Add a binemit test command.

This makes it possible to write file tests that verify the binary
encoding of machine code.

docs/testing.rst

@@ -314,3 +314,25 @@ Second, the register allocator is run on the function, inserting spill code and
 assigning registers and stack slots to all values.
 
 The resulting function is then run through filecheck.
+
+`test binemit`
+--------------
+
+Test the emission of binary machine code.
+
+The functions must contains instructions that are annotated with both encodings
+and value locations (registers or stack slots). For instructions that are
+annotated with a `bin:` directive, the emitted hexadecimal machine code for
+that instruction is compared to the directive::
+
+    test binemit
+    isa riscv
+
+    function int32() {
+    ebb0:
+        [-,%x5]             v1 = iconst.i32 1
+        [-,%x6]             v2 = iconst.i32 2
+        [R#0c,%x7]          v10 = iadd v1, v2       ; bin: 006283b3
+        [R#200c,%x8]        v11 = isub v1, v2       ; bin: 40628433
+        return
+    }

filetests/isa/riscv/binary32.cton

@@ -0,0 +1,13 @@
+; Binary emission of 32-bit code.
+test binemit
+isa riscv
+
+function int32() {
+ebb0:
+    [-,%x5]             v1 = iconst.i32 1
+    [-,%x6]             v2 = iconst.i32 2
+    [R#0c,%x7]          v10 = iadd v1, v2       ; bin: 006283b3
+    [R#200c,%x8]        v11 = isub v1, v2       ; bin: 40628433
+    [R#10c]             v12 = imul v1, v2
+    return
+}

src/filetest/binemit.rs

@@ -0,0 +1,107 @@
+//! Test command for testing the binary machine code emission.
+//!
+//! The `binemit` test command generates binary machine code for every instruction in the input
+//! functions and compares the results to the expected output.
+
+use std::borrow::{Borrow, Cow};
+use std::fmt::Write;
+use cretonne::binemit;
+use cretonne::ir;
+use cretonne::ir::entities::AnyEntity;
+use cton_reader::TestCommand;
+use filetest::subtest::{SubTest, Context, Result};
+use utils::match_directive;
+
+struct TestBinEmit;
+
+pub fn subtest(parsed: &TestCommand) -> Result<Box<SubTest>> {
+    assert_eq!(parsed.command, "binemit");
+    if !parsed.options.is_empty() {
+        Err(format!("No options allowed on {}", parsed))
+    } else {
+        Ok(Box::new(TestBinEmit))
+    }
+}
+
+// Code sink that generates text.
+struct TextSink {
+    text: String,
+}
+
+impl binemit::CodeSink for TextSink {
+    fn put1(&mut self, x: u8) {
+        write!(self.text, "{:02x} ", x).unwrap();
+    }
+
+    fn put2(&mut self, x: u16) {
+        write!(self.text, "{:04x} ", x).unwrap();
+    }
+
+    fn put4(&mut self, x: u32) {
+        write!(self.text, "{:08x} ", x).unwrap();
+    }
+
+    fn put8(&mut self, x: u64) {
+        write!(self.text, "{:016x} ", x).unwrap();
+    }
+
+    fn reloc_func(&mut self, _: binemit::Reloc, _: ir::FuncRef) {
+        unimplemented!()
+    }
+
+    fn reloc_jt(&mut self, _: binemit::Reloc, _: ir::JumpTable) {
+        unimplemented!()
+    }
+}
+
+impl SubTest for TestBinEmit {
+    fn name(&self) -> Cow<str> {
+        Cow::from("binemit")
+    }
+
+    fn is_mutating(&self) -> bool {
+        false
+    }
+
+    fn needs_isa(&self) -> bool {
+        true
+    }
+
+    fn run(&self, func: Cow<ir::Function>, context: &Context) -> Result<()> {
+        let isa = context.isa.expect("binemit needs an ISA");
+        // TODO: Run a verifier pass over the code first to detect any bad encodings or missing/bad
+        // value locations. The current error reporting is just crashing...
+        let func = func.borrow();
+
+        let mut sink = TextSink { text: String::new() };
+
+        for comment in &context.details.comments {
+            if let Some(want) = match_directive(comment.text, "bin:") {
+                let inst = match comment.entity {
+                    AnyEntity::Inst(inst) => inst,
+                    _ => {
+                        return Err(format!("annotation on non-inst {}: {}",
+                                           comment.entity,
+                                           comment.text))
+                    }
+                };
+                sink.text.clear();
+                isa.emit_inst(&func, inst, &mut sink);
+                let have = sink.text.trim();
+                if have != want {
+                    return Err(format!("Bad machine code for {}: {}\nWant: {}\nGot:  {}",
+                                       inst,
+                                       func.dfg.display_inst(inst),
+                                       want,
+                                       have));
+                }
+            }
+        }
+
+        if sink.text.is_empty() {
+            Err("No bin: directives found".to_string())
+        } else {
+            Ok(())
+        }
+    }
+}

src/filetest/mod.rs

@@ -13,6 +13,7 @@ use filetest::runner::TestRunner;
 
 pub mod subtest;
 
+mod binemit;
 mod concurrent;
 mod domtree;
 mod legalizer;
@@ -60,6 +61,7 @@ fn new_subtest(parsed: &TestCommand) -> subtest::Result<Box<subtest::SubTest>> {
         "verifier" => verifier::subtest(parsed),
         "legalizer" => legalizer::subtest(parsed),
         "regalloc" => regalloc::subtest(parsed),
+        "binemit" => binemit::subtest(parsed),
         _ => Err(format!("unknown test command '{}'", parsed.command)),
     }
 }