Fix random-inl for the deprecated HWY_SCALAR target

AESRound is not supported there.
Also lint fix for size_t and random_device.

PiperOrigin-RevId: 907659857

Author: jan-wassenberg

hwy/contrib/random/random-inl.h

@@ -21,6 +21,8 @@
 #define HIGHWAY_HWY_CONTRIB_RANDOM_RANDOM_H_
 #endif
 
+#include <stddef.h>
+
 #include <array>
 #include <cstdint>
 #include <limits>
@@ -201,7 +203,7 @@ class VectorXoshiro {
 
   HWY_INLINE VU64 operator()() noexcept { return Next(); }
 
-  AlignedVector<std::uint64_t> operator()(const std::size_t n) {
+  AlignedVector<std::uint64_t> operator()(const size_t n) {
     AlignedVector<std::uint64_t> result(n);
     const ScalableTag<std::uint64_t> tag{};
     auto s0 = Load(tag, state_[{0}].data());
@@ -254,7 +256,7 @@ class VectorXoshiro {
     return Mul(real, MUL_VALUE);
   }
 
-  AlignedVector<double> Uniform(const std::size_t n) {
+  AlignedVector<double> Uniform(const size_t n) {
     AlignedVector<double> result(n);
     const ScalableTag<std::uint64_t> tag{};
     const ScalableTag<double> real_tag{};
@@ -371,7 +373,7 @@ class CachedXoshiro {
  private:
   VectorXoshiro generator_;
   alignas(HWY_ALIGNMENT) std::array<result_type, size> cache_;
-  std::size_t index_;
+  size_t index_;
 
   static_assert((size & (size - 1)) == 0 && size != 0,
                 "only power of 2 are supported");
@@ -420,6 +422,7 @@ class alignas(16) AesCtrEngine {
   // users generally call once at a time, this requires buffering, which is not
   // worth the complexity in this application.
   uint64_t operator()(uint64_t stream, uint64_t counter) const {
+#if HWY_TARGET != HWY_SCALAR
     using D = Full128<uint8_t>;  // 128 bits for AES
     using V = Vec<D>;
     const Repartition<uint64_t, D> d64;
@@ -441,6 +444,12 @@ class alignas(16) AesCtrEngine {
 
     // Return lower 64 bits of the u8 vector.
     return GetLane(BitCast(d64, state));
+#else
+    HWY_DASSERT(0);  // Not supported.
+    (void)stream;
+    (void)counter;
+    return 0;
+#endif  // HWY_TARGET != HWY_SCALAR
   }
 
  private:

hwy/contrib/random/random_test.cc

@@ -73,7 +73,7 @@ void TestSeeding() {
 
 void TestMultiThreadSeeding() {
   const std::uint64_t seed = GetSeed();
-  const std::uint64_t threadId = std::random_device()() % 1000;
+  const std::uint64_t threadId = GetSeed() % 1000;
   VectorXoshiro generator{seed, threadId};
   internal::Xoshiro reference{seed};
 
@@ -293,6 +293,8 @@ void TestUniformCachedXorshiro() {
 
 // ----- AesCtrEngine / RngStream / RandomNormalizedFloat tests -----
 
+#if HWY_TARGET != HWY_SCALAR
+
 void TestAesCtrDeterministic() {
   const AesCtrEngine engine1(/*deterministic=*/true);
   const AesCtrEngine engine2(/*deterministic=*/true);
@@ -406,6 +408,22 @@ void TestRandomNormalizedFloat() {
   HWY_ASSERT(-0.01 < mean && mean < 0.01);
 }
 
+#else
+
+void TestAesCtrDeterministic() {}
+
+void TestAesCtrSeeded() {}
+
+void TestAesCtrStreamsDiffer() {}
+
+void TestAesCtrBitDistribution() {}
+
+void TestAesCtrChiSquared() {}
+
+void TestRandomNormalizedFloat() {}
+
+#endif  // HWY_TARGET != HWY_SCALAR
+
 }  // namespace
 // NOLINTNEXTLINE(google-readability-namespace-comments)
 }  // namespace HWY_NAMESPACE