Optimize to i64.store[less] (#792)

3 files changed, 26 insertions, 4 deletions

diff --git a/src/passes/OptimizeInstructions.cpp b/src/passes/OptimizeInstructions.cpp
index 0b54f9756..7f1483371 100644
--- a/src/passes/OptimizeInstructions.cpp
+++ b/src/passes/OptimizeInstructions.cpp
@@ -314,18 +314,24 @@ struct OptimizeInstructions : public WalkerPass<PostWalker<OptimizeInstructions,
       }
     } else if (auto* store = curr->dynCast<Store>()) {
       // stores of fewer bits truncates anyhow
-      if (auto* value = store->value->dynCast<Binary>()) {
-        if (value->op == AndInt32) {
-          if (auto* right = value->right->dynCast<Const>()) {
+      if (auto* binary = store->value->dynCast<Binary>()) {
+        if (binary->op == AndInt32) {
+          if (auto* right = binary->right->dynCast<Const>()) {
             if (right->type == i32) {
               auto mask = right->value.geti32();
               if ((store->bytes == 1 && mask == 0xff) ||
                   (store->bytes == 2 && mask == 0xffff)) {
-                store->value = value->left;
+                store->value = binary->left;
               }
             }
           }
         }
+      } else if (auto* unary = store->value->dynCast<Unary>()) {
+        if (unary->op == WrapInt64) {
+          // instead of wrapping to 32, just store some of the bits in the i64
+          store->valueType = i64;
+          store->value = unary->value;
+        }
       }
     }
     return nullptr;
diff --git a/test/passes/optimize-instructions.txt b/test/passes/optimize-instructions.txt
index 73076b0c5..ca5898e73 100644
--- a/test/passes/optimize-instructions.txt
+++ b/test/passes/optimize-instructions.txt
@@ -289,6 +289,18 @@
         (i32.const 65534)
       )
     )
+    (i64.store8
+      (i32.const 11)
+      (i64.const 1)
+    )
+    (i64.store16
+      (i32.const 11)
+      (i64.const 2)
+    )
+    (i64.store32
+      (i32.const 11)
+      (i64.const 3)
+    )
   )
   (func $and-neg1 (type $1)
     (drop
diff --git a/test/passes/optimize-instructions.wast b/test/passes/optimize-instructions.wast
index 9701941c7..e6d18240d 100644
--- a/test/passes/optimize-instructions.wast
+++ b/test/passes/optimize-instructions.wast
@@ -266,6 +266,10 @@
     (i32.store8 (i32.const 9) (i32.and (i32.const -2) (i32.const 254)))
     (i32.store16 (i32.const 10) (i32.and (i32.const -3) (i32.const 65535)))
     (i32.store16 (i32.const 11) (i32.and (i32.const -4) (i32.const 65534)))
+    ;;
+    (i32.store8 (i32.const 11) (i32.wrap/i64 (i64.const 1)))
+    (i32.store16 (i32.const 11) (i32.wrap/i64 (i64.const 2)))
+    (i32.store (i32.const 11) (i32.wrap/i64 (i64.const 3)))
   )
   (func $and-neg1
     (drop (i32.and (i32.const 100) (i32.const -1)))