Flatten tee (WebAssembly#1296)

* flatten tee_local in flatten, as it leads to more-optimizable code (tee_local, when nested, can introduce side effects in bad places).
* also fix some test stuff from recent merges

src/passes/Flatten.cpp

@@ -46,6 +46,8 @@
 //     anything else is written to a local earlier.
 //  2. Disallow block, loop, and if return values, i.e., do not use
 //     control flow to pass around values.
+//  3. Disallow tee_local, setting a local is always done in a set_local
+//     on a non-nested-expression location.
 //
 
 #include <wasm.h>
@@ -185,7 +187,19 @@ struct Flatten : public WalkerPass<ExpressionStackWalker<Flatten, UnifiedExpress
         ourPreludes.swap(iter->second);
       }
       // special handling
-      if (auto* br = curr->dynCast<Break>()) {
+      if (auto* set = curr->dynCast<SetLocal>()) {
+        if (set->isTee()) {
+          // we disallow tee_local
+          if (set->value->type == unreachable) {
+            replaceCurrent(set->value); // trivial, no set happens
+          } else {
+            // use a set in a prelude + a get
+            set->setTee(false);
+            ourPreludes.push_back(set);
+            replaceCurrent(builder.makeGetLocal(set->index, set->value->type));
+          }
+        }
+      } else if (auto* br = curr->dynCast<Break>()) {
         if (br->value) {
           auto type = br->value->type;
           if (isConcreteWasmType(type)) {

test/binaryen.js/kitchen-sink.js

@@ -214,7 +214,7 @@ function test_core() {
   console.log("getExpressionType=" + Binaryen.getExpressionType(valueList[3]));
   console.log(Binaryen.emitText(valueList[3])); // test printing a standalone expression
   console.log(Binaryen.getConstValueI32(module.i32.const(5)));
-  console.log(Binaryen.getConstValueI64(module.i64.const(6, 7)));
+  console.log(JSON.stringify(Binaryen.getConstValueI64(module.i64.const(6, 7))));
   console.log(Binaryen.getConstValueF32(module.f32.const(8.5)));
   console.log(Binaryen.getConstValueF64(module.f64.const(9.5)));
 

test/binaryen.js/kitchen-sink.js.txt

@@ -38,7 +38,7 @@ getExpressionType=3
 )
 
 5
-{ low: 6, high: 7 }
+{"low":6,"high":7}
 8.5
 9.5
 (module
@@ -1403,7 +1403,7 @@ getExpressionType=3
   expressions[248] = BinaryenConst(the_module, BinaryenLiteralInt64(30064771078));
   BinaryenConstGetValueI64Low(expressions[248]);
   BinaryenConstGetValueI64High(expressions[248]);
-{ low: 6, high: 7 }
+{"low":6,"high":7}
   expressions[249] = BinaryenConst(the_module, BinaryenLiteralFloat32(8.5));
   BinaryenConstGetValueF32(expressions[249]);
 8.5

test/passes/flatten.txt

@@ -112,10 +112,11 @@
   (local $6 i32)
   (local $7 i32)
   (block $block
+   (set_local $x
+    (i32.const 0)
+   )
    (set_local $1
-    (tee_local $x
-     (i32.const 0)
-    )
+    (get_local $x)
    )
    (set_local $2
     (get_local $1)
@@ -125,10 +126,11 @@
    (get_local $2)
   )
   (block $block1
+   (set_local $x
+    (i32.const 1)
+   )
    (set_local $4
-    (tee_local $x
-     (i32.const 1)
-    )
+    (get_local $x)
    )
    (set_local $5
     (get_local $4)
@@ -160,10 +162,11 @@
   (local $9 i32)
   (block $block
    (block $block2
+    (set_local $x
+     (i32.const 0)
+    )
     (set_local $1
-     (tee_local $x
-      (i32.const 0)
-     )
+     (get_local $x)
     )
     (set_local $2
      (get_local $1)
@@ -173,10 +176,11 @@
     (get_local $2)
    )
    (block $block3
+    (set_local $x
+     (i32.const 1)
+    )
     (set_local $4
-     (tee_local $x
-      (i32.const 1)
-     )
+     (get_local $x)
     )
     (set_local $5
      (get_local $4)
@@ -240,10 +244,11 @@
      )
      (br $outer)
      (unreachable)
+     (set_local $x
+      (i32.const 3)
+     )
      (set_local $5
-      (tee_local $x
-       (i32.const 3)
-      )
+      (get_local $x)
      )
      (set_local $6
       (get_local $5)
@@ -344,10 +349,11 @@
     (get_local $2)
    )
    (nop)
+   (set_local $x
+    (i32.const 2)
+   )
    (set_local $3
-    (tee_local $x
-     (i32.const 2)
-    )
+    (get_local $x)
    )
    (set_local $1
     (get_local $3)
@@ -362,10 +368,11 @@
     (get_local $4)
    )
    (nop)
+   (set_local $x
+    (i32.const 5)
+   )
    (set_local $5
-    (tee_local $x
-     (i32.const 5)
-    )
+    (get_local $x)
    )
    (set_local $1
     (i32.const 4)
@@ -380,15 +387,17 @@
     (get_local $6)
    )
    (nop)
+   (set_local $x
+    (i32.const 6)
+   )
    (set_local $7
-    (tee_local $x
-     (i32.const 6)
-    )
+    (get_local $x)
+   )
+   (set_local $x
+    (i32.const 7)
    )
    (set_local $8
-    (tee_local $x
-     (i32.const 7)
-    )
+    (get_local $x)
    )
    (set_local $1
     (get_local $7)
@@ -556,10 +565,11 @@
   (local $6 i32)
   (local $7 i32)
   (block $label$1
+   (set_local $x
+    (i32.const 1)
+   )
    (set_local $1
-    (tee_local $x
-     (i32.const 1)
-    )
+    (get_local $x)
    )
    (block $label$2
     (set_local $x
@@ -612,10 +622,11 @@
   (set_local $1
    (get_local $var$0)
   )
+  (set_local $var$0
+   (f32.const -137438953472)
+  )
   (set_local $2
-   (tee_local $var$0
-    (f32.const -137438953472)
-   )
+   (get_local $var$0)
   )
   (set_local $3
    (get_local $var$0)
@@ -1128,9 +1139,7 @@
     (i32.const 11)
     (block
      (unreachable)
-     (tee_local $x
-      (unreachable)
-     )
+     (unreachable)
      (unreachable)
     )
    )
@@ -2399,4 +2408,44 @@
    (get_local $9)
   )
  )
+ (func $tees (; 41 ;) (type $ii) (param $x i32) (param $y i32)
+  (local $2 i32)
+  (local $3 i32)
+  (local $4 i32)
+  (block
+   (set_local $x
+    (i32.const 1)
+   )
+   (set_local $2
+    (get_local $x)
+   )
+   (drop
+    (get_local $2)
+   )
+   (nop)
+   (unreachable)
+   (unreachable)
+   (drop
+    (unreachable)
+   )
+   (unreachable)
+   (set_local $x
+    (i32.const 2)
+   )
+   (set_local $3
+    (get_local $x)
+   )
+   (set_local $y
+    (get_local $3)
+   )
+   (set_local $4
+    (get_local $y)
+   )
+   (drop
+    (get_local $4)
+   )
+   (nop)
+  )
+  (unreachable)
+ )
 )

test/passes/flatten.wast

@@ -1011,4 +1011,9 @@
     )
    )
   )
+  (func $tees (param $x i32) (param $y i32)
+    (drop (tee_local $x (i32.const 1)))
+    (drop (tee_local $x (unreachable)))
+    (drop (tee_local $y (tee_local $x (i32.const 2))))
+  )
 )

test/passes/inlining.txt

@@ -225,7 +225,7 @@
  (memory $0 0)
  (func $0 (; 0 ;) (type $1)
   (block $__inlined_func$1
-   (call_indirect $T
+   (call_indirect (type $T)
     (if (result i32)
      (i32.const 0)
      (unreachable)

test/passes/inlining.wast

@@ -152,7 +152,7 @@
   (call $1)
  )
  (func $1
-  (call_indirect $T
+  (call_indirect (type $T)
    (if (result i32) ;; if copy must preserve the forced type
     (i32.const 0)
     (unreachable)