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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/JitCompilerX86.cpp
+8 -97
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@@ -21,7 +21,7 @@ along with RandomX. If not, see<http://www.gnu.org/licenses/>.
#include <stdexcept>
#include "JitCompilerX86.hpp"
#include "Program.hpp"
#include "divideByConstantCodegen.h"
#include "reciprocal.h"
#include "virtualMemory.hpp"
namespace RandomX {
@@ -395,106 +395,17 @@ namespace RandomX {
emitByte(0xc2 + 8 * instr.dst);
}
void JitCompilerX86::h_IDIV_C(Instruction& instr) {
void JitCompilerX86::h_IMUL_RCP(Instruction& instr) {
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) {
emit(MOV_RAX_I);
emit64(mi.multiplier);
emit(REX_MUL_R);
emitByte(0xe0 + instr.dst);
}
else {
emit(REX_MOV_RR64);
emitByte(0xc0 + instr.dst);
if (mi.pre_shift > 0) {
emit(REX_SHR_RAX);
emitByte(mi.pre_shift);
}
if (mi.increment) {
emit(RAX_ADD_SBB_1);
}
emit(MOV_RCX_I);
emit64(mi.multiplier);
emit(MUL_RCX);
}
if (mi.post_shift > 0) {
emit(REX_SHR_RDX);
emitByte(mi.post_shift);
}
emit(REX_ADD_RM);
emitByte(0xc2 + 8 * instr.dst);
}
else { //divisor is a power of two
int shift = 0;
while (divisor >>= 1)
++shift;
if (shift > 0) {
emit(REX_SH);
emitByte(0xe8 + instr.dst);
}
}
emit(MOV_RAX_I);
emit64(reciprocal(instr.imm32));
emit(REX_IMUL_RM);
emitByte(0xc0 + 8 * instr.dst);
}
}
void JitCompilerX86::h_ISDIV_C(Instruction& instr) {
int64_t divisor = (int32_t)instr.imm32;
if ((divisor & -divisor) == divisor || (divisor & -divisor) == -divisor) {
emit(REX_MOV_RR64);
emitByte(0xc0 + instr.dst);
// +/- 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) {
emit(MOV_RCX_RAX_SAR_RCX_63);
uint32_t mask = (1ULL << shift) - 1;
emit(AND_ECX_I);
emit32(mask);
emit(ADD_RAX_RCX);
emit(SAR_RAX_I8);
emitByte(shift);
}
if (negative)
emit(NEG_RAX);
emit(ADD_R_RAX);
emitByte(0xc0 + instr.dst);
}
else if (divisor != 0) {
magics_info mi = compute_signed_magic_info(divisor);
emit(MOV_RAX_I);
emit64(mi.multiplier);
emit(REX_MUL_R);
emitByte(0xe8 + instr.dst);
emit(XOR_EAX_EAX);
bool haveSF = false;
if (divisor > 0 && mi.multiplier < 0) {
emit(ADD_RDX_R);
emitByte(0xc2 + 8 * instr.dst);
haveSF = true;
}
if (divisor < 0 && mi.multiplier > 0) {
emit(SUB_RDX_R);
emitByte(0xc2 + 8 * instr.dst);
haveSF = true;
}
if (mi.shift > 0) {
emit(SAR_RDX_I8);
emitByte(mi.shift);
haveSF = true;
}
if (!haveSF)
emit(TEST_RDX_RDX);
emit(SETS_AL_ADD_RDX_RAX);
emit(ADD_R_RAX);
emitByte(0xc2 + 8 * instr.dst);
}
}
void JitCompilerX86::h_INEG_R(Instruction& instr) {
@@ -748,7 +659,7 @@ 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)