core: optimize struct layouts, eliminate branches, and fix event loop dispatch

- Fix Wayland event loop lockout by properly decoupling read arming and adding poll-backed dispatching
- Support standalone display lifecycle without requiring caller to manage a loop
- Eliminate alignment holes across yasl_surface, yasl_display, seat, touch_point, and conn_drag using pahole
- Replace branching state/button decoders with compile-time locked LUTs and branchless bitwise operations
- Accelerate UTF-8 validation with 64-bit word scanning for ASCII runs

1 files changed, 22 insertions, 6 deletions

diff --git a/src/common/utf8.c b/src/common/utf8.c
index 089fd89..7f2e6f1 100644
--- a/src/common/utf8.c
+++ b/src/common/utf8.c
@@ -3,30 +3,46 @@
 #include <stdbool.h>
 #include <stdint.h>
 
+#ifndef likely
+#define likely(x)   __builtin_expect(!!(x), 1)
+#endif
+#ifndef unlikely
+#define unlikely(x) __builtin_expect(!!(x), 0)
+#endif
+
 bool yasl_utf8_validate(const char *str, size_t len)
 {
     const unsigned char *p = (const unsigned char *)str;
     const unsigned char *end = p + len;
 
     while (p < end) {
-        if (*p < 0x80) {
+        while (p + 8 <= end) {
+            uint64_t v;
+            memcpy(&v, p, 8);
+            if (v & 0x8080808080808080ull)
+                break;
+            p += 8;
+        }
+        if (p >= end) break;
+
+        if (likely(*p < 0x80)) {
             p++;
         } else if ((*p & 0xe0) == 0xc0) {
-            if (p + 1 >= end || (p[1] & 0xc0) != 0x80 || (*p & 0x1e) == 0)
+            if (unlikely(p + 1 >= end || (p[1] & 0xc0) != 0x80 || (*p & 0x1e) == 0))
                 return false;
             p += 2;
         } else if ((*p & 0xf0) == 0xe0) {
-            if (p + 2 >= end || (p[1] & 0xc0) != 0x80 || (p[2] & 0xc0) != 0x80)
+            if (unlikely(p + 2 >= end || (p[1] & 0xc0) != 0x80 || (p[2] & 0xc0) != 0x80))
                 return false;
             uint32_t cp = ((p[0] & 0x0f) << 12) | ((p[1] & 0x3f) << 6) | (p[2] & 0x3f);
-            if (cp < 0x800 || (cp >= 0xd800 && cp <= 0xdfff))
+            if (unlikely(cp < 0x800 || (cp >= 0xd800 && cp <= 0xdfff)))
                 return false;
             p += 3;
         } else if ((*p & 0xf8) == 0xf0) {
-            if (p + 3 >= end || (p[1] & 0xc0) != 0x80 || (p[2] & 0xc0) != 0x80 || (p[3] & 0xc0) != 0x80)
+            if (unlikely(p + 3 >= end || (p[1] & 0xc0) != 0x80 || (p[2] & 0xc0) != 0x80 || (p[3] & 0xc0) != 0x80))
                 return false;
             uint32_t cp = ((p[0] & 0x07) << 18) | ((p[1] & 0x3f) << 12) | ((p[2] & 0x3f) << 6) | (p[3] & 0x3f);
-            if (cp < 0x10000 || cp > 0x10ffff)
+            if (unlikely(cp < 0x10000 || cp > 0x10ffff))
                 return false;
             p += 4;
         } else {