Add early-stage optimization crate (#556)

* Add simple constant folding and folding tests

lib/filetests/src/lib.rs

@@ -24,6 +24,7 @@
 )]
 
 extern crate cranelift_codegen;
+extern crate cranelift_preopt;
 extern crate cranelift_reader;
 extern crate file_per_thread_logger;
 extern crate filecheck;
@@ -56,6 +57,7 @@ mod test_print_cfg;
 mod test_regalloc;
 mod test_shrink;
 mod test_simple_gvn;
+mod test_simple_preopt;
 mod test_verifier;
 
 /// The result of running the test in a file.
@@ -127,12 +129,13 @@ fn new_subtest(parsed: &TestCommand) -> subtest::SubtestResult<Box<subtest::SubT
         "legalizer" => test_legalizer::subtest(parsed),
         "licm" => test_licm::subtest(parsed),
         "postopt" => test_postopt::subtest(parsed),
-        "preopt" => test_preopt::subtest(parsed),
+        "simple_preopt" => test_simple_preopt::subtest(parsed),
         "print-cfg" => test_print_cfg::subtest(parsed),
         "regalloc" => test_regalloc::subtest(parsed),
         "shrink" => test_shrink::subtest(parsed),
         "simple-gvn" => test_simple_gvn::subtest(parsed),
         "verifier" => test_verifier::subtest(parsed),
+        "preopt" => test_preopt::subtest(parsed),
         _ => Err(format!("unknown test command '{}'", parsed.command)),
     }
 }

lib/filetests/src/test_preopt.rs

@@ -1,10 +1,14 @@
-//! Test command for testing the preopt pass.
+//! Test command for testing the constant folding pass.
+//!
+//! The `dce` test command runs each function through the constant folding pass after ensuring
+//! that all instructions are legal for the target.
 //!
 //! The resulting function is sent to `filecheck`.
 
 use cranelift_codegen;
 use cranelift_codegen::ir::Function;
 use cranelift_codegen::print_errors::pretty_error;
+use cranelift_preopt::optimize;
 use cranelift_reader::TestCommand;
 use std::borrow::Cow;
 use subtest::{run_filecheck, Context, SubTest, SubtestResult};
@@ -29,16 +33,18 @@ impl SubTest for TestPreopt {
         true
     }
 
-    fn run(&self, func: Cow<Function>, context: &Context) -> SubtestResult<()> {
-        let mut comp_ctx = cranelift_codegen::Context::for_function(func.into_owned());
-        let isa = context.isa.expect("preopt needs an ISA");
+    fn needs_isa(&self) -> bool {
+        true
+    }
 
-        comp_ctx.flowgraph();
-        comp_ctx
-            .preopt(isa)
+    fn run(&self, func: Cow<Function>, context: &Context) -> SubtestResult<()> {
+        let isa = context.isa.expect("compile needs an ISA");
+        let mut comp_ctx = cranelift_codegen::Context::for_function(func.into_owned());
+
+        optimize(&mut comp_ctx, isa)
             .map_err(|e| pretty_error(&comp_ctx.func, context.isa, Into::into(e)))?;
 
-        let text = &comp_ctx.func.display(isa).to_string();
+        let text = comp_ctx.func.display(context.isa).to_string();
         run_filecheck(&text, context)
     }
 }

lib/filetests/src/test_simple_preopt.rs

@@ -0,0 +1,44 @@
+//! Test command for testing the preopt pass.
+//!
+//! The resulting function is sent to `filecheck`.
+
+use cranelift_codegen;
+use cranelift_codegen::ir::Function;
+use cranelift_codegen::print_errors::pretty_error;
+use cranelift_reader::TestCommand;
+use std::borrow::Cow;
+use subtest::{run_filecheck, Context, SubTest, SubtestResult};
+
+struct TestSimplePreopt;
+
+pub fn subtest(parsed: &TestCommand) -> SubtestResult<Box<SubTest>> {
+    assert_eq!(parsed.command, "simple_preopt");
+    if !parsed.options.is_empty() {
+        Err(format!("No options allowed on {}", parsed))
+    } else {
+        Ok(Box::new(TestSimplePreopt))
+    }
+}
+
+impl SubTest for TestSimplePreopt {
+    fn name(&self) -> &'static str {
+        "simple_preopt"
+    }
+
+    fn is_mutating(&self) -> bool {
+        true
+    }
+
+    fn run(&self, func: Cow<Function>, context: &Context) -> SubtestResult<()> {
+        let mut comp_ctx = cranelift_codegen::Context::for_function(func.into_owned());
+        let isa = context.isa.expect("preopt needs an ISA");
+
+        comp_ctx.flowgraph();
+        comp_ctx
+            .preopt(isa)
+            .map_err(|e| pretty_error(&comp_ctx.func, context.isa, Into::into(e)))?;
+
+        let text = &comp_ctx.func.display(isa).to_string();
+        run_filecheck(&text, context)
+    }
+}