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* [Bug tree-optimization/42436] VRP should mark non-trapping integer divisions
[not found] <bug-42436-4@http.gcc.gnu.org/bugzilla/>
@ 2022-01-12 16:14 ` amacleod at redhat dot com
2022-01-13 7:13 ` rguenth at gcc dot gnu.org
1 sibling, 0 replies; 3+ messages in thread
From: amacleod at redhat dot com @ 2022-01-12 16:14 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=42436
--- Comment #3 from Andrew Macleod <amacleod at redhat dot com> ---
What needs to be done here? anything?
Looking at VRP1, there is only a single divide left at that point:
countm1.6_54 = _12 / _13;
and VRP1 is setting the global range of _13 to:
_13: unsigned int [2, 2147483647]
So at least from that point on, it is trivial to determine the divide is
non-trapping even using the global ranges.
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug tree-optimization/42436] VRP should mark non-trapping integer divisions
[not found] <bug-42436-4@http.gcc.gnu.org/bugzilla/>
2022-01-12 16:14 ` [Bug tree-optimization/42436] VRP should mark non-trapping integer divisions amacleod at redhat dot com
@ 2022-01-13 7:13 ` rguenth at gcc dot gnu.org
1 sibling, 0 replies; 3+ messages in thread
From: rguenth at gcc dot gnu.org @ 2022-01-13 7:13 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=42436
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Resolution|--- |FIXED
Status|NEW |RESOLVED
--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
I think this was trying to cover things like
if (d != 0)
tem = a / d;
where the non-zero range of d on the division cannot be put in global ranges
for its SSA name since that would be incorrect for uses not guarded by the
condition. So it would ask for a new flag on GIMPLE statements to mark the
division not trapping (like we have TREE_THIS_NOTRAP). Transforms like
PRE or LIM that do code motion of course have to be careful to not move
the stmt outside of the condition that made it not trapping - something which
would be as hard to guarantee as computing the non-trappingness in the first
place.
So yes, the case that made me file this bug is fixed with global ranges.
Let's close this bug since it's quite unspecific.
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug tree-optimization/42436] VRP should mark non-trapping integer divisions
2009-12-19 19:41 [Bug tree-optimization/42436] New: " rguenth at gcc dot gnu dot org
@ 2009-12-19 19:42 ` rguenth at gcc dot gnu dot org
0 siblings, 0 replies; 3+ messages in thread
From: rguenth at gcc dot gnu dot org @ 2009-12-19 19:42 UTC (permalink / raw)
To: gcc-bugs
------- Comment #1 from rguenth at gcc dot gnu dot org 2009-12-19 19:42 -------
I'll take care of this during 4.6 development.
--
rguenth at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
AssignedTo|unassigned at gcc dot gnu |rguenth at gcc dot gnu dot
|dot org |org
Status|UNCONFIRMED |ASSIGNED
Ever Confirmed|0 |1
Last reconfirmed|0000-00-00 00:00:00 |2009-12-19 19:42:12
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42436
^ permalink raw reply [flat|nested] 3+ messages in thread
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[not found] <bug-42436-4@http.gcc.gnu.org/bugzilla/>
2022-01-12 16:14 ` [Bug tree-optimization/42436] VRP should mark non-trapping integer divisions amacleod at redhat dot com
2022-01-13 7:13 ` rguenth at gcc dot gnu.org
2009-12-19 19:41 [Bug tree-optimization/42436] New: " rguenth at gcc dot gnu dot org
2009-12-19 19:42 ` [Bug tree-optimization/42436] " rguenth at gcc dot gnu dot org
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