MergeBlocks: canonicalize loop exit block position on the inside (#1736)

* move a loop exit block (block with a name, and one child which is the loop) into the loop in MergeBlocks, as that is better for other passes

8 files changed, 108 insertions, 77 deletions

diff --git a/test/emcc_hello_world.fromasm b/test/emcc_hello_world.fromasm
index f730a33e7..c243b2c8e 100644
--- a/test/emcc_hello_world.fromasm
+++ b/test/emcc_hello_world.fromasm
@@ -269,32 +269,32 @@
   (local $2 i32)
   (block $__rjto$1
    (block $__rjti$1
-    (block $__rjti$0
-     (loop $while-in
-      (br_if $__rjti$0
-       (i32.eq
-        (i32.load8_u offset=687
-         (get_local $1)
-        )
-        (get_local $0)
+    (loop $while-in
+     (if
+      (i32.ne
+       (i32.load8_u offset=687
+        (get_local $1)
        )
+       (get_local $0)
       )
-      (br_if $while-in
-       (i32.ne
-        (tee_local $1
-         (i32.add
-          (get_local $1)
-          (i32.const 1)
+      (block
+       (br_if $while-in
+        (i32.ne
+         (tee_local $1
+          (i32.add
+           (get_local $1)
+           (i32.const 1)
+          )
          )
+         (i32.const 87)
         )
+       )
+       (set_local $1
         (i32.const 87)
        )
+       (br $__rjti$1)
       )
      )
-     (set_local $1
-      (i32.const 87)
-     )
-     (br $__rjti$1)
     )
     (br_if $__rjti$1
      (get_local $1)
@@ -780,8 +780,8 @@
   )
   (block $__rjto$1
    (block $__rjti$1
-    (block $__rjti$0
-     (loop $while-in
+    (loop $while-in
+     (block $__rjti$0
       (if
        (i32.load
         (i32.const 16)
diff --git a/test/emcc_hello_world.fromasm.clamp b/test/emcc_hello_world.fromasm.clamp
index c9ca55f67..5ee4c0133 100644
--- a/test/emcc_hello_world.fromasm.clamp
+++ b/test/emcc_hello_world.fromasm.clamp
@@ -267,32 +267,32 @@
   (local $2 i32)
   (block $__rjto$1
    (block $__rjti$1
-    (block $__rjti$0
-     (loop $while-in
-      (br_if $__rjti$0
-       (i32.eq
-        (i32.load8_u offset=687
-         (get_local $1)
-        )
-        (get_local $0)
+    (loop $while-in
+     (if
+      (i32.ne
+       (i32.load8_u offset=687
+        (get_local $1)
        )
+       (get_local $0)
       )
-      (br_if $while-in
-       (i32.ne
-        (tee_local $1
-         (i32.add
-          (get_local $1)
-          (i32.const 1)
+      (block
+       (br_if $while-in
+        (i32.ne
+         (tee_local $1
+          (i32.add
+           (get_local $1)
+           (i32.const 1)
+          )
          )
+         (i32.const 87)
         )
+       )
+       (set_local $1
         (i32.const 87)
        )
+       (br $__rjti$1)
       )
      )
-     (set_local $1
-      (i32.const 87)
-     )
-     (br $__rjti$1)
     )
     (br_if $__rjti$1
      (get_local $1)
@@ -778,8 +778,8 @@
   )
   (block $__rjto$1
    (block $__rjti$1
-    (block $__rjti$0
-     (loop $while-in
+    (loop $while-in
+     (block $__rjti$0
       (if
        (i32.load
         (i32.const 16)
diff --git a/test/emcc_hello_world.fromasm.imprecise b/test/emcc_hello_world.fromasm.imprecise
index 50bd5f37a..70aea54a9 100644
--- a/test/emcc_hello_world.fromasm.imprecise
+++ b/test/emcc_hello_world.fromasm.imprecise
@@ -266,32 +266,32 @@
   (local $2 i32)
   (block $__rjto$1
    (block $__rjti$1
-    (block $__rjti$0
-     (loop $while-in
-      (br_if $__rjti$0
-       (i32.eq
-        (i32.load8_u offset=687
-         (get_local $1)
-        )
-        (get_local $0)
+    (loop $while-in
+     (if
+      (i32.ne
+       (i32.load8_u offset=687
+        (get_local $1)
        )
+       (get_local $0)
       )
-      (br_if $while-in
-       (i32.ne
-        (tee_local $1
-         (i32.add
-          (get_local $1)
-          (i32.const 1)
+      (block
+       (br_if $while-in
+        (i32.ne
+         (tee_local $1
+          (i32.add
+           (get_local $1)
+           (i32.const 1)
+          )
          )
+         (i32.const 87)
         )
+       )
+       (set_local $1
         (i32.const 87)
        )
+       (br $__rjti$1)
       )
      )
-     (set_local $1
-      (i32.const 87)
-     )
-     (br $__rjti$1)
     )
     (br_if $__rjti$1
      (get_local $1)
@@ -772,8 +772,8 @@
   )
   (block $__rjto$1
    (block $__rjti$1
-    (block $__rjti$0
-     (loop $while-in
+    (loop $while-in
+     (block $__rjti$0
       (if
        (i32.load
         (i32.const 16)
diff --git a/test/passes/1.txt b/test/passes/1.txt
index 72d0c87b8..22b7032fe 100644
--- a/test/passes/1.txt
+++ b/test/passes/1.txt
@@ -45,8 +45,8 @@
     (get_local $0)
    )
   )
-  (block $block$11$break
-   (loop $shape$9$continue
+  (loop $shape$9$continue
+   (block $block$11$break
     (call $trivial)
     (br_if $block$11$break
      (i32.eqz
diff --git a/test/passes/merge-blocks.txt b/test/passes/merge-blocks.txt
index 8a74ed895..908339b37 100644
--- a/test/passes/merge-blocks.txt
+++ b/test/passes/merge-blocks.txt
@@ -90,8 +90,8 @@
   (drop
    (block $label$0 (result i32)
     (drop
-     (block $label$1
-      (loop $label$2
+     (loop $label$2
+      (block $label$1
        (br $label$2)
       )
      )
diff --git a/test/passes/merge-blocks_remove-unused-brs.txt b/test/passes/merge-blocks_remove-unused-brs.txt
new file mode 100644
index 000000000..62be8f17c
--- /dev/null
+++ b/test/passes/merge-blocks_remove-unused-brs.txt
@@ -0,0 +1,17 @@
+(module
+ (type $0 (func (param i32)))
+ (func $func (; 0 ;) (type $0) (param $x i32)
+  (loop $loop
+   (block $out
+    (if
+     (get_local $x)
+     (nop)
+     (block
+      (nop)
+      (br $loop)
+     )
+    )
+   )
+  )
+ )
+)
diff --git a/test/passes/merge-blocks_remove-unused-brs.wast b/test/passes/merge-blocks_remove-unused-brs.wast
new file mode 100644
index 000000000..5c9f59963
--- /dev/null
+++ b/test/passes/merge-blocks_remove-unused-brs.wast
@@ -0,0 +1,14 @@
+(module
+  (func $func (param $x i32)
+    (block $out
+      (loop $loop
+        (br_if $out
+          (get_local $x)
+        )
+        (nop)
+        (br $loop)
+      )
+    )
+  )
+)
+
diff --git a/test/passes/remove-unused-names_merge-blocks.txt b/test/passes/remove-unused-names_merge-blocks.txt
index 5cc6ca891..69a83d725 100644
--- a/test/passes/remove-unused-names_merge-blocks.txt
+++ b/test/passes/remove-unused-names_merge-blocks.txt
@@ -1095,30 +1095,30 @@
   (drop
    (i32.const 3)
   )
-  (block $b1
-   (loop $l3
+  (loop $l3
+   (block $b1
     (br_if $b1
      (i32.const 4)
     )
     (br_if $l3
      (i32.const 5)
     )
-   )
-   (drop
-    (i32.const 6)
+    (drop
+     (i32.const 6)
+    )
    )
   )
-  (block $b2
-   (loop $l4
+  (loop $l4
+   (block $b2
     (br_if $l4
      (i32.const 7)
     )
-   )
-   (br_if $b2
-    (i32.const 8)
-   )
-   (drop
-    (i32.const 9)
+    (br_if $b2
+     (i32.const 8)
+    )
+    (drop
+     (i32.const 9)
+    )
    )
   )
   (loop $l5