ARM Skia NEON patches - 41 - arm64: SkXfermode::xfer32
Currently the NEON code for Xfermodes performs well on arm64
targets except for dstout and dstin which are significantly
slower than the C code. This patch fixes this and gives
further improvements on other modes.
Here are some perf results:
+------------+------------+------------+
| mode | Cortex-A53 | Cortex-A57 |
+------------+------------+------------+
| multiply | +24.58% | +23.71% |
+------------+------------+------------+
| exclusion | +22.72% | +22.05% |
+------------+------------+------------+
| difference | +34.67% | +36.82% |
+------------+------------+------------+
| hardlight | +17.07% | +14.74% |
+------------+------------+------------+
| lighten | +38.21% | +32.87% |
+------------+------------+------------+
| darken | +37.59% | +32.99% |
+------------+------------+------------+
| overlay | +17.36% | +16.88% |
+------------+------------+------------+
| screen | +52.56% | +54.43% |
+------------+------------+------------+
| modulate | +62.85% | +61.32% |
+------------+------------+------------+
| plus | +91.52% | +117.41% |
+------------+------------+------------+
| xor | +42.86% | +43.38% |
+------------+------------+------------+
| dstatop | +48.46% | +48.99% |
+------------+------------+------------+
| srcatop | +50.50% | +48.51% |
+------------+------------+------------+
| dstout | +67.83% | +78.09% |
+------------+------------+------------+
| srcout | +69.02% | +78.26% |
+------------+------------+------------+
| dstin | +70.92% | +79.24% |
+------------+------------+------------+
| srcin | +68.90% | +78.23% |
+------------+------------+------------+
| dstover | +73.80% | +68.10% |
+------------+------------+------------+
Signed-off-by: Kévin PETIT <kevin.petit@arm.com>
BUG=skia
R=mtklein@google.com, djsollen@google.com
Author: kevin.petit@arm.com
Review URL: https://codereview.chromium.org/350343002
diff --git a/src/opts/SkXfermode_opts_arm_neon.cpp b/src/opts/SkXfermode_opts_arm_neon.cpp
index 70e92af..88c179d 100644
--- a/src/opts/SkXfermode_opts_arm_neon.cpp
+++ b/src/opts/SkXfermode_opts_arm_neon.cpp
@@ -748,8 +748,9 @@
fProcSIMD = reinterpret_cast<void*>(gNEONXfermodeProcs[this->getMode()]);
}
-void SkNEONProcCoeffXfermode::xfer32(SkPMColor dst[], const SkPMColor src[],
- int count, const SkAlpha aa[]) const {
+void SkNEONProcCoeffXfermode::xfer32(SkPMColor* SK_RESTRICT dst,
+ const SkPMColor* SK_RESTRICT src, int count,
+ const SkAlpha* SK_RESTRICT aa) const {
SkASSERT(dst && src && count >= 0);
SkXfermodeProc proc = this->getProc();
@@ -758,13 +759,16 @@
if (NULL == aa) {
// Unrolled NEON code
+ // We'd like to just do this (modulo a few casts):
+ // vst4_u8(dst, procSIMD(vld4_u8(src), vld4_u8(dst)));
+ // src += 8;
+ // dst += 8;
+ // but that tends to generate miserable code. Here are a bunch of faster
+ // workarounds for different architectures and compilers.
while (count >= 8) {
- uint8x8x4_t vsrc, vdst, vres;
-#ifdef SK_CPU_ARM64
- vsrc = vld4_u8((uint8_t*)src);
- vdst = vld4_u8((uint8_t*)dst);
-#else
+#ifdef SK_CPU_ARM32
+ uint8x8x4_t vsrc, vdst, vres;
#if (__GNUC__ > 4) || ((__GNUC__ == 4) && (__GNUC_MINOR__ > 6))
asm volatile (
"vld4.u8 %h[vsrc], [%[src]]! \t\n"
@@ -797,17 +801,36 @@
vsrc.val[2] = d2; vdst.val[2] = d6;
vsrc.val[3] = d3; vdst.val[3] = d7;
#endif
-#endif // #ifdef SK_CPU_ARM64
vres = procSIMD(vsrc, vdst);
vst4_u8((uint8_t*)dst, vres);
- count -= 8;
dst += 8;
-#ifdef SK_CPU_ARM64
- src += 8;
-#endif
+
+#else // #ifdef SK_CPU_ARM32
+
+ asm volatile (
+ "ld4 {v0.8b - v3.8b}, [%[src]], #32 \t\n"
+ "ld4 {v4.8b - v7.8b}, [%[dst]] \t\n"
+ "blr %[proc] \t\n"
+ "st4 {v0.8b - v3.8b}, [%[dst]], #32 \t\n"
+ : [src] "+&r" (src), [dst] "+&r" (dst)
+ : [proc] "r" (procSIMD)
+ : "cc", "memory",
+ /* We don't know what proc is going to clobber so we must
+ * add everything that is not callee-saved.
+ */
+ "x0", "x1", "x2", "x3", "x4", "x5", "x6", "x7", "x8", "x9",
+ "x10", "x11", "x12", "x13", "x14", "x15", "x16", "x17", "x18",
+ "v0", "v1", "v2", "v3", "v4", "v5", "v6", "v7", "v16", "v17",
+ "v18", "v19", "v20", "v21", "v22", "v23", "v24", "v25", "v26",
+ "v27", "v28", "v29", "v30", "v31"
+ );
+
+#endif // #ifdef SK_CPU_ARM32
+
+ count -= 8;
}
// Leftovers
for (int i = 0; i < count; i++) {