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* [Bug tree-optimization/113189] New: `(-X * Y) * -X` can be optimized to `(X * Y) * X`
@ 2024-01-01 9:39 pinskia at gcc dot gnu.org
2024-01-01 9:43 ` [Bug tree-optimization/113189] " pinskia at gcc dot gnu.org
2024-01-01 13:31 ` jsm28 at gcc dot gnu.org
0 siblings, 2 replies; 3+ messages in thread
From: pinskia at gcc dot gnu.org @ 2024-01-01 9:39 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113189
Bug ID: 113189
Summary: `(-X * Y) * -X` can be optimized to `(X * Y) * X`
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Keywords: missed-optimization, TREE
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 f(int X, int Y)
{
return (-X * Y) * -X;
}
double fd(double X, double Y)
{
return (-X * Y) * -X;
}
int g(int X, int Y)
{
return ((-X) << Y) * -X;
}
```
The negative should be optimized away but currently is only optimized at the
RTL level.
^ permalink raw reply [flat|nested] 3+ messages in thread* [Bug tree-optimization/113189] `(-X * Y) * -X` can be optimized to `(X * Y) * X` 2024-01-01 9:39 [Bug tree-optimization/113189] New: `(-X * Y) * -X` can be optimized to `(X * Y) * X` pinskia at gcc dot gnu.org @ 2024-01-01 9:43 ` pinskia at gcc dot gnu.org 2024-01-01 13:31 ` jsm28 at gcc dot gnu.org 1 sibling, 0 replies; 3+ messages in thread From: pinskia at gcc dot gnu.org @ 2024-01-01 9:43 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113189 --- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> --- Other examples where the negative can be removed: ``` int foo(int a) { return -a * (-a * a); } int bar(int a) { return (-a * -a) * a; } int foo1(int a, int b, int c) { return -a * (-b * c); } ``` bar is handled at the gimple level but foo and foo1 are not. ^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug tree-optimization/113189] `(-X * Y) * -X` can be optimized to `(X * Y) * X` 2024-01-01 9:39 [Bug tree-optimization/113189] New: `(-X * Y) * -X` can be optimized to `(X * Y) * X` pinskia at gcc dot gnu.org 2024-01-01 9:43 ` [Bug tree-optimization/113189] " pinskia at gcc dot gnu.org @ 2024-01-01 13:31 ` jsm28 at gcc dot gnu.org 1 sibling, 0 replies; 3+ messages in thread From: jsm28 at gcc dot gnu.org @ 2024-01-01 13:31 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113189 --- Comment #2 from Joseph S. Myers <jsm28 at gcc dot gnu.org> --- If Y is INT_MIN and X is -1, removing the negations introduces undefined behavior in the first example (-(-1) * INT_MIN * -(-1) is valid, -1 * INT_MIN * -1 has undefined behavior). For floating types, removing the negations isn't valid if flag_rounding_math. ^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2024-01-01 13:31 UTC | newest] Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2024-01-01 9:39 [Bug tree-optimization/113189] New: `(-X * Y) * -X` can be optimized to `(X * Y) * X` pinskia at gcc dot gnu.org 2024-01-01 9:43 ` [Bug tree-optimization/113189] " pinskia at gcc dot gnu.org 2024-01-01 13:31 ` jsm28 at gcc dot gnu.org
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