On 11/14/22 10:12, Richard Biener wrote: > On Sat, Nov 12, 2022 at 7:30 PM Aldy Hernandez wrote: >> >> It irks me that a PR named "we should track ranges for floating-point >> hasn't been closed in this release. This is an attempt to do just >> that. >> >> As mentioned in the PR, even though we track ranges for floats, it has >> been suggested that avoiding recursing through SSA defs in >> gimple_assign_nonnegative_warnv_p is also a goal. We can do this with >> various ranger components without the need for a heavy handed approach >> (i.e. a full ranger). >> >> I have implemented two versions of known_float_sign_p() that answer >> the question whether we definitely know the sign for an operation or a >> tree expression. >> >> Both versions use get_global_range_query, which is a wrapper to query >> global ranges. This means, that no caching or propagation is done. >> In the case of an SSA, we just return the global range for it (think >> SSA_NAME_RANGE_INFO). In the case of a tree code with operands, we >> also use get_global_range_query to resolve the operands, and then call >> into range-ops, which is our lowest level component. There is no >> ranger or gori involved. All we're doing is resolving the operation >> with the ranges passed. >> >> This is enough to avoid recursing in the case where we definitely know >> the sign of a range. Otherwise, we still recurse. >> >> Note that instead of get_global_range_query(), we could use >> get_range_query() which uses a ranger (if active in a pass), or >> get_global_range_query if not. This would allow passes that have an >> active ranger (with enable_ranger) to use a full ranger. These passes >> are currently, VRP, loop unswitching, DOM, loop versioning, etc. If >> no ranger is active, get_range_query defaults to global ranges, so >> there's no additional penalty. >> >> Would this be acceptable, at least enough to close (or rename the PR ;-))? > > I think the checks would belong to the gimple_stmt_nonnegative_warnv_p function > only (that's the SSA name entry from the fold-const.cc ones)? That was my first approach, but I thought I'd cover the unary and binary operators as well, since they had other callers. But I'm happy with just the top-level tweak. It's a lot less code :). > > I also notice the use of 'bool' for the "sign". That's not really > descriptive. We > have SIGNED and UNSIGNED (aka enum signop), not sure if that's the > perfect match vs. NEGATIVE and NONNEGATIVE. Maybe the functions > name is just bad and they should be known_float_negative_p? The bool sign is to keep in line with real.*, and was suggested by Jeff (in real.* not here). I'm happy to change the entire frange API to use sgnop. It is cleaner. If that's acceptable, I could do that as a follow-up. How's this, pending tests once I figure out why my trees have been broken all day :-/. Aldy p.s. First it was sphinx failure, now I'm seeing this: /home/aldyh/src/clean/gcc/match.pd:7935:8 error: return statement not allowed in C expression return NULL_TREE; ^