[JSC] Do not emit jsUndefined constant

https://bugs.webkit.org/show_bug.cgi?id=270662 rdar://124234204 Reviewed by Keith Miller. We observed massive unnecessary mov due to this. * Source/JavaScriptCore/bytecompiler/NodesCodegen.cpp: (JSC::PropertyListNode::emitBytecode): * Source/JavaScriptCore/llint/LLIntSlowPaths.cpp: (JSC::LLInt::LLINT_SLOW_PATH_DECL): Canonical link: https://commits.webkit.org/275813@main
WebKit · Mar 8, 2024 · 3bc33cf · 3bc33cf
1 parent ce0c253
commit 3bc33cf
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Showing 2 changed files with 6 additions and 10 deletions.
diff --git a/Source/JavaScriptCore/bytecompiler/NodesCodegen.cpp b/Source/JavaScriptCore/bytecompiler/NodesCodegen.cpp
@@ -811,21 +811,17 @@ RegisterID* PropertyListNode::emitBytecode(BytecodeGenerator& generator, Registe
                     ASSERT(pair.second->m_type & PropertyNode::Setter);
                     setterReg = generator.emitNode(pair.second->m_assign);
                     secondReg = setterReg.get();
-                } else {
-                    setterReg = generator.newTemporary();
-                    generator.emitLoad(setterReg.get(), jsUndefined());
-                }
+                } else
+                    setterReg = generator.emitLoad(nullptr, jsUndefined());
             } else {
                 ASSERT(node->m_type & PropertyNode::Setter);
                 setterReg = value;
                 if (pair.second) {
                     ASSERT(pair.second->m_type & PropertyNode::Getter);
                     getterReg = generator.emitNode(pair.second->m_assign);
                     secondReg = getterReg.get();
-                } else {
-                    getterReg = generator.newTemporary();
-                    generator.emitLoad(getterReg.get(), jsUndefined());
-                }
+                } else
+                    getterReg = generator.emitLoad(nullptr, jsUndefined());
             }
 
             ASSERT(!pair.second || needsSuperBinding == pair.second->needsSuperBinding());

diff --git a/Source/JavaScriptCore/llint/LLIntSlowPaths.cpp b/Source/JavaScriptCore/llint/LLIntSlowPaths.cpp
@@ -1628,8 +1628,8 @@ LLINT_SLOW_PATH_DECL(slow_path_put_getter_setter_by_id)
     ASSERT(getNonConstantOperand(callFrame, bytecode.m_base).isObject());
     JSObject* baseObject = asObject(getNonConstantOperand(callFrame, bytecode.m_base));
 
-    JSValue getter = getNonConstantOperand(callFrame, bytecode.m_getter);
-    JSValue setter = getNonConstantOperand(callFrame, bytecode.m_setter);
+    JSValue getter = getOperand(callFrame, bytecode.m_getter);
+    JSValue setter = getOperand(callFrame, bytecode.m_setter);
     ASSERT(getter.isObject() || setter.isObject());
     GetterSetter* accessor = GetterSetter::create(vm, globalObject, getter, setter);