From f6f8c9351beaad3176a1414f80a2124f30f05da7 Mon Sep 17 00:00:00 2001
From: HongyuJia <jiahongyu@baidu.com>
Date: Wed, 28 Sep 2022 17:23:20 +0800
Subject: [PATCH] [phi Backend] Change BackendSet from uint64_t to uint32_t
 (#46532)

* change BackendSet from 64bits to 32bits

* fix _MSC_VER error, __lzcnt32->__lzcnt

* fix __GNUC__ error, __builtin_clzl->__builtin_clz
---
 paddle/phi/api/lib/backend_set.h      |  6 +++---
 paddle/phi/api/lib/kernel_dispatch.cc | 12 ++++++------
 paddle/phi/api/lib/kernel_dispatch.h  |  6 +++---
 3 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/paddle/phi/api/lib/backend_set.h b/paddle/phi/api/lib/backend_set.h
index 93f8f05b74b..51e08374bc9 100644
--- a/paddle/phi/api/lib/backend_set.h
+++ b/paddle/phi/api/lib/backend_set.h
@@ -36,7 +36,7 @@ class BackendSet final {
                     ? 0
                     : 1ULL << (static_cast<uint8_t>(b) - 1)) {}
 
-  inline uint64_t bitset() const { return bitset_; }
+  inline uint32_t bitset() const { return bitset_; }
 
   bool inline Has(Backend b) const {
     PD_CHECK(b != Backend::UNDEFINED, "Backend argument can't be UNDEFINED.");
@@ -62,8 +62,8 @@ class BackendSet final {
   }
 
  private:
-  constexpr BackendSet(uint64_t bitset) : bitset_(bitset) {}
-  uint64_t bitset_;
+  constexpr BackendSet(uint32_t bitset) : bitset_(bitset) {}
+  uint32_t bitset_;
 };
 
 }  // namespace experimental
diff --git a/paddle/phi/api/lib/kernel_dispatch.cc b/paddle/phi/api/lib/kernel_dispatch.cc
index 75ea1d493d9..ccf070c7249 100644
--- a/paddle/phi/api/lib/kernel_dispatch.cc
+++ b/paddle/phi/api/lib/kernel_dispatch.cc
@@ -68,18 +68,18 @@ BackendSet GetTensorBackendSet(const phi::TensorBase& t) {
   return BackendSet(Backend::UNDEFINED);
 }
 
-std::size_t CountLeadingZeros(uint64_t val) {
+std::size_t CountLeadingZeros(uint32_t val) {
 #if defined(__clang__) || defined(__GNUC__)
-  return __builtin_clzl(val);
+  return __builtin_clz(val);
 #elif defined(_MSC_VER)
-  return __lzcnt64(val);
+  return __lzcnt(val);
 #else
   if (val == 0) {
-    return 64;
+    return 32;
   }
   std::size_t zero_bits = 0;
-  for (std::size_t shift = 64 >> 1; shift; shift >>= 1) {
-    uint64_t tmp = val >> shift;
+  for (std::size_t shift = 32 >> 1; shift; shift >>= 1) {
+    uint32_t tmp = val >> shift;
     if (tmp) {
       val = tmp;
     } else {
diff --git a/paddle/phi/api/lib/kernel_dispatch.h b/paddle/phi/api/lib/kernel_dispatch.h
index 1091e0556da..1ed695f8e0a 100644
--- a/paddle/phi/api/lib/kernel_dispatch.h
+++ b/paddle/phi/api/lib/kernel_dispatch.h
@@ -36,7 +36,7 @@ namespace experimental {
 
 namespace detail {
 BackendSet GetTensorBackendSet(const phi::TensorBase& t);
-std::size_t CountLeadingZeros(uint64_t val);
+std::size_t CountLeadingZeros(uint32_t val);
 }  // namespace detail
 
 phi::DeviceContext* GetDeviceContextByBackend(phi::Backend backend);
@@ -56,7 +56,7 @@ struct KernelKeySet {
 
   // TODO(chenweihang): iterate all kernelkey for kernel selection
   phi::KernelKey GetHighestPriorityKernelKey() {
-    return phi::KernelKey(static_cast<Backend>(64 - detail::CountLeadingZeros(
+    return phi::KernelKey(static_cast<Backend>(32 - detail::CountLeadingZeros(
                                                         backend_set.bitset())),
                           layout,
                           dtype);
@@ -184,7 +184,7 @@ template <typename T, typename... Args>
 Backend ParseBackend(T t, Args... args) {
   auto backend_set =
       BackendSet(ParseBackend(t)) | BackendSet(ParseBackend(args...));
-  return static_cast<Backend>(64 -
+  return static_cast<Backend>(32 -
                               detail::CountLeadingZeros(backend_set.bitset()));
 }
 Backend ParseBackendWithInputOrder(const Place& place, const Tensor& tensor);
-- 
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