On Thu, Aug 6, 2015 at 11:19 AM, Richard Sandiford <rdsandif...@googlemail.com> wrote: > "H.J. Lu" <hongjiu...@intel.com> writes: >> Since ira_implicitly_set_insn_hard_regs may be called outside of >> ira-lives.c, it can't use the local variable, preferred_alternatives. >> This patch adds an alternative_mask argument to >> ira_implicitly_set_insn_hard_regs. >> >> OK for master and 5 branch if there are no regressions on Linux/x86-64? > > Thanks for working on this. The patch looks good to me FWIW. > > I think this version is safer than the second one you posted. With that > version we could end up with the same sort of bug, e.g. because a function > passes false to extract_insn without realising that one of the functions > that it calls later needs the preferred alternatives to be set. > Or maybe (as with my patch) a function starts to use preferred_alternatives > and one of its callers gets missed. > > Sorry for the breakage. >
I think local variable preferred_alternatives in ira-lives.c is problematic by itself. It is easy to become stale. recog_data_d is the natural place for it. But as you pointed out, it has its own problem. I don't know if we should always call get_preferred_alternatives to initialize it even if it isn't used. Or we can make preferred_alternatives a pointer in recog_data_d. If it isn't initialized, you will get a segfault when you use it. This one indirection. This is just my observation. I will do whatever is approved. Thanks. -- H.J.
