From 1d8a601f968bb3b4e388b255676d861c335be288 Mon Sep 17 00:00:00 2001
From: Andreas Kling <kling@serenityos.org>
Date: Fri, 24 Nov 2023 09:31:23 +0100
Subject: [PATCH] LibJS/JIT: Add builtin for Math.log()

Note that we still call out to a C++ helper, but by having a builtin,
we still avoid the cost of a full JS function call.
---
 Userland/Libraries/LibJS/Bytecode/Builtins.h    |  5 +++--
 Userland/Libraries/LibJS/JIT/Compiler.cpp       | 14 ++++++++++++++
 Userland/Libraries/LibJS/Runtime/MathObject.cpp | 12 +++++++++---
 Userland/Libraries/LibJS/Runtime/MathObject.h   |  2 ++
 4 files changed, 28 insertions(+), 5 deletions(-)

diff --git a/Userland/Libraries/LibJS/Bytecode/Builtins.h b/Userland/Libraries/LibJS/Bytecode/Builtins.h
index b67de4b855..e69762819c 100644
--- a/Userland/Libraries/LibJS/Bytecode/Builtins.h
+++ b/Userland/Libraries/LibJS/Bytecode/Builtins.h
@@ -12,8 +12,9 @@
 namespace JS::Bytecode {
 
 // TitleCaseName, snake_case_name, base, property, argument_count
-#define JS_ENUMERATE_BUILTINS(O) \
-    O(MathAbs, math_abs, Math, abs, 1)
+#define JS_ENUMERATE_BUILTINS(O)       \
+    O(MathAbs, math_abs, Math, abs, 1) \
+    O(MathLog, math_log, Math, log, 1)
 
 enum class Builtin {
 #define DEFINE_BUILTIN_ENUM(name, ...) name,
diff --git a/Userland/Libraries/LibJS/JIT/Compiler.cpp b/Userland/Libraries/LibJS/JIT/Compiler.cpp
index b26efd471e..6d13442599 100644
--- a/Userland/Libraries/LibJS/JIT/Compiler.cpp
+++ b/Userland/Libraries/LibJS/JIT/Compiler.cpp
@@ -18,6 +18,7 @@
 #include <LibJS/Runtime/ECMAScriptFunctionObject.h>
 #include <LibJS/Runtime/FunctionEnvironment.h>
 #include <LibJS/Runtime/GlobalEnvironment.h>
+#include <LibJS/Runtime/MathObject.h>
 #include <LibJS/Runtime/ObjectEnvironment.h>
 #include <LibJS/Runtime/VM.h>
 #include <LibJS/Runtime/ValueInlines.h>
@@ -2623,6 +2624,19 @@ void Compiler::compile_builtin(Bytecode::Builtin builtin, Assembler::Label& slow
     }
 }
 
+static Value cxx_math_log(VM& vm, Value, Value value)
+{
+    return TRY_OR_SET_EXCEPTION(MathObject::log_impl(vm, value));
+}
+
+void Compiler::compile_builtin_math_log(Assembler::Label&, Assembler::Label& end)
+{
+    native_call((void*)cxx_math_log);
+    store_accumulator(RET);
+    check_exception();
+    m_assembler.jump(end);
+}
+
 void Compiler::compile_builtin_math_abs(Assembler::Label& slow_case, Assembler::Label& end)
 {
     branch_if_int32(ARG2, [&] {
diff --git a/Userland/Libraries/LibJS/Runtime/MathObject.cpp b/Userland/Libraries/LibJS/Runtime/MathObject.cpp
index 8225b5bc6e..19608dede4 100644
--- a/Userland/Libraries/LibJS/Runtime/MathObject.cpp
+++ b/Userland/Libraries/LibJS/Runtime/MathObject.cpp
@@ -58,7 +58,7 @@ void MathObject::initialize(Realm& realm)
     define_native_function(realm, vm.names.fround, fround, 1, attr);
     define_native_function(realm, vm.names.hypot, hypot, 2, attr);
     define_native_function(realm, vm.names.imul, imul, 2, attr);
-    define_native_function(realm, vm.names.log, log, 1, attr);
+    define_native_function(realm, vm.names.log, log, 1, attr, Bytecode::Builtin::MathLog);
     define_native_function(realm, vm.names.log2, log2, 1, attr);
     define_native_function(realm, vm.names.log10, log10, 1, attr);
     define_native_function(realm, vm.names.sinh, sinh, 1, attr);
@@ -555,10 +555,10 @@ JS_DEFINE_NATIVE_FUNCTION(MathObject::imul)
 }
 
 // 21.3.2.20 Math.log ( x ), https://tc39.es/ecma262/#sec-math.log
-JS_DEFINE_NATIVE_FUNCTION(MathObject::log)
+ThrowCompletionOr<Value> MathObject::log_impl(VM& vm, Value x)
 {
     // 1. Let n be ? ToNumber(x).
-    auto number = TRY(vm.argument(0).to_number(vm));
+    auto number = TRY(x.to_number(vm));
 
     // 2. If n is NaN or n is +∞𝔽, return n.
     if (number.is_nan() || number.is_positive_infinity())
@@ -580,6 +580,12 @@ JS_DEFINE_NATIVE_FUNCTION(MathObject::log)
     return Value(::log(number.as_double()));
 }
 
+// 21.3.2.20 Math.log ( x ), https://tc39.es/ecma262/#sec-math.log
+JS_DEFINE_NATIVE_FUNCTION(MathObject::log)
+{
+    return log_impl(vm, vm.argument(0));
+}
+
 // 21.3.2.21 Math.log1p ( x ), https://tc39.es/ecma262/#sec-math.log1p
 JS_DEFINE_NATIVE_FUNCTION(MathObject::log1p)
 {
diff --git a/Userland/Libraries/LibJS/Runtime/MathObject.h b/Userland/Libraries/LibJS/Runtime/MathObject.h
index 81ba320efc..7fdb665f39 100644
--- a/Userland/Libraries/LibJS/Runtime/MathObject.h
+++ b/Userland/Libraries/LibJS/Runtime/MathObject.h
@@ -18,6 +18,8 @@ public:
     virtual void initialize(Realm&) override;
     virtual ~MathObject() override = default;
 
+    static ThrowCompletionOr<Value> log_impl(VM&, Value);
+
 private:
     explicit MathObject(Realm&);