Apply register diversions during binemit tests.

When "binemit" tests encode instructions, keep track of the current set
of register diversions, and use the diverted locations to check operand
constraints.

This matches how constraints are applied during a real binemit phase.

cranelift/src/filetest/binemit.rs

@@ -114,6 +114,7 @@ impl SubTest for TestBinEmit {
         let is_compressed = isa.flags().is_compressed();
 
         // Give an encoding to any instruction that doesn't already have one.
+        let mut divert = RegDiversions::new();
         for ebb in func.layout.ebbs() {
             for inst in func.layout.ebb_insts(ebb) {
                 if !func.encodings[inst].is_legal() {
@@ -128,7 +129,7 @@ impl SubTest for TestBinEmit {
                         legal_encodings
                             .filter(|e| {
                                 let recipe_constraints = &encinfo.constraints[e.recipe()];
-                                recipe_constraints.satisfied(inst, &func)
+                                recipe_constraints.satisfied(inst, &divert, &func)
                             })
                             .min_by_key(|&e| encinfo.bytes(e))
                     } else {
@@ -140,6 +141,7 @@ impl SubTest for TestBinEmit {
                         func.encodings[inst] = enc;
                     }
                 }
+                divert.apply(&func.dfg[inst]);
             }
         }
 
@@ -178,8 +180,8 @@ impl SubTest for TestBinEmit {
         }
 
         // Now emit all instructions.
+        divert.clear();
         let mut sink = TextSink::new(isa);
-        let mut divert = RegDiversions::new();
         for ebb in func.layout.ebbs() {
             divert.clear();
             // Correct header offsets should have been computed by `relax_branches()`.