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RandomX: optimized CFROUND elimination

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This commit is contained in:
SChernykh 2022-09-15 18:58:06 +02:00
parent 1c4eb6c5fe
commit f0e7de8c71
1 changed files with 18 additions and 13 deletions
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31
src/crypto/randomx/jit_compiler_x86.cpp
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@ -167,6 +167,11 @@ namespace randomx {
static const uint8_t* NOPX[] = { NOP1, NOP2, NOP3, NOP4, NOP5, NOP6, NOP7, NOP8, NOP9 };
static const uint8_t NOP13[] = { 0x0F, 0x1F, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00, 0x0F, 0x1F, 0x44, 0x00, 0x00 };
static const uint8_t NOP14[] = { 0x0F, 0x1F, 0x80, 0x00, 0x00, 0x00, 0x00, 0x0F, 0x1F, 0x80, 0x00, 0x00, 0x00, 0x00 };
static const uint8_t NOP25[] = { 0x66, 0x0F, 0x1F, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00, 0x0F, 0x1F, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00, 0x0F, 0x1F, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00 };
static const uint8_t NOP26[] = { 0x66, 0x0F, 0x1F, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00, 0x66, 0x0F, 0x1F, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00, 0x0F, 0x1F, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00 };
static const uint8_t JMP_ALIGN_PREFIX[14][16] = {
{},
{0x2E},
@ -1287,13 +1292,10 @@ namespace randomx {
if (pos) {
if (vm_flags & RANDOMX_FLAG_AMD) {
memcpy(p + pos + 0, NOP9, 9);
memcpy(p + pos + 9, NOP9, 9);
memcpy(p + pos + 18, NOP8, 8);
memcpy(p + pos, NOP26, 26);
}
else {
memcpy(p + pos + 0, NOP8, 8);
memcpy(p + pos + 8, NOP6, 6);
memcpy(p + pos, NOP14, 14);
}
}
@ -1326,13 +1328,10 @@ namespace randomx {
if (pos) {
if (vm_flags & RANDOMX_FLAG_AMD) {
memcpy(p + pos + 0, NOP9, 9);
memcpy(p + pos + 9, NOP9, 9);
memcpy(p + pos + 18, NOP7, 7);
memcpy(p + pos, NOP25, 25);
}
else {
memcpy(p + pos + 0, NOP8, 8);
memcpy(p + pos + 8, NOP5, 5);
memcpy(p + pos, NOP13, 13);
}
}
@ -1363,10 +1362,16 @@ namespace randomx {
uint8_t* const p = code;
uint32_t pos = codePos;
prevCFROUND = 0;
const int reg = instr.dst % RegistersCount;
int32_t jmp_offset = registerUsage[reg] - (pos + 16);
int32_t jmp_offset = registerUsage[reg];
// if it jumps over the previous CFROUND, it can't be safely eliminated
const uint32_t t = prevCFROUND;
if (t && (jmp_offset < t)) {
prevCFROUND = 0;
}
jmp_offset -= pos + 16;
if (jccErratum) {
const uint32_t branch_begin = static_cast<uint32_t>(pos + 7);