Run the filetests as part of "cargo test".

Refactor the filetests harness so that it can be run as part of
`cargo test`. And begin reorganizing the test harness code in preparation
for moving it out of the src directory.
 - Test subcommand files are now named `test_*.rs`.
 - cton-util subcommand files now just export their `run` and nothing else.
 - src/filetest/mod.rs now also just exports `run` and nothing else.
 - Tests are now run in release mode (with debug assertions enabled).

lib/cretonne/src/cfg_printer.rs

@@ -0,0 +1,76 @@
+//! The `CFGPrinter` utility.
+
+use std::fmt::{Result, Write, Display, Formatter};
+
+use flowgraph::ControlFlowGraph;
+use ir::Function;
+use ir::instructions::BranchInfo;
+
+/// A utility for pretty-printing the CFG of a `Function`.
+pub struct CFGPrinter<'a> {
+    func: &'a Function,
+    cfg: ControlFlowGraph,
+}
+
+/// A utility for pretty-printing the CFG of a `Function`.
+impl<'a> CFGPrinter<'a> {
+    /// Create a new CFGPrinter.
+    pub fn new(func: &'a Function) -> CFGPrinter<'a> {
+        CFGPrinter {
+            func,
+            cfg: ControlFlowGraph::with_function(func),
+        }
+    }
+
+    /// Write the CFG for this function to `w`.
+    pub fn write(&self, w: &mut Write) -> Result {
+        self.header(w)?;
+        self.ebb_nodes(w)?;
+        self.cfg_connections(w)?;
+        writeln!(w, "}}")
+    }
+
+    fn header(&self, w: &mut Write) -> Result {
+        writeln!(w, "digraph \"{}\" {{", self.func.name)?;
+        if let Some(entry) = self.func.layout.entry_block() {
+            writeln!(w, "    {{rank=min; {}}}", entry)?;
+        }
+        Ok(())
+    }
+
+    fn ebb_nodes(&self, w: &mut Write) -> Result {
+        for ebb in &self.func.layout {
+            write!(w, "    {} [shape=record, label=\"{{{}", ebb, ebb)?;
+            // Add all outgoing branch instructions to the label.
+            for inst in self.func.layout.ebb_insts(ebb) {
+                let idata = &self.func.dfg[inst];
+                match idata.analyze_branch(&self.func.dfg.value_lists) {
+                    BranchInfo::SingleDest(dest, _) => {
+                        write!(w, " | <{}>{} {}", inst, idata.opcode(), dest)?
+                    }
+                    BranchInfo::Table(table) => {
+                        write!(w, " | <{}>{} {}", inst, idata.opcode(), table)?
+                    }
+                    BranchInfo::NotABranch => {}
+                }
+            }
+            writeln!(w, "}}\"]")?
+        }
+        Ok(())
+    }
+
+    fn cfg_connections(&self, w: &mut Write) -> Result {
+        for ebb in &self.func.layout {
+            for (parent, inst) in self.cfg.pred_iter(ebb) {
+                writeln!(w, "    {}:{} -> {}", parent, inst, ebb)?;
+            }
+        }
+        Ok(())
+    }
+}
+
+impl<'a> Display for CFGPrinter<'a> {
+    fn fmt(&self, f: &mut Formatter) -> Result {
+        self.write(f)
+    }
+}

lib/cretonne/src/lib.rs

@@ -19,6 +19,7 @@ pub mod entity;
 
 pub mod bforest;
 pub mod binemit;
+pub mod cfg_printer;
 pub mod cursor;
 pub mod dominator_tree;
 pub mod flowgraph;