fix bug with turning if into br_if without checking for reordering dangers

4 files changed, 167 insertions, 20 deletions

diff --git a/test/emcc_hello_world.fromasm b/test/emcc_hello_world.fromasm
index 4680aea58..9f0d1ee47 100644
--- a/test/emcc_hello_world.fromasm
+++ b/test/emcc_hello_world.fromasm
@@ -3252,9 +3252,8 @@
                               (get_local $7)
                             )
                           )
-                          (br_if $label$break$L46
-                            (get_local $5)
-                            (i32.ge_u
+                          (if
+                            (i32.lt_u
                               (tee_local $9
                                 (i32.add
                                   (i32.load8_s
@@ -3270,15 +3269,18 @@
                               )
                               (i32.const 10)
                             )
-                          )
-                          (block
-                            (set_local $10
-                              (get_local $7)
+                            (block
+                              (set_local $10
+                                (get_local $7)
+                              )
+                              (set_local $7
+                                (get_local $9)
+                              )
+                              (br $while-in$18)
                             )
-                            (set_local $7
-                              (get_local $9)
+                            (br $label$break$L46
+                              (get_local $5)
                             )
-                            (br $while-in$18)
                           )
                         )
                       )
diff --git a/test/emcc_hello_world.fromasm.imprecise b/test/emcc_hello_world.fromasm.imprecise
index 66c49ce29..88532cef3 100644
--- a/test/emcc_hello_world.fromasm.imprecise
+++ b/test/emcc_hello_world.fromasm.imprecise
@@ -3245,9 +3245,8 @@
                               (get_local $7)
                             )
                           )
-                          (br_if $label$break$L46
-                            (get_local $5)
-                            (i32.ge_u
+                          (if
+                            (i32.lt_u
                               (tee_local $9
                                 (i32.add
                                   (i32.load8_s
@@ -3263,15 +3262,18 @@
                               )
                               (i32.const 10)
                             )
-                          )
-                          (block
-                            (set_local $10
-                              (get_local $7)
+                            (block
+                              (set_local $10
+                                (get_local $7)
+                              )
+                              (set_local $7
+                                (get_local $9)
+                              )
+                              (br $while-in$18)
                             )
-                            (set_local $7
-                              (get_local $9)
+                            (br $label$break$L46
+                              (get_local $5)
                             )
-                            (br $while-in$18)
                           )
                         )
                       )
diff --git a/test/passes/remove-unused-brs.txt b/test/passes/remove-unused-brs.txt
index 9eb413294..94b214588 100644
--- a/test/passes/remove-unused-brs.txt
+++ b/test/passes/remove-unused-brs.txt
@@ -3,6 +3,7 @@
   (type $0 (func (param i32)))
   (type $1 (func))
   (type $2 (func (result i32)))
+  (type $3 (func (param i32 i32) (result i32)))
   (func $b0-yes (type $0) (param $i1 i32)
     (block $topmost
     )
@@ -760,4 +761,86 @@
       )
     )
   )
+  (func $if-to-br_if-conflict (type $3) (param $x i32) (param $y i32) (result i32)
+    (block $leave
+      (set_local $y
+        (block $out
+          (if
+            (get_local $x)
+            (br $out
+              (block $block1
+                (set_local $x
+                  (i32.const 0)
+                )
+                (i32.const 1)
+              )
+            )
+            (br_if $leave
+              (i32.const 1)
+            )
+          )
+          (unreachable)
+        )
+      )
+    )
+    (i32.add
+      (get_local $x)
+      (get_local $y)
+    )
+  )
+  (func $if-to-br_if-conflict2 (type $3) (param $x i32) (param $y i32) (result i32)
+    (block $leave
+      (set_local $y
+        (block $out
+          (if
+            (get_local $x)
+            (br_if $leave
+              (i32.const 1)
+            )
+            (br $out
+              (block $block2
+                (set_local $x
+                  (i32.const 0)
+                )
+                (i32.const 1)
+              )
+            )
+          )
+          (unreachable)
+        )
+      )
+    )
+    (i32.add
+      (get_local $x)
+      (get_local $y)
+    )
+  )
+  (func $if-to-br_if-value-sideeffect (type $3) (param $x i32) (param $y i32) (result i32)
+    (block $leave
+      (set_local $y
+        (block $out
+          (if
+            (get_local $x)
+            (br $out
+              (block $block1
+                (drop
+                  (call $if-to-br_if-value-sideeffect
+                    (i32.const 0)
+                    (i32.const 1)
+                  )
+                )
+                (nop)
+                (i32.const 1)
+              )
+            )
+          )
+          (unreachable)
+        )
+      )
+    )
+    (i32.add
+      (get_local $x)
+      (get_local $y)
+    )
+  )
 )
diff --git a/test/passes/remove-unused-brs.wast b/test/passes/remove-unused-brs.wast
index e777efa5b..ecbcb6caa 100644
--- a/test/passes/remove-unused-brs.wast
+++ b/test/passes/remove-unused-brs.wast
@@ -700,4 +700,64 @@
       (br $stack1)
     )
   )
+  (func $if-to-br_if-conflict (param $x i32) (param $y i32) (result i32)
+    (block $leave
+      (set_local $y
+        (block $out
+          (if
+            (get_local $x)
+            (br $out
+              (block
+                (set_local $x (i32.const 0))
+                (i32.const 1)
+              )
+            )
+            (br_if $leave (i32.const 1))
+          )
+          (unreachable)
+        )
+      )
+    )
+    (i32.add (get_local $x) (get_local $y))
+  )
+  (func $if-to-br_if-conflict2 (param $x i32) (param $y i32) (result i32)
+    (block $leave
+      (set_local $y
+        (block $out
+          (if
+            (get_local $x)
+            (br_if $leave (i32.const 1))
+            (br $out
+              (block
+                (set_local $x (i32.const 0))
+                (i32.const 1)
+              )
+            )
+          )
+          (unreachable)
+        )
+      )
+    )
+    (i32.add (get_local $x) (get_local $y))
+  )
+  (func $if-to-br_if-value-sideeffect (param $x i32) (param $y i32) (result i32)
+    (block $leave
+      (set_local $y
+        (block $out
+          (if
+            (get_local $x)
+            (br $out
+              (block
+                (drop (call $if-to-br_if-value-sideeffect (i32.const 0) (i32.const 1)))
+                (nop)
+                (i32.const 1)
+              )
+            )
+          )
+          (unreachable)
+        )
+      )
+    )
+    (i32.add (get_local $x) (get_local $y))
+  )
 )