[DOMJIT] Not emit exception case if it is not necessary

https://bugs.webkit.org/show_bug.cgi?id=163589

Reviewed by Sam Weinig.

We should not emit exception case if we do not use the slow path calls.
For example, nodeType accessor does not use the slow path calls.

* bytecode/PolymorphicAccess.cpp:
(JSC::AccessCase::emitDOMJITGetter):


Canonical link: https://commits.webkit.org/181378@main
git-svn-id: https://svn.webkit.org/repository/webkit/trunk@207465 268f45cc-cd09-0410-ab3c-d52691b4dbfc

Source/JavaScriptCore/ChangeLog

@@ -1,3 +1,16 @@
+2016-10-18  Yusuke Suzuki  <utatane.tea@gmail.com>
+
+        [DOMJIT] Not emit exception case if it is not necessary
+        https://bugs.webkit.org/show_bug.cgi?id=163589
+
+        Reviewed by Sam Weinig.
+
+        We should not emit exception case if we do not use the slow path calls.
+        For example, nodeType accessor does not use the slow path calls.
+
+        * bytecode/PolymorphicAccess.cpp:
+        (JSC::AccessCase::emitDOMJITGetter):
+
 2016-10-18  Caitlin Potter  <caitp@igalia.com>
 
         [JSC] ES6 Method functions should not have prototype

Source/JavaScriptCore/bytecode/PolymorphicAccess.cpp

@@ -1535,9 +1535,11 @@ void AccessCase::emitDOMJITGetter(AccessGenerationState& state, GPRReg baseForGe
     state.succeed();
 
     CCallHelpers::JumpList exceptions = params.emitSlowPathCalls(state, registersToSpillForCCall, jit);
-    exceptions.link(&jit);
-    allocator.restoreReusedRegistersByPopping(jit, preservedState);
-    state.emitExplicitExceptionHandler();
+    if (!exceptions.empty()) {
+        exceptions.link(&jit);
+        allocator.restoreReusedRegistersByPopping(jit, preservedState);
+        state.emitExplicitExceptionHandler();
+    }
 }
 
 PolymorphicAccess::PolymorphicAccess() { }