------- Comment #34 from kenner at vlsi1 dot ultra dot nyu dot edu 2007-03-09 13:59 ------- Subject: Re: [4.3 regression] ACATS cxh1001 fails
> You may well respond that you are only supposed to forget > information you deduced from the range of the type, not information > you worked out by some other means. But these cannot really be > distinguished, c.f. VRP. Exactly. That's indeed the problem. It's similar to the whole signed-overflow issue: what you're able to safely do with with VRP-derived information depends on how you derived it and there's no way of tracking that. > Surely you only have to prove that it is in the range of Y, since if it > is not in the range of X then you have a bounded error, and doing a NOP_EXPR > should be perfectly legal. Think of a range check being done in a subscript reference in the LHS of an assignment. A bounded error is not allowed to cause a memory store outside the bounds of an array. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26797
