From 449ea84dcc7dffb2f042fc414eb7238ae842d596 Mon Sep 17 00:00:00 2001
From: Gaming4JC <g4jc@hyperbola.info>
Date: Sun, 14 Jul 2019 19:04:34 -0400
Subject: 1344477 - Part 1: Add JSOP_CALL_IGNORES_RV for function call that
 ignores return value.

---
 js/public/CallArgs.h | 22 +++++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

(limited to 'js/public/CallArgs.h')

diff --git a/js/public/CallArgs.h b/js/public/CallArgs.h
index a7774309a..aae7121ad 100644
--- a/js/public/CallArgs.h
+++ b/js/public/CallArgs.h
@@ -128,7 +128,10 @@ class MOZ_STACK_CLASS CallArgsBase : public WantUsedRval
   protected:
     Value* argv_;
     unsigned argc_;
-    bool constructing_;
+    bool constructing_:1;
+
+    // True if the caller does not use the return value.
+    bool ignoresReturnValue_:1;
 
   public:
     // CALLEE ACCESS
@@ -164,6 +167,10 @@ class MOZ_STACK_CLASS CallArgsBase : public WantUsedRval
         return true;
     }
 
+    bool ignoresReturnValue() const {
+        return ignoresReturnValue_;
+    }
+
     MutableHandleValue newTarget() const {
         MOZ_ASSERT(constructing_);
         return MutableHandleValue::fromMarkedLocation(&this->argv_[argc_]);
@@ -280,14 +287,17 @@ class MOZ_STACK_CLASS CallArgs : public detail::CallArgsBase<detail::IncludeUsed
 {
   private:
     friend CallArgs CallArgsFromVp(unsigned argc, Value* vp);
-    friend CallArgs CallArgsFromSp(unsigned stackSlots, Value* sp, bool constructing);
+    friend CallArgs CallArgsFromSp(unsigned stackSlots, Value* sp, bool constructing,
+                                   bool ignoresReturnValue);
 
-    static CallArgs create(unsigned argc, Value* argv, bool constructing) {
+    static CallArgs create(unsigned argc, Value* argv, bool constructing,
+                           bool ignoresReturnValue = false) {
         CallArgs args;
         args.clearUsedRval();
         args.argv_ = argv;
         args.argc_ = argc;
         args.constructing_ = constructing;
+        args.ignoresReturnValue_ = ignoresReturnValue;
 #ifdef DEBUG
         for (unsigned i = 0; i < argc; ++i)
             MOZ_ASSERT_IF(argv[i].isGCThing(), !GCThingIsMarkedGray(GCCellPtr(argv[i])));
@@ -314,9 +324,11 @@ CallArgsFromVp(unsigned argc, Value* vp)
 // eventually move it to an internal header.  Embedders should use
 // JS::CallArgsFromVp!
 MOZ_ALWAYS_INLINE CallArgs
-CallArgsFromSp(unsigned stackSlots, Value* sp, bool constructing = false)
+CallArgsFromSp(unsigned stackSlots, Value* sp, bool constructing = false,
+               bool ignoresReturnValue = false)
 {
-    return CallArgs::create(stackSlots - constructing, sp - stackSlots, constructing);
+    return CallArgs::create(stackSlots - constructing, sp - stackSlots, constructing,
+                            ignoresReturnValue);
 }
 
 } // namespace JS
-- 
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