On Mon, Nov 14, 2022 at 8:05 PM Aldy Hernandez <al...@redhat.com> wrote: > > > > On 11/14/22 10:12, Richard Biener wrote: > > On Sat, Nov 12, 2022 at 7:30 PM Aldy Hernandez <al...@redhat.com> 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 :).
@@ -9234,6 +9235,15 @@ bool gimple_stmt_nonnegative_warnv_p (gimple *stmt, bool *strict_overflow_p, int depth) { + tree type = gimple_range_type (stmt); + if (type && frange::supports_p (type)) + { + frange r; + bool sign; + return (get_global_range_query ()->range_of_stmt (r, stmt) + && r.signbit_p (sign) + && sign == false); + } the above means we never fall through to the switch below if frange::supports_p (type) - that's eventually good enough, I don't think we ever call this very function directly but it gets invoked via recursion through operands only. But of course I wonder what types are not supported by frange and whether the manual processing we fall through to does anything meaningful for those? I won't ask you to thoroughly answer this now but please put in a comment reflecting the above before the switch stmt. switch (gimple_code (stmt)) Otherwise OK, in case you tree gets back to bootstrapping ;) > > > > 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; > ^ Supposedly somebody pushed and reverted this transient error? Yep, Tamar did. Richard.