arm-none-eabi-gcc 4.9.3: local varible optimize away even if volatile added

[vaughn]

I post a question in KDS: variable optimized out when compile with O2 and LTO option , and the last question is that:

as a sample followed:

when compiled with O2 and linked with LTO, the local varible addr will be optimized away even if the volatile added, maybe there has relation with the gcc's version.

I searched google, test some answer, and found no one satisfied.

[vaughn]

thanks Jorge.

I have try it again just like this:

int volatile addr;

addr = (int)(&__SP_INIT);

The local addr optimized.

I'm not familay with assembly, so I have not try same as your's, which defined as a pointer. It will be no effect.

The differency should be the version of arm gcc, I'm using arm-none-eabi-gcc 4.9.2, I use it for a long time, there's maybe some risk changing other version of gcc, I doubt.

Which version of gcc you are using?

[jorge_a_vazquez]

Hi

I'm using the KDS with default installation:

Release notes for
*************************************************
GNU Tools for ARM Embedded Processors 4.8

Best regards

Jorge Alcala