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compiler warning in function with embedded assembly

Note: This was originally posted on 9th May 2012 at http://forums.arm.com

I'm using inline ARM assembly in C++ functions and I was wondering how to avoid "control reaches end of non-void function" warnings when my code is storing the final value in R0.

For example this function works fine, but the compiler will raise the warning:


int Math::test_iadd(int a, int 
{   
  __asm volatile 
 (
  "add r0, %0, %1   \n\t"

  : 
  : "r" (a), "r" (
  : "r0"
 );
}

An easy fix is rewriting the function as:


int Math::test_iadd2(int a, int 
{
 int ret;

 __asm volatile 
 (
  "add %0, %1, %2   \n\t"
 
  : "=r" (ret)
  : "r" (a), "r" (
  : "r0"
 );


 return ret;
}

But this shouldn't be required as the assembly generated by the compiler is basically the same code I use in the former function.

Any suggestion?

Parents

Stefan Pachner over 12 years ago

Note: This was originally posted on 10th May 2012 at http://forums.arm.com

I would say the warning is produced by the C compiler which does not recognize what you are doing in the assembler statements. So a missing return will throw the warning.

spachner
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Stefan Pachner over 12 years ago

Note: This was originally posted on 10th May 2012 at http://forums.arm.com

I would say the warning is produced by the C compiler which does not recognize what you are doing in the assembler statements. So a missing return will throw the warning.

spachner
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