From 1610e6b3f5148d47c4f352c528db7d24bcfa598c Mon Sep 17 00:00:00 2001
From: Alon Zakai <azakai@google.com>
Date: Mon, 8 Aug 2022 11:39:00 -0700
Subject: [Wasm GC] Fix SignaturePruning on CallWithoutEffects (#4882)

call.without.effects will turn into a normal call of the last parameter later,

(call $call.without.effects
  A
  B
  (ref.func $foo)
)
;; => intrinsic lowering
(call $foo
  A
  B
)

SignaturePruning needs to be aware of that: we can't remove a parameter from $foo without
also updating relevant calls to $call.without.effects. Rather than handle that, just skip such
cases, and leave them to be optimized after intrinsics are lowered away.
---
 test/lit/passes/signature-pruning.wast | 38 ++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)

(limited to 'test')

diff --git a/test/lit/passes/signature-pruning.wast b/test/lit/passes/signature-pruning.wast
index 3c4500eaf..79f658007 100644
--- a/test/lit/passes/signature-pruning.wast
+++ b/test/lit/passes/signature-pruning.wast
@@ -810,3 +810,41 @@
     )
   )
 )
+
+;; Do not prune signatures used in the call.without.effects intrinsic.
+(module
+  ;; CHECK:      (type $i32_funcref_=>_i32 (func_subtype (param i32 funcref) (result i32) func))
+
+  ;; CHECK:      (type $i32_=>_i32 (func_subtype (param i32) (result i32) func))
+
+  ;; CHECK:      (type $none_=>_i32 (func_subtype (result i32) func))
+
+  ;; CHECK:      (import "binaryen-intrinsics" "call.without.effects" (func $cwe (param i32 funcref) (result i32)))
+  (import "binaryen-intrinsics" "call.without.effects" (func $cwe (param i32 funcref) (result i32)))
+
+  ;; CHECK:      (elem declare func $func)
+
+  ;; CHECK:      (func $func (type $i32_=>_i32) (param $0 i32) (result i32)
+  ;; CHECK-NEXT:  (i32.const 1)
+  ;; CHECK-NEXT: )
+  (func $func (param i32) (result i32)
+    ;; The parameter is unused, so we want to prune it. We won't because of the
+    ;; situation in the calling function, below.
+    (i32.const 1)
+  )
+
+  ;; CHECK:      (func $caller (type $none_=>_i32) (result i32)
+  ;; CHECK-NEXT:  (call $cwe
+  ;; CHECK-NEXT:   (i32.const 41)
+  ;; CHECK-NEXT:   (ref.func $func)
+  ;; CHECK-NEXT:  )
+  ;; CHECK-NEXT: )
+  (func $caller (result i32)
+    ;; We call $func using call.without.effects. This causes us to not optimize
+    ;; in this case.
+    (call $cwe
+      (i32.const 41)
+      (ref.func $func)
+    )
+  )
+)
-- 
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