From 0c51a72bfe020f250750474afb38cf55d49de87e Mon Sep 17 00:00:00 2001
From: "Yukihiro \"Matz\" Matsumoto" <matz@ruby.or.jp>
Date: Fri, 23 May 2025 23:10:45 +0900
Subject: [PATCH] string.c (popcount): support when sizeof(int) == 4

This function is used when the compiler does not support builtin
popcount operation (namely VC++).
---
 src/string.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/string.c b/src/string.c
index df7363d3d..7837d2e3a 100644
--- a/src/string.c
+++ b/src/string.c
@@ -407,12 +407,13 @@ mrb_utf8len(const char* p, const char* e)
 # define popcount(x) __builtin_popcountl(x)
 # endif
 #else
+#define POPC_SHIFT (8 * sizeof(bitint) - 8)
 static inline uint32_t popcount(bitint x)
 {
   x = (x & (MASK01*0x55)) + ((x >>  1) & (MASK01*0x55));
   x = (x & (MASK01*0x33)) + ((x >>  2) & (MASK01*0x33));
   x = (x & (MASK01*0x0F)) + ((x >>  4) & (MASK01*0x0F));
-  return (x * MASK01) >> 56;
+  return (uint32_t)((x * MASK01) >> POPC_SHIFT);
 }
 #endif