From a521ace63ad1fa624aa692617c48b287dd2cfa5d Mon Sep 17 00:00:00 2001
From: dzhwinter <dzhwinter@gmail.com>
Date: Sun, 24 Dec 2017 03:03:58 -0800
Subject: [PATCH] "remove hash combine"
---
paddle/framework/op_kernel_type.h | 32 +++++++++++--------------------
paddle/platform/device_context.h | 4 ++--
2 files changed, 13 insertions(+), 23 deletions(-)
diff --git a/paddle/framework/op_kernel_type.h b/paddle/framework/op_kernel_type.h
index 45bbbe580d..a1dea0d9d8 100644
--- a/paddle/framework/op_kernel_type.h
+++ b/paddle/framework/op_kernel_type.h
@@ -22,33 +22,23 @@ limitations under the License. */
namespace paddle {
namespace framework {
-/*
-Refer to https://stackoverflow.com/questions/35985960/
-c-why-is-boosthash-combine-the-best-way-to-combine-hash-values
-*/
-template <class T>
-inline void HashCombine(const T& v, std::size_t* seed) {
- std::hash<T> hasher;
- *seed ^= hasher(v) + 0x9e3779b9 + (*seed << 6) + (*seed >> 2);
-}
-
struct OpKernelType {
struct Hash {
size_t operator()(const OpKernelType& key) const {
- int place = key.place_.which();
- int data_type = static_cast<int>(key.data_type_);
- int data_layout = static_cast<int>(key.data_layout_);
- int library_type = static_cast<int>(key.library_type_);
-
- size_t seed = 0;
- HashCombine(place, &seed);
- HashCombine(data_type, &seed);
- HashCombine(data_layout, &seed);
- HashCombine(library_type, &seed);
- return seed;
+ int place = key.place_.which() + (1 << LEFT_SHIFT);
+ int data_type =
+ static_cast<int>(key.data_type_) + (1 << (LEFT_SHIFT + 1));
+ int data_layout =
+ static_cast<int>(key.data_layout_) + (1 << (LEFT_SHIFT + 2));
+ int library_type =
+ static_cast<int>(key.library_type_) + (1 << (LEFT_SHIFT + 3));
+ std::hash<int> hasher;
+ return hasher(place + data_type + data_layout + library_type);
}
};
+ // place, data_type, library_type kinds less than 2^8
+ constexpr static int LEFT_SHIFT = 8;
proto::DataType data_type_;
DataLayout data_layout_;
platform::Place place_;
diff --git a/paddle/platform/device_context.h b/paddle/platform/device_context.h
index 1d46ce5c70..9b958f7c92 100644
--- a/paddle/platform/device_context.h
+++ b/paddle/platform/device_context.h
@@ -137,11 +137,11 @@ class DeviceContextPool {
private:
static DeviceContextPool* pool;
+ constexpr static int LEFT_SHIFT = 8;
struct Hash {
std::hash<int> hash_;
size_t operator()(const platform::Place& place) const {
- int pre_hash = place.which()
- << (sizeof(int) * 8 - NUM_PLACE_TYPE_LIMIT_IN_BIT);
+ int pre_hash = place.which() + (1 << LEFT_SHIFT);
if (platform::is_gpu_place(place)) {
pre_hash += boost::get<platform::GPUPlace>(place).GetDeviceId();
}