Allow for unencoded instructions in the binemit tests.

If an instruction doesn't have an associated encoding, use the standard
TargetIsa hook to encode it.

The test still fails if an instruction can't be encoded. There is no
legalization step.

cranelift/src/filetest/binemit.rs

@@ -3,7 +3,7 @@
 //! The `binemit` test command generates binary machine code for every instruction in the input
 //! functions and compares the results to the expected output.
 
-use std::borrow::{Borrow, Cow};
+use std::borrow::Cow;
 use std::fmt::Write;
 use cretonne::binemit;
 use cretonne::ir;
@@ -60,7 +60,7 @@ impl SubTest for TestBinEmit {
     }
 
     fn is_mutating(&self) -> bool {
-        false
+        true
     }
 
     fn needs_isa(&self) -> bool {
@@ -71,7 +71,7 @@ impl SubTest for TestBinEmit {
         let isa = context.isa.expect("binemit needs an ISA");
         // TODO: Run a verifier pass over the code first to detect any bad encodings or missing/bad
         // value locations. The current error reporting is just crashing...
-        let func = func.borrow();
+        let mut func = func.into_owned();
 
         let mut sink = TextSink { text: String::new() };
 
@@ -85,6 +85,22 @@ impl SubTest for TestBinEmit {
                                            comment.text))
                     }
                 };
+
+                // Compute an encoding for `inst` if one wasn't provided.
+                if !func.encodings
+                        .get(inst)
+                        .map(|e| e.is_legal())
+                        .unwrap_or(false) {
+                    match isa.encode(&func.dfg, &func.dfg[inst]) {
+                        Ok(enc) => *func.encodings.ensure(inst) = enc,
+                        Err(_) => {
+                            return Err(format!("{} can't be encoded: {}",
+                                               inst,
+                                               func.dfg.display_inst(inst)))
+                        }
+                    }
+                }
+
                 sink.text.clear();
                 isa.emit_inst(&func, inst, &mut sink);
                 let have = sink.text.trim();