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Replaced division instructions with IMUL_RCP

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This commit is contained in:
tevador
2019-02-22 17:48:26 +01:00
parent 9d5f621d5c
commit f3b114af88
14 changed files with 814 additions and 938 deletions
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src/AssemblyGeneratorX86.cpp
+8 -88
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@@ -17,12 +17,10 @@ You should have received a copy of the GNU General Public License
along with RandomX. If not, see<http://www.gnu.org/licenses/>.
*/
//#define TRACE
#define MAGIC_DIVISION
#include "AssemblyGeneratorX86.hpp"
#include "common.hpp"
#ifdef MAGIC_DIVISION
#include "divideByConstantCodegen.h"
#endif
#include "reciprocal.h"
#include "Program.hpp"
namespace RandomX {
@@ -276,38 +274,12 @@ namespace RandomX {
traceint(instr);
}
//~6 uOPs
void AssemblyGeneratorX86::h_IDIV_C(Instruction& instr, int i) {
//2 uOPs
void AssemblyGeneratorX86::h_IMUL_RCP(Instruction& instr, int i) {
if (instr.imm32 != 0) {
uint32_t divisor = instr.imm32;
if (divisor & (divisor - 1)) {
magicu_info mi = compute_unsigned_magic_info(divisor, sizeof(uint64_t) * 8);
if (mi.pre_shift == 0 && !mi.increment) {
asmCode << "\tmov rax, " << mi.multiplier << std::endl;
asmCode << "\tmul " << regR[instr.dst] << std::endl;
}
else {
asmCode << "\tmov rax, " << regR[instr.dst] << std::endl;
if (mi.pre_shift > 0)
asmCode << "\tshr rax, " << mi.pre_shift << std::endl;
if (mi.increment) {
asmCode << "\tadd rax, 1" << std::endl;
asmCode << "\tsbb rax, 0" << std::endl;
}
asmCode << "\tmov rcx, " << mi.multiplier << std::endl;
asmCode << "\tmul rcx" << std::endl;
}
if (mi.post_shift > 0)
asmCode << "\tshr rdx, " << mi.post_shift << std::endl;
asmCode << "\tadd " << regR[instr.dst] << ", rdx" << std::endl;
}
else { //divisor is a power of two
int shift = 0;
while (divisor >>= 1)
++shift;
if(shift > 0)
asmCode << "\tshr " << regR[instr.dst] << ", " << shift << std::endl;
}
asmCode << "\tmov rax, " << reciprocal(instr.imm32) << std::endl;
asmCode << "\timul " << regR[instr.dst] << ", rax" << std::endl;
traceint(instr);
}
else {
@@ -317,59 +289,7 @@ namespace RandomX {
//~8.5 uOPs
void AssemblyGeneratorX86::h_ISDIV_C(Instruction& instr, int i) {
int64_t divisor = (int32_t)instr.imm32;
if ((divisor & -divisor) == divisor || (divisor & -divisor) == -divisor) {
asmCode << "\tmov rax, " << regR[instr.dst] << std::endl;
// +/- power of two
bool negative = divisor < 0;
if (negative)
divisor = -divisor;
int shift = 0;
uint64_t unsignedDivisor = divisor;
while (unsignedDivisor >>= 1)
++shift;
if (shift > 0) {
asmCode << "\tmov rcx, rax" << std::endl;
asmCode << "\tsar rcx, 63" << std::endl;
uint32_t mask = (1ULL << shift) + 0xFFFFFFFF;
asmCode << "\tand ecx, 0" << std::hex << mask << std::dec << "h" << std::endl;
asmCode << "\tadd rax, rcx" << std::endl;
asmCode << "\tsar rax, " << shift << std::endl;
}
if (negative)
asmCode << "\tneg rax" << std::endl;
asmCode << "\tadd " << regR[instr.dst] << ", rax" << std::endl;
traceint(instr);
}
else if (divisor != 0) {
magics_info mi = compute_signed_magic_info(divisor);
asmCode << "\tmov rax, " << mi.multiplier << std::endl;
asmCode << "\timul " << regR[instr.dst] << std::endl;
//asmCode << "\tmov rax, rdx" << std::endl;
asmCode << "\txor eax, eax" << std::endl;
bool haveSF = false;
if (divisor > 0 && mi.multiplier < 0) {
asmCode << "\tadd rdx, " << regR[instr.dst] << std::endl;
haveSF = true;
}
if (divisor < 0 && mi.multiplier > 0) {
asmCode << "\tsub rdx, " << regR[instr.dst] << std::endl;
haveSF = true;
}
if (mi.shift > 0) {
asmCode << "\tsar rdx, " << mi.shift << std::endl;
haveSF = true;
}
if (!haveSF)
asmCode << "\ttest rdx, rdx" << std::endl;
asmCode << "\tsets al" << std::endl;
asmCode << "\tadd rdx, rax" << std::endl;
asmCode << "\tadd " << regR[instr.dst] << ", rdx" << std::endl;
traceint(instr);
}
else {
tracenop(instr);
}
tracenop(instr);
}
//2 uOPs
@@ -570,7 +490,7 @@ namespace RandomX {
INST_HANDLE(IMULH_M)
INST_HANDLE(ISMULH_R)
INST_HANDLE(ISMULH_M)
INST_HANDLE(IDIV_C)
INST_HANDLE(IMUL_RCP)
INST_HANDLE(ISDIV_C)
INST_HANDLE(INEG_R)
INST_HANDLE(IXOR_R)