commit baf8921806c2a86e95e5e826adef27d4f64a70fc
author Mike Klein <mtklein@google.com> Tue May 05 13:20:11 2020 -0500
committer Skia Commit-Bot <skia-commit-bot@chromium.org> Mon May 11 13:54:18 2020 +0000
tree f154f0f79ba37c33bc654005330a0f150a06aabd
parent d7a5b59b1ef0832429a72f221b9cff4c5e7370a7

xor to make zero

Just noticed this while digging through skia:10210.

Not super important, but does make programs a little smaller,
and the vpxor reg,reg,reg stands out clearly in disassembly.

Could do the same for all-ones, but I think that's mostly
used from memory directly, by vptest.

Change-Id: I8372f7071a3c951f879d440bbd32640ebdfabf08
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/287858
Commit-Queue: Mike Reed <reed@google.com>
Auto-Submit: Mike Klein <mtklein@google.com>
Reviewed-by: Mike Reed <reed@google.com>

src/core/SkVM.cpp

diff --git a/src/core/SkVM.cpp b/src/core/SkVM.cpp
index 831da8e..e42c095 100644
--- a/src/core/SkVM.cpp
+++ b/src/core/SkVM.cpp
@@ -2772,7 +2772,11 @@
 
         auto load_from_memory = [&](Reg r, Val v) {
             if (instructions[v].op == Op::splat) {
-                a->vmovups(r, &constants[instructions[v].immy]);
+                if (instructions[v].immy == 0) {
+                    a->vpxor(r,r,r);
+                } else {
+                    a->vmovups(r, &constants[instructions[v].immy]);
+                }
             } else {
                 SkASSERT(stack_slot[v] != NA);
                 a->vmovups(r, A::Mem{A::rsp, stack_slot[v]*K*4});
@@ -2800,7 +2804,11 @@
 
         auto load_from_memory = [&](Reg r, Val v) {
             if (instructions[v].op == Op::splat) {
-                a->ldrq(r, &constants[instructions[v].immy]);
+                if (instructions[v].immy == 0) {
+                    a->eor16b(r,r,r);
+                } else {
+                    a->ldrq(r, &constants[instructions[v].immy]);
+                }
             } else {
                 SkASSERT(stack_slot[v] != NA);
                 a->ldrq(r, A::sp, stack_slot[v]);