From 4950c366b12265f1ea390a6feb8dbbd0d850d206 Mon Sep 17 00:00:00 2001
From: Guillem Jover <guillem@hadrons.org>
Date: Mon, 12 Oct 2015 01:45:37 +0200
Subject: [PATCH v2] 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 pair of privately
exported functions to avoid duplicating the logic, and do so in
functions instead of class members to avoid changing the class
signatures.

Version: 5.7.x
Bug-Debian: https://bugs.debian.org/792594
---
 src/qml/jit/qv4isel_masm.cpp    |  2 ++
 src/qml/jit/qv4isel_masm_p.h    | 18 ++++++++++++++++++
 src/qml/jsruntime/qv4engine.cpp |  1 +
 src/qml/qml/v8/qv8engine.cpp    |  7 -------
 tools/qmljs/qmljs.cpp           |  7 +++----
 5 files changed, 24 insertions(+), 11 deletions(-)

--- a/src/qml/jit/qv4isel_masm.cpp
+++ b/src/qml/jit/qv4isel_masm.cpp
@@ -72,6 +72,8 @@ InstructionSelection<JITAssembler>::Inst
     , compilationUnit(new CompilationUnit)
     , qmlEngine(qmlEngine)
 {
+    checkRequiredCpuSupport();
+
     compilationUnit->codeRefs.resize(module->functions.size());
     module->unitFlags |= QV4::CompiledData::Unit::ContainsMachineCode;
 }
--- a/src/qml/jit/qv4isel_masm_p.h
+++ b/src/qml/jit/qv4isel_masm_p.h
@@ -60,6 +60,7 @@
 
 #include <QtCore/QHash>
 #include <QtCore/QStack>
+#include <private/qsimd_p.h>
 #include <config.h>
 #include <wtf/Vector.h>
 
@@ -72,6 +73,23 @@ QT_BEGIN_NAMESPACE
 namespace QV4 {
 namespace JIT {
 
+Q_QML_PRIVATE_EXPORT inline bool hasRequiredCpuSupport()
+{
+#ifdef Q_PROCESSOR_X86_32
+    return qCpuHasFeature(SSE2);
+#else
+    return true;
+#endif
+}
+
+Q_QML_PRIVATE_EXPORT inline void checkRequiredCpuSupport()
+{
+#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
+}
+
 template <typename JITAssembler = Assembler<DefaultAssemblerTargetConfiguration>>
 class Q_QML_EXPORT InstructionSelection:
         protected IR::IRDecoder,
--- a/src/qml/jsruntime/qv4engine.cpp
+++ b/src/qml/jsruntime/qv4engine.cpp
@@ -165,6 +165,7 @@ ExecutionEngine::ExecutionEngine(EvalISe
 
 #ifdef V4_ENABLE_JIT
         static const bool forceMoth = !qEnvironmentVariableIsEmpty("QV4_FORCE_INTERPRETER") ||
+                                      !JIT::hasRequiredCpuSupport() ||
                                       !OSAllocator::canAllocateExecutableMemory();
         if (forceMoth) {
             factory = new Moth::ISelFactory;
--- 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> >();
--- 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;