From 7737e87ac4582d57945f3ffbbae1012f62c6b482 Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Sun, 15 Oct 2017 16:21:03 -0400
Subject: [PATCH] Properly detect vector_size attribute and use fallback
 otherwise

---
 src/hb-private.hh     | 67 +++++++++++++++++++++++++++++++++++++++++++
 src/hb-set-private.hh | 62 ++-------------------------------------
 2 files changed, 69 insertions(+), 60 deletions(-)

diff --git a/src/hb-private.hh b/src/hb-private.hh
index 46bffac28..3cf8b8d3e 100644
--- a/src/hb-private.hh
+++ b/src/hb-private.hh
@@ -1058,6 +1058,73 @@ hb_codepoint_parse (const char *s, unsigned int len, int base, hb_codepoint_t *o
 }
 
 
+/* Vectorization */
+
+struct HbOpOr
+{
+  static const bool passthru_left = true;
+  static const bool passthru_right = true;
+  template <typename T> static void process (T &o, const T &a, const T &b) { o = a | b; }
+};
+struct HbOpAnd
+{
+  static const bool passthru_left = false;
+  static const bool passthru_right = false;
+  template <typename T> static void process (T &o, const T &a, const T &b) { o = a & b; }
+};
+struct HbOpMinus
+{
+  static const bool passthru_left = true;
+  static const bool passthru_right = false;
+  template <typename T> static void process (T &o, const T &a, const T &b) { o = a & ~b; }
+};
+struct HbOpXor
+{
+  static const bool passthru_left = true;
+  static const bool passthru_right = true;
+  template <typename T> static void process (T &o, const T &a, const T &b) { o = a ^ b; }
+};
+
+/* Type behaving similar to vectorized vars defined using __attribute__((vector_size(...))). */
+template <typename elt_t, unsigned int byte_size>
+struct hb_vector_size_t
+{
+  elt_t& operator [] (unsigned int i) { return v[i]; }
+  const elt_t& operator [] (unsigned int i) const { return v[i]; }
+
+  template <class Op>
+  inline hb_vector_size_t process (const hb_vector_size_t &o) const
+  {
+    hb_vector_size_t r;
+    for (unsigned int i = 0; i < ARRAY_LENGTH (v); i++)
+      Op::process (r.v[i], v[i], o.v[i]);
+    return r;
+  }
+  inline hb_vector_size_t operator | (const hb_vector_size_t &o) const
+  { return process<HbOpOr> (o); }
+  inline hb_vector_size_t operator & (const hb_vector_size_t &o) const
+  { return process<HbOpAnd> (o); }
+  inline hb_vector_size_t operator ^ (const hb_vector_size_t &o) const
+  { return process<HbOpXor> (o); }
+  inline hb_vector_size_t operator ~ () const
+  {
+    hb_vector_size_t r;
+    for (unsigned int i = 0; i < ARRAY_LENGTH (v); i++)
+      r.v[i] = ~v[i];
+    return r;
+  }
+
+  private:
+  static_assert (byte_size / sizeof (elt_t) * sizeof (elt_t) == byte_size);
+  elt_t v[byte_size / sizeof (elt_t)];
+};
+
+/* The `vector_size' attribute was introduced in gcc 3.1. */
+#if defined( __GNUC__ ) && ( __GNUC__ >= 4 )
+#define HAVE_VECTOR_SIZE 1
+#endif
+
+
 /* Global runtime options. */
 
 struct hb_options_t
diff --git a/src/hb-set-private.hh b/src/hb-set-private.hh
index 227a5507a..7bb57d9f4 100644
--- a/src/hb-set-private.hh
+++ b/src/hb-set-private.hh
@@ -35,64 +35,6 @@
  * hb_set_t
  */
 
-struct HbOpOr
-{
-  static const bool passthru_left = true;
-  static const bool passthru_right = true;
-  template <typename T> static void process (T &o, const T &a, const T &b) { o = a | b; }
-};
-struct HbOpAnd
-{
-  static const bool passthru_left = false;
-  static const bool passthru_right = false;
-  template <typename T> static void process (T &o, const T &a, const T &b) { o = a & b; }
-};
-struct HbOpMinus
-{
-  static const bool passthru_left = true;
-  static const bool passthru_right = false;
-  template <typename T> static void process (T &o, const T &a, const T &b) { o = a & ~b; }
-};
-struct HbOpXor
-{
-  static const bool passthru_left = true;
-  static const bool passthru_right = true;
-  template <typename T> static void process (T &o, const T &a, const T &b) { o = a ^ b; }
-};
-
-template <typename elt_t, unsigned int byte_size>
-struct vector_like_t
-{
-  elt_t& operator [] (unsigned int i) { return v[i]; }
-  const elt_t& operator [] (unsigned int i) const { return v[i]; }
-
-  template <class Op>
-  inline vector_like_t process (const vector_like_t &o) const
-  {
-    vector_like_t r;
-    for (unsigned int i = 0; i < ARRAY_LENGTH (v); i++)
-      Op::process (r.v[i], v[i], o.v[i]);
-    return r;
-  }
-  inline vector_like_t operator | (const vector_like_t &o) const
-  { return process<HbOpOr> (o); }
-  inline vector_like_t operator & (const vector_like_t &o) const
-  { return process<HbOpAnd> (o); }
-  inline vector_like_t operator ^ (const vector_like_t &o) const
-  { return process<HbOpXor> (o); }
-  inline vector_like_t operator ~ () const
-  {
-    vector_like_t r;
-    for (unsigned int i = 0; i < ARRAY_LENGTH (v); i++)
-      r.v[i] = ~v[i];
-    return r;
-  }
-
-  private:
-  static_assert (byte_size / sizeof (elt_t) * sizeof (elt_t) == byte_size);
-  elt_t v[byte_size / sizeof (elt_t)];
-};
-
 struct hb_set_t
 {
   struct page_map_t
@@ -194,10 +136,10 @@ struct hb_set_t
 
     typedef uint64_t elt_t;
 
-#if 0
+#if HAVE_VECTOR_SIZE
     typedef elt_t vector_t __attribute__((vector_size (PAGE_BITS / 8)));
 #else
-    typedef vector_like_t<elt_t, PAGE_BITS / 8> vector_t;
+    typedef hb_vector_size_t<elt_t, PAGE_BITS / 8> vector_t;
 #endif
 
     vector_t v;