Start a very simple GVN pass (#79)

* Skeleton simple_gvn pass.
* Basic testing infrastructure for simple-gvn.
* Add can_load and can_store flags to instructions.
* Move the replace_values function into the DataFlowGraph.
* Make InstructionData derive from Hash, PartialEq, and Eq.
* Make EntityList's hash and eq functions panic.
* Change Ieee32 and Ieee64 to store u32 and u64, respectively.

src/filetest/mod.rs

@@ -20,6 +20,7 @@ mod legalizer;
 mod regalloc;
 mod runner;
 mod runone;
+mod simple_gvn;
 mod verifier;
 
 /// The result of running the test in a file.
@@ -62,6 +63,7 @@ fn new_subtest(parsed: &TestCommand) -> subtest::Result<Box<subtest::SubTest>> {
         "legalizer" => legalizer::subtest(parsed),
         "regalloc" => regalloc::subtest(parsed),
         "binemit" => binemit::subtest(parsed),
+        "simple-gvn" => simple_gvn::subtest(parsed),
         _ => Err(format!("unknown test command '{}'", parsed.command)),
     }
 }

src/filetest/simple_gvn.rs

@@ -0,0 +1,51 @@
+//! Test command for testing the simple GVN pass.
+//!
+//! The `simple-gvn` test command runs each function through the simple GVN pass after ensuring
+//! that all instructions are legal for the target.
+//!
+//! The resulting function is sent to `filecheck`.
+
+use cretonne::ir::Function;
+use cretonne;
+use cton_reader::TestCommand;
+use filetest::subtest::{SubTest, Context, Result, run_filecheck};
+use std::borrow::Cow;
+use std::fmt::Write;
+use utils::pretty_error;
+
+struct TestSimpleGVN;
+
+pub fn subtest(parsed: &TestCommand) -> Result<Box<SubTest>> {
+    assert_eq!(parsed.command, "simple-gvn");
+    if !parsed.options.is_empty() {
+        Err(format!("No options allowed on {}", parsed))
+    } else {
+        Ok(Box::new(TestSimpleGVN))
+    }
+}
+
+impl SubTest for TestSimpleGVN {
+    fn name(&self) -> Cow<str> {
+        Cow::from("simple-gvn")
+    }
+
+    fn is_mutating(&self) -> bool {
+        true
+    }
+
+    fn run(&self, func: Cow<Function>, context: &Context) -> Result<()> {
+        // Create a compilation context, and drop in the function.
+        let mut comp_ctx = cretonne::Context::new();
+        comp_ctx.func = func.into_owned();
+
+        comp_ctx.flowgraph();
+        comp_ctx
+            .simple_gvn()
+            .map_err(|e| pretty_error(&comp_ctx.func, e))?;
+
+        let mut text = String::new();
+        write!(&mut text, "{}", &comp_ctx.func)
+            .map_err(|e| e.to_string())?;
+        run_filecheck(&text, context)
+    }
+}