFICAND_MASK != 0)
+            && (rhs_abs & Self::EXPONENT_MASK == Self::EXPONENT_MASK
+                && rhs_abs & Self::SIGNIFICAND_MASK != 0)
         {
             // One of the floats is a NaN.
             return None;
@@ -1323,8 +1359,8 @@ impl PartialOrd for Ieee128 {
             // Zeros are always equal regardless of sign.
             return Some(Ordering::Equal);
         }
-        let lhs_positive = self.bits() & sign_mask == 0;
-        let rhs_positive = rhs.bits() & sign_mask == 0;
+        let lhs_positive = self.bits() & Self::SIGN_MASK == 0;
+        let rhs_positive = rhs.bits() & Self::SIGN_MASK == 0;
         if lhs_positive != rhs_positive {
             // Different signs: negative < positive
             return lhs_positive.partial_cmp(&rhs_positive);
@@ -1357,6 +1393,20 @@ impl FromStr for Ieee128 {
     }
 }
 
+impl IntoBytes for Ieee128 {
+    fn into_bytes(self) -> Vec<u8> {
+        self.bits().to_le_bytes().to_vec()
+    }
+}
+
+impl Neg for Ieee128 {
+    type Output = Self;
+
+    fn neg(self) -> Self {
+        Self::with_bits(self.bits() ^ Self::SIGN_MASK)
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

cranelift/codegen/src/isle_prelude.rs

@@ -938,6 +938,18 @@ macro_rules! isle_common_prelude_methods {
             }
         }
 
+        fn f16_neg(&mut self, n: Ieee16) -> Ieee16 {
+            -n
+        }
+
+        fn f16_abs(&mut self, n: Ieee16) -> Ieee16 {
+            n.abs()
+        }
+
+        fn f16_copysign(&mut self, a: Ieee16, b: Ieee16) -> Ieee16 {
+            a.copysign(b)
+        }
+
         fn f32_neg(&mut self, n: Ieee32) -> Ieee32 {
             n.neg()
         }
@@ -961,5 +973,17 @@ macro_rules! isle_common_prelude_methods {
         fn f64_copysign(&mut self, a: Ieee64, b: Ieee64) -> Ieee64 {
             a.copysign(b)
         }
+
+        fn f128_neg(&mut self, n: Ieee128) -> Ieee128 {
+            -n
+        }
+
+        fn f128_abs(&mut self, n: Ieee128) -> Ieee128 {
+            n.abs()
+        }
+
+        fn f128_copysign(&mut self, a: Ieee128, b: Ieee128) -> Ieee128 {
+            a.copysign(b)
+        }
     };
 }

cranelift/codegen/src/machinst/isle.rs

@@ -253,7 +253,7 @@ macro_rules! isle_lower_prelude_methods {
                         return self.zero_value(arg);
                     }
                     InstructionData::UnaryConst {
-                        opcode: Opcode::Vconst,
+                        opcode: Opcode::Vconst | Opcode::F128const,
                         constant_handle,
                     } => {
                         let constant_data =
@@ -271,6 +271,13 @@ macro_rules! isle_lower_prelude_methods {
                             return None;
                         }
                     }
+                    InstructionData::UnaryIeee16 { imm, .. } => {
+                        if imm.bits() == 0 {
+                            return Some(value);
+                        } else {
+                            return None;
+                        }
+                    }
                     InstructionData::UnaryIeee32 { imm, .. } => {
                         if imm.bits() == 0 {
                             return Some(value);