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Rework OperandRef::extract_field to stop calling to_immediate_scalar on things which are already immediates

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That means it stops trying to truncate things that are already `i1`s.
This commit is contained in:
Scott McMurray 2025-02-15 16:07:18 -08:00
parent 642a705f71
commit 6f9cfd694d
9 changed files with 164 additions and 87 deletions
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12
compiler/rustc_codegen_gcc/src/builder.rs
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@ -989,10 +989,14 @@ impl<'a, 'gcc, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'gcc, 'tcx> {
OperandValue::Ref(place.val)
} else if place.layout.is_gcc_immediate() {
let load = self.load(place.layout.gcc_type(self), place.val.llval, place.val.align);
if let abi::BackendRepr::Scalar(ref scalar) = place.layout.backend_repr {
scalar_load_metadata(self, load, scalar);
}
OperandValue::Immediate(self.to_immediate(load, place.layout))
OperandValue::Immediate(
if let abi::BackendRepr::Scalar(ref scalar) = place.layout.backend_repr {
scalar_load_metadata(self, load, scalar);
self.to_immediate_scalar(load, *scalar)
} else {
load
},
)
} else if let abi::BackendRepr::ScalarPair(ref a, ref b) = place.layout.backend_repr {
let b_offset = a.size(self).align_to(b.align(self).abi);

11
compiler/rustc_codegen_gcc/src/intrinsic/mod.rs
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@ -9,7 +9,7 @@ use gccjit::FunctionType;
use gccjit::{ComparisonOp, Function, RValue, ToRValue, Type, UnaryOp};
#[cfg(feature = "master")]
use rustc_abi::ExternAbi;
use rustc_abi::HasDataLayout;
use rustc_abi::{BackendRepr, HasDataLayout};
use rustc_codegen_ssa::MemFlags;
use rustc_codegen_ssa::base::wants_msvc_seh;
use rustc_codegen_ssa::common::IntPredicate;
@ -181,14 +181,19 @@ impl<'a, 'gcc, 'tcx> IntrinsicCallBuilderMethods<'tcx> for Builder<'a, 'gcc, 'tc
sym::volatile_load | sym::unaligned_volatile_load => {
let tp_ty = fn_args.type_at(0);
let ptr = args[0].immediate();
let layout = self.layout_of(tp_ty);
let load = if let PassMode::Cast { cast: ref ty, pad_i32: _ } = fn_abi.ret.mode {
let gcc_ty = ty.gcc_type(self);
self.volatile_load(gcc_ty, ptr)
} else {
self.volatile_load(self.layout_of(tp_ty).gcc_type(self), ptr)
self.volatile_load(layout.gcc_type(self), ptr)
};
// TODO(antoyo): set alignment.
self.to_immediate(load, self.layout_of(tp_ty))
if let BackendRepr::Scalar(scalar) = layout.backend_repr {
self.to_immediate_scalar(load, scalar)
} else {
load
}
}
sym::volatile_store => {
let dst = args[0].deref(self.cx());

10
compiler/rustc_codegen_llvm/src/builder.rs
View File

@ -746,10 +746,12 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
let load = self.load(llty, place.val.llval, place.val.align);
if let abi::BackendRepr::Scalar(scalar) = place.layout.backend_repr {
scalar_load_metadata(self, load, scalar, place.layout, Size::ZERO);
self.to_immediate_scalar(load, scalar)
} else {
load
}
load
});
OperandValue::Immediate(self.to_immediate(llval, place.layout))
OperandValue::Immediate(llval)
} else if let abi::BackendRepr::ScalarPair(a, b) = place.layout.backend_repr {
let b_offset = a.size(self).align_to(b.align(self).abi);
@ -943,6 +945,8 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
}
fn unchecked_utrunc(&mut self, val: &'ll Value, dest_ty: &'ll Type) -> &'ll Value {
debug_assert_ne!(self.val_ty(val), dest_ty);
let trunc = self.trunc(val, dest_ty);
if llvm_util::get_version() >= (19, 0, 0) {
unsafe {
@ -955,6 +959,8 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
}
fn unchecked_strunc(&mut self, val: &'ll Value, dest_ty: &'ll Type) -> &'ll Value {
debug_assert_ne!(self.val_ty(val), dest_ty);
let trunc = self.trunc(val, dest_ty);
if llvm_util::get_version() >= (19, 0, 0) {
unsafe {

10
compiler/rustc_codegen_ssa/src/mir/block.rs
View File

@ -1040,7 +1040,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
let (idx, _) = op.layout.non_1zst_field(bx).expect(
"not exactly one non-1-ZST field in a `DispatchFromDyn` type",
);
op = op.extract_field(bx, idx);
op = op.extract_field(self, bx, idx);
}
// Now that we have `*dyn Trait` or `&dyn Trait`, split it up into its
@ -1072,7 +1072,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
let (idx, _) = op.layout.non_1zst_field(bx).expect(
"not exactly one non-1-ZST field in a `DispatchFromDyn` type",
);
op = op.extract_field(bx, idx);
op = op.extract_field(self, bx, idx);
}
// Make sure that we've actually unwrapped the rcvr down
@ -1572,9 +1572,9 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
if scalar.is_bool() {
bx.range_metadata(llval, WrappingRange { start: 0, end: 1 });
}
// We store bools as `i8` so we need to truncate to `i1`.
llval = bx.to_immediate_scalar(llval, scalar);
}
// We store bools as `i8` so we need to truncate to `i1`.
llval = bx.to_immediate(llval, arg.layout);
}
}
@ -1604,7 +1604,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
} else {
// If the tuple is immediate, the elements are as well.
for i in 0..tuple.layout.fields.count() {
let op = tuple.extract_field(bx, i);
let op = tuple.extract_field(self, bx, i);
self.codegen_argument(bx, op, llargs, &args[i]);
}
}

131
compiler/rustc_codegen_ssa/src/mir/operand.rs
View File

@ -1,15 +1,14 @@
use std::assert_matches::assert_matches;
use std::fmt;
use arrayvec::ArrayVec;
use either::Either;
use rustc_abi as abi;
use rustc_abi::{Align, BackendRepr, Size};
use rustc_middle::bug;
use rustc_middle::mir::interpret::{Pointer, Scalar, alloc_range};
use rustc_middle::mir::{self, ConstValue};
use rustc_middle::ty::Ty;
use rustc_middle::ty::layout::{LayoutOf, TyAndLayout};
use rustc_middle::{bug, span_bug};
use tracing::debug;
use super::place::{PlaceRef, PlaceValue};
@ -352,79 +351,83 @@ impl<'a, 'tcx, V: CodegenObject> OperandRef<'tcx, V> {
pub(crate) fn extract_field<Bx: BuilderMethods<'a, 'tcx, Value = V>>(
&self,
fx: &mut FunctionCx<'a, 'tcx, Bx>,
bx: &mut Bx,
i: usize,
) -> Self {
let field = self.layout.field(bx.cx(), i);
let offset = self.layout.fields.offset(i);
let mut val = match (self.val, self.layout.backend_repr) {
// If the field is ZST, it has no data.
_ if field.is_zst() => OperandValue::ZeroSized,
// Newtype of a scalar, scalar pair or vector.
(OperandValue::Immediate(_) | OperandValue::Pair(..), _)
if field.size == self.layout.size =>
{
assert_eq!(offset.bytes(), 0);
self.val
let val = if field.is_zst() {
OperandValue::ZeroSized
} else if field.size == self.layout.size {
assert_eq!(offset.bytes(), 0);
if let Some(field_val) = fx.codegen_transmute_operand(bx, *self, field) {
field_val
} else {
// we have to go through memory for things like
// Newtype vector of array, e.g. #[repr(simd)] struct S([i32; 4]);
let place = PlaceRef::alloca(bx, field);
self.val.store(bx, place.val.with_type(self.layout));
bx.load_operand(place).val
}
// Extract a scalar component from a pair.
(OperandValue::Pair(a_llval, b_llval), BackendRepr::ScalarPair(a, b)) => {
if offset.bytes() == 0 {
assert_eq!(field.size, a.size(bx.cx()));
OperandValue::Immediate(a_llval)
} else {
assert_eq!(offset, a.size(bx.cx()).align_to(b.align(bx.cx()).abi));
assert_eq!(field.size, b.size(bx.cx()));
OperandValue::Immediate(b_llval)
} else {
let (in_scalar, imm) = match (self.val, self.layout.backend_repr) {
// Extract a scalar component from a pair.
(OperandValue::Pair(a_llval, b_llval), BackendRepr::ScalarPair(a, b)) => {
if offset.bytes() == 0 {
assert_eq!(field.size, a.size(bx.cx()));
(Some(a), a_llval)
} else {
assert_eq!(offset, a.size(bx.cx()).align_to(b.align(bx.cx()).abi));
assert_eq!(field.size, b.size(bx.cx()));
(Some(b), b_llval)
}
}
}
// `#[repr(simd)]` types are also immediate.
(OperandValue::Immediate(llval), BackendRepr::Vector { .. }) => {
OperandValue::Immediate(bx.extract_element(llval, bx.cx().const_usize(i as u64)))
}
// `#[repr(simd)]` types are also immediate.
(OperandValue::Immediate(llval), BackendRepr::Vector { .. }) => {
(None, bx.extract_element(llval, bx.cx().const_usize(i as u64)))
}
_ => bug!("OperandRef::extract_field({:?}): not applicable", self),
_ => {
span_bug!(fx.mir.span, "OperandRef::extract_field({:?}): not applicable", self)
}
};
OperandValue::Immediate(match field.backend_repr {
BackendRepr::Vector { .. } => imm,
BackendRepr::Scalar(out_scalar) => {
let Some(in_scalar) = in_scalar else {
span_bug!(
fx.mir.span,
"OperandRef::extract_field({:?}): missing input scalar for output scalar",
self
)
};
if in_scalar != out_scalar {
// If the backend and backend_immediate types might differ,
// flip back to the backend type then to the new immediate.
// This avoids nop truncations, but still handles things like
// Bools in union fields needs to be truncated.
let backend = bx.from_immediate(imm);
bx.to_immediate_scalar(backend, out_scalar)
} else {
imm
}
}
BackendRepr::Memory { sized: true } => {
span_bug!(
fx.mir.span,
"Projecting into a simd type with padding doesn't work; \
See <https://github.com/rust-lang/rust/issues/137108>",
);
}
BackendRepr::Uninhabited
| BackendRepr::ScalarPair(_, _)
| BackendRepr::Memory { sized: false } => bug!(),
})
};
match (&mut val, field.backend_repr) {
(OperandValue::ZeroSized, _) => {}
(
OperandValue::Immediate(llval),
BackendRepr::Scalar(_) | BackendRepr::ScalarPair(..) | BackendRepr::Vector { .. },
) => {
// Bools in union fields needs to be truncated.
*llval = bx.to_immediate(*llval, field);
}
(OperandValue::Pair(a, b), BackendRepr::ScalarPair(a_abi, b_abi)) => {
// Bools in union fields needs to be truncated.
*a = bx.to_immediate_scalar(*a, a_abi);
*b = bx.to_immediate_scalar(*b, b_abi);
}
// Newtype vector of array, e.g. #[repr(simd)] struct S([i32; 4]);
(OperandValue::Immediate(llval), BackendRepr::Memory { sized: true }) => {
assert_matches!(self.layout.backend_repr, BackendRepr::Vector { .. });
let llfield_ty = bx.cx().backend_type(field);
// Can't bitcast an aggregate, so round trip through memory.
let llptr = bx.alloca(field.size, field.align.abi);
bx.store(*llval, llptr, field.align.abi);
*llval = bx.load(llfield_ty, llptr, field.align.abi);
}
(
OperandValue::Immediate(_),
BackendRepr::Uninhabited | BackendRepr::Memory { sized: false },
) => {
bug!()
}
(OperandValue::Pair(..), _) => bug!(),
(OperandValue::Ref(..), _) => bug!(),
}
OperandRef { val, layout: field }
}
}
@ -587,7 +590,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
"Bad PlaceRef: destructing pointers should use cast/PtrMetadata, \
but tried to access field {f:?} of pointer {o:?}",
);
o = o.extract_field(bx, f.index());
o = o.extract_field(self, bx, f.index());
}
mir::ProjectionElem::Index(_)
| mir::ProjectionElem::ConstantIndex { .. } => {

4
compiler/rustc_codegen_ssa/src/mir/rvalue.rs
View File

@ -231,7 +231,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
///
/// Returns `None` for cases that can't work in that framework, such as for
/// `Immediate`->`Ref` that needs an `alloc` to get the location.
fn codegen_transmute_operand(
pub(crate) fn codegen_transmute_operand(
&mut self,
bx: &mut Bx,
operand: OperandRef<'tcx, Bx::Value>,
@ -260,6 +260,8 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
OperandValue::Ref(source_place_val) => {
assert_eq!(source_place_val.llextra, None);
assert_matches!(operand_kind, OperandValueKind::Ref);
// The existing alignment is part of `source_place_val`,
// so that alignment will be used, not `cast`'s.
Some(bx.load_operand(source_place_val.with_type(cast)).val)
}
OperandValue::ZeroSized => {

9
compiler/rustc_codegen_ssa/src/traits/builder.rs
View File

@ -1,7 +1,7 @@
use std::assert_matches::assert_matches;
use std::ops::Deref;
use rustc_abi::{Align, BackendRepr, Scalar, Size, WrappingRange};
use rustc_abi::{Align, Scalar, Size, WrappingRange};
use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrs;
use rustc_middle::ty::layout::{FnAbiOf, LayoutOf, TyAndLayout};
use rustc_middle::ty::{Instance, Ty};
@ -223,13 +223,6 @@ pub trait BuilderMethods<'a, 'tcx>:
) -> (Self::Value, Self::Value);
fn from_immediate(&mut self, val: Self::Value) -> Self::Value;
fn to_immediate(&mut self, val: Self::Value, layout: TyAndLayout<'_>) -> Self::Value {
if let BackendRepr::Scalar(scalar) = layout.backend_repr {
self.to_immediate_scalar(val, scalar)
} else {
val
}
}
fn to_immediate_scalar(&mut self, val: Self::Value, scalar: Scalar) -> Self::Value;
fn alloca(&mut self, size: Size, align: Align) -> Self::Value;

31
tests/codegen/simd/project-to-simd-array-field.rs Normal file
View File

@ -0,0 +1,31 @@
//@compile-flags: -Copt-level=3
#![crate_type = "lib"]
#![feature(repr_simd, core_intrinsics)]
#[allow(non_camel_case_types)]
#[derive(Clone, Copy)]
#[repr(simd)]
struct i32x4([i32; 4]);
#[inline(always)]
fn to_array4(a: i32x4) -> [i32; 4] {
a.0
}
// CHECK-LABEL: simd_add_self_then_return_array(
// CHECK-SAME: ptr{{.+}}sret{{.+}}%[[RET:.+]],
// CHECK-SAME: ptr{{.+}}%a)
#[no_mangle]
pub fn simd_add_self_then_return_array(a: &i32x4) -> [i32; 4] {
// It would be nice to just ban `.0` into simd types,
// but until we do this has to keep working.
// See also <https://github.com/rust-lang/rust/issues/105439>
// CHECK: %[[T1:.+]] = load <4 x i32>, ptr %a
// CHECK: %[[T2:.+]] = shl <4 x i32> %[[T1]], {{splat \(i32 1\)|<i32 1, i32 1, i32 1, i32 1>}}
// CHECK: store <4 x i32> %[[T2]], ptr %[[RET]]
let a = *a;
let b = unsafe { core::intrinsics::simd::simd_add(a, a) };
to_array4(b)
}

33
tests/crashes/project-to-simd-array-field.rs Normal file
View File

@ -0,0 +1,33 @@
//@ known-bug: #137108
//@compile-flags: -Copt-level=3
// If you fix this, put it in the corresponding codegen test,
// not in a UI test like the readme says.
#![crate_type = "lib"]
#![feature(repr_simd, core_intrinsics)]
#[allow(non_camel_case_types)]
#[derive(Clone, Copy)]
#[repr(simd)]
struct i32x3([i32; 3]);
const _: () = { assert!(size_of::<i32x3>() == 16) };
#[inline(always)]
fn to_array3(a: i32x3) -> [i32; 3] {
a.0
}
// CHECK-LABEL: simd_add_self_then_return_array_packed(
// CHECK-SAME: ptr{{.+}}sret{{.+}}%[[RET:.+]],
// CHECK-SAME: ptr{{.+}}%a)
#[no_mangle]
pub fn simd_add_self_then_return_array_packed(a: i32x3) -> [i32; 3] {
// CHECK: %[[T1:.+]] = load <3 x i32>, ptr %a
// CHECK: %[[T2:.+]] = shl <3 x i32> %[[T1]], <i32 1, i32 1, i32 1>
// CHECK: store <3 x i32> %[[T2]], ptr %[[RET]]
let b = unsafe { core::intrinsics::simd::simd_add(a, a) };
to_array3(b)
}