Remove BranchRange

cranelift/codegen/src/isa/constraints.rs

@@ -1,66 +0,0 @@
-//! Register constraints for instruction operands.
-//!
-//! An encoding recipe specifies how an instruction is encoded as binary machine code, but it only
-//! works if the operands and results satisfy certain constraints. Constraints on immediate
-//! operands are checked by instruction predicates when the recipe is chosen.
-//!
-//! It is the register allocator's job to make sure that the register constraints on value operands
-//! are satisfied.
-
-use crate::binemit::CodeOffset;
-
-/// Constraints on the range of a branch instruction.
-///
-/// A branch instruction usually encodes its destination as a signed n-bit offset from an origin.
-/// The origin depends on the ISA and the specific instruction:
-///
-/// - RISC-V and ARM Aarch64 use the address of the branch instruction, `origin = 0`.
-/// - x86 uses the address of the instruction following the branch, `origin = 2` for a 2-byte
-///   branch instruction.
-/// - ARM's A32 encoding uses the address of the branch instruction + 8 bytes, `origin = 8`.
-#[derive(Clone, Copy, Debug)]
-pub struct BranchRange {
-    /// Offset in bytes from the address of the branch instruction to the origin used for computing
-    /// the branch displacement. This is the destination of a branch that encodes a 0 displacement.
-    pub origin: u8,
-
-    /// Number of bits in the signed byte displacement encoded in the instruction. This does not
-    /// account for branches that can only target aligned addresses.
-    pub bits: u8,
-}
-
-impl BranchRange {
-    /// Determine if this branch range can represent the range from `branch` to `dest`, where
-    /// `branch` is the code offset of the branch instruction itself and `dest` is the code offset
-    /// of the destination block header.
-    ///
-    /// This method does not detect if the range is larger than 2 GB.
-    pub fn contains(self, branch: CodeOffset, dest: CodeOffset) -> bool {
-        let d = dest.wrapping_sub(branch + CodeOffset::from(self.origin)) as i32;
-        let s = 32 - self.bits;
-        d == d << s >> s
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn branch_range() {
-        // ARM T1 branch.
-        let t1 = BranchRange { origin: 4, bits: 9 };
-        assert!(t1.contains(0, 0));
-        assert!(t1.contains(0, 2));
-        assert!(t1.contains(2, 0));
-        assert!(t1.contains(1000, 1000));
-
-        // Forward limit.
-        assert!(t1.contains(1000, 1258));
-        assert!(!t1.contains(1000, 1260));
-
-        // Backward limit
-        assert!(t1.contains(1000, 748));
-        assert!(!t1.contains(1000, 746));
-    }
-}

cranelift/codegen/src/isa/mod.rs

@@ -44,7 +44,6 @@
 //! concurrent function compilations.
 
 pub use crate::isa::call_conv::CallConv;
-pub use crate::isa::constraints::BranchRange;
 
 use crate::flowgraph;
 use crate::ir;
@@ -76,7 +75,6 @@ mod s390x;
 pub mod unwind;
 
 mod call_conv;
-mod constraints;
 
 #[cfg(test)]
 mod test_utils;