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.

cranelift/src/filetest/regalloc.rs

@@ -5,11 +5,12 @@
 //!
 //! The resulting function is sent to `filecheck`.
 
-use std::borrow::Cow;
-use cretonne::{self, write_function};
 use cretonne::ir::Function;
+use cretonne::{self, write_function};
 use cton_reader::TestCommand;
 use filetest::subtest::{SubTest, Context, Result, run_filecheck};
+use std::borrow::Cow;
+use utils::pretty_verifier_error;
 
 struct TestRegalloc;
 
@@ -46,6 +47,7 @@ impl SubTest for TestRegalloc {
         // TODO: Should we have an option to skip legalization?
         comp_ctx.legalize(isa);
         comp_ctx.regalloc(isa);
+        comp_ctx.verify(isa).map_err(|e| pretty_verifier_error(&comp_ctx.func, e))?;
 
         let mut text = String::new();
         write_function(&mut text, &comp_ctx.func, Some(isa)).map_err(|e| e.to_string())?;