From dc0aee1432ed99fec674c715c668243d48fc9de6 Mon Sep 17 00:00:00 2001
From: SChernykh <sergey.v.chernykh@gmail.com>
Date: Wed, 10 Jun 2020 21:49:43 +0200
Subject: [PATCH] KawPow: fixed crash on old CPUs
- Use `popcnt` instruction only when it's supported
---
src/backend/cpu/interfaces/ICpuInfo.h | 1 +
src/backend/cpu/platform/BasicCpuInfo.cpp | 2 ++
src/crypto/kawpow/KPHash.cpp | 27 ++++++++++++++++++++---
3 files changed, 27 insertions(+), 3 deletions(-)
diff --git a/src/backend/cpu/interfaces/ICpuInfo.h b/src/backend/cpu/interfaces/ICpuInfo.h
index badb44c0d..bc73e75aa 100644
--- a/src/backend/cpu/interfaces/ICpuInfo.h
+++ b/src/backend/cpu/interfaces/ICpuInfo.h
@@ -61,6 +61,7 @@ public:
FLAG_SSE2,
FLAG_SSSE3,
FLAG_XOP,
+ FLAG_POPCNT,
FLAG_MAX
};
diff --git a/src/backend/cpu/platform/BasicCpuInfo.cpp b/src/backend/cpu/platform/BasicCpuInfo.cpp
index 3c48b10f1..71bfa3b1c 100644
--- a/src/backend/cpu/platform/BasicCpuInfo.cpp
+++ b/src/backend/cpu/platform/BasicCpuInfo.cpp
@@ -142,6 +142,7 @@ static inline bool has_pdpe1gb() { return has_feature(PROCESSOR_EXT_INFO,
static inline bool has_sse2() { return has_feature(PROCESSOR_INFO, EDX_Reg, 1 << 26); }
static inline bool has_ssse3() { return has_feature(PROCESSOR_INFO, ECX_Reg, 1 << 9); }
static inline bool has_xop() { return has_feature(0x80000001, ECX_Reg, 1 << 11); }
+static inline bool has_popcnt() { return has_feature(PROCESSOR_INFO, ECX_Reg, 1 << 23); }
} // namespace xmrig
@@ -176,6 +177,7 @@ xmrig::BasicCpuInfo::BasicCpuInfo() :
m_flags.set(FLAG_SSE2, has_sse2());
m_flags.set(FLAG_SSSE3, has_ssse3());
m_flags.set(FLAG_XOP, has_xop());
+ m_flags.set(FLAG_POPCNT, has_popcnt());
# ifdef XMRIG_FEATURE_ASM
if (hasAES()) {
diff --git a/src/crypto/kawpow/KPHash.cpp b/src/crypto/kawpow/KPHash.cpp
index 243d20afa..fe5873a6d 100644
--- a/src/crypto/kawpow/KPHash.cpp
+++ b/src/crypto/kawpow/KPHash.cpp
@@ -25,6 +25,7 @@
*/
+#include "backend/cpu/Cpu.h"
#include "crypto/kawpow/KPHash.h"
#include "crypto/kawpow/KPCache.h"
#include "3rdparty/libethash/ethash.h"
@@ -156,7 +157,22 @@ static inline uint32_t popcount(uint32_t a)
}
-static inline uint32_t random_math(uint32_t a, uint32_t b, uint32_t selector)
+// Taken from https://en.wikipedia.org/wiki/Hamming_weight
+static inline uint32_t popcount_soft(uint64_t x)
+{
+ constexpr uint64_t m1 = 0x5555555555555555ull;
+ constexpr uint64_t m2 = 0x3333333333333333ull;
+ constexpr uint64_t m4 = 0x0f0f0f0f0f0f0f0full;
+ constexpr uint64_t h01 = 0x0101010101010101ull;
+
+ x -= (x >> 1) & m1; //put count of each 2 bits into those 2 bits
+ x = (x & m2) + ((x >> 2) & m2); //put count of each 4 bits into those 4 bits
+ x = (x + (x >> 4)) & m4; //put count of each 8 bits into those 8 bits
+ return (x * h01) >> 56; //returns left 8 bits of x + (x<<8) + (x<<16) + (x<<24) + ...
+}
+
+
+static inline uint32_t random_math(uint32_t a, uint32_t b, uint32_t selector, bool has_popcnt)
{
switch (selector % 11)
{
@@ -181,7 +197,10 @@ static inline uint32_t random_math(uint32_t a, uint32_t b, uint32_t selector)
case 9:
return clz(a) + clz(b);
case 10:
- return popcount(a) + popcount(b);
+ if (has_popcnt)
+ return popcount(a) + popcount(b);
+ else
+ return popcount_soft(a) + popcount_soft(b);
default:
#ifdef _MSC_VER
__assume(false);
@@ -260,6 +279,8 @@ void KPHash::calculate(const KPCache& light_cache, uint32_t block_height, const
uint32_t jsr0 = jsr;
uint32_t jcong0 = jcong;
+ const bool has_popcnt = Cpu::info()->has(ICpuInfo::FLAG_POPCNT);
+
for (uint32_t r = 0; r < ETHASH_ACCESSES; ++r) {
uint32_t item_index = (mix[r % LANES][0] % num_items) * 4;
@@ -302,7 +323,7 @@ void KPHash::calculate(const KPCache& light_cache, uint32_t block_height, const
for (size_t l = 0; l < LANES; ++l)
{
- const uint32_t data = random_math(mix[l][src1], mix[l][src2], sel1);
+ const uint32_t data = random_math(mix[l][src1], mix[l][src2], sel1, has_popcnt);
random_merge(mix[l][dst], data, sel2);
}
}