Run verifier after legalizer and regalloc file tests.

Run the verify_contexti() function after invoking the legalize() and
regalloc() context functions. This will help catch bad code produced by
these passes.

lib/cretonne/src/context.rs

@@ -15,6 +15,7 @@ use ir::Function;
 use isa::TargetIsa;
 use legalize_function;
 use regalloc;
+use verifier;
 
 /// Persistent data structures and compilation pipeline.
 pub struct Context {
@@ -45,6 +46,16 @@ impl Context {
         }
     }
 
+    /// Run the verifier on the function.
+    ///
+    /// Also check that the dominator tree and control flow graph are consistent with the function.
+    ///
+    /// The `TargetIsa` argument is currently unused, but the verifier will soon be able to also
+    /// check ISA-dependent constraints.
+    pub fn verify<'a, ISA: Into<Option<&'a TargetIsa>>>(&self, _isa: ISA) -> verifier::Result<()> {
+        verifier::verify_context(self)
+    }
+
     /// Run the legalizer for `isa` on the function.
     pub fn legalize(&mut self, isa: &TargetIsa) {
         legalize_function(&mut self.func, &mut self.cfg, isa);