Group reference types in binary format. Fixes #4773

src/wasm/wasm-stack.cpp

@@ -2308,6 +2308,29 @@ void BinaryInstWriter::mapLocalsAndEmitHeader() {
     }
   }
   countScratchLocals();
+
+  if (parent.getModule()->features.hasReferenceTypes()) {
+    // Sort local types in a way that keeps all MVP types together and all
+    // reference types together. E.g. it is helpful to avoid a block of i32s in
+    // between blocks of different reference types, since clearing out reference
+    // types may require different work.
+    //
+    // See https://github.com/WebAssembly/binaryen/issues/4773
+    //
+    // In order to decide whether to put MVP types or reference types first,
+    // look at the type of the first local. In an optimized binary we will have
+    // sorted the locals by frequency of uses, so this way we'll keep the most
+    // commonly-used local at the top, which should work well in many cases.
+    bool refsFirst = !localTypes.empty() && localTypes[0].isRef();
+    std::stable_sort(localTypes.begin(), localTypes.end(), [&](Type a, Type b) {
+      if (refsFirst) {
+        return a.isRef() && !b.isRef();
+      } else {
+        return !a.isRef() && b.isRef();
+      }
+    });
+  }
+
   std::unordered_map<Type, size_t> currLocalsByType;
   for (Index i = func->getVarIndexBase(); i < func->getNumLocals(); i++) {
     Index j = 0;

test/typed-function-references.wast

@@ -41,4 +41,45 @@
       )
     )
   )
+  (func $ref-types-first
+    ;; 6 reference types and 3 MVP types. The binary format should emit all the
+    ;; reference types first since a reference type appears first. In addition,
+    ;; types should be emitted in blocks there, that is, locals of identical
+    ;; types should be adjacent.
+    (local $r1 (ref null $mixed_results))
+    (local $r2 (ref null $mixed_results))
+    (local $i1 i32)
+    (local $r3 anyref)
+    (local $i2 i64)
+    (local $r4 anyref)
+    (local $i3 i64)
+    (local $r5 anyref)
+    (local $r6 funcref)
+  )
+  (func $mvp-types-first
+    ;; Reversed from before, now an MVP type appears first, so they should all
+    ;; be before reference types in the binary format.
+    (local $i1 i32) ;; only this local was moved up.
+    (local $r1 (ref null $mixed_results))
+    (local $r2 (ref null $mixed_results))
+    (local $r3 anyref)
+    (local $i2 i64)
+    (local $r4 anyref)
+    (local $i3 i64)
+    (local $r5 anyref)
+    (local $r6 funcref)
+  )
+  (func $mvp-types-first-param (param $r0 (ref null $mixed_results))
+    ;; As before, but now there is a reference type *parameter*. We should
+    ;; ignore that and sort as in the last function.
+    (local $i1 i32) ;; only this local was moved up.
+    (local $r1 (ref null $mixed_results))
+    (local $r2 (ref null $mixed_results))
+    (local $r3 anyref)
+    (local $i2 i64)
+    (local $r4 anyref)
+    (local $i3 i64)
+    (local $r5 anyref)
+    (local $r6 funcref)
+  )
 )

test/typed-function-references.wast.from-wast

@@ -1,4 +1,5 @@
 (module
+ (type $mixed_results (func (result anyref f32 anyref f32)))
  (type $none_=>_none (func))
  (type $i32-i32 (func (param i32) (result i32)))
  (type $=>eqref (func (result eqref)))
@@ -8,7 +9,7 @@
  (type $f64_=>_ref_null<_->_eqref> (func (param f64) (result (ref null $=>eqref))))
  (type $=>anyref (func (result anyref)))
  (type $none_=>_i32_ref?|$mixed_results|_f64 (func (result i32 (ref null $mixed_results) f64)))
- (type $mixed_results (func (result anyref f32 anyref f32)))
+ (type $ref?|$mixed_results|_=>_none (func (param (ref null $mixed_results))))
  (elem declare func $call-ref $call-ref-more)
  (func $call-ref
   (call_ref
@@ -62,4 +63,40 @@
    )
   )
  )
+ (func $ref-types-first
+  (local $r1 (ref null $mixed_results))
+  (local $r2 (ref null $mixed_results))
+  (local $i1 i32)
+  (local $r3 anyref)
+  (local $i2 i64)
+  (local $r4 anyref)
+  (local $i3 i64)
+  (local $r5 anyref)
+  (local $r6 funcref)
+  (nop)
+ )
+ (func $mvp-types-first
+  (local $i1 i32)
+  (local $r1 (ref null $mixed_results))
+  (local $r2 (ref null $mixed_results))
+  (local $r3 anyref)
+  (local $i2 i64)
+  (local $r4 anyref)
+  (local $i3 i64)
+  (local $r5 anyref)
+  (local $r6 funcref)
+  (nop)
+ )
+ (func $mvp-types-first-param (param $r0 (ref null $mixed_results))
+  (local $i1 i32)
+  (local $r1 (ref null $mixed_results))
+  (local $r2 (ref null $mixed_results))
+  (local $r3 anyref)
+  (local $i2 i64)
+  (local $r4 anyref)
+  (local $i3 i64)
+  (local $r5 anyref)
+  (local $r6 funcref)
+  (nop)
+ )
 )

test/typed-function-references.wast.fromBinary

@@ -1,14 +1,15 @@
 (module
+ (type $mixed_results (func (result anyref f32 anyref f32)))
  (type $none_=>_none (func))
  (type $i32-i32 (func (param i32) (result i32)))
- (type $mixed_results (func (result anyref f32 anyref f32)))
  (type $=>eqref (func (result eqref)))
  (type $ref|$i32-i32|_=>_i32 (func (param (ref $i32-i32)) (result i32)))
  (type $ref?|$i32-i32|_=>_i32 (func (param (ref null $i32-i32)) (result i32)))
  (type $none_=>_i32 (func (result i32)))
  (type $f64_=>_ref_null<_->_eqref> (func (param f64) (result (ref null $=>eqref))))
  (type $=>anyref (func (result anyref)))
  (type $none_=>_i32_ref?|$mixed_results|_f64 (func (result i32 (ref null $mixed_results) f64)))
+ (type $ref?|$mixed_results|_=>_none (func (param (ref null $mixed_results))))
  (elem declare func $call-ref $call-ref-more)
  (func $call-ref
   (call_ref
@@ -53,8 +54,8 @@
  )
  (func $type-only-in-tuple-local
   (local $x i32)
-  (local $1 (ref null $=>anyref))
-  (local $2 f64)
+  (local $1 f64)
+  (local $2 (ref null $=>anyref))
   (nop)
  )
  (func $type-only-in-tuple-block
@@ -92,5 +93,41 @@
    )
   )
  )
+ (func $ref-types-first
+  (local $r1 (ref null $mixed_results))
+  (local $r2 (ref null $mixed_results))
+  (local $r3 anyref)
+  (local $r4 anyref)
+  (local $r5 anyref)
+  (local $r6 funcref)
+  (local $i1 i32)
+  (local $i2 i64)
+  (local $i3 i64)
+  (nop)
+ )
+ (func $mvp-types-first
+  (local $i1 i32)
+  (local $i2 i64)
+  (local $i3 i64)
+  (local $r1 (ref null $mixed_results))
+  (local $r2 (ref null $mixed_results))
+  (local $r3 anyref)
+  (local $r4 anyref)
+  (local $r5 anyref)
+  (local $r6 funcref)
+  (nop)
+ )
+ (func $mvp-types-first-param (param $r0 (ref null $mixed_results))
+  (local $i1 i32)
+  (local $i2 i64)
+  (local $i3 i64)
+  (local $r1 (ref null $mixed_results))
+  (local $r2 (ref null $mixed_results))
+  (local $r3 anyref)
+  (local $r4 anyref)
+  (local $r5 anyref)
+  (local $r6 funcref)
+  (nop)
+ )
 )
 

test/typed-function-references.wast.fromBinary.noDebugInfo

@@ -1,14 +1,15 @@
 (module
+ (type $none_=>_anyref_f32_anyref_f32 (func (result anyref f32 anyref f32)))
  (type $none_=>_none (func))
  (type $i32_=>_i32 (func (param i32) (result i32)))
- (type $none_=>_anyref_f32_anyref_f32 (func (result anyref f32 anyref f32)))
  (type $none_=>_eqref (func (result eqref)))
  (type $ref|i32_->_i32|_=>_i32 (func (param (ref $i32_=>_i32)) (result i32)))
  (type $ref?|i32_->_i32|_=>_i32 (func (param (ref null $i32_=>_i32)) (result i32)))
  (type $none_=>_i32 (func (result i32)))
  (type $f64_=>_ref?|none_->_eqref| (func (param f64) (result (ref null $none_=>_eqref))))
  (type $none_=>_anyref (func (result anyref)))
  (type $none_=>_i32_ref?|none_->_anyref_f32_anyref_f32|_f64 (func (result i32 (ref null $none_=>_anyref_f32_anyref_f32) f64)))
+ (type $ref?|none_->_anyref_f32_anyref_f32|_=>_none (func (param (ref null $none_=>_anyref_f32_anyref_f32))))
  (elem declare func $0 $2)
  (func $0
   (call_ref
@@ -53,8 +54,8 @@
  )
  (func $7
   (local $0 i32)
-  (local $1 (ref null $none_=>_anyref))
-  (local $2 f64)
+  (local $1 f64)
+  (local $2 (ref null $none_=>_anyref))
   (nop)
  )
  (func $8
@@ -92,5 +93,41 @@
    )
   )
  )
+ (func $9
+  (local $0 (ref null $none_=>_anyref_f32_anyref_f32))
+  (local $1 (ref null $none_=>_anyref_f32_anyref_f32))
+  (local $2 anyref)
+  (local $3 anyref)
+  (local $4 anyref)
+  (local $5 funcref)
+  (local $6 i32)
+  (local $7 i64)
+  (local $8 i64)
+  (nop)
+ )
+ (func $10
+  (local $0 i32)
+  (local $1 i64)
+  (local $2 i64)
+  (local $3 (ref null $none_=>_anyref_f32_anyref_f32))
+  (local $4 (ref null $none_=>_anyref_f32_anyref_f32))
+  (local $5 anyref)
+  (local $6 anyref)
+  (local $7 anyref)
+  (local $8 funcref)
+  (nop)
+ )
+ (func $11 (param $0 (ref null $none_=>_anyref_f32_anyref_f32))
+  (local $1 i32)
+  (local $2 i64)
+  (local $3 i64)
+  (local $4 (ref null $none_=>_anyref_f32_anyref_f32))
+  (local $5 (ref null $none_=>_anyref_f32_anyref_f32))
+  (local $6 anyref)
+  (local $7 anyref)
+  (local $8 anyref)
+  (local $9 funcref)
+  (nop)
+ )
 )