On Tue, Sep 23, 2014 at 5:11 PM, Bin Meng <bmeng...@gmail.com> wrote: > > Sorry I still don't get it. The inline-asm codes are put in the very end > of the test function just before return, so the clobbered registers are > not used by gcc. The %edx gets overwritten before the inline-asm block. > > I just did a modification to the inline-asm codes to indicate to gcc that > %edx is clobbered, but it did not help. >
PS: if turning on WORKAROUND define in my test code, the generated codes are correct. I believe the issue is not with the inline assembly constraints but with '-Os' plus '-regparm=3' combination. With '-Os' gcc optimization goes too far to generate nothing for the C code 'params.a = d;' and gcc simply takes %edx (supposed to be the 2nd parameter of test function) for a scratch register. Regards, Bin
