带有霓虹灯说明的Linpack的clang O3/O2错误

Question

我使用来自[http://www.roylongbottom.org.uk/Raspberry_Pi_Benchmarks.zip][1]的代码Neonlinpack代码

当我使用clang编译它时，没有任何优化标志，它运行正常。但当我在命令中使用O3/O2标志时，

clang -target armv7a-linux-gnueabihf -mfpu=neon -mfloat-abi=hard linpackneon.c cpuidc.c -O3 -o linpackneon

我得到以下错误

In file included from cpuidc.c:13:
In file included from /usr/include/math.h:426:
/usr/include/bits/mathinline.h:756:25: error: invalid output constraint '=&q' in
      asm
                    : "=t" (__value), "=&q" (__ignore), "=m" (__cwtmp),       \
                                      ^
/usr/include/bits/mathinline.h:756:25: error: invalid output constraint '=&q' in
      asm
/usr/include/bits/mathinline.h:756:25: error: invalid output constraint '=&q' in
      asm
/usr/include/bits/mathinline.h:774:25: error: invalid output constraint '=&q' in
      asm
                    : "=t" (__value), "=&q" (__ignore), "=m" (__cwtmp),       \
                                      ^
/usr/include/bits/mathinline.h:774:25: error: invalid output constraint '=&q' in
      asm
/usr/include/bits/mathinline.h:774:25: error: invalid output constraint '=&q' in
      asm
/usr/include/bits/mathinline.h:881:3: error: unknown register name 'st' in asm
  __lrint_code;
  ^
/usr/include/bits/mathinline.h:876:40: note: expanded from macro '__lrint_code'
     : "=m" (__lrintres) : "t" (__x) : "st");

这些错误背后的原因是什么？我在GCC身上没有遇到过这样的错误。

Answer 1

cpuid.c所做的就是从Linux获取时间/计时和配置细节。要么单独编译，不做优化，要么根据需要注释掉语句。只需要定时数据。