Transform V4_ENABLE_JIT into a feature

This way you can enable or disable the JIT when configuring Qt. The
conditions for the availability of the JIT have also been cleaned up.
There is no reason anymore to artificially restrict availability on x86
and x86_64. The reason for the existence of those clauses are old
problems on windows that have been fixed by now. However, on arm and
arm64, we need a specialization of the cacheFlush() function for each OS
to be supported. Therefore, restrict to the systems for which such a
specialization exists. iOS and tvOS are technically supported and you
can enable the JIT via the feature flag now. Due to Apple's policy we
disable it by default, though.

Change-Id: I5fe2a2bf6799b2d11b7ae7c7a85962bcbf44f919
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

15 files changed, 88 insertions, 82 deletions

diff --git a/src/3rdparty/masm/masm-defs.pri b/src/3rdparty/masm/masm-defs.pri
index 08c46a7ac2..90a795c6ce 100644
--- a/src/3rdparty/masm/masm-defs.pri
+++ b/src/3rdparty/masm/masm-defs.pri
@@ -33,10 +33,6 @@ disassembler {
     DEFINES += WTF_USE_UDIS86=0
 }
 
-force-compile-jit {
-    DEFINES += V4_FORCE_COMPILE_JIT
-}
-
 INCLUDEPATH += $$PWD/disassembler
 INCLUDEPATH += $$PWD/disassembler/udis86
 INCLUDEPATH += $$_OUT_PWD
diff --git a/src/qml/configure.json b/src/qml/configure.json
index c35f5be06b..ef6a9f5e7e 100644
--- a/src/qml/configure.json
+++ b/src/qml/configure.json
@@ -24,6 +24,52 @@
                 ],
                 "qmake": "CONFIG += c++11"
             }
+        },
+        "pointer_32bit": {
+            "label": "32bit pointers",
+            "type": "compile",
+            "test": {
+                "main": "static_assert(sizeof(void *) == 4, \"fail\");"
+            }
+        },
+        "pointer_64bit": {
+            "label": "64bit pointers",
+            "type": "compile",
+            "test": {
+                "main": "static_assert(sizeof(void *) == 8, \"fail\");"
+            }
+        },
+        "arm_thumb": {
+            "label": "THUMB mode on ARM",
+            "type": "compile",
+            "test": {
+                "main": [
+                    "#if defined(thumb2) || defined(__thumb2__)",
+                    "#    define THUMB_OK",
+                    "#elif (defined(__thumb) || defined(__thumb__)) && __TARGET_ARCH_THUMB-0 == 4",
+                    "#    define THUMB_OK",
+                    "#elif defined(__ARM_ARCH_ISA_THUMB) && __ARM_ARCH_ISA_THUMB == 2",
+                    "// clang 3.5 and later will set this if the core supports the Thumb-2 ISA.",
+                    "#    define THUMB_OK",
+                    "#else",
+                    "#    error \"fail\"",
+                    "#endif"
+                ]
+            }
+        },
+        "arm_fp": {
+            "label": "Sufficiently recent FPU on ARM",
+            "type": "compile",
+            "test": {
+                "main": [
+                    "// if !defined(__ARM_FP) we might be on MSVC or we might have a device",
+                    "// without an FPU.",
+                    "// TODO: The latter case is not supported, but the test still succeeds.",
+                    "#if defined(__ARM_FP) && (__ARM_FP <= 0x04)",
+                    "#    error \"fail\"",
+                    "#endif"
+                ]
+            }
         }
     },
 
@@ -40,10 +86,32 @@
             "condition": "features.network",
             "output": [ "publicFeature" ]
         },
+        "qml-jit": {
+            "label": "QML just-in-time compiler",
+            "purpose": "Provides a JIT for QML and JavaScript",
+            "section": "QML",
+            "condition": [
+                "   (arch.i386   && tests.pointer_32bit)
+                 || (arch.x86_64 && tests.pointer_64bit)
+                 || (arch.arm    && tests.pointer_32bit && tests.arm_fp && tests.arm_thumb
+                     && (config.linux || config.ios || config.tvos || config.qnx))
+                 || (arch.arm64  && tests.pointer_64bit && tests.arm_fp
+                     && (config.linux || config.ios || config.tvos || config.qnx || config.integrity))"
+            ],
+            "output": [ "privateFeature" ],
+            "autoDetect": "!config.ios && !config.tvos",
+            "comment": "On arm and arm64 we need a specialization of cacheFlush() for each OS to be
+                        enabeled. Therefore the config white list.
+                        Also Mind that e.g. x86_32 has arch.x86_64 but 32bit pointers. Therefore
+                        the checks for architecture and pointer size.
+                        Finally, ios and tvos can technically use the JIT but Apple does not allow
+                        it. Therefore, it's disabled by default."
+        },
         "qml-tracing": {
             "label": "QML tracing JIT support",
             "purpose": "Provides a JIT that uses trace information generated by the interpreter.",
             "section": "QML",
+            "condition": "features.qml-jit",
             "output": [ "privateFeature" ],
             "autoDetect": false
         },
@@ -140,6 +208,7 @@
             "entries": [
                 "qml-network",
                 "qml-debug",
+                "qml-jit",
                 "qml-tracing",
                 "qml-sequence-object",
                 "qml-list-model",
diff --git a/src/qml/jit/qv4assemblercommon.cpp b/src/qml/jit/qv4assemblercommon.cpp
index dd810d9d70..800ee22cd7 100644
--- a/src/qml/jit/qv4assemblercommon.cpp
+++ b/src/qml/jit/qv4assemblercommon.cpp
@@ -53,8 +53,6 @@
 
 #undef ENABLE_ALL_ASSEMBLERS_FOR_REFACTORING_PURPOSES
 
-#ifdef V4_ENABLE_JIT
-
 QT_BEGIN_NAMESPACE
 namespace QV4 {
 namespace JIT {
@@ -366,5 +364,3 @@ void PlatformAssemblerCommon::storeInt32AsValue(int srcInt, Address destAddr)
 } // QV4 namepsace
 
 QT_END_NAMESPACE
-
-#endif // V4_ENABLE_JIT
diff --git a/src/qml/jit/qv4assemblercommon_p.h b/src/qml/jit/qv4assemblercommon_p.h
index d3d7eedae2..e5c2aff1a7 100644
--- a/src/qml/jit/qv4assemblercommon_p.h
+++ b/src/qml/jit/qv4assemblercommon_p.h
@@ -58,7 +58,7 @@
 #include <wtf/Vector.h>
 #include <assembler/MacroAssembler.h>
 
-#ifdef V4_ENABLE_JIT
+QT_REQUIRE_CONFIG(qml_jit);
 
 QT_BEGIN_NAMESPACE
 
@@ -735,6 +735,4 @@ private:
 
 QT_END_NAMESPACE
 
-#endif // V4_ENABLE_JIT
-
 #endif // QV4PLATFORMASSEMBLER_P_H
diff --git a/src/qml/jit/qv4baselineassembler.cpp b/src/qml/jit/qv4baselineassembler.cpp
index 238c11f478..5e34087ff5 100644
--- a/src/qml/jit/qv4baselineassembler.cpp
+++ b/src/qml/jit/qv4baselineassembler.cpp
@@ -55,8 +55,6 @@
 
 #undef ENABLE_ALL_ASSEMBLERS_FOR_REFACTORING_PURPOSES
 
-#ifdef V4_ENABLE_JIT
-
 QT_BEGIN_NAMESPACE
 namespace QV4 {
 namespace JIT {
@@ -1620,5 +1618,3 @@ void BaselineAssembler::ret()
 } // QV4 namepsace
 
 QT_END_NAMESPACE
-
-#endif // V4_ENABLE_JIT
diff --git a/src/qml/jit/qv4baselineassembler_p.h b/src/qml/jit/qv4baselineassembler_p.h
index 3bbaefd000..5e5d9d0672 100644
--- a/src/qml/jit/qv4baselineassembler_p.h
+++ b/src/qml/jit/qv4baselineassembler_p.h
@@ -55,6 +55,8 @@
 #include <private/qv4function_p.h>
 #include <QHash>
 
+QT_REQUIRE_CONFIG(qml_jit);
+
 QT_BEGIN_NAMESPACE
 
 namespace QV4 {
diff --git a/src/qml/jit/qv4baselinejit.cpp b/src/qml/jit/qv4baselinejit.cpp
index 80155d7b20..60880419a6 100644
--- a/src/qml/jit/qv4baselinejit.cpp
+++ b/src/qml/jit/qv4baselinejit.cpp
@@ -42,8 +42,6 @@
 #include <private/qv4lookup_p.h>
 #include <private/qv4generatorobject_p.h>
 
-#ifdef V4_ENABLE_JIT
-
 QT_USE_NAMESPACE
 using namespace QV4;
 using namespace QV4::JIT;
@@ -913,5 +911,3 @@ void BaselineJIT::endInstruction(Instr::Type instr)
 {
     Q_UNUSED(instr);
 }
-
-#endif // V4_ENABLE_JIT
diff --git a/src/qml/jit/qv4baselinejit_p.h b/src/qml/jit/qv4baselinejit_p.h
index 37ab37eac2..941e0cd408 100644
--- a/src/qml/jit/qv4baselinejit_p.h
+++ b/src/qml/jit/qv4baselinejit_p.h
@@ -56,7 +56,7 @@
 #include <private/qv4instr_moth_p.h>
 #include <private/qv4bytecodehandler_p.h>
 
-//QT_REQUIRE_CONFIG(qml_jit);
+QT_REQUIRE_CONFIG(qml_jit);
 
 QT_BEGIN_NAMESPACE
 
@@ -65,7 +65,6 @@ namespace JIT {
 
 class BaselineAssembler;
 
-#ifdef V4_ENABLE_JIT
 class BaselineJIT final: public Moth::ByteCodeHandler
 {
 public:
@@ -214,7 +213,6 @@ private:
     QScopedPointer<BaselineAssembler> as;
     QSet<int> labels;
 };
-#endif // V4_ENABLE_JIT
 
 } // namespace JIT
 } // namespace QV4
diff --git a/src/qml/jsruntime/qv4engine.cpp b/src/qml/jsruntime/qv4engine.cpp
index 18927c637c..b9130aa7f8 100644
--- a/src/qml/jsruntime/qv4engine.cpp
+++ b/src/qml/jsruntime/qv4engine.cpp
@@ -165,7 +165,7 @@ ExecutionEngine::ExecutionEngine(QJSEngine *jsEngine)
     , m_engineId(engineSerial.fetchAndAddOrdered(1))
     , regExpCache(nullptr)
     , m_multiplyWrappedQObjects(nullptr)
-#if defined(V4_ENABLE_JIT) && !defined(V4_BOOTSTRAP)
+#if QT_CONFIG(qml_jit)
     , m_canAllocateExecutableMemory(OSAllocator::canAllocateExecutableMemory())
 #endif
 {
diff --git a/src/qml/jsruntime/qv4engine_p.h b/src/qml/jsruntime/qv4engine_p.h
index 6df4545014..d0c58eee8f 100644
--- a/src/qml/jsruntime/qv4engine_p.h
+++ b/src/qml/jsruntime/qv4engine_p.h
@@ -464,7 +464,7 @@ public:
     // but any time a QObject is wrapped a second time in another engine, we have to do
     // bookkeeping.
     MultiplyWrappedQObjectMap *m_multiplyWrappedQObjects;
-#if defined(V4_ENABLE_JIT) && !defined(V4_BOOTSTRAP)
+#if QT_CONFIG(qml_jit)
     const bool m_canAllocateExecutableMemory;
 #endif
 
@@ -595,7 +595,7 @@ public:
 
     bool canJIT(Function *f = nullptr)
     {
-#if defined(V4_ENABLE_JIT) && !defined(V4_BOOTSTRAP)
+#if QT_CONFIG(qml_jit)
         if (!m_canAllocateExecutableMemory)
             return false;
         if (f)
diff --git a/src/qml/jsruntime/qv4global_p.h b/src/qml/jsruntime/qv4global_p.h
index d47393b3bb..8a0ef5aa30 100644
--- a/src/qml/jsruntime/qv4global_p.h
+++ b/src/qml/jsruntime/qv4global_p.h
@@ -82,53 +82,9 @@ inline bool isfinite(double d) { return _finite(d); }
 inline double trunc(double d) { return d > 0 ? floor(d) : ceil(d); }
 #endif
 
-// Decide whether to enable or disable the JIT
-
-// White list architectures
-//
-// NOTE: This should match the logic in qv4targetplatform_p.h!
-
-#if defined(Q_PROCESSOR_X86_32) && (QT_POINTER_SIZE == 4) \
-    && (defined(Q_OS_WIN) || defined(Q_OS_LINUX) || defined(Q_OS_QNX) || defined(Q_OS_FREEBSD))
-#  define V4_ENABLE_JIT
-#elif defined(Q_PROCESSOR_X86_64) && (QT_POINTER_SIZE == 8) \
-    && (defined(Q_OS_WIN) || defined(Q_OS_LINUX) || defined(Q_OS_QNX) || defined(Q_OS_MAC) || defined(Q_OS_FREEBSD))
-#  define V4_ENABLE_JIT
-#elif defined(Q_PROCESSOR_ARM_32) && (QT_POINTER_SIZE == 4) \
-    && (defined(Q_OS_LINUX) || defined(Q_OS_QNX) || defined(Q_OS_FREEBSD) || defined(Q_OS_INTEGRITY))
-#  if defined(thumb2) || defined(__thumb2__) || ((defined(__thumb) || defined(__thumb__)) && __TARGET_ARCH_THUMB-0 == 4)
-#    define V4_ENABLE_JIT
-#  elif defined(__ARM_ARCH_ISA_THUMB) && __ARM_ARCH_ISA_THUMB == 2 // clang 3.5 and later will set this if the core supports the Thumb-2 ISA.
-#    define V4_ENABLE_JIT
-#  endif
-#elif defined(Q_PROCESSOR_ARM_64) && (QT_POINTER_SIZE == 8)
-#  if defined(Q_OS_LINUX) || defined(Q_OS_QNX) || defined(Q_OS_INTEGRITY)
-#    define V4_ENABLE_JIT
-#  endif
-//#elif defined(Q_PROCESSOR_MIPS_32) && defined(Q_OS_LINUX)
-//#  define V4_ENABLE_JIT
-#endif
-
-// check FPU with double precision on ARM platform
-#if (defined(Q_PROCESSOR_ARM_64) || defined(Q_PROCESSOR_ARM_32)) && defined(V4_ENABLE_JIT) && defined(__ARM_FP) && (__ARM_FP <= 0x04)
-#  undef V4_ENABLE_JIT
-#endif
-
-// Black list some platforms
-#if defined(V4_ENABLE_JIT)
-#if defined(Q_OS_IOS) || defined(Q_OS_TVOS)
-#    undef V4_ENABLE_JIT
-#endif
-#endif
-
-// For debug purposes: add CONFIG+=force-compile-jit to qmake's command-line to always compile the JIT.
-#if defined(V4_FORCE_COMPILE_JIT) && !defined(V4_ENABLE_JIT)
-#  define V4_ENABLE_JIT
-#endif
-
 // Do certain things depending on whether the JIT is enabled or disabled
 
-#ifdef V4_ENABLE_JIT
+#if QT_CONFIG(qml_jit)
 #define ENABLE_YARR_JIT 1
 #define ENABLE_JIT 1
 #define ENABLE_ASSEMBLER 1
diff --git a/src/qml/jsruntime/qv4vme_moth.cpp b/src/qml/jsruntime/qv4vme_moth.cpp
index 98e4f4f7b9..71e35bdc07 100644
--- a/src/qml/jsruntime/qv4vme_moth.cpp
+++ b/src/qml/jsruntime/qv4vme_moth.cpp
@@ -61,7 +61,9 @@
 
 #include "qv4alloca_p.h"
 
+#if QT_CONFIG(qml_jit)
 #include <private/qv4baselinejit_p.h>
+#endif
 
 #undef COUNT_INSTRUCTIONS
 
@@ -499,7 +501,7 @@ ReturnedValue VME::exec(CppStackFrame *frame, ExecutionEngine *engine)
     Profiling::FunctionCallProfiler profiler(engine, function); // start execution profiling
     QV4::Debugging::Debugger *debugger = engine->debugger();
 
-#ifdef V4_ENABLE_JIT
+#if QT_CONFIG(qml_jit)
     if (debugger == nullptr) {
         if (function->jittedCode == nullptr) {
             if (engine->canJIT(function)) {
@@ -514,7 +516,7 @@ ReturnedValue VME::exec(CppStackFrame *frame, ExecutionEngine *engine)
             }
         }
     }
-#endif // V4_ENABLE_JIT
+#endif // QT_CONFIG(qml_jit)
 
     // interpreter
     if (debugger)
diff --git a/src/qml/qml.pro b/src/qml/qml.pro
index d96a1c285a..ca3282556e 100644
--- a/src/qml/qml.pro
+++ b/src/qml/qml.pro
@@ -70,7 +70,9 @@ include(parser/parser.pri)
 include(compiler/compiler.pri)
 include(jsapi/jsapi.pri)
 include(jsruntime/jsruntime.pri)
-include(jit/jit.pri)
+qtConfig(qml-jit) {
+    include(jit/jit.pri)
+}
 include(qml/qml.pri)
 include(debugger/debugger.pri)
 include(qmldirparser/qmldirparser.pri)
diff --git a/src/qml/qtqmlglobal.h b/src/qml/qtqmlglobal.h
index 090b830b3c..348cfd86b8 100644
--- a/src/qml/qtqmlglobal.h
+++ b/src/qml/qtqmlglobal.h
@@ -53,6 +53,7 @@
 #else
 #  define QT_FEATURE_qml_debug -1
 #  define QT_FEATURE_qml_sequence_object 1
+#  define QT_FEATURE_qml_jit -1
 #  define QT_FEATURE_qml_tracing -1
 #endif
 
diff --git a/tests/auto/qml/qv4assembler/tst_qv4assembler.cpp b/tests/auto/qml/qv4assembler/tst_qv4assembler.cpp
index fd50ff5020..392ce16880 100644
--- a/tests/auto/qml/qv4assembler/tst_qv4assembler.cpp
+++ b/tests/auto/qml/qv4assembler/tst_qv4assembler.cpp
@@ -140,23 +140,17 @@ void tst_QV4Assembler::functionTable()
 #endif
 }
 
-#ifdef V4_ENABLE_JIT
-#define JIT_ENABLED 1
-#else
-#define JIT_ENABLED 0
-#endif
-
 void tst_QV4Assembler::jitEnabled()
 {
 #if defined(Q_OS_IOS) || defined(Q_OS_TVOS)
     /* JIT should be disabled on iOS and tvOS. */
-    QCOMPARE(JIT_ENABLED, 0);
+    QVERIFY(!QT_CONFIG(qml_jit));
 #elif defined(Q_OS_WIN) && defined(Q_PROCESSOR_ARM)
     /* JIT should be disabled Windows on ARM/ARM64 for now. */
-    QCOMPARE(JIT_ENABLED, 0);
+    QVERIFY(!QT_CONFIG(qml_jit));
 #else
     /* JIT should be enabled on all other architectures/OSes tested in CI. */
-    QCOMPARE(JIT_ENABLED, 1);
+    QVERIFY(QT_CONFIG(qml_jit));
 #endif
 }