From bcc76146fed433cbc8ba01a9f568d979c145110b Mon Sep 17 00:00:00 2001
From: Heejin Ahn <aheejin@gmail.com>
Date: Mon, 30 Dec 2019 17:55:20 -0800
Subject: Add support for reference types proposal (#2451)

This adds support for the reference type proposal. This includes support
for all reference types (`anyref`, `funcref`(=`anyfunc`), and `nullref`)
and four new instructions: `ref.null`, `ref.is_null`, `ref.func`, and
new typed `select`. This also adds subtype relationship support between
reference types.

This does not include table instructions yet. This also does not include
wasm2js support.

Fixes #2444 and fixes #2447.
---
 src/passes/MergeLocals.cpp | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

(limited to 'src/passes/MergeLocals.cpp')

diff --git a/src/passes/MergeLocals.cpp b/src/passes/MergeLocals.cpp
index 0116753f1..2223594b6 100644
--- a/src/passes/MergeLocals.cpp
+++ b/src/passes/MergeLocals.cpp
@@ -100,7 +100,8 @@ struct MergeLocals
       return;
     }
     // compute all dependencies
-    LocalGraph preGraph(getFunction());
+    auto* func = getFunction();
+    LocalGraph preGraph(func);
     preGraph.computeInfluences();
     // optimize each copy
     std::unordered_map<LocalSet*, LocalSet*> optimizedToCopy,
@@ -119,6 +120,11 @@ struct MergeLocals
           if (preGraph.getSetses[influencedGet].size() == 1) {
             // this is ok
             assert(*preGraph.getSetses[influencedGet].begin() == trivial);
+            // If local types are different (when one is a subtype of the
+            // other), don't optimize
+            if (func->getLocalType(copy->index) != influencedGet->type) {
+              canOptimizeToCopy = false;
+            }
           } else {
             canOptimizeToCopy = false;
             break;
@@ -152,6 +158,11 @@ struct MergeLocals
               if (preGraph.getSetses[influencedGet].size() == 1) {
                 // this is ok
                 assert(*preGraph.getSetses[influencedGet].begin() == copy);
+                // If local types are different (when one is a subtype of the
+                // other), don't optimize
+                if (func->getLocalType(trivial->index) != influencedGet->type) {
+                  canOptimizeToTrivial = false;
+                }
               } else {
                 canOptimizeToTrivial = false;
                 break;
@@ -176,7 +187,7 @@ struct MergeLocals
       // if one does not work, we need to undo all its siblings (don't extend
       // the live range unless we are definitely removing a conflict, same
       // logic as before).
-      LocalGraph postGraph(getFunction());
+      LocalGraph postGraph(func);
       postGraph.computeInfluences();
       for (auto& pair : optimizedToCopy) {
         auto* copy = pair.first;
-- 
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