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* [Bug tree-optimization/113339] New: `-a/-b` is not simplified to `a/b` if done in seperate statements
@ 2024-01-11 19:20 pinskia at gcc dot gnu.org
2024-01-11 19:23 ` [Bug tree-optimization/113339] " pinskia at gcc dot gnu.org
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: pinskia at gcc dot gnu.org @ 2024-01-11 19:20 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113339
Bug ID: 113339
Summary: `-a/-b` is not simplified to `a/b` if done in seperate
statements
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: enhancement
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: pinskia at gcc dot gnu.org
Target Milestone: ---
Take:
```
int unopt(int a, int b) {
a = -a;
b = -b;
return a / b;
}
int opt(int a, int b) {
return -a / -b;
}
```
I would have expected these 2 would produce the same assembly but only opt is
optimized to a/b and the neg is removed.
Note LLVM does not do either: https://github.com/llvm/llvm-project/issues/77717
.
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug tree-optimization/113339] `-a/-b` is not simplified to `a/b` if done in seperate statements
2024-01-11 19:20 [Bug tree-optimization/113339] New: `-a/-b` is not simplified to `a/b` if done in seperate statements pinskia at gcc dot gnu.org
@ 2024-01-11 19:23 ` pinskia at gcc dot gnu.org
2024-01-11 19:33 ` pinskia at gcc dot gnu.org
2024-01-11 21:23 ` pinskia at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: pinskia at gcc dot gnu.org @ 2024-01-11 19:23 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113339
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |ASSIGNED
Assignee|unassigned at gcc dot gnu.org |pinskia at gcc dot gnu.org
Ever confirmed|0 |1
Last reconfirmed| |2024-01-11
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
This is currently done only in fold:
```
/* (-A) / (-B) -> A / B */
if (TREE_CODE (arg0) == NEGATE_EXPR && negate_expr_p (arg1))
return fold_build2_loc (loc, RDIV_EXPR, type,
TREE_OPERAND (arg0, 0),
negate_expr (arg1));
if (TREE_CODE (arg1) == NEGATE_EXPR && negate_expr_p (arg0))
return fold_build2_loc (loc, RDIV_EXPR, type,
negate_expr (arg0),
TREE_OPERAND (arg1, 0));
return NULL_TREE;
```
I am going to handle the simple cases for GCC 15 here ...
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug tree-optimization/113339] `-a/-b` is not simplified to `a/b` if done in seperate statements
2024-01-11 19:20 [Bug tree-optimization/113339] New: `-a/-b` is not simplified to `a/b` if done in seperate statements pinskia at gcc dot gnu.org
2024-01-11 19:23 ` [Bug tree-optimization/113339] " pinskia at gcc dot gnu.org
@ 2024-01-11 19:33 ` pinskia at gcc dot gnu.org
2024-01-11 21:23 ` pinskia at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: pinskia at gcc dot gnu.org @ 2024-01-11 19:33 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113339
--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Note the fold was added here:
https://gcc.gnu.org/pipermail/gcc-patches/1999-October/020476.html .
^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug tree-optimization/113339] `-a/-b` is not simplified to `a/b` if done in seperate statements
2024-01-11 19:20 [Bug tree-optimization/113339] New: `-a/-b` is not simplified to `a/b` if done in seperate statements pinskia at gcc dot gnu.org
2024-01-11 19:23 ` [Bug tree-optimization/113339] " pinskia at gcc dot gnu.org
2024-01-11 19:33 ` pinskia at gcc dot gnu.org
@ 2024-01-11 21:23 ` pinskia at gcc dot gnu.org
2 siblings, 0 replies; 4+ messages in thread
From: pinskia at gcc dot gnu.org @ 2024-01-11 21:23 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113339
--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
So I looked into the wrong part of fold, but anyways PR 23669 added the folding
to fold instead (and I just noticed I implemented it originally).
^ permalink raw reply [flat|nested] 4+ messages in thread
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