Improve migration lint #58
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One key observation while going over the closure size profile of rustc
was that we are disjointly capturing one or more fields starting at an
immutable reference.
Disjoint capture over immutable reference doesn't add too much value
because the fields can either be borrowed immutably or copied.
One possible edge case of the optimization is when a fields of a struct
have a longer lifetime than the structure, therefore we can't completely
get rid of all the accesses on top of sharef refs, only the rightmost
one. Here is a possible example:
```rust
struct MyStruct<'a> {
a: &'static A,
b: B,
c: C<'a>,
}
fn foo<'a, 'b>(m: &'a MyStruct<'b>) -> impl FnMut() + 'static {
let c = || drop(&*m.a.field_of_a);
// Here we really do want to capture `*m.a` because that outlives `'static`
// If we capture `m`, then the closure no longer outlives `'static'
// it is constrained to `'a`
}
```
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special case for integer log10 Now that rust-lang#80918 has been merged, this PR provides a faster version of `log10`. The PR also adds some tests for values close to all powers of 10.
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- Add `:Sized` assertion in interpreter impl - Use `Scalar::from_bool` instead of `ScalarInt: From<bool>` - Remove unneeded comparison in intrinsic typeck - Make this UB to call with undef, not just return undef in that case
Showing that this avoids an alloca and private constant.
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2229: Reduce the size of closures with `capture_disjoint_fields`
One key observation while going over the closure size profile of rustc
was that we are disjointly capturing one or more fields starting at an
immutable reference.
Disjoint capture over immutable reference doesn't add too much value
because the fields can either be borrowed immutably or copied.
One possible edge case of the optimization is when a fields of a struct
have a longer lifetime than the structure, therefore we can't completely
get rid of all the accesses on top of sharef refs, only the rightmost
one. Here is a possible example:
```rust
struct MyStruct<'a> {
a: &'static A,
b: B,
c: C<'a>,
}
fn foo<'a, 'b>(m: &'a MyStruct<'b>) -> impl FnMut() + 'static {
let c = || drop(&*m.a.field_of_a);
// Here we really do want to capture `*m.a` because that outlives `'static`
// If we capture `m`, then the closure no longer outlives `'static'
// it is constrained to `'a`
}
```
r? `@nikomatsakis`
…-kind, r=nikomatsakis Account for capture kind in auto traits migration Modifies the current auto traits migration for RFC2229 so it takes into account capture kind Closes rust-lang/project-rfc-2229#51 r? `@nikomatsakis`
…, r=nikomatsakis Check FromIterator trait impl in prelude collision check. Fixes rust-lang#86902.
Stop generating `alloca`s & `memcmp` for simple short array equality
Example:
```rust
pub fn demo(x: [u16; 6], y: [u16; 6]) -> bool { x == y }
```
Before:
```llvm
define zeroext i1 `@_ZN10playground4demo17h48537f7eac23948fE(i96` %0, i96 %1) unnamed_addr #0 {
start:
%y = alloca [6 x i16], align 8
%x = alloca [6 x i16], align 8
%.0..sroa_cast = bitcast [6 x i16]* %x to i96*
store i96 %0, i96* %.0..sroa_cast, align 8
%.0..sroa_cast3 = bitcast [6 x i16]* %y to i96*
store i96 %1, i96* %.0..sroa_cast3, align 8
%_11.i.i.i = bitcast [6 x i16]* %x to i8*
%_14.i.i.i = bitcast [6 x i16]* %y to i8*
%bcmp.i.i.i = call i32 `@bcmp(i8*` nonnull dereferenceable(12) %_11.i.i.i, i8* nonnull dereferenceable(12) %_14.i.i.i, i64 12) #2, !alias.scope !2
%2 = icmp eq i32 %bcmp.i.i.i, 0
ret i1 %2
}
```
```x86
playground::demo: # `@playground::demo`
sub rsp, 32
mov qword ptr [rsp], rdi
mov dword ptr [rsp + 8], esi
mov qword ptr [rsp + 16], rdx
mov dword ptr [rsp + 24], ecx
xor rdi, rdx
xor esi, ecx
or rsi, rdi
sete al
add rsp, 32
ret
```
After:
```llvm
define zeroext i1 `@_ZN4mini4demo17h7a8994aaa314c981E(i96` %0, i96 %1) unnamed_addr #0 {
start:
%2 = icmp eq i96 %0, %1
ret i1 %2
}
```
```x86
_ZN4mini4demo17h7a8994aaa314c981E:
xor rcx, r8
xor edx, r9d
or rdx, rcx
sete al
ret
```
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Current state of the migration lint improvement.
Example of drop migration lint:
Example of trait migration lint: