ShuriZma
/
xenia-canary
mirror of https://github.com/xenia-canary/xenia-canary.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

[x64] Add `GFNI`-based optimization for `VECTOR_SH{R,L}_V128(Int8)` 

In the `Int8` case of `VECTOR_SH{R,L}_V128`, when all the values are the
same, then a single-instruction `gf2p8affineqb` can be emitted that does
an int8-based arithmetic-shift, utilizing GF(8) arithmetic.

More info here:
https://wunkolo.github.io/post/2020/11/gf2p8affineqb-int8-shifting/

Also fixes the iteration-type for when detecting if all of the simd
lanes are the same value(was iterating `u16` and not `u8`)
This commit is contained in:
Wunkolo 2022-01-23 10:25:01 -08:00 committed by Rick Gibbed
parent 7418011ab5
commit bd9a290b30
1 changed files with 40 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

42
src/xenia/cpu/backend/x64/x64_seq_vector.cc
View File

@ -731,6 +731,25 @@ struct VECTOR_SHL_V128
static void EmitInt8(X64Emitter& e, const EmitArgType& i) {
// TODO(benvanik): native version (with shift magic).
if (i.src2.is_constant) {
if (e.IsFeatureEnabled(kX64EmitGFNI)) {
const auto& shamt = i.src2.constant();
bool all_same = true;
for (size_t n = 0; n < 16 - n; ++n) {
if (shamt.u8[n] != shamt.u8[n + 1]) {
all_same = false;
break;
}
}
if (all_same) {
// Every count is the same, so we can use gf2p8affineqb.
const uint8_t shift_amount = shamt.u8[0];
const uint64_t shift_matrix =
0x0102040810204080 >> (shift_amount * 8);
e.vgf2p8affineqb(i.dest, i.src1,
e.StashConstantXmm(0, vec128q(shift_matrix)), 0);
return;
}
}
e.lea(e.GetNativeParam(1), e.StashConstantXmm(1, i.src2.constant()));
} else {
e.lea(e.GetNativeParam(1), e.StashXmm(1, i.src2));
@ -920,6 +939,25 @@ struct VECTOR_SHR_V128
static void EmitInt8(X64Emitter& e, const EmitArgType& i) {
// TODO(benvanik): native version (with shift magic).
if (i.src2.is_constant) {
if (e.IsFeatureEnabled(kX64EmitGFNI)) {
const auto& shamt = i.src2.constant();
bool all_same = true;
for (size_t n = 0; n < 16 - n; ++n) {
if (shamt.u8[n] != shamt.u8[n + 1]) {
all_same = false;
break;
}
}
if (all_same) {
// Every count is the same, so we can use gf2p8affineqb.
const uint8_t shift_amount = shamt.u8[0];
const uint64_t shift_matrix = 0x0102040810204080
<< (shift_amount * 8);
e.vgf2p8affineqb(i.dest, i.src1,
e.StashConstantXmm(0, vec128q(shift_matrix)), 0);
return;
}
}
e.lea(e.GetNativeParam(1), e.StashConstantXmm(1, i.src2.constant()));
} else {
e.lea(e.GetNativeParam(1), e.StashXmm(1, i.src2));
@ -1087,8 +1125,8 @@ struct VECTOR_SHA_V128
if (e.IsFeatureEnabled(kX64EmitGFNI)) {
const auto& shamt = i.src2.constant();
bool all_same = true;
for (size_t n = 0; n < 8 - n; ++n) {
if (shamt.u16[n] != shamt.u16[n + 1]) {
for (size_t n = 0; n < 16 - n; ++n) {
if (shamt.u8[n] != shamt.u8[n + 1]) {
all_same = false;
break;
}