From 22648824a351bfec8e01979257c24e3ba440104a 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: 5.7.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 |  1 +
 src/qml/qml/v8/qv8engine.cpp    |  7 -------
 tools/qmljs/qmljs.cpp           |  7 +++----
 5 files changed, 17 insertions(+), 11 deletions(-)

diff --git a/src/qml/jit/qv4isel_masm.cpp b/src/qml/jit/qv4isel_masm.cpp
index d047623ac..4d65fbb62 100644
--- a/src/qml/jit/qv4isel_masm.cpp
+++ b/src/qml/jit/qv4isel_masm.cpp
@@ -265,6 +265,9 @@ 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 1e6ac1f51..8bd7313a7 100644
--- a/src/qml/jit/qv4isel_masm_p.h
+++ b/src/qml/jit/qv4isel_masm_p.h
@@ -59,6 +59,7 @@
 
 #include <QtCore/QHash>
 #include <QtCore/QStack>
+#include <private/qsimd_p.h>
 #include <config.h>
 #include <wtf/Vector.h>
 
@@ -71,6 +72,15 @@ 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 26f473a7a..5e4100ac0 100644
--- a/src/qml/jsruntime/qv4engine.cpp
+++ b/src/qml/jsruntime/qv4engine.cpp
@@ -162,6 +162,7 @@ ExecutionEngine::ExecutionEngine(EvalISelFactory *factory)
 
 #ifdef V4_ENABLE_JIT
         static const bool forceMoth = !qEnvironmentVariableIsEmpty("QV4_FORCE_INTERPRETER") ||
+                                      !JIT::hasRequiredCpuSupport() ||
                                       !OSAllocator::canAllocateExecutableMemory();
         if (forceMoth) {
             factory = new Moth::ISelFactory;
diff --git a/src/qml/qml/v8/qv8engine.cpp b/src/qml/qml/v8/qv8engine.cpp
index 46fd4fbbe..20ed1ddb4 100644
--- a/src/qml/qml/v8/qv8engine.cpp
+++ b/src/qml/qml/v8/qv8engine.cpp
@@ -65,7 +65,6 @@
 #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>
@@ -130,12 +129,6 @@ 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 68aa52ce9..94b10f2b3 100644
--- a/tools/qmljs/qmljs.cpp
+++ b/tools/qmljs/qmljs.cpp
@@ -135,11 +135,10 @@ 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;
-- 
2.11.0