On 03/05/13 06:03, reed kotler wrote: > On 05/02/2013 08:41 PM, Chung-Ju Wu wrote: >> 2013/5/3 reed kotler <rkot...@mips.com>: >>> Should a return statement be emitted in a function that has the naked >>> attribute. >>> >>> There seems to be some confusion here and apparently disagreement >>> between >>> various >>> gcc compilers. >>> >> IMHO, it depends on how you define the word 'naked' for a function >> and how you expect one writing functions with 'naked' attribute. >> >> If you think one is supposed to have *complete* control in the function >> (i.e. only inline assembly code, without using any C statement and >> variables), >> then the asm 'ret' can be omitted. Porgrammers must explicitly >> emit 'ret' in the inline asm. >> >> If you allow user using C statement in the function with 'naked' >> attribute, >> the asm 'ret' is still required. Because compiler may produce a branch >> to the epilogue position where 'ret' is expected to exist. >> >> AFAIK, there is no standard defining what 'naked' behavior should be. >> So gcc leaves it to back-end developers. >> >> >> Best regards, >> jasonwucj > I think that the compiler should respect any return statements you > explicitly enter, but should not create any that are implied as in > reaching the end of the function. >
100% agreed. It is good to allow C code in "naked" functions - but the user must obviously be aware of what they can and cannot do. Anything using a stack frame is right out, for example.
