On the true side of x == -0.0, we can't just blindly value propagate
the -0.0 into every use of x because x could be +0.0 (or vice versa).
With this change, we only allow the transformation if
!HONOR_SIGNED_ZEROS or if the range is known not to contain 0.
Will commit after tests complete.
gcc/ChangeLog:
* range-op-float.cc (foperator_equal::op1_range): Do not blindly
copy op2 range when honoring signed zeros.
---
gcc/range-op-float.cc | 17 +++++++++++++++--
1 file changed, 15 insertions(+), 2 deletions(-)
diff --git a/gcc/range-op-float.cc b/gcc/range-op-float.cc
index ad2fae578d2..ff9fe312acf 100644
--- a/gcc/range-op-float.cc
+++ b/gcc/range-op-float.cc
@@ -252,8 +252,21 @@ foperator_equal::op1_range (frange &r, tree type,
switch (get_bool_state (r, lhs, type))
{
case BRS_TRUE:
- // If it's true, the result is the same as OP2.
- r = op2;
+ if (HONOR_SIGNED_ZEROS (type)
+ && op2.contains_p (build_zero_cst (type)))
+ {
+ // With signed zeros, x == -0.0 does not mean we can replace
+ // x with -0.0, because x may be either +0.0 or -0.0.
+ r.set_varying (type);
+ }
+ else
+ {
+ // If it's true, the result is the same as OP2.
+ //
+ // If the range does not actually contain zeros, this should
+ // always be OK.
+ r = op2;
+ }
// The TRUE side of op1 == op2 implies op1 is !NAN.
r.set_nan (fp_prop::NO);
break;
--
2.37.1
