From e4d805163f0942693ae15fee3e3a8bdd9a08554b Mon Sep 17 00:00:00 2001
From: Mike Pall <mike>
Date: Sat, 25 Jul 2026 20:53:11 +0200
Subject: FFI: Fix widening semantics for 64 bit arithmetic.

Thanks to Frityet. #1492
---
 src/lj_crecord.c  | 2 +-
 src/lj_opt_fold.c | 4 ----
 2 files changed, 1 insertion(+), 5 deletions(-)

diff --git a/src/lj_crecord.c b/src/lj_crecord.c
index 4adfefe63..59420184a 100644
--- a/src/lj_crecord.c
+++ b/src/lj_crecord.c
@@ -1249,7 +1249,7 @@ static TRef crec_arith_int64(jit_State *J, TRef *sp, CType **s, MMS mm)
 	sp[i] = emitconv(sp[i], dt, st, IRCONV_TRUNC|IRCONV_ANY);
       else if (!(st == IRT_I64 || st == IRT_U64))
 	sp[i] = emitconv(sp[i], dt, IRT_INT,
-			 (s[i]->info & CTF_UNSIGNED) ? 0 : IRCONV_SEXT);
+			 ((st - IRT_I8) & 1) ? 0 : IRCONV_SEXT);
     }
     if (mm < MM_add) {
     comp:
diff --git a/src/lj_opt_fold.c b/src/lj_opt_fold.c
index b8676a577..03d869d00 100644
--- a/src/lj_opt_fold.c
+++ b/src/lj_opt_fold.c
@@ -956,14 +956,10 @@ LJFOLDF(simplify_conv_i64_num)
     fins->op2 = ((IRT_I64<<5)|IRT_INT|IRCONV_SEXT);
     return RETRYFOLD;
   } else if ((fleft->op2 & IRCONV_SRCMASK) == IRT_U32) {
-#if LJ_TARGET_X64
-    return fleft->op1;
-#else
     /* Reduce to a zero-extension. */
     fins->op1 = fleft->op1;
     fins->op2 = (IRT_I64<<5)|IRT_U32;
     return RETRYFOLD;
-#endif
   }
   return NEXTFOLD;
 }
-- 
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