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Remove powi, "square can be computed more efficiently"

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powi(2) produces exactly the same native code as x * x
This commit is contained in:
Bruno A. Muciño 2021-05-17 21:59:08 -05:00
parent 65951c969f
commit be540e6596
4 changed files with 18 additions and 38 deletions
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12
clippy_lints/src/floating_point_arithmetic.rs
View file

@ -323,7 +323,7 @@ fn check_powi(cx: &LateContext<'_>, expr: &Expr<'_>, args: &[Expr<'_>]) {
cx,
SUBOPTIMAL_FLOPS,
parent.span,
"square can be computed more efficiently",
"multiply and add expressions can be calculated more efficiently and accurately",
"consider using",
format!(
"{}.mul_add({}, {})",
@ -337,16 +337,6 @@ fn check_powi(cx: &LateContext<'_>, expr: &Expr<'_>, args: &[Expr<'_>]) {
return;
}
}
span_lint_and_sugg(
cx,
SUBOPTIMAL_FLOPS,
expr.span,
"square can be computed more efficiently",
"consider using",
format!("{} * {}", Sugg::hir(cx, &args[0], ".."), Sugg::hir(cx, &args[0], "..")),
Applicability::MachineApplicable,
);
}
}
}

5
tests/ui/floating_point_powi.fixed
View file

@ -4,8 +4,6 @@
fn main() {
let one = 1;
let x = 3f32;
let _ = x * x;
let _ = x * x;
let y = 4f32;
let _ = x.mul_add(x, y);
@ -13,7 +11,10 @@ fn main() {
let _ = x.mul_add(x, y).sqrt();
let _ = y.mul_add(y, x).sqrt();
// Cases where the lint shouldn't be applied
let _ = x.powi(2);
let _ = x.powi(1 + 1);
let _ = x.powi(3);
let _ = x.powi(4) + y;
let _ = x.powi(one + 1);
let _ = (x.powi(2) + y.powi(2)).sqrt();
}

5
tests/ui/floating_point_powi.rs
View file

@ -4,8 +4,6 @@
fn main() {
let one = 1;
let x = 3f32;
let _ = x.powi(2);
let _ = x.powi(1 + 1);
let y = 4f32;
let _ = x.powi(2) + y;
@ -13,7 +11,10 @@ fn main() {
let _ = (x.powi(2) + y).sqrt();
let _ = (x + y.powi(2)).sqrt();
// Cases where the lint shouldn't be applied
let _ = x.powi(2);
let _ = x.powi(1 + 1);
let _ = x.powi(3);
let _ = x.powi(4) + y;
let _ = x.powi(one + 1);
let _ = (x.powi(2) + y.powi(2)).sqrt();
}

34
tests/ui/floating_point_powi.stderr
View file

@ -1,40 +1,28 @@
error: square can be computed more efficiently
--> $DIR/floating_point_powi.rs:7:13
|
LL | let _ = x.powi(2);
| ^^^^^^^^^ help: consider using: `x * x`
|
= note: `-D clippy::suboptimal-flops` implied by `-D warnings`
error: square can be computed more efficiently
--> $DIR/floating_point_powi.rs:8:13
|
LL | let _ = x.powi(1 + 1);
| ^^^^^^^^^^^^^ help: consider using: `x * x`
error: square can be computed more efficiently
--> $DIR/floating_point_powi.rs:11:13
error: multiply and add expressions can be calculated more efficiently and accurately
--> $DIR/floating_point_powi.rs:9:13
|
LL | let _ = x.powi(2) + y;
| ^^^^^^^^^^^^^ help: consider using: `x.mul_add(x, y)`
|
= note: `-D clippy::suboptimal-flops` implied by `-D warnings`
error: square can be computed more efficiently
--> $DIR/floating_point_powi.rs:12:13
error: multiply and add expressions can be calculated more efficiently and accurately
--> $DIR/floating_point_powi.rs:10:13
|
LL | let _ = x + y.powi(2);
| ^^^^^^^^^^^^^ help: consider using: `y.mul_add(y, x)`
error: square can be computed more efficiently
--> $DIR/floating_point_powi.rs:13:13
error: multiply and add expressions can be calculated more efficiently and accurately
--> $DIR/floating_point_powi.rs:11:13
|
LL | let _ = (x.powi(2) + y).sqrt();
| ^^^^^^^^^^^^^^^ help: consider using: `x.mul_add(x, y)`
error: square can be computed more efficiently
--> $DIR/floating_point_powi.rs:14:13
error: multiply and add expressions can be calculated more efficiently and accurately
--> $DIR/floating_point_powi.rs:12:13
|
LL | let _ = (x + y.powi(2)).sqrt();
| ^^^^^^^^^^^^^^^ help: consider using: `y.mul_add(y, x)`
error: aborting due to 6 previous errors
error: aborting due to 4 previous errors