1 files changed, 56 insertions, 0 deletions
diff --git a/third_party/rust/regalloc/src/pretty_print.rs b/third_party/rust/regalloc/src/pretty_print.rs
new file mode 100644
index 0000000000..8f01c0766e
--- /dev/null
+++ b/third_party/rust/regalloc/src/pretty_print.rs
@@ -0,0 +1,56 @@
+//! Pretty-printing for the main data structures.
+
+use crate::data_structures::WritableBase;
+use crate::{RealRegUniverse, Reg, Writable};
+
+/// A trait for printing instruction bits and pieces, with the the ability to take a
+/// contextualising `RealRegUniverse` that is used to give proper names to registers.
+pub trait PrettyPrint {
+    /// Return a string that shows the implementing object in context of the given
+    /// `RealRegUniverse`, if provided.
+    fn show_rru(&self, maybe_reg_universe: Option<&RealRegUniverse>) -> String;
+}
+
+/// Same as `PrettyPrint`, but can also take a size hint into account to specialize the displayed
+/// string.
+pub trait PrettyPrintSized: PrettyPrint {
+    /// The same as |show_rru|, but with an optional hint giving a size in bytes. Its
+    /// interpretation is object-dependent, and it is intended to pass around enough information to
+    /// facilitate printing sub-parts of real registers correctly. Objects may ignore size hints
+    /// that are irrelevant to them.
+    ///
+    /// The default implementation ignores the size hint.
+    fn show_rru_sized(&self, maybe_reg_universe: Option<&RealRegUniverse>, _size: u8) -> String {
+        self.show_rru(maybe_reg_universe)
+    }
+}
+
+impl PrettyPrint for Reg {
+    fn show_rru(&self, maybe_reg_universe: Option<&RealRegUniverse>) -> String {
+        if self.is_real() {
+            if let Some(rru) = maybe_reg_universe {
+                let reg_ix = self.get_index();
+                assert!(
+                    reg_ix < rru.regs.len(),
+                    "unknown real register with index {:?}",
+                    reg_ix
+                );
+                return rru.regs[reg_ix].1.to_string();
+            }
+        }
+        // The reg is virtual, or we have no universe. Be generic.
+        format!("%{:?}", self)
+    }
+}
+
+impl<R: PrettyPrint + WritableBase> PrettyPrint for Writable<R> {
+    fn show_rru(&self, maybe_reg_universe: Option<&RealRegUniverse>) -> String {
+        self.to_reg().show_rru(maybe_reg_universe)
+    }
+}
+
+impl<R: PrettyPrintSized + WritableBase> PrettyPrintSized for Writable<R> {
+    fn show_rru_sized(&self, maybe_reg_universe: Option<&RealRegUniverse>, size: u8) -> String {
+        self.to_reg().show_rru_sized(maybe_reg_universe, size)
+    }
+}