Bug 1827566 - Isolate SSE2 requirements to SSE-compiled file r=glandium

Only provide forward declaration to the generic code.

Differential Revision: https://phabricator.services.mozilla.com/D175742

dom/base/nsTextFragment.cpp

@@ -159,7 +159,7 @@ static inline int32_t FirstNon8BitUnvectorized(const char16_t* str,
 }
 
 #if defined(MOZILLA_MAY_SUPPORT_SSE2)
-#  include "nsTextFragmentGeneric.h"
+#  include "nsTextFragmentGenericFwd.h"
 #endif
 
 #ifdef __powerpc__

dom/base/nsTextFragmentGeneric.h

@@ -4,10 +4,14 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
+#ifndef nsTextFragmentGeneric_h__
+#define nsTextFragmentGeneric_h__
+
+#include "nsTextFragmentGenericFwd.h"
+
 #include "nscore.h"
 #include "nsTextFragmentImpl.h"
 #include <algorithm>
-#include <xsimd/xsimd.hpp>
 
 namespace mozilla {
 
@@ -57,3 +61,5 @@ int32_t FirstNon8Bit(const char16_t* str, const char16_t* end) {
 }
 
 }  // namespace mozilla
+
+#endif

dom/base/nsTextFragmentGenericFwd.h

@@ -0,0 +1,20 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsTextFragmentGenericFwd_h__
+#define nsTextFragmentGenericFwd_h__
+
+#include <cstdint>
+#include <xsimd/xsimd.hpp>
+
+namespace mozilla {
+
+template <class Arch>
+int32_t FirstNon8Bit(const char16_t* str, const char16_t* end);
+
+}  // namespace mozilla
+
+#endif