From cd96f5305064ef4eb6551c329c4cd4d2f5e6588d Mon Sep 17 00:00:00 2001
From: Jorge Aparicio <japaricious@gmail.com>
Date: Mon, 6 Mar 2017 10:34:27 -0500
Subject: [PATCH] fix infinite recursion in divmoddi4 / mulodi4

on ARMv7-M processors, divmoddi4 was calling mulodi4 and mulodi4 was calling
divmoddi4 leading to infinite recursion. This commit breaks the cycle by using
wrapping multiplication in divmoddi4.

fixes #145
---
 library/compiler-builtins/src/int/sdiv.rs | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/library/compiler-builtins/src/int/sdiv.rs b/library/compiler-builtins/src/int/sdiv.rs
index 51d9c3769765..d00f89a27881 100644
--- a/library/compiler-builtins/src/int/sdiv.rs
+++ b/library/compiler-builtins/src/int/sdiv.rs
@@ -55,7 +55,9 @@ macro_rules! divmod {
                 #[cfg(all(feature = "c", any(target_arch = "x86")))]
                 () => unsafe { $div(a, b) },
             };
-            *rem = a - (r * b);
+            // NOTE won't overflow because it's using the result from the
+            // previous division
+            *rem = a - r.wrapping_mul(b);
             r
         }
     }