Build fails on i386 with -march=nehalem or newer about astc-encoder

[solidpixel]

That fix is broken - it's truncating the value to 32-bits before taking the popcount.

Any reason you don't use the __builtin_popcountll() fallback, the same as __MINGW32__? I suspect that fallback could just be

#if !defined(__x86_64__)
        return static_cast<int>(__builtin_popcountll(v));
#else

[VVD]

I'm new to this, so I did it this way.
Your patch fixed the build issue too and look better.
Thanks!

[solidpixel]

Thanks for confirming - I'll get that in for 4.9.

[VVD]

If, before writing the patch, I had read what the popcnt instructions do, I would have suggested the following patch:

return static_cast<int>(_mm_popcnt_u32(static_cast<uint32_t>(v)) + _mm_popcnt_u32(static_cast<uint32_t>(v >> 32)));

:-)

[VVD]

Patch against main branch:

--- Source/astcenc_vecmathlib_sse_4.h.orig      2024-05-07 09:59:55 UTC
+++ Source/astcenc_vecmathlib_sse_4.h
@@ -1307,7 +1307,11 @@ ASTCENC_SIMD_INLINE vfloat4 dot3(vfloat4 a, vfloat4 b)
  */
 ASTCENC_SIMD_INLINE int popcount(uint64_t v)
 {
+#if defined(__x86_64__)
        return static_cast<int>(_mm_popcnt_u64(v));
+#else
+       return static_cast<int>(__builtin_popcountll(v));
+#endif
 }

 #endif // ASTCENC_POPCNT >= 1

[solidpixel]

Fixed on main.