cranelift x64: use the LZCNT instruction for Clz when it's available;

2021-01-27 18:44:14 +01:00
parent b1b078e2bc
commit d3acd9a283
4 changed files with 79 additions and 12 deletions
--- a/cranelift/codegen/src/isa/x64/inst/args.rs
+++ b/cranelift/codegen/src/isa/x64/inst/args.rs
@@ -402,6 +402,8 @@ pub enum UnaryRmROpcode {
    Bsr,
    /// Bit-scan forward.
    Bsf,
+    /// Counts leading zeroes (Leading Zero CouNT).
+    Lzcnt,
 }

 impl fmt::Debug for UnaryRmROpcode {
@@ -409,6 +411,7 @@ impl fmt::Debug for UnaryRmROpcode {
        match self {
            UnaryRmROpcode::Bsr => write!(fmt, "bsr"),
            UnaryRmROpcode::Bsf => write!(fmt, "bsf"),
+            UnaryRmROpcode::Lzcnt => write!(fmt, "lzcnt"),
        }
    }
 }