On Fri, 19 Apr 2019 14:14:05 -0700, Alexei Starovoitov wrote: > > This reminds me, I'm not entirely clear on the need to propagate the > > zext through stack slots... Pointers are guaranteed to be 64bit, we > > don't save parentage on scalars (AFAICT), > > scalars have parentage chain too. > we don't track them precisely when they're spilled to stack. > That actually caused an issue recently when valid program was rejected, > so we might add a feature to track full contents of scalars in the stack. Interesting.. > > why not pass REG_LIVE_READ > > or READ64 to mark_reg_read() from stack_read? > > can we agree on only two states first ? ;) Yess, the LIVE_READ was thought to be more of a mask for those accesses that only care about "any read" being set, to be honest. As you said read64 is a strict superset of read32. Keeping the name REG_LIVE_READ, rather than REG_LIVE_READ_ANY or _MASK let us leave some of the existing code untouched. Jiong's original idea was to add a read32, and have read mean read64. I think you said we should have read32 and read64 flags, but clear read32 once read64 gets set? SGTM!
