From 81f22ede89b9ea37d785af01d1aef42c82c072f6 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: 5.8.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 6b8264d80..1a814d15d 100644
--- a/src/qml/jit/qv4isel_masm.cpp
+++ b/src/qml/jit/qv4isel_masm.cpp
@@ -251,6 +251,9 @@ 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());
     module->unitFlags |= QV4::CompiledData::Unit::ContainsMachineCode;
 }
diff --git a/src/qml/jit/qv4isel_masm_p.h b/src/qml/jit/qv4isel_masm_p.h
index b6ddd3c1c..11c3af8c4 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 8c4c39b77..d555ec074 100644
--- a/src/qml/jsruntime/qv4engine.cpp
+++ b/src/qml/jsruntime/qv4engine.cpp
@@ -164,6 +164,7 @@ 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 dadff819c..0a53d26d8 100644
--- a/src/qml/qml/v8/qv8engine.cpp
+++ b/src/qml/qml/v8/qv8engine.cpp
@@ -64,7 +64,6 @@
 #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>
@@ -129,12 +128,6 @@ 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 dd1898a88..1d5c27002 100644
--- a/tools/qmljs/qmljs.cpp
+++ b/tools/qmljs/qmljs.cpp
@@ -92,11 +92,10 @@ 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