From 7a7d850eb6820c9dd2ec0db3ea7c9d103c166cf2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Andr=C3=A9=20Bargull?= <andre.bargull@gmail.com>
Date: Thu, 27 Apr 2017 09:24:08 -0700
Subject: [PATCH] Bug 1360220 - Replace emitRequireObjectCoercible with
 JSOP_CHECKOBJCOERCIBLE. r=shu

--HG--
extra : rebase_source : cef0f46847a0aded63dbbcdfa497dc9b5a7d5259
---
 js/src/frontend/BytecodeEmitter.cpp           | 38 +------------------
 js/src/frontend/BytecodeEmitter.h             |  4 --
 .../tests/basic/expression-autopsy.js         | 20 ++--------
 3 files changed, 5 insertions(+), 57 deletions(-)

diff --git a/js/src/frontend/BytecodeEmitter.cpp b/js/src/frontend/BytecodeEmitter.cpp
index b866492a07fd..d6e4ae297890 100644
--- a/js/src/frontend/BytecodeEmitter.cpp
+++ b/js/src/frontend/BytecodeEmitter.cpp
@@ -5894,7 +5894,7 @@ BytecodeEmitter::emitDestructuringOpsObject(ParseNode* pattern, DestructuringFla
 
     MOZ_ASSERT(this->stackDepth > 0);                             // ... RHS
 
-    if (!emitRequireObjectCoercible())                            // ... RHS
+    if (!emit1(JSOP_CHECKOBJCOERCIBLE))                           // ... RHS
         return false;
 
     bool needsRestPropertyExcludedSet = pattern->pn_count > 1 &&
@@ -6929,42 +6929,6 @@ BytecodeEmitter::emitWith(ParseNode* pn)
     return emitterScope.leave(this);
 }
 
-bool
-BytecodeEmitter::emitRequireObjectCoercible()
-{
-    // For simplicity, handle this in self-hosted code, at cost of 13 bytes of
-    // bytecode versus 1 byte for a dedicated opcode.  As more places need this
-    // behavior, we may want to reconsider this tradeoff.
-
-#ifdef DEBUG
-    auto depth = this->stackDepth;
-#endif
-    MOZ_ASSERT(depth > 0);                 // VAL
-    if (!emit1(JSOP_DUP))                  // VAL VAL
-        return false;
-
-    // Note that "intrinsic" is a misnomer: we're calling a *self-hosted*
-    // function that's not an intrinsic!  But it nonetheless works as desired.
-    if (!emitAtomOp(cx->names().RequireObjectCoercible,
-                    JSOP_GETINTRINSIC))    // VAL VAL REQUIREOBJECTCOERCIBLE
-    {
-        return false;
-    }
-    if (!emit1(JSOP_UNDEFINED))            // VAL VAL REQUIREOBJECTCOERCIBLE UNDEFINED
-        return false;
-    if (!emit2(JSOP_PICK, 2))              // VAL REQUIREOBJECTCOERCIBLE UNDEFINED VAL
-        return false;
-    if (!emitCall(JSOP_CALL_IGNORES_RV, 1))// VAL IGNORED
-        return false;
-    checkTypeSet(JSOP_CALL_IGNORES_RV);
-
-    if (!emit1(JSOP_POP))                  // VAL
-        return false;
-
-    MOZ_ASSERT(depth == this->stackDepth);
-    return true;
-}
-
 bool
 BytecodeEmitter::emitCopyDataProperties(CopyOption option)
 {
diff --git a/js/src/frontend/BytecodeEmitter.h b/js/src/frontend/BytecodeEmitter.h
index 4f60bf8b0550..6c339d2b67aa 100644
--- a/js/src/frontend/BytecodeEmitter.h
+++ b/js/src/frontend/BytecodeEmitter.h
@@ -708,10 +708,6 @@ struct MOZ_STACK_CLASS BytecodeEmitter
     template <typename NameEmitter>
     MOZ_MUST_USE bool emitDestructuringDeclsWithEmitter(ParseNode* pattern, NameEmitter emitName);
 
-    // Throw a TypeError if the value atop the stack isn't convertible to an
-    // object, with no overall effect on the stack.
-    MOZ_MUST_USE bool emitRequireObjectCoercible();
-
     enum class CopyOption {
         Filtered, Unfiltered
     };
diff --git a/js/src/jit-test/tests/basic/expression-autopsy.js b/js/src/jit-test/tests/basic/expression-autopsy.js
index de2d0a5efa11..e942ff2deafb 100644
--- a/js/src/jit-test/tests/basic/expression-autopsy.js
+++ b/js/src/jit-test/tests/basic/expression-autopsy.js
@@ -183,22 +183,10 @@ check_one("[...].foo",
           function() { [undefined, ...[]].foo(); },
           " is not a function");
 
-// Manual testing for this case: the only way to trigger an error is *not* on
-// an attempted property access during destructuring, and the error message
-// invoking ToObject(null) is different: "can't convert {0} to object".
-try
-{
-  (function() {
-    var [{x}] = [null, {}];
-   })();
-  throw new Error("didn't throw");
-}
-catch (e)
-{
-  assertEq(e instanceof TypeError, true,
-           "expected TypeError, got " + e);
-  assertEq(e.message, "can't convert null to object");
-}
+check_one("[...][Symbol.iterator](...).next(...).value",
+          function () { var [{x}] = [null, {}]; }, " is null");
+check_one("[...][Symbol.iterator](...).next(...).value",
+          function () { var [{x}] = [void 0, {}]; }, " is undefined");
 
 try {
   (function() {