From 35e4f43ac749a479dee960452e866cb575b588a0 Mon Sep 17 00:00:00 2001
From: Dmitrii Kovalkov <dimas.kovas@gmail.com>
Date: Mon, 18 May 2020 09:24:22 +0200
Subject: [PATCH] Add alternative implenetation for rand

---
 src/Functions/FunctionsRandom.cpp | 46 +++++++++++++++++++++++++++++++
 src/Functions/FunctionsRandom.h   | 12 ++++++--
 src/Functions/RandXorshift.h      |  5 ----
 3 files changed, 56 insertions(+), 7 deletions(-)

diff --git a/src/Functions/FunctionsRandom.cpp b/src/Functions/FunctionsRandom.cpp
index 11861d2d12c..9c6d90e9e73 100644
--- a/src/Functions/FunctionsRandom.cpp
+++ b/src/Functions/FunctionsRandom.cpp
@@ -66,6 +66,52 @@ void RandImpl::execute(char * output, size_t size)
     /// It is guaranteed (by PaddedPODArray) that we can overwrite up to 15 bytes after end.
 }
 
+void RandImpl2::execute(char * output, size_t size)
+{
+    if (size == 0)
+        return;
+
+    LinearCongruentialGenerator generator0;
+    LinearCongruentialGenerator generator1;
+    LinearCongruentialGenerator generator2;
+    LinearCongruentialGenerator generator3;
+    LinearCongruentialGenerator generator4;
+    LinearCongruentialGenerator generator5;
+    LinearCongruentialGenerator generator6;
+    LinearCongruentialGenerator generator7;
+
+    seed(generator0, 0xfb4121280b2ab902ULL + reinterpret_cast<intptr_t>(output));
+    seed(generator1, 0x0121cf76df39c673ULL + reinterpret_cast<intptr_t>(output));
+    seed(generator2, 0x17ae86e3a19a602fULL + reinterpret_cast<intptr_t>(output));
+    seed(generator3, 0x8b6e16da7e06d622ULL + reinterpret_cast<intptr_t>(output));
+    seed(generator4, 0xfb4122280b2ab102ULL + reinterpret_cast<intptr_t>(output));
+    seed(generator5, 0x0121c276df39c173ULL + reinterpret_cast<intptr_t>(output));
+    seed(generator6, 0x17ae82e3a19a612fULL + reinterpret_cast<intptr_t>(output));
+    seed(generator7, 0x8b6e12da7e06d122ULL + reinterpret_cast<intptr_t>(output));
+
+    const char * end = output + size;
+
+    for (; (end - output + 15) <= 32; output += 32)
+    {
+        unalignedStore<UInt32>(output, generator0.next());
+        unalignedStore<UInt32>(output + 4, generator1.next());
+        unalignedStore<UInt32>(output + 8, generator2.next());
+        unalignedStore<UInt32>(output + 12, generator3.next());
+        unalignedStore<UInt32>(output + 16, generator4.next());
+        unalignedStore<UInt32>(output + 20, generator5.next());
+        unalignedStore<UInt32>(output + 24, generator6.next());
+        unalignedStore<UInt32>(output + 28, generator7.next());
+    }
+
+    while (end - output > 0) {
+        unalignedStore<UInt32>(output, generator0.next());
+        unalignedStore<UInt32>(output + 4, generator1.next());
+        unalignedStore<UInt32>(output + 8, generator2.next());
+        unalignedStore<UInt32>(output + 12, generator3.next());
+        output += 16;
+    }
+}
+
 ) //DECLARE_MULTITARGET_CODE
 
 }
diff --git a/src/Functions/FunctionsRandom.h b/src/Functions/FunctionsRandom.h
index a716826d4e1..443f44a4e44 100644
--- a/src/Functions/FunctionsRandom.h
+++ b/src/Functions/FunctionsRandom.h
@@ -7,8 +7,7 @@
 
 #include <Functions/TargetSpecific.h>
 #include <Functions/PerformanceAdaptors.h>
-// #include "TargetSpecific.h"
-// #include "PerformanceAdaptors.h"
+
 namespace DB
 {
 
@@ -45,6 +44,12 @@ struct RandImpl
     static String getImplementationTag() { return ToString(BuildArch); }
 };
 
+struct RandImpl2
+{
+    static void execute(char * output, size_t size);
+    static String getImplementationTag() { return ToString(BuildArch) + "_v2"; }
+};
+
 ) // DECLARE_MULTITARGET_CODE
 
 template <typename RandImpl, typename ToType, typename Name>
@@ -106,6 +111,9 @@ public:
             registerImplementation<FunctionRandomImpl<TargetSpecific::AVX::RandImpl,     ToType, Name>>(TargetArch::AVX);
             registerImplementation<FunctionRandomImpl<TargetSpecific::AVX2::RandImpl,    ToType, Name>>(TargetArch::AVX2);
             registerImplementation<FunctionRandomImpl<TargetSpecific::AVX512F::RandImpl, ToType, Name>>(TargetArch::AVX512F);
+
+            registerImplementation<FunctionRandomImpl<TargetSpecific::Default::RandImpl2, ToType, Name>>(TargetArch::Default);
+            registerImplementation<FunctionRandomImpl<TargetSpecific::AVX2::RandImpl2,    ToType, Name>>(TargetArch::AVX2);
         }
     }
 
diff --git a/src/Functions/RandXorshift.h b/src/Functions/RandXorshift.h
index 2dd7723ff0a..b74fdeecbef 100644
--- a/src/Functions/RandXorshift.h
+++ b/src/Functions/RandXorshift.h
@@ -12,11 +12,6 @@
 namespace DB
 {
 
-namespace ErrorCodes
-{
-    extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
-}
-
 DECLARE_MULTITARGET_CODE(
 
 struct RandXorshiftImpl