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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/110873] [14 Regression] Dead Code Elimination Regression at -O2 since r14-376-g47a76439911
Date: Thu, 03 Aug 2023 02:59:06 +0000 [thread overview]
Message-ID: <bug-110873-4-gNY2mwKlBq@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-110873-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110873
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Last reconfirmed| |2023-08-03
Status|UNCONFIRMED |NEW
Ever confirmed|0 |1
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
GCC 13 had:
```
Registering value_relation (h_29 == h_13) (bb10) at h_29 = PHI <h_13(9)>
Loops range found for h_29: [irange] unsigned char [5, 5] NONZERO 0x5 and
calculated range :[irange] unsigned char [0, 5] NONZERO 0x7
Global Exported: h_29 = [irange] unsigned char [5, 5] NONZERO 0x5
Folding PHI node: h_29 = PHI <h_13(9)>
Queued PHI for removal. Folds to: 5
Folding statement: if (h_29 <= 4)
gimple_simplified to if (0 != 0)
gimple_simplified to if (0 != 0)
Folded into: if (0 != 0)
``
While trunk does:
```
redicate evaluates to: DON'T KNOW
Not folded
Registering value_relation (h_29 == h_13) (bb10) at h_29 = PHI <h_13(9)>
Global Exported: h_29 = [irange] unsigned char [0, 5] MASK 0xfe VALUE 0xe7
Folding PHI node: h_29 = PHI <h_13(9)>
No folding possible
Folding statement: if (h_29 <= 4)
Visiting conditional with predicate: if (h_29 <= 4)
With known ranges
h_29: [irange] unsigned char [0, 5] MASK 0xfe VALUE 0xe7
Predicate evaluates to: DON'T KNOW
Simplified relational if (h_29 <= 4)
into if (h_29 != 5)
Folded into: if (h_29 != 5)
```
Which totally misses that h_29 was just 5.
next prev parent reply other threads:[~2023-08-03 2:59 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-02 12:34 [Bug tree-optimization/110873] New: " scherrer.sv at gmail dot com
2023-08-02 13:02 ` [Bug tree-optimization/110873] " rguenth at gcc dot gnu.org
2023-08-03 2:59 ` pinskia at gcc dot gnu.org [this message]
2023-08-03 3:00 ` pinskia at gcc dot gnu.org
2024-03-07 23:27 ` law at gcc dot gnu.org
2024-05-07 7:41 ` [Bug tree-optimization/110873] [14/15 " rguenth at gcc dot gnu.org
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