From bb5425ed3d8cc04e4242059a17912752d6b48c53 Mon Sep 17 00:00:00 2001
From: Noel Grandin <noel@peralex.com>
Date: Sat, 28 Aug 2021 18:53:07 +0200
Subject: tdf#135683 speed up writer layout cache access

can be hot, so use a std::unordered_map

Change-Id: I70e34e80cad67536414c71facbe0222dd88c65a7
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/121208
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>
---
 include/o3tl/hash_combine.hxx | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

(limited to 'include/o3tl/hash_combine.hxx')

diff --git a/include/o3tl/hash_combine.hxx b/include/o3tl/hash_combine.hxx
index 139ee981699c..f56beda62672 100644
--- a/include/o3tl/hash_combine.hxx
+++ b/include/o3tl/hash_combine.hxx
@@ -11,6 +11,17 @@
 
 namespace o3tl
 {
+template <typename T, typename N>
+inline std::enable_if_t<(sizeof(N) == 4)> hash_combine(N& nSeed, T const* pValue, size_t nCount)
+{
+    static_assert(sizeof(nSeed) == 4);
+    for (size_t i = 0; i < nCount; ++i)
+    {
+        nSeed ^= std::hash<T>{}(*pValue) + 0x9E3779B9u + (nSeed << 6) + (nSeed >> 2);
+        ++pValue;
+    }
+}
+
 template <typename T, typename N>
 inline std::enable_if_t<(sizeof(N) == 4)> hash_combine(N& nSeed, T const& nValue)
 {
@@ -18,6 +29,17 @@ inline std::enable_if_t<(sizeof(N) == 4)> hash_combine(N& nSeed, T const& nValue
     nSeed ^= std::hash<T>{}(nValue) + 0x9E3779B9u + (nSeed << 6) + (nSeed >> 2);
 }
 
+template <typename T, typename N>
+inline std::enable_if_t<(sizeof(N) == 8)> hash_combine(N& nSeed, T const* pValue, size_t nCount)
+{
+    static_assert(sizeof(nSeed) == 8);
+    for (size_t i = 0; i < nCount; ++i)
+    {
+        nSeed ^= std::hash<T>{}(*pValue) + 0x9E3779B97F4A7C15llu + (nSeed << 12) + (nSeed >> 4);
+        ++pValue;
+    }
+}
+
 template <typename T, typename N>
 inline std::enable_if_t<(sizeof(N) == 8)> hash_combine(N& nSeed, T const& nValue)
 {
-- 
cgit