Mesa (main): aco: lower masked swizzle to DPP8

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Module: Mesa
Branch: main
Commit: 31d839aacc63831e7e13c46d5070672fb09ff844
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=31d839aacc63831e7e13c46d5070672fb09ff844

Author: Tatsuyuki Ishi <ishitatsuyuki at gmail.com>
Date:   Mon Nov 29 00:12:18 2021 +0900

aco: lower masked swizzle to DPP8

Reviewed-by: Rhys Perry <pendingchaos02 at gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/13971>

---

 src/amd/compiler/aco_instruction_selection.cpp | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/src/amd/compiler/aco_instruction_selection.cpp b/src/amd/compiler/aco_instruction_selection.cpp
index 04adddd264f..bd9eff72647 100644
--- a/src/amd/compiler/aco_instruction_selection.cpp
+++ b/src/amd/compiler/aco_instruction_selection.cpp
@@ -243,7 +243,6 @@ emit_masked_swizzle(isel_context* ctx, Builder& bld, Temp src, unsigned mask)
 
       uint16_t dpp_ctrl = 0xffff;
 
-      // TODO: we could use DPP8 for some swizzles
       if (and_mask == 0x1f && or_mask < 4 && xor_mask < 4) {
          unsigned res[4] = {0, 1, 2, 3};
          for (unsigned i = 0; i < 4; i++)
@@ -255,6 +254,13 @@ emit_masked_swizzle(isel_context* ctx, Builder& bld, Temp src, unsigned mask)
          dpp_ctrl = dpp_row_mirror;
       } else if (and_mask == 0x1f && !or_mask && xor_mask == 0x7) {
          dpp_ctrl = dpp_row_half_mirror;
+      } else if (ctx->options->chip_class >= GFX10 && (and_mask & 0x18) == 0x18 && or_mask < 8 && xor_mask < 8) {
+         // DPP8 comes last, as it does not allow several modifiers like `abs` that are available with DPP16
+         Builder::Result ret = bld.vop1_dpp8(aco_opcode::v_mov_b32, bld.def(v1), src);
+         for (unsigned i = 0; i < 8; i++) {
+            ret.instr->dpp8().lane_sel[i] = (((i & and_mask) | or_mask) ^ xor_mask) & 0x7;
+         }
+         return ret;
       }
 
       if (dpp_ctrl != 0xffff)