From 0947940c43c1d08caec50e92e9aa33a45762501f Mon Sep 17 00:00:00 2001
From: Chris Fallin <chris@cfallin.org>
Date: Sun, 12 Dec 2021 20:11:28 -0800
Subject: [PATCH] Refactor

---
 src/backend/locations.rs |  9 ++++++++
 src/backend/mod.rs       |  2 ++
 src/frontend.rs          | 50 +++++++++++++++++++---------------------
 src/ir.rs                |  2 +-
 4 files changed, 36 insertions(+), 27 deletions(-)
 create mode 100644 src/backend/locations.rs

diff --git a/src/backend/locations.rs b/src/backend/locations.rs
new file mode 100644
index 0000000..2098cbb
--- /dev/null
+++ b/src/backend/locations.rs
@@ -0,0 +1,9 @@
+//! Location assignment (pseudo-regalloc) for SSA values onto
+//! locals/operand-stack values.
+
+use crate::LocalId;
+
+pub enum Location {
+    Local(LocalId),
+    // TODO: use operand stack
+}
diff --git a/src/backend/mod.rs b/src/backend/mod.rs
index 3b2699b..9cbdf46 100644
--- a/src/backend/mod.rs
+++ b/src/backend/mod.rs
@@ -2,3 +2,5 @@
 
 mod stackify;
 pub(crate) use stackify::*;
+mod locations;
+pub(crate) use locations::*;
diff --git a/src/frontend.rs b/src/frontend.rs
index 8a69dc3..8a2ea5f 100644
--- a/src/frontend.rs
+++ b/src/frontend.rs
@@ -554,7 +554,7 @@ impl<'a, 'b> FunctionBodyBuilder<'a, 'b> {
         match &op {
             wasmparser::Operator::Unreachable => {
                 if let Some(block) = self.cur_block {
-                    self.body.blocks[block].terminator = Terminator::None;
+                    self.body.end_block(block, Terminator::None);
                     self.locals.finish_block();
                 }
                 self.cur_block = None;
@@ -1033,12 +1033,11 @@ impl<'a, 'b> FunctionBodyBuilder<'a, 'b> {
         );
         if let Some(block) = self.cur_block {
             let args = args.to_vec();
-            self.body.add_edge(block, target);
             let target = BlockTarget {
                 block: target,
                 args,
             };
-            self.body.blocks[block].terminator = Terminator::Br { target };
+            self.body.end_block(block, Terminator::Br { target });
             self.cur_block = None;
             self.locals.finish_block();
         }
@@ -1063,19 +1062,20 @@ impl<'a, 'b> FunctionBodyBuilder<'a, 'b> {
         if let Some(block) = self.cur_block {
             let if_true_args = if_true_args.to_vec();
             let if_false_args = if_false_args.to_vec();
-            self.body.blocks[block].terminator = Terminator::CondBr {
-                cond,
-                if_true: BlockTarget {
-                    block: if_true,
-                    args: if_true_args,
+            self.body.end_block(
+                block,
+                Terminator::CondBr {
+                    cond,
+                    if_true: BlockTarget {
+                        block: if_true,
+                        args: if_true_args,
+                    },
+                    if_false: BlockTarget {
+                        block: if_false,
+                        args: if_false_args,
+                    },
                 },
-                if_false: BlockTarget {
-                    block: if_false,
-                    args: if_false_args,
-                },
-            };
-            self.body.add_edge(block, if_true);
-            self.body.add_edge(block, if_false);
+            );
             self.cur_block = None;
             self.locals.finish_block();
         }
@@ -1112,16 +1112,14 @@ impl<'a, 'b> FunctionBodyBuilder<'a, 'b> {
                 args: default_args,
             };
 
-            for &target in indexed_targets {
-                self.body.add_edge(block, target);
-            }
-            self.body.add_edge(block, default_target);
-
-            self.body.blocks[block].terminator = Terminator::Select {
-                value: index,
-                targets,
-                default,
-            };
+            self.body.end_block(
+                block,
+                Terminator::Select {
+                    value: index,
+                    targets,
+                    default,
+                },
+            );
             self.cur_block = None;
             self.locals.finish_block();
         }
@@ -1130,7 +1128,7 @@ impl<'a, 'b> FunctionBodyBuilder<'a, 'b> {
     fn emit_ret(&mut self, values: &[Value]) {
         if let Some(block) = self.cur_block {
             let values = values.to_vec();
-            self.body.blocks[block].terminator = Terminator::Return { values };
+            self.body.end_block(block, Terminator::Return { values });
         }
     }
 
diff --git a/src/ir.rs b/src/ir.rs
index 49007d7..138c508 100644
--- a/src/ir.rs
+++ b/src/ir.rs
@@ -90,7 +90,7 @@ impl FunctionBody {
         assert_ne!(to, Value::undef());
         log::trace!("set_alias: value {:?} to {:?}", value, to);
         // Resolve the `to` value through all existing aliases.
-        let to = self.resolve_alias(to);
+        let to = self.resolve_and_update_alias(to);
         // Disallow cycles.
         if to == value {
             panic!("Cannot create an alias cycle");