From 360d7e48ab2d3c205b74523a075d92cbe3e72a7b Mon Sep 17 00:00:00 2001
From: tangyuxin <tangyuxin@rt-thread.com>
Date: Mon, 1 Feb 2021 21:01:14 +0800
Subject: [PATCH] =?UTF-8?q?[libcpu][cm33]=20=E4=BF=AE=E5=A4=8D=E4=B8=8D?=
 =?UTF-8?q?=E5=90=8C=E4=BC=98=E5=8C=96=E7=AD=89=E7=BA=A7=EF=BC=8C=E5=87=BD?=
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 =?UTF-8?q?=E9=97=AE=E9=A2=98?=
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---
 libcpu/arm/cortex-m33/cpuport.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/libcpu/arm/cortex-m33/cpuport.c b/libcpu/arm/cortex-m33/cpuport.c
index 42b5798507..41325105d7 100644
--- a/libcpu/arm/cortex-m33/cpuport.c
+++ b/libcpu/arm/cortex-m33/cpuport.c
@@ -473,17 +473,13 @@ exit
 #elif defined(__CLANG_ARM)
 int __rt_ffs(int value)
 {
-    __asm volatile(
-        "CMP     r0, #0x00            \n"
-        "BEQ     1f                   \n"
+    if (value == 0) return value;
 
+    __asm volatile(
         "RBIT    r0, r0               \n"
         "CLZ     r0, r0               \n"
         "ADDS    r0, r0, #0x01        \n"
 
-        "1:                           \n"
-        "BX      lr                   \n"
-
         : "=r"(value)
         : "r"(value)
     );