folly::simd::contains, all types. (facebook#2306)

Summary:
Pull Request resolved: facebook#2306

extended the SimdCharPlatform => SimdPlatform to support all unsigned types.

Reviewed By: Gownta

Differential Revision: D63548781

folly/algorithm/simd/detail/BUCK

@@ -16,8 +16,8 @@ cpp_library(
 )
 
 cpp_library(
-    name = "simd_char_platform",
-    headers = ["SimdCharPlatform.h"],
+    name = "simd_platform",
+    headers = ["SimdPlatform.h"],
     exported_deps = [
         "//folly:portability",
         "//folly/algorithm/simd:ignore",
@@ -31,7 +31,7 @@ cpp_library(
     headers = ["ContainsImpl.h"],
     exported_deps = [
         ":simd_any_of",
-        ":simd_char_platform",
+        ":simd_platform",
         "//folly:c_portability",
         "//folly/container:span",
     ],
@@ -45,6 +45,7 @@ cpp_library(
         "//folly:c_portability",
         "//folly:traits",
         "//folly/algorithm/simd:ignore",
+        "//folly/lang:align",
     ],
 )
 

folly/algorithm/simd/detail/ContainsImpl.h

@@ -23,7 +23,7 @@
 
 #include <folly/CPortability.h>
 #include <folly/algorithm/simd/detail/SimdAnyOf.h>
-#include <folly/algorithm/simd/detail/SimdCharPlatform.h>
+#include <folly/algorithm/simd/detail/SimdPlatform.h>
 #include <folly/container/span.h>
 
 namespace folly::simd::detail {
@@ -62,20 +62,20 @@ FOLLY_ERASE bool containsImplStd(folly::span<const T> haystack, T needle) {
 
 template <typename T>
 constexpr bool hasHandwrittenContains() {
-  return std::is_same_v<T, std::uint8_t> &&
-      !std::is_same_v<SimdCharPlatform, void>;
+  return !std::is_same_v<SimdPlatform<T>, void> &&
+      (std::is_same_v<std::uint8_t, T> || std::is_same_v<std::uint16_t, T> ||
+       std::is_same_v<std::uint32_t, T> || std::is_same_v<std::uint64_t, T>);
 }
 
 template <typename T>
 FOLLY_ERASE bool containsImplHandwritten(
     folly::span<const T> haystack, T needle) {
-  static_assert(std::is_same_v<T, std::uint8_t>, "");
-  auto as_chars = folly::reinterpret_span_cast<const char>(haystack);
-  return simdAnyOf<SimdCharPlatform, 4>(
-      as_chars.data(),
-      as_chars.data() + as_chars.size(),
-      [&](SimdCharPlatform::reg_t x) {
-        return SimdCharPlatform::equal(x, static_cast<char>(needle));
+  static_assert(!std::is_same_v<SimdPlatform<T>, void>, "");
+  return simdAnyOf<SimdPlatform<T>, 4>(
+      haystack.data(),
+      haystack.data() + haystack.size(),
+      [&](typename SimdPlatform<T>::reg_t x) {
+        return SimdPlatform<T>::equal(x, static_cast<T>(needle));
       });
 }
 

folly/algorithm/simd/detail/SimdForEach.h

@@ -20,6 +20,7 @@
 #include <folly/Traits.h>
 #include <folly/algorithm/simd/Ignore.h>
 #include <folly/algorithm/simd/detail/UnrollUtils.h>
+#include <folly/lang/Align.h>
 
 #include <array>
 #include <cstdint>
@@ -67,15 +68,12 @@ FOLLY_ALWAYS_INLINE void simdForEachAligning(
 /**
  * previousAlignedAddress
  *
- * Given a pointer returns a closest pointer aligned to a given size.
- * (it just masks out some lower bits)
+ * Given a pointer returns a closest pointer aligned to a given size
+ * (in elements).
  */
 template <typename T>
 FOLLY_ALWAYS_INLINE T* previousAlignedAddress(T* ptr, int to) {
-  std::uintptr_t uptr = reinterpret_cast<std::uintptr_t>(ptr);
-  std::uintptr_t uto = static_cast<std::uintptr_t>(to);
-  uptr &= ~(uto - 1);
-  return reinterpret_cast<T*>(uptr);
+  return align_floor(ptr, sizeof(T) * to);
 }
 
 /**