Move the filetest harness into its own crate.

This allows us to run the tests via a library call rather than just
as a command execution. And, it's a step toward a broader goal, which
is to keep the code in the top-level src directory minimal, with
important functionality exposed as crates.

lib/filetests/src/test_compile.rs

@@ -0,0 +1,114 @@
+//! Test command for testing the code generator pipeline
+//!
+//! The `compile` test command runs each function through the full code generator pipeline
+
+use cretonne::binemit;
+use cretonne::ir;
+use cretonne;
+use cretonne::print_errors::pretty_error;
+use cton_reader::TestCommand;
+use subtest::{SubTest, Context, Result, run_filecheck};
+use std::borrow::Cow;
+use std::fmt::Write;
+
+struct TestCompile;
+
+pub fn subtest(parsed: &TestCommand) -> Result<Box<SubTest>> {
+    assert_eq!(parsed.command, "compile");
+    if !parsed.options.is_empty() {
+        Err(format!("No options allowed on {}", parsed))
+    } else {
+        Ok(Box::new(TestCompile))
+    }
+}
+
+impl SubTest for TestCompile {
+    fn name(&self) -> Cow<str> {
+        Cow::from("compile")
+    }
+
+    fn is_mutating(&self) -> bool {
+        true
+    }
+
+    fn needs_isa(&self) -> bool {
+        true
+    }
+
+    fn run(&self, func: Cow<ir::Function>, context: &Context) -> Result<()> {
+        let isa = context.isa.expect("compile needs an ISA");
+
+        // Create a compilation context, and drop in the function.
+        let mut comp_ctx = cretonne::Context::new();
+        comp_ctx.func = func.into_owned();
+
+        let code_size = comp_ctx.compile(isa).map_err(|e| {
+            pretty_error(&comp_ctx.func, context.isa, e)
+        })?;
+
+        dbg!(
+            "Generated {} bytes of code:\n{}",
+            code_size,
+            comp_ctx.func.display(isa)
+        );
+
+        // Verify that the returned code size matches the emitted bytes.
+        let mut sink = SizeSink { offset: 0 };
+        binemit::emit_function(
+            &comp_ctx.func,
+            |func, inst, div, sink| isa.emit_inst(func, inst, div, sink),
+            &mut sink,
+        );
+
+        if sink.offset != code_size {
+            return Err(format!(
+                "Expected code size {}, got {}",
+                code_size,
+                sink.offset
+            ));
+        }
+
+        // Run final code through filecheck.
+        let mut text = String::new();
+        write!(&mut text, "{}", &comp_ctx.func.display(Some(isa)))
+            .map_err(|e| e.to_string())?;
+        run_filecheck(&text, context)
+    }
+}
+
+// Code sink that simply counts bytes.
+struct SizeSink {
+    offset: binemit::CodeOffset,
+}
+
+impl binemit::CodeSink for SizeSink {
+    fn offset(&self) -> binemit::CodeOffset {
+        self.offset
+    }
+
+    fn put1(&mut self, _: u8) {
+        self.offset += 1;
+    }
+
+    fn put2(&mut self, _: u16) {
+        self.offset += 2;
+    }
+
+    fn put4(&mut self, _: u32) {
+        self.offset += 4;
+    }
+
+    fn put8(&mut self, _: u64) {
+        self.offset += 8;
+    }
+
+    fn reloc_ebb(&mut self, _reloc: binemit::Reloc, _ebb_offset: binemit::CodeOffset) {}
+    fn reloc_external(
+        &mut self,
+        _reloc: binemit::Reloc,
+        _name: &ir::ExternalName,
+        _addend: binemit::Addend,
+    ) {
+    }
+    fn reloc_jt(&mut self, _reloc: binemit::Reloc, _jt: ir::JumpTable) {}
+}