Add x86 encoding for SIMD icmp eq

Also adds a predicate for matching the `eq` IntCC code (TODO this should be replaced by something more general)

cranelift/codegen/src/predicates.rs

@@ -10,6 +10,8 @@
 //! dead code warning.
 
 use crate::ir;
+use crate::ir::condcodes::IntCC;
+use std::string::ToString;
 
 /// Check that an integer value is zero.
 #[allow(dead_code)]
@@ -83,6 +85,14 @@ pub fn has_length_of(value_list: &ir::ValueList, num: usize, func: &ir::Function
     value_list.len(&func.dfg.value_lists) == num
 }
 
+#[allow(dead_code)]
+pub fn match_condition_code_to_str(
+    condition_code: IntCC,
+    stringified_condition_code: &str,
+) -> bool {
+    condition_code.to_string().eq(stringified_condition_code)
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -136,4 +146,10 @@ mod tests {
         assert!(!is_all_ones_128_bit(&[0; 16]));
         assert!(is_all_ones_128_bit(&[0xff; 16]));
     }
+
+    #[test]
+    fn condition_code() {
+        assert!(match_condition_code_to_str(IntCC::Equal, "eq"));
+        assert!(!match_condition_code_to_str(IntCC::Equal, "ne"));
+    }
 }