From 8d659f352a159d9348ad51de86706fd842e026de Mon Sep 17 00:00:00 2001
From: Guillem Jover <guillem@hadrons.org>
Date: Mon, 12 Oct 2015 01:45:37 +0200
Subject: [PATCH] Do not make lack of SSE2 support on x86-32 fatal

When an x86-32 CPU does not have SSE2 support (which is the case for
all AMD CPUs, and older Intel CPUs), fallback to use the interpreter,
otherwise use the JIT engine.

Even then, make the lack of SSE2 support on x86-32 fatal when trying
to instantiate a JIT engine, which does require it.

Refactor the required CPU support check into a new privately exported
function to avoid duplicating the logic, and do so in a function
instead of a class member to avoid changing the class signatures.

Version: 5.6.x
Bug-Debian: https://bugs.debian.org/792594
---
 src/qml/jit/qv4isel_masm.cpp    |  3 +++
 src/qml/jit/qv4isel_masm_p.h    | 10 ++++++++++
 src/qml/jsruntime/qv4engine.cpp |  4 ++--
 src/qml/qml/v8/qv8engine.cpp    |  7 -------
 tools/qmljs/qmljs.cpp           |  7 +++----
 5 files changed, 18 insertions(+), 13 deletions(-)

diff --git a/src/qml/jit/qv4isel_masm.cpp b/src/qml/jit/qv4isel_masm.cpp
index 6de6524..f9b4640 100644
--- a/src/qml/jit/qv4isel_masm.cpp
+++ b/src/qml/jit/qv4isel_masm.cpp
@@ -259,6 +259,9 @@ InstructionSelection::InstructionSelection(QQmlEnginePrivate *qmlEngine, QV4::Ex
     , compilationUnit(new CompilationUnit)
     , qmlEngine(qmlEngine)
 {
+    if (!hasRequiredCpuSupport())
+        qFatal("This program requires an X86 processor that supports SSE2 extension, at least a Pentium 4 or newer");
+
     compilationUnit->codeRefs.resize(module->functions.size());
 }
 
diff --git a/src/qml/jit/qv4isel_masm_p.h b/src/qml/jit/qv4isel_masm_p.h
index 6e9b02b..0cde542 100644
--- a/src/qml/jit/qv4isel_masm_p.h
+++ b/src/qml/jit/qv4isel_masm_p.h
@@ -53,6 +53,7 @@
 
 #include <QtCore/QHash>
 #include <QtCore/QStack>
+#include <private/qsimd_p.h>
 #include <config.h>
 #include <wtf/Vector.h>
 
@@ -65,6 +66,15 @@ QT_BEGIN_NAMESPACE
 namespace QV4 {
 namespace JIT {
 
+inline bool Q_QML_PRIVATE_EXPORT hasRequiredCpuSupport()
+{
+#ifdef Q_PROCESSOR_X86_32
+    return qCpuHasFeature(SSE2);
+#else
+    return true;
+#endif
+}
+
 class Q_QML_EXPORT InstructionSelection:
         protected IR::IRDecoder,
         public EvalInstructionSelection
diff --git a/src/qml/jsruntime/qv4engine.cpp b/src/qml/jsruntime/qv4engine.cpp
index e31d9b1..a7e1656 100644
--- a/src/qml/jsruntime/qv4engine.cpp
+++ b/src/qml/jsruntime/qv4engine.cpp
@@ -218,8 +218,8 @@ ExecutionEngine::ExecutionEngine(EvalISelFactory *factory)
     if (!factory) {
 
 #ifdef V4_ENABLE_JIT
-        static const bool forceMoth = !qEnvironmentVariableIsEmpty("QV4_FORCE_INTERPRETER");
-        if (forceMoth)
+        static const bool useMoth = !qEnvironmentVariableIsEmpty("QV4_FORCE_INTERPRETER") || !JIT::hasRequiredCpuSupport();
+        if (useMoth)
             factory = new Moth::ISelFactory;
         else
             factory = new JIT::ISelFactory;
diff --git a/src/qml/qml/v8/qv8engine.cpp b/src/qml/qml/v8/qv8engine.cpp
index dae932e..c6d3a81 100644
--- a/src/qml/qml/v8/qv8engine.cpp
+++ b/src/qml/qml/v8/qv8engine.cpp
@@ -59,7 +59,6 @@
 #include <QtCore/qjsonvalue.h>
 #include <QtCore/qdatetime.h>
 #include <QtCore/qdatastream.h>
-#include <private/qsimd_p.h>
 
 #include <private/qv4value_p.h>
 #include <private/qv4dateobject_p.h>
@@ -123,12 +122,6 @@ QV8Engine::QV8Engine(QJSEngine* qq)
     , m_xmlHttpRequestData(0)
     , m_listModelData(0)
 {
-#ifdef Q_PROCESSOR_X86_32
-    if (!qCpuHasFeature(SSE2)) {
-        qFatal("This program requires an X86 processor that supports SSE2 extension, at least a Pentium 4 or newer");
-    }
-#endif
-
     QML_MEMORY_SCOPE_STRING("QV8Engine::QV8Engine");
     qMetaTypeId<QJSValue>();
     qMetaTypeId<QList<int> >();
diff --git a/tools/qmljs/qmljs.cpp b/tools/qmljs/qmljs.cpp
index 27aeed4..e1929df 100644
--- a/tools/qmljs/qmljs.cpp
+++ b/tools/qmljs/qmljs.cpp
@@ -140,11 +140,10 @@ int main(int argc, char *argv[])
     enum {
         use_masm,
         use_moth
-    } mode;
+    } mode = use_moth;
 #ifdef V4_ENABLE_JIT
-    mode = use_masm;
-#else
-    mode = use_moth;
+    if (QV4::JIT::hasRequiredCpuSupport())
+        mode = use_masm;
 #endif
 
     bool runAsQml = false;
-- 
2.6.2.409.gb049f0a