precompute-propagate may benefit from multiple passes (#1518)

One pass may remove code that includes a tee which then makes more optimization possible. Found by the Souper investigations.

2 files changed, 23 insertions, 0 deletions

diff --git a/test/passes/precompute-propagate.txt b/test/passes/precompute-propagate.txt
index 15abe1f2e..919d8f3e7 100644
--- a/test/passes/precompute-propagate.txt
+++ b/test/passes/precompute-propagate.txt
@@ -2,6 +2,7 @@
  (type $0 (func (param i32)))
  (type $1 (func (param i32) (result i32)))
  (type $2 (func (param i32 i32) (result i32)))
+ (type $3 (func (param i32 i32 i32) (result i32)))
  (func $basic (; 0 ;) (type $0) (param $p i32)
   (local $x i32)
   (set_local $x
@@ -233,4 +234,10 @@
    (i32.const 7)
   )
  )
+ (func $multipass (; 15 ;) (type $3) (param $0 i32) (param $1 i32) (param $2 i32) (result i32)
+  (local $3 i32)
+  (nop)
+  (nop)
+  (get_local $2)
+ )
 )
diff --git a/test/passes/precompute-propagate.wast b/test/passes/precompute-propagate.wast
index 4cf440829..5cdc720ba 100644
--- a/test/passes/precompute-propagate.wast
+++ b/test/passes/precompute-propagate.wast
@@ -137,5 +137,21 @@
       )
     )
   )
+  (func $multipass (param $0 i32) (param $1 i32) (param $2 i32) (result i32)
+   (local $3 i32)
+   (if
+    (get_local $3)
+    (set_local $3 ;; this set is completely removed, allowing later opts
+     (i32.const 24)
+    )
+   )
+   (if
+    (get_local $3)
+    (set_local $2
+     (i32.const 0)
+    )
+   )
+   (get_local $2)
+  )
 )