From 30a9e6795a8b7023a555f47bbc142f7985e43446 Mon Sep 17 00:00:00 2001 From: dnovillo Date: Sat, 1 Oct 2005 14:01:10 +0000 Subject: [PATCH] * tree-vrp.c (value_inside_range, range_includes_zero_p): Add FIXME note regarding quirky semantics. git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@104860 138bc75d-0d04-0410-961f-82ee72b054a4 --- gcc/ChangeLog | 5 +++++ gcc/tree-vrp.c | 24 ++++++++++++++++++++++-- 2 files changed, 27 insertions(+), 2 deletions(-) diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 2971178cb4a..b644aaa85ef 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,5 +1,10 @@ 2005-10-01 Diego Novillo + * tree-vrp.c (value_inside_range, range_includes_zero_p): Add + FIXME note regarding quirky semantics. + +2005-10-01 Diego Novillo + PR 24141 * tree-vrp.c (vrp_meet): Clear VR0->EQUIV when building a non-null range as a last resort. diff --git a/gcc/tree-vrp.c b/gcc/tree-vrp.c index 0e5ea09b5d5..de7a931cb15 100644 --- a/gcc/tree-vrp.c +++ b/gcc/tree-vrp.c @@ -564,7 +564,23 @@ compare_values (tree val1, tree val2) /* Return 1 if VAL is inside value range VR (VR->MIN <= VAL <= VR->MAX), 0 if VAL is not inside VR, - -2 if we cannot tell either way. */ + -2 if we cannot tell either way. + + FIXME, the current semantics of this functions are a bit quirky + when taken in the context of VRP. In here we do not care + about VR's type. If VR is the anti-range ~[3, 5] the call + value_inside_range (4, VR) will return 1. + + This is counter-intuitive in a strict sense, but the callers + currently expect this. They are calling the function + merely to determine whether VR->MIN <= VAL <= VR->MAX. The + callers are applying the VR_RANGE/VR_ANTI_RANGE semantics + themselves. + + This also applies to value_ranges_intersect_p and + range_includes_zero_p. The semantics of VR_RANGE and + VR_ANTI_RANGE should be encoded here, but that also means + adapting the users of these functions to the new semantics. */ static inline int value_inside_range (tree val, value_range_t *vr) @@ -596,7 +612,11 @@ value_ranges_intersect_p (value_range_t *vr0, value_range_t *vr1) } -/* Return true if VR includes the value zero, false otherwise. */ +/* Return true if VR includes the value zero, false otherwise. FIXME, + currently this will return false for an anti-range like ~[-4, 3]. + This will be wrong when the semantics of value_inside_range are + modified (currently the users of this function expect these + semantics). */ static inline bool range_includes_zero_p (value_range_t *vr) -- 2.11.0