73 lines
2.2 KiB
Rust
73 lines
2.2 KiB
Rust
//! Predicate functions for testing instruction fields.
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//!
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//! This module defines functions that are used by the instruction predicates defined by
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//! `lib/cretonne/meta/cretonne/predicates.py` classes.
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//!
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//! The predicates the operate on integer fields use `Into<i64>` as a shared trait bound. This
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//! bound is implemented by all the native integer types as well as `Imm64`.
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//!
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//! Some of these predicates may be unused in certain ISA configurations, so we suppress the
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//! dead_code warning.
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/// Check that `x` is the same as `y`.
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#[allow(dead_code)]
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pub fn is_equal<T: Eq + Copy>(x: T, y: T) -> bool {
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x == y
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}
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/// Check that `x` can be represented as a `wd`-bit signed integer with `sc` low zero bits.
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#[allow(dead_code)]
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pub fn is_signed_int<T: Into<i64>>(x: T, wd: u8, sc: u8) -> bool {
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let s = x.into();
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s == (s >> sc << (64 - wd + sc) >> (64 - wd))
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}
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/// Check that `x` can be represented as a `wd`-bit unsigned integer with `sc` low zero bits.
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#[allow(dead_code)]
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pub fn is_unsigned_int<T: Into<i64>>(x: T, wd: u8, sc: u8) -> bool {
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let u = x.into() as u64;
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// Bit-mask of the permitted bits.
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let m = (1 << wd) - (1 << sc);
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u == (u & m)
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn cvt_u32() {
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let x1 = 0u32;
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let x2 = 1u32;
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let x3 = 0xffff_fff0u32;
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assert!(is_signed_int(x1, 1, 0));
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assert!(is_signed_int(x1, 2, 1));
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assert!(is_signed_int(x2, 2, 0));
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assert!(!is_signed_int(x2, 2, 1));
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// `u32` doesn't sign-extend when converted to `i64`.
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assert!(!is_signed_int(x3, 8, 0));
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assert!(is_unsigned_int(x1, 1, 0));
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assert!(is_unsigned_int(x1, 8, 4));
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assert!(is_unsigned_int(x2, 1, 0));
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assert!(!is_unsigned_int(x2, 8, 4));
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assert!(!is_unsigned_int(x3, 1, 0));
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assert!(is_unsigned_int(x3, 32, 4));
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}
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#[test]
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fn cvt_imm64() {
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use ir::immediates::Imm64;
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let x1 = Imm64::new(-8);
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let x2 = Imm64::new(8);
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assert!(is_signed_int(x1, 16, 2));
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assert!(is_signed_int(x2, 16, 2));
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assert!(!is_signed_int(x1, 16, 4));
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assert!(!is_signed_int(x2, 16, 4));
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}
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}
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