Integer Overflow/Wrap and GCC Optimizations

[Florian Weimer]

On 01/24/2013 04:02 PM, Jeffrey Walton wrote:

> I have a small library that uses inline assembly to check OV/CY flags
> for both x86/x64 and ARM. x86/x64 uses FLAGS/EFLAGS, while ARM uses
> CPSR.

Please show some sample code.

You can check the flags set by a preceding arithmetic/logical 
instruction in the *same* asm statement.  You cannot use asm statements 
to access such flags set by other asm statements, or by code emitted by GCC.

-- 
Florian Weimer / Red Hat Product Security Team