add a learning local coalescer

2 files changed, 1274 insertions, 0 deletions

diff --git a/test/passes/coalesce-locals-learning.txt b/test/passes/coalesce-locals-learning.txt
new file mode 100644
index 000000000..03e58347a
--- /dev/null
+++ b/test/passes/coalesce-locals-learning.txt
@@ -0,0 +1,680 @@
+(module
+  (memory 10)
+  (type $FUNCSIG$iiii (func (param i32 i32 i32) (result i32)))
+  (type $FUNCSIG$iii (func (param i32 i32) (result i32)))
+  (import $_emscripten_autodebug_i32 "env" "_emscripten_autodebug_i32" (param i32 i32) (result i32))
+  (func $nothing-to-do
+    (local $0 i32)
+    (nop)
+  )
+  (func $merge
+    (local $0 i32)
+    (nop)
+  )
+  (func $leave-type
+    (local $0 i32)
+    (local $1 f32)
+    (nop)
+  )
+  (func $leave-interfere
+    (local $0 i32)
+    (local $1 i32)
+    (set_local $0
+      (i32.const 0)
+    )
+    (set_local $1
+      (i32.const 0)
+    )
+    (get_local $0)
+    (get_local $1)
+  )
+  (func $almost-interfere
+    (local $0 i32)
+    (set_local $0
+      (i32.const 0)
+    )
+    (get_local $0)
+    (set_local $0
+      (i32.const 0)
+    )
+    (get_local $0)
+  )
+  (func $redundant-copy
+    (local $0 i32)
+    (set_local $0
+      (i32.const 0)
+    )
+    (get_local $0)
+    (get_local $0)
+  )
+  (func $ineffective-store
+    (local $0 i32)
+    (i32.const 0)
+    (set_local $0
+      (i32.const 0)
+    )
+    (get_local $0)
+  )
+  (func $block
+    (local $0 i32)
+    (block $block0
+      (set_local $0
+        (i32.const 0)
+      )
+    )
+    (get_local $0)
+  )
+  (func $see-both-sides
+    (local $0 i32)
+    (local $1 i32)
+    (set_local $0
+      (i32.const 0)
+    )
+    (block $block0
+      (set_local $1
+        (i32.const 0)
+      )
+    )
+    (get_local $0)
+    (get_local $1)
+  )
+  (func $see-br-and-ignore-dead
+    (local $0 i32)
+    (set_local $0
+      (i32.const 0)
+    )
+    (block $block
+      (br $block)
+      (i32.const 0)
+      (get_local $0)
+      (i32.const -1)
+    )
+    (get_local $0)
+  )
+  (func $see-block-body
+    (local $0 i32)
+    (local $1 i32)
+    (set_local $0
+      (i32.const 0)
+    )
+    (block $block
+      (set_local $1
+        (i32.const 0)
+      )
+      (get_local $1)
+      (br $block)
+    )
+    (get_local $0)
+  )
+  (func $zero-init
+    (local $0 i32)
+    (local $1 i32)
+    (get_local $0)
+    (get_local $1)
+  )
+  (func $multi
+    (local $0 i32)
+    (local $1 i32)
+    (get_local $0)
+    (get_local $1)
+  )
+  (func $if-else
+    (local $0 i32)
+    (local $1 i32)
+    (if
+      (i32.const 0)
+      (get_local $0)
+      (get_local $1)
+    )
+  )
+  (func $if-else-parallel
+    (local $0 i32)
+    (if
+      (i32.const 0)
+      (block $block1
+        (set_local $0
+          (i32.const 0)
+        )
+        (get_local $0)
+      )
+      (block $block3
+        (set_local $0
+          (i32.const 1)
+        )
+        (get_local $0)
+      )
+    )
+  )
+  (func $if-else-after
+    (local $0 i32)
+    (local $1 i32)
+    (if
+      (i32.const 0)
+      (set_local $0
+        (i32.const 0)
+      )
+      (set_local $1
+        (i32.const 1)
+      )
+    )
+    (get_local $0)
+    (get_local $1)
+  )
+  (func $if-else-through
+    (local $0 i32)
+    (local $1 i32)
+    (set_local $0
+      (i32.const 0)
+    )
+    (set_local $1
+      (i32.const 1)
+    )
+    (if
+      (i32.const 0)
+      (i32.const 1)
+      (i32.const 2)
+    )
+    (get_local $0)
+    (get_local $1)
+  )
+  (func $if-through
+    (local $0 i32)
+    (local $1 i32)
+    (set_local $0
+      (i32.const 0)
+    )
+    (set_local $1
+      (i32.const 1)
+    )
+    (if
+      (i32.const 0)
+      (i32.const 1)
+    )
+    (get_local $0)
+    (get_local $1)
+  )
+  (func $if-through2
+    (local $0 i32)
+    (local $1 i32)
+    (set_local $0
+      (i32.const 0)
+    )
+    (if
+      (i32.const 0)
+      (set_local $1
+        (i32.const 1)
+      )
+    )
+    (get_local $0)
+    (get_local $1)
+  )
+  (func $if-through2
+    (local $0 i32)
+    (local $1 i32)
+    (set_local $0
+      (i32.const 0)
+    )
+    (if
+      (i32.const 0)
+      (block $block1
+        (get_local $0)
+        (get_local $1)
+      )
+    )
+  )
+  (func $if2
+    (local $0 i32)
+    (local $1 i32)
+    (if
+      (set_local $0
+        (i32.const 0)
+      )
+      (block $block1
+        (get_local $0)
+        (get_local $1)
+      )
+    )
+  )
+  (func $if3
+    (local $0 i32)
+    (local $1 i32)
+    (if
+      (i32.const 0)
+      (block $block1
+        (set_local $0
+          (i32.const 0)
+        )
+        (get_local $0)
+      )
+    )
+    (get_local $1)
+  )
+  (func $if4
+    (local $0 i32)
+    (if
+      (i32.const 0)
+      (block $block1
+        (set_local $0
+          (i32.const 0)
+        )
+        (get_local $0)
+        (set_local $0
+          (i32.const 1)
+        )
+      )
+    )
+    (get_local $0)
+  )
+  (func $if5
+    (local $0 i32)
+    (local $1 i32)
+    (if
+      (i32.const 0)
+      (block $block1
+        (get_local $0)
+        (set_local $1
+          (i32.const 1)
+        )
+      )
+    )
+    (get_local $1)
+  )
+  (func $loop
+    (local $0 i32)
+    (local $1 i32)
+    (loop $out $in
+      (get_local $0)
+      (set_local $0
+        (i32.const 0)
+      )
+      (get_local $1)
+      (br $in)
+    )
+  )
+  (func $interfere-in-dead
+    (local $0 i32)
+    (block $block
+      (br $block)
+      (get_local $0)
+      (get_local $0)
+    )
+  )
+  (func $interfere-in-dead2
+    (local $0 i32)
+    (block $block
+      (unreachable)
+      (get_local $0)
+      (get_local $0)
+    )
+  )
+  (func $interfere-in-dead3
+    (local $0 i32)
+    (block $block
+      (return)
+      (get_local $0)
+      (get_local $0)
+    )
+  )
+  (func $params (param $0 i32) (param $1 f32)
+    (local $2 i32)
+    (local $3 i32)
+    (get_local $0)
+    (get_local $2)
+    (get_local $3)
+  )
+  (func $interfere-in-dead
+    (local $0 i32)
+    (local $1 i32)
+    (block $block
+      (br_if $block
+        (i32.const 0)
+      )
+      (get_local $0)
+      (get_local $1)
+    )
+  )
+  (func $switch
+    (local $0 i32)
+    (local $1 i32)
+    (local $2 i32)
+    (block $switch$def
+      (block $switch-case$1
+        (block $switch-case$2
+          (br_table $switch-case$1 $switch-case$2 $switch-case$1 $switch-case$1 $switch$def
+            (i32.const 100)
+          )
+          (get_local $0)
+        )
+        (get_local $0)
+      )
+      (get_local $1)
+    )
+    (get_local $2)
+  )
+  (func $greedy-can-be-happy
+    (local $0 i32)
+    (local $1 i32)
+    (if
+      (i32.const 0)
+      (if
+        (i32.const 1)
+        (if
+          (i32.const 2)
+          (block $block3
+            (set_local $0
+              (i32.const 100)
+            )
+            (set_local $1
+              (i32.const 101)
+            )
+            (get_local $0)
+            (get_local $1)
+          )
+          (block $block5
+            (set_local $0
+              (i32.const 102)
+            )
+            (set_local $1
+              (i32.const 103)
+            )
+            (get_local $0)
+            (get_local $1)
+          )
+        )
+        (if
+          (i32.const 3)
+          (block $block8
+            (set_local $0
+              (i32.const 104)
+            )
+            (set_local $1
+              (i32.const 105)
+            )
+            (get_local $0)
+            (get_local $1)
+          )
+          (block $block10
+            (set_local $0
+              (i32.const 106)
+            )
+            (set_local $1
+              (i32.const 107)
+            )
+            (get_local $0)
+            (get_local $1)
+          )
+        )
+      )
+      (if
+        (i32.const 4)
+        (block $block13
+          (set_local $0
+            (i32.const 108)
+          )
+          (set_local $1
+            (i32.const 109)
+          )
+          (get_local $0)
+          (get_local $1)
+        )
+        (block $block15
+          (set_local $0
+            (i32.const 110)
+          )
+          (set_local $1
+            (i32.const 111)
+          )
+          (get_local $0)
+          (get_local $1)
+        )
+      )
+    )
+  )
+  (func $greedy-can-be-sad
+    (local $0 i32)
+    (local $1 i32)
+    (if
+      (i32.const 0)
+      (if
+        (i32.const 1)
+        (if
+          (i32.const 2)
+          (block $block3
+            (set_local $1
+              (i32.const 100)
+            )
+            (set_local $0
+              (i32.const 101)
+            )
+            (get_local $1)
+            (get_local $0)
+          )
+          (block $block5
+            (set_local $1
+              (i32.const 102)
+            )
+            (set_local $0
+              (i32.const 103)
+            )
+            (get_local $1)
+            (get_local $0)
+          )
+        )
+        (if
+          (i32.const 3)
+          (block $block8
+            (set_local $1
+              (i32.const 104)
+            )
+            (set_local $0
+              (i32.const 105)
+            )
+            (get_local $1)
+            (get_local $0)
+          )
+          (block $block10
+            (set_local $1
+              (i32.const 106)
+            )
+            (set_local $0
+              (i32.const 107)
+            )
+            (get_local $1)
+            (get_local $0)
+          )
+        )
+      )
+      (if
+        (i32.const 4)
+        (block $block13
+          (set_local $1
+            (i32.const 108)
+          )
+          (set_local $0
+            (i32.const 109)
+          )
+          (get_local $1)
+          (get_local $0)
+        )
+        (block $block15
+          (set_local $1
+            (i32.const 110)
+          )
+          (set_local $0
+            (i32.const 111)
+          )
+          (get_local $1)
+          (get_local $0)
+        )
+      )
+    )
+  )
+  (func $_memcpy (param $0 i32) (param $1 i32) (param $2 i32) (result i32)
+    (local $3 i32)
+    (if
+      (i32.ge_s
+        (get_local $2)
+        (i32.const 4096)
+      )
+      (get_local $0)
+    )
+    (set_local $3
+      (get_local $0)
+    )
+    (if
+      (i32.eq
+        (i32.and
+          (get_local $0)
+          (i32.const 3)
+        )
+        (i32.and
+          (get_local $1)
+          (i32.const 3)
+        )
+      )
+      (block $block2
+        (loop $while-out$0 $while-in$1
+          (if
+            (i32.eqz
+              (i32.and
+                (get_local $0)
+                (i32.const 3)
+              )
+            )
+            (br $while-out$0)
+          )
+          (block $block4
+            (if
+              (i32.eqz
+                (get_local $2)
+              )
+              (return
+                (get_local $3)
+              )
+            )
+            (i32.store8
+              (get_local $0)
+              (i32.load8_s
+                (get_local $1)
+              )
+            )
+            (set_local $0
+              (i32.add
+                (get_local $0)
+                (i32.const 1)
+              )
+            )
+            (set_local $1
+              (i32.add
+                (get_local $1)
+                (i32.const 1)
+              )
+            )
+            (set_local $2
+              (i32.sub
+                (get_local $2)
+                (i32.const 1)
+              )
+            )
+          )
+          (br $while-in$1)
+        )
+        (loop $while-out$2 $while-in$3
+          (if
+            (i32.eqz
+              (i32.ge_s
+                (get_local $2)
+                (i32.const 4)
+              )
+            )
+            (br $while-out$2)
+          )
+          (block $block7
+            (i32.store
+              (get_local $0)
+              (i32.load
+                (get_local $1)
+              )
+            )
+            (set_local $0
+              (i32.add
+                (get_local $0)
+                (i32.const 4)
+              )
+            )
+            (set_local $1
+              (i32.add
+                (get_local $1)
+                (i32.const 4)
+              )
+            )
+            (set_local $2
+              (i32.sub
+                (get_local $2)
+                (i32.const 4)
+              )
+            )
+          )
+          (br $while-in$3)
+        )
+      )
+    )
+    (loop $while-out$4 $while-in$5
+      (if
+        (i32.eqz
+          (i32.gt_s
+            (get_local $2)
+            (i32.const 0)
+          )
+        )
+        (br $while-out$4)
+      )
+      (block $block9
+        (i32.store8
+          (get_local $0)
+          (i32.load8_s
+            (get_local $1)
+          )
+        )
+        (set_local $0
+          (i32.add
+            (get_local $0)
+            (i32.const 1)
+          )
+        )
+        (set_local $1
+          (i32.add
+            (get_local $1)
+            (i32.const 1)
+          )
+        )
+        (set_local $2
+          (i32.sub
+            (get_local $2)
+            (i32.const 1)
+          )
+        )
+      )
+      (br $while-in$5)
+    )
+    (return
+      (get_local $3)
+    )
+  )
+  (func $this-is-effective-i-tell-you (param $0 i32)
+    (if
+      (i32.const -1)
+      (block $block1
+        (if
+          (i32.const 0)
+          (nop)
+        )
+        (set_local $0
+          (i32.const 1)
+        )
+      )
+      (nop)
+    )
+    (get_local $0)
+  )
+)
diff --git a/test/passes/coalesce-locals-learning.wast b/test/passes/coalesce-locals-learning.wast
new file mode 100644
index 000000000..a7152d16a
--- /dev/null
+++ b/test/passes/coalesce-locals-learning.wast
@@ -0,0 +1,594 @@
+(module
+  (memory 10)
+  (type $FUNCSIG$iiii (func (param i32 i32 i32) (result i32)))
+  (import $_emscripten_autodebug_i32 "env" "_emscripten_autodebug_i32" (param i32 i32) (result i32))
+  (table)
+  (func $nothing-to-do
+    (local $x i32)
+  )
+  (func $merge
+    (local $x i32)
+    (local $y i32)
+  )
+  (func $leave-type
+    (local $x i32)
+    (local $y f32)
+  )
+  (func $leave-interfere
+    (local $x i32)
+    (local $y i32)
+    (set_local $x (i32.const 0))
+    (set_local $y (i32.const 0))
+    (get_local $x)
+    (get_local $y)
+  )
+  (func $almost-interfere
+    (local $x i32)
+    (local $y i32)
+    (set_local $x (i32.const 0))
+    (get_local $x)
+    (set_local $y (i32.const 0))
+    (get_local $y)
+  )
+  (func $redundant-copy
+    (local $x i32)
+    (local $y i32)
+    (set_local $x (i32.const 0))
+    (set_local $y (get_local $x))
+    (get_local $y)
+  )
+  (func $ineffective-store
+    (local $x i32)
+    (set_local $x (i32.const 0))
+    (set_local $x (i32.const 0))
+    (get_local $x)
+  )
+  (func $block
+    (local $x i32)
+    (block
+      (set_local $x (i32.const 0))
+    )
+    (get_local $x)
+  )
+  (func $see-both-sides
+    (local $x i32)
+    (local $y i32)
+    (set_local $x (i32.const 0))
+    (block
+      (set_local $y (i32.const 0))
+    )
+    (get_local $x)
+    (get_local $y)
+  )
+  (func $see-br-and-ignore-dead
+    (local $x i32)
+    (local $y i32)
+    (set_local $x (i32.const 0))
+    (block $block
+      (br $block)
+      (set_local $y (i32.const 0))
+      (get_local $y)
+      (set_local $x (i32.const -1))
+    )
+    (get_local $x)
+  )
+  (func $see-block-body
+    (local $x i32)
+    (local $y i32)
+    (set_local $x (i32.const 0))
+    (block $block
+      (set_local $y (i32.const 0))
+      (get_local $y)
+      (br $block)
+    )
+    (get_local $x)
+  )
+  (func $zero-init
+    (local $x i32)
+    (local $y i32)
+    (get_local $x)
+    (get_local $y)
+  )
+  (func $multi
+    (local $x i32) ;; x is free, but y and z conflict
+    (local $y i32)
+    (local $z i32)
+    (get_local $y)
+    (get_local $z)
+  )
+  (func $if-else
+    (local $x i32)
+    (local $y i32)
+    (if ;; x and y conflict when they are merged into their shared predecessor
+      (i32.const 0)
+      (get_local $x)
+      (get_local $y)
+    )
+  )
+  (func $if-else-parallel
+    (local $x i32)
+    (local $y i32)
+    (if
+      (i32.const 0)
+      (block
+        (set_local $x (i32.const 0))
+        (get_local $x)
+      )
+      (block
+        (set_local $y (i32.const 1))
+        (get_local $y)
+      )
+    )
+  )
+  (func $if-else-after
+    (local $x i32)
+    (local $y i32)
+    (if
+      (i32.const 0)
+      (set_local $x (i32.const 0))
+      (set_local $y (i32.const 1))
+    )
+    (get_local $x)
+    (get_local $y)
+  )
+  (func $if-else-through
+    (local $x i32)
+    (local $y i32)
+    (set_local $x (i32.const 0))
+    (set_local $y (i32.const 1))
+    (if
+      (i32.const 0)
+      (i32.const 1)
+      (i32.const 2)
+    )
+    (get_local $x)
+    (get_local $y)
+  )
+  (func $if-through
+    (local $x i32)
+    (local $y i32)
+    (set_local $x (i32.const 0))
+    (set_local $y (i32.const 1))
+    (if
+      (i32.const 0)
+      (i32.const 1)
+    )
+    (get_local $x)
+    (get_local $y)
+  )
+  (func $if-through2
+    (local $x i32)
+    (local $y i32)
+    (set_local $x (i32.const 0))
+    (if
+      (i32.const 0)
+      (set_local $y (i32.const 1))
+    )
+    (get_local $x)
+    (get_local $y)
+  )
+  (func $if-through2
+    (local $x i32)
+    (local $y i32)
+    (set_local $x (i32.const 0))
+    (if
+      (i32.const 0)
+      (block
+        (get_local $x)
+        (get_local $y)
+      )
+    )
+  )
+  (func $if2
+    (local $x i32)
+    (local $y i32)
+    (if
+      (set_local $x (i32.const 0))
+      (block
+        (get_local $x)
+        (get_local $y)
+      )
+    )
+  )
+  (func $if3
+    (local $x i32)
+    (local $y i32)
+    (if
+      (i32.const 0)
+      (block
+        (set_local $x (i32.const 0))
+        (get_local $x)
+      )
+    )
+    (get_local $y)
+  )
+  (func $if4
+    (local $x i32)
+    (local $y i32)
+    (if
+      (i32.const 0)
+      (block
+        (set_local $x (i32.const 0))
+        (get_local $x)
+        (set_local $y (i32.const 1)) ;; we might not go through here, but it's ok
+      )
+    )
+    (get_local $y)
+  )
+  (func $if5
+    (local $x i32)
+    (local $y i32)
+    (if
+      (i32.const 0)
+      (block
+        (get_local $x) ;; we might go through here, and it causes interference
+        (set_local $y (i32.const 1))
+      )
+    )
+    (get_local $y)
+  )
+  (func $loop
+    (local $x i32)
+    (local $y i32)
+    (loop $out $in
+      (get_local $x)
+      (set_local $x (i32.const 0)) ;; effective, due to looping
+      (get_local $y)
+      (br $in)
+    )
+  )
+  (func $interfere-in-dead
+    (local $x i32)
+    (local $y i32)
+    (block $block
+      (br $block)
+      (get_local $x)
+      (get_local $y)
+    )
+  )
+  (func $interfere-in-dead2
+    (local $x i32)
+    (local $y i32)
+    (block $block
+      (unreachable)
+      (get_local $x)
+      (get_local $y)
+    )
+  )
+  (func $interfere-in-dead3
+    (local $x i32)
+    (local $y i32)
+    (block $block
+      (return)
+      (get_local $x)
+      (get_local $y)
+    )
+  )
+  (func $params (param $p i32) (param $q f32)
+    (local $x i32) ;; x is free, but others conflict
+    (local $y i32)
+    (local $z i32)
+    (local $w i32)
+    (get_local $y)
+    (get_local $z)
+    (get_local $w)
+  )
+  (func $interfere-in-dead
+    (local $x i32)
+    (local $y i32)
+    (block $block
+      (br_if $block (i32.const 0))
+      (get_local $x)
+      (get_local $y)
+    )
+  )
+  (func $switch
+    (local $x i32)
+    (local $y i32)
+    (local $z i32)
+    (local $w i32)
+    (block $switch$def
+      (block $switch-case$1
+        (block $switch-case$2
+          (br_table $switch-case$1 $switch-case$2 $switch-case$1 $switch-case$1 $switch$def
+            (i32.const 100)
+          )
+          (get_local $x) ;; unreachable
+        )
+        (get_local $y)
+      )
+      (get_local $z)
+    )
+    (get_local $w)
+  )
+  (func $greedy-can-be-happy
+    (local $x1 i32)
+    (local $x2 i32)
+    (local $x3 i32)
+    (local $y1 i32)
+    (local $y2 i32)
+    (local $y3 i32)
+    (if
+      (i32.const 0)
+      (if
+        (i32.const 1)
+        (if
+          (i32.const 2)
+          (block
+            (set_local $x1 (i32.const 100))
+            (set_local $y2 (i32.const 101))
+            (get_local $x1)
+            (get_local $y2)
+          )
+          (block
+            (set_local $x1 (i32.const 102))
+            (set_local $y3 (i32.const 103))
+            (get_local $x1)
+            (get_local $y3)
+          )
+        )
+        (if
+          (i32.const 3)
+          (block
+            (set_local $x2 (i32.const 104))
+            (set_local $y1 (i32.const 105))
+            (get_local $x2)
+            (get_local $y1)
+          )
+          (block
+            (set_local $x2 (i32.const 106))
+            (set_local $y3 (i32.const 107))
+            (get_local $x2)
+            (get_local $y3)
+          )
+        )
+      )
+      (if
+        (i32.const 4)
+        (block
+          (set_local $x3 (i32.const 108))
+          (set_local $y1 (i32.const 109))
+          (get_local $x3)
+          (get_local $y1)
+        )
+        (block
+          (set_local $x3 (i32.const 110))
+          (set_local $y2 (i32.const 111))
+          (get_local $x3)
+          (get_local $y2)
+        )
+      )
+    )
+  )
+  (func $greedy-can-be-sad
+    (local $x1 i32)
+    (local $y1 i32)
+    (local $x2 i32)
+    (local $y2 i32)
+    (local $x3 i32)
+    (local $y3 i32)
+    (if
+      (i32.const 0)
+      (if
+        (i32.const 1)
+        (if
+          (i32.const 2)
+          (block
+            (set_local $x1 (i32.const 100))
+            (set_local $y2 (i32.const 101))
+            (get_local $x1)
+            (get_local $y2)
+          )
+          (block
+            (set_local $x1 (i32.const 102))
+            (set_local $y3 (i32.const 103))
+            (get_local $x1)
+            (get_local $y3)
+          )
+        )
+        (if
+          (i32.const 3)
+          (block
+            (set_local $x2 (i32.const 104))
+            (set_local $y1 (i32.const 105))
+            (get_local $x2)
+            (get_local $y1)
+          )
+          (block
+            (set_local $x2 (i32.const 106))
+            (set_local $y3 (i32.const 107))
+            (get_local $x2)
+            (get_local $y3)
+          )
+        )
+      )
+      (if
+        (i32.const 4)
+        (block
+          (set_local $x3 (i32.const 108))
+          (set_local $y1 (i32.const 109))
+          (get_local $x3)
+          (get_local $y1)
+        )
+        (block
+          (set_local $x3 (i32.const 110))
+          (set_local $y2 (i32.const 111))
+          (get_local $x3)
+          (get_local $y2)
+        )
+      )
+    )
+  )
+  (func $_memcpy (param $i1 i32) (param $i2 i32) (param $i3 i32) (result i32)
+    (local $i4 i32)
+    (if
+      (i32.ge_s
+        (get_local $i3)
+        (i32.const 4096)
+      )
+      (get_local $i1)
+      (get_local $i2)
+      (get_local $i3)
+      (return)
+    )
+    (set_local $i4
+      (get_local $i1)
+    )
+    (if
+      (i32.eq
+        (i32.and
+          (get_local $i1)
+          (i32.const 3)
+        )
+        (i32.and
+          (get_local $i2)
+          (i32.const 3)
+        )
+      )
+      (block
+        (loop $while-out$0 $while-in$1
+          (if
+            (i32.eqz
+              (i32.and
+                (get_local $i1)
+                (i32.const 3)
+              )
+            )
+            (br $while-out$0)
+          )
+          (block
+            (if
+              (i32.eqz
+                (get_local $i3)
+              )
+              (return
+                (get_local $i4)
+              )
+            )
+            (i32.store8
+              (get_local $i1)
+              (i32.load8_s
+                (get_local $i2)
+              )
+            )
+            (set_local $i1
+              (i32.add
+                (get_local $i1)
+                (i32.const 1)
+              )
+            )
+            (set_local $i2
+              (i32.add
+                (get_local $i2)
+                (i32.const 1)
+              )
+            )
+            (set_local $i3
+              (i32.sub
+                (get_local $i3)
+                (i32.const 1)
+              )
+            )
+          )
+          (br $while-in$1)
+        )
+        (loop $while-out$2 $while-in$3
+          (if
+            (i32.eqz
+              (i32.ge_s
+                (get_local $i3)
+                (i32.const 4)
+              )
+            )
+            (br $while-out$2)
+          )
+          (block
+            (i32.store
+              (get_local $i1)
+              (i32.load
+                (get_local $i2)
+              )
+            )
+            (set_local $i1
+              (i32.add
+                (get_local $i1)
+                (i32.const 4)
+              )
+            )
+            (set_local $i2
+              (i32.add
+                (get_local $i2)
+                (i32.const 4)
+              )
+            )
+            (set_local $i3
+              (i32.sub
+                (get_local $i3)
+                (i32.const 4)
+              )
+            )
+          )
+          (br $while-in$3)
+        )
+      )
+    )
+    (loop $while-out$4 $while-in$5
+      (if
+        (i32.eqz
+          (i32.gt_s
+            (get_local $i3)
+            (i32.const 0)
+          )
+        )
+        (br $while-out$4)
+      )
+      (block
+        (i32.store8
+          (get_local $i1)
+          (i32.load8_s
+            (get_local $i2)
+          )
+        )
+        (set_local $i1
+          (i32.add
+            (get_local $i1)
+            (i32.const 1)
+          )
+        )
+        (set_local $i2
+          (i32.add
+            (get_local $i2)
+            (i32.const 1)
+          )
+        )
+        (set_local $i3
+          (i32.sub
+            (get_local $i3)
+            (i32.const 1)
+          )
+        )
+      )
+      (br $while-in$5)
+    )
+    (return
+      (get_local $i4)
+    )
+  )
+  (func $this-is-effective-i-tell-you (param $x i32)
+    (if
+      (i32.const -1)
+      (block
+        (if ;; this is important for the bug
+          (i32.const 0)
+          (nop)
+        )
+        (set_local $x ;; this set is effective!
+          (i32.const 1)
+        )
+      )
+      (nop) ;; this is enough for the bug
+    )
+    (get_local $x) ;; this ends up with the wrong value in the test
+  )
+)
+