bjoernager/rust
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Use load-store instead of memcpy for short integer arrays

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This commit is contained in:
Scott McMurray 2023-05-26 03:32:22 -07:00
parent cce0b52e7b
commit e1b020df9f
8 changed files with 136 additions and 16 deletions
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3
compiler/rustc_codegen_llvm/src/type_.rs
View file

@ -288,6 +288,9 @@ impl<'ll, 'tcx> LayoutTypeMethods<'tcx> for CodegenCx<'ll, 'tcx> {
fn reg_backend_type(&self, ty: &Reg) -> &'ll Type {
ty.llvm_type(self)
}
fn scalar_copy_backend_type(&self, layout: TyAndLayout<'tcx>) -> Option<Self::Type> {
layout.scalar_copy_llvm_type(self)
}
}
impl<'ll, 'tcx> TypeMembershipMethods<'tcx> for CodegenCx<'ll, 'tcx> {

33
compiler/rustc_codegen_llvm/src/type_of.rs
View file

@ -6,6 +6,7 @@ use rustc_middle::bug;
use rustc_middle::ty::layout::{FnAbiOf, LayoutOf, TyAndLayout};
use rustc_middle::ty::print::{with_no_trimmed_paths, with_no_visible_paths};
use rustc_middle::ty::{self, Ty, TypeVisitableExt};
use rustc_target::abi::HasDataLayout;
use rustc_target::abi::{Abi, Align, FieldsShape};
use rustc_target::abi::{Int, Pointer, F32, F64};
use rustc_target::abi::{PointeeInfo, Scalar, Size, TyAbiInterface, Variants};
@ -192,6 +193,7 @@ pub trait LayoutLlvmExt<'tcx> {
) -> &'a Type;
fn llvm_field_index<'a>(&self, cx: &CodegenCx<'a, 'tcx>, index: usize) -> u64;
fn pointee_info_at<'a>(&self, cx: &CodegenCx<'a, 'tcx>, offset: Size) -> Option<PointeeInfo>;
fn scalar_copy_llvm_type<'a>(&self, cx: &CodegenCx<'a, 'tcx>) -> Option<&'a Type>;
}
impl<'tcx> LayoutLlvmExt<'tcx> for TyAndLayout<'tcx> {
@ -414,4 +416,35 @@ impl<'tcx> LayoutLlvmExt<'tcx> for TyAndLayout<'tcx> {
cx.pointee_infos.borrow_mut().insert((self.ty, offset), result);
result
}
fn scalar_copy_llvm_type<'a>(&self, cx: &CodegenCx<'a, 'tcx>) -> Option<&'a Type> {
debug_assert!(self.is_sized());
// FIXME: this is a fairly arbitrary choice, but 128 bits on WASM
// (matching the 128-bit SIMD types proposal) and 256 bits on x64
// (like AVX2 registers) seems at least like a tolerable starting point.
let threshold = cx.data_layout().pointer_size * 4;
if self.layout.size() > threshold {
return None;
}
// Vectors, even for non-power-of-two sizes, have the same layout as
// arrays but don't count as aggregate types
if let FieldsShape::Array { count, .. } = self.layout.fields()
&& let element = self.field(cx, 0)
&& element.ty.is_integral()
{
// `cx.type_ix(bits)` is tempting here, but while that works great
// for things that *stay* as memory-to-memory copies, it also ends
// up suppressing vectorization as it introduces shifts when it
// extracts all the individual values.
let ety = element.llvm_type(cx);
return Some(cx.type_vector(ety, *count));
}
// FIXME: The above only handled integer arrays; surely more things
// would also be possible. Be careful about provenance, though!
None
}
}