bjoernager/rust
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Auto merge of #88242 - bonega:allocation_range, r=oli-obk

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Use custom wrap-around type instead of RangeInclusive

Two reasons:

1. More memory is allocated than necessary for `valid_range` in `Scalar`. The range is not used as an iterator and `exhausted` is never used.
2. `contains`, `count` etc. methods in `RangeInclusive` are doing very unhelpful(and dangerous!) things when used as a wrap-around range. - In general this PR wants to limit potentially confusing methods, that have a low probability of working.

Doing a local perf run, every metric shows improvement except for instructions.
Max-rss seem to have a very consistent improvement.

Sorry - newbie here, probably doing something wrong.
This commit is contained in:
bors 2021-08-25 02:17:41 +00:00
commit e5484cec0e
8 changed files with 115 additions and 81 deletions
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3
compiler/rustc_codegen_llvm/src/builder.rs
View file

@ -462,7 +462,6 @@ impl BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
load: &'ll Value,
scalar: &abi::Scalar,
) {
let vr = scalar.valid_range.clone();
match scalar.value {
abi::Int(..) => {
let range = scalar.valid_range_exclusive(bx);
@ -470,7 +469,7 @@ impl BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
bx.range_metadata(load, range);
}
}
abi::Pointer if vr.start() < vr.end() && !vr.contains(&0) => {
abi::Pointer if !scalar.valid_range.contains_zero() => {
bx.nonnull_metadata(load);
}
_ => {}

6
compiler/rustc_codegen_llvm/src/consts.rs
View file

@ -16,7 +16,9 @@ use rustc_middle::mir::interpret::{
use rustc_middle::mir::mono::MonoItem;
use rustc_middle::ty::{self, Instance, Ty};
use rustc_middle::{bug, span_bug};
use rustc_target::abi::{AddressSpace, Align, HasDataLayout, LayoutOf, Primitive, Scalar, Size};
use rustc_target::abi::{
AddressSpace, Align, HasDataLayout, LayoutOf, Primitive, Scalar, Size, WrappingRange,
};
use tracing::debug;
pub fn const_alloc_to_llvm(cx: &CodegenCx<'ll, '_>, alloc: &Allocation) -> &'ll Value {
@ -59,7 +61,7 @@ pub fn const_alloc_to_llvm(cx: &CodegenCx<'ll, '_>, alloc: &Allocation) -> &'ll
Pointer::new(alloc_id, Size::from_bytes(ptr_offset)),
&cx.tcx,
),
&Scalar { value: Primitive::Pointer, valid_range: 0..=!0 },
&Scalar { value: Primitive::Pointer, valid_range: WrappingRange { start: 0, end: !0 } },
cx.type_i8p_ext(address_space),
));
next_offset = offset + pointer_size;