From 7fe9c22cf28aa6fa63d48605335672492282a7a8 Mon Sep 17 00:00:00 2001
From: Benjamin Oldenburg <benjamin.oldenburg@ordis.co.th>
Date: Fri, 20 Mar 2026 19:59:27 +0700
Subject: [PATCH] arm64-asm.c: reject invalid registers in address operands

parse_addr_operand() silently accepted invalid register names like
[xyz] without error. Now explicitly validates the register and calls
tcc_error() if arm64_parse_regvar() returns -1 or >= 32.

Before: invalid registers caused silent wrong code or confusing errors
After: clear error message 'invalid register in address operand'
---
 arm64-asm.c | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/arm64-asm.c b/arm64-asm.c
index 9ad446e6..1897cacd 100644
--- a/arm64-asm.c
+++ b/arm64-asm.c
@@ -293,17 +293,19 @@ static void parse_addr_operand(TCCState *s1, Operand *op)
 
     skip('[');
     reg = arm64_parse_regvar(tok);
-    if (reg >= 0 && reg < 32) {
-        op->reg = reg;
-        op->reg_tok = tok;
+    if (reg < 0 || reg >= 32) {
+        tcc_error("invalid register in address operand");
+        return;
+    }
+    op->reg = reg;
+    op->reg_tok = tok;
+    next();
+    /* Check for offset */
+    if (tok == ',') {
         next();
-        /* Check for offset */
-        if (tok == ',') {
+        if (tok == '#' || tok == '@' || tok == '$')
             next();
-            if (tok == '#' || tok == '@' || tok == '$')
-                next();
-            asm_expr(s1, &op->e);
-        }
+        asm_expr(s1, &op->e);
     }
     skip(']');
     if (tok == '!') {