From 14d1ad0038645a1b60a197d72e6774addc1eb667 Mon Sep 17 00:00:00 2001 From: "Yukihiro \"Matz\" Matsumoto" Date: Sat, 23 Aug 2025 10:58:18 +0900 Subject: [PATCH] mruby-bigint: remove broken MSVC _umul128 optimization path The MSVC _umul128 code path was designed for 64-bit limbs but mruby's bigint implementation uses 32-bit limbs even on 64-bit builds. This fundamental mismatch caused incorrect bigint calculations on VC 64-bit builds, producing results like "100000000000000000000" -> "1661992960". Removed the MSVC optimization to fall back to the portable double-limb arithmetic which correctly handles 32-bit limbs. Co-authored-by: Claude --- mrbgems/mruby-bigint/core/bigint.c | 91 ------------------------------ 1 file changed, 91 deletions(-) diff --git a/mrbgems/mruby-bigint/core/bigint.c b/mrbgems/mruby-bigint/core/bigint.c index 63bd3b24b..06066d736 100644 --- a/mrbgems/mruby-bigint/core/bigint.c +++ b/mrbgems/mruby-bigint/core/bigint.c @@ -784,97 +784,6 @@ limb_addmul_1(mp_limb *rp, const mp_limb *s1p, size_t n, mp_limb limb) return (mp_limb)acc; -#elif defined(_MSC_VER) && defined(MRB_64BIT) && !defined(MRB_NO_MPZ64BIT) - /* 64-bit limbs on MSVC with 6x unrolling: use _umul128 */ - unsigned long long carry = 0; - size_t i; - - /* 6x unrolled loop for large operands */ - for (i = 0; i + 6 <= n; i += 6) { - unsigned long long hi, lo, sum; - - lo = _umul128((unsigned long long)s1p[i], (unsigned long long)limb, &hi); - unsigned long long rp_val = (unsigned long long)rp[i]; - unsigned long long temp = rp_val + lo; - sum = temp + carry; - rp[i] = (mp_limb)sum; - carry = hi + (temp < rp_val) + (sum < temp); - - lo = _umul128((unsigned long long)s1p[i+1], (unsigned long long)limb, &hi); - unsigned long long rp_val1 = (unsigned long long)rp[i+1]; - unsigned long long temp1 = rp_val1 + lo; - sum = temp1 + carry; - rp[i+1] = (mp_limb)sum; - carry = hi + (temp1 < rp_val1) + (sum < temp1); - - lo = _umul128((unsigned long long)s1p[i+2], (unsigned long long)limb, &hi); - unsigned long long rp_val2 = (unsigned long long)rp[i+2]; - unsigned long long temp2 = rp_val2 + lo; - sum = temp2 + carry; - rp[i+2] = (mp_limb)sum; - carry = hi + (temp2 < rp_val2) + (sum < temp2); - - lo = _umul128((unsigned long long)s1p[i+3], (unsigned long long)limb, &hi); - unsigned long long rp_val3 = (unsigned long long)rp[i+3]; - unsigned long long temp3 = rp_val3 + lo; - sum = temp3 + carry; - rp[i+3] = (mp_limb)sum; - carry = hi + (temp3 < rp_val3) + (sum < temp3); - - lo = _umul128((unsigned long long)s1p[i+4], (unsigned long long)limb, &hi); - unsigned long long rp_val4 = (unsigned long long)rp[i+4]; - unsigned long long temp4 = rp_val4 + lo; - sum = temp4 + carry; - rp[i+4] = (mp_limb)sum; - carry = hi + (temp4 < rp_val4) + (sum < temp4); - - lo = _umul128((unsigned long long)s1p[i+5], (unsigned long long)limb, &hi); - unsigned long long rp_val5 = (unsigned long long)rp[i+5]; - unsigned long long temp5 = rp_val5 + lo; - sum = temp5 + carry; - rp[i+5] = (mp_limb)sum; - carry = hi + (temp5 < rp_val5) + (sum < temp5); - } - - /* 3x unrolled loop for medium operands */ - for (; i + 3 <= n; i += 3) { - unsigned long long hi, lo, sum; - - lo = _umul128((unsigned long long)s1p[i], (unsigned long long)limb, &hi); - unsigned long long rp_val = (unsigned long long)rp[i]; - unsigned long long temp = rp_val + lo; - sum = temp + carry; - rp[i] = (mp_limb)sum; - carry = hi + (temp < rp_val) + (sum < temp); - - lo = _umul128((unsigned long long)s1p[i+1], (unsigned long long)limb, &hi); - unsigned long long rp_val1 = (unsigned long long)rp[i+1]; - unsigned long long temp1 = rp_val1 + lo; - sum = temp1 + carry; - rp[i+1] = (mp_limb)sum; - carry = hi + (temp1 < rp_val1) + (sum < temp1); - - lo = _umul128((unsigned long long)s1p[i+2], (unsigned long long)limb, &hi); - unsigned long long rp_val2 = (unsigned long long)rp[i+2]; - unsigned long long temp2 = rp_val2 + lo; - sum = temp2 + carry; - rp[i+2] = (mp_limb)sum; - carry = hi + (temp2 < rp_val2) + (sum < temp2); - } - - /* Handle remaining elements */ - for (; i < n; i++) { - unsigned long long hi, lo; - lo = _umul128((unsigned long long)s1p[i], (unsigned long long)limb, &hi); - unsigned long long rp_val = (unsigned long long)rp[i]; - unsigned long long temp = rp_val + lo; - unsigned long long sum = temp + carry; - rp[i] = (mp_limb)sum; - carry = hi + (temp < rp_val) + (sum < temp); - } - - return (mp_limb)carry; - #else /* Portable double-limb path with 4x unrolling */ mp_dbl_limb acc = 0;