when removing an if-copy in coalesce-locals, if it's a tee, we do still need the get in that arm. only when it is not a tee can we remove that arm and make the if-else into an if

Author: kripken

src/passes/CoalesceLocals.cpp

@@ -597,11 +597,13 @@ void CoalesceLocals::pickIndices(std::vector<Index>& indices) {
 // Remove a copy from a set of an if, where one if arm is a get of the same set
 static void removeIfCopy(Expression** origin, SetLocal* set, If* iff, Expression*& copy, Expression*& other, Module* module) {
   // replace the origin with the if, and sink the set into the other non-copying arm
+  bool tee = set->isTee();
   *origin = iff;
   set->value = other;
   set->finalize();
   other = set;
-  if (!isConcreteWasmType(set->type)) {
+  // if this is not a tee, then we can get rid of the copy in that arm
+  if (!tee) {
     // we don't need the copy at all
     copy = nullptr;
     if (!iff->ifTrue) {

test/passes/coalesce-locals.txt

@@ -7,6 +7,7 @@
  (type $FUNCSIG$i (func (result i32)))
  (type $FUNCSIG$vi (func (param i32)))
  (type $7 (func (param i32) (result i32)))
+ (type $8 (func (param f64 i32) (result i64)))
  (import "env" "_emscripten_autodebug_i32" (func $_emscripten_autodebug_i32 (param i32 i32) (result i32)))
  (import "env" "get" (func $get (result i32)))
  (import "env" "set" (func $set (param i32)))
@@ -1122,4 +1123,34 @@
    )
   )
  )
+ (func $tee_if_with_unreachable_else (type $8) (param $0 f64) (param $1 i32) (result i64)
+  (call $tee_if_with_unreachable_else
+   (if (result f64)
+    (get_local $1)
+    (get_local $0)
+    (tee_local $0
+     (unreachable)
+    )
+   )
+   (f64.lt
+    (f64.const -128)
+    (get_local $0)
+   )
+  )
+ )
+ (func $tee_if_with_unreachable_true (type $8) (param $0 f64) (param $1 i32) (result i64)
+  (call $tee_if_with_unreachable_else
+   (if (result f64)
+    (get_local $1)
+    (tee_local $0
+     (unreachable)
+    )
+    (get_local $0)
+   )
+   (f64.lt
+    (f64.const -128)
+    (get_local $0)
+   )
+  )
+ )
 )

test/passes/coalesce-locals.wast

@@ -1097,4 +1097,34 @@
     )
    )
   )
+  (func $tee_if_with_unreachable_else (param $0 f64) (param $1 i32) (result i64)
+    (call $tee_if_with_unreachable_else
+     (tee_local $0
+      (if (result f64)
+       (get_local $1)
+       (get_local $0)
+       (unreachable)
+      )
+     )
+     (f64.lt
+      (f64.const -128)
+      (get_local $0)
+     )
+    )
+  )
+  (func $tee_if_with_unreachable_true (param $0 f64) (param $1 i32) (result i64)
+    (call $tee_if_with_unreachable_else
+     (tee_local $0
+      (if (result f64)
+       (get_local $1)
+       (unreachable)
+       (get_local $0)
+      )
+     )
+     (f64.lt
+      (f64.const -128)
+      (get_local $0)
+     )
+    )
+  )
 )