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Rollup merge of rust-lang#125558 - Amanieu:const-asm-type, r=lcnr
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Tweak type inference for `const` operands in inline asm

Previously these would be treated like integer literals and default to `i32` if a type could not be determined. To allow for forward-compatibility with `str` constants in the future, this PR changes type inference to use an unbound type variable instead.

The actual type checking is deferred until after typeck where we still ensure that the final type for the `const` operand is an integer type.

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@tgross35
tgross35 committed Aug 5, 2024
2 parents cf0989c + eb726a5 commit 13b85f8
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Showing 13 changed files with 295 additions and 265 deletions.
40 changes: 15 additions & 25 deletions compiler/rustc_hir_analysis/src/check/intrinsicck.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,7 @@ use rustc_ast::InlineAsmTemplatePiece;
use rustc_data_structures::fx::FxIndexSet;
use rustc_hir::{self as hir, LangItem};
use rustc_middle::bug;
use rustc_middle::ty::{self, Article, FloatTy, IntTy, Ty, TyCtxt, TypeVisitableExt, UintTy};
use rustc_middle::ty::{self, FloatTy, IntTy, Ty, TyCtxt, TypeVisitableExt, UintTy};
use rustc_session::lint;
use rustc_span::def_id::LocalDefId;
use rustc_span::Symbol;
Expand Down Expand Up @@ -455,32 +455,22 @@ impl<'a, 'tcx> InlineAsmCtxt<'a, 'tcx> {
);
}
}
// No special checking is needed for these:
// - Typeck has checked that Const operands are integers.
// - AST lowering guarantees that SymStatic points to a static.
hir::InlineAsmOperand::Const { .. } | hir::InlineAsmOperand::SymStatic { .. } => {}
// Check that sym actually points to a function. Later passes
// depend on this.
// Typeck has checked that Const operands are integers.
hir::InlineAsmOperand::Const { anon_const } => {
debug_assert!(matches!(
self.tcx.type_of(anon_const.def_id).instantiate_identity().kind(),
ty::Error(_) | ty::Int(_) | ty::Uint(_)
));
}
// Typeck has checked that SymFn refers to a function.
hir::InlineAsmOperand::SymFn { anon_const } => {
let ty = self.tcx.type_of(anon_const.def_id).instantiate_identity();
match ty.kind() {
ty::Never | ty::Error(_) => {}
ty::FnDef(..) => {}
_ => {
self.tcx
.dcx()
.struct_span_err(*op_sp, "invalid `sym` operand")
.with_span_label(
self.tcx.def_span(anon_const.def_id),
format!("is {} `{}`", ty.kind().article(), ty),
)
.with_help(
"`sym` operands must refer to either a function or a static",
)
.emit();
}
};
debug_assert!(matches!(
self.tcx.type_of(anon_const.def_id).instantiate_identity().kind(),
ty::Error(_) | ty::FnDef(..)
));
}
// AST lowering guarantees that SymStatic points to a static.
hir::InlineAsmOperand::SymStatic { .. } => {}
// No special checking is needed for labels.
hir::InlineAsmOperand::Label { .. } => {}
}
Expand Down
66 changes: 59 additions & 7 deletions compiler/rustc_hir_analysis/src/collect/type_of.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -7,7 +7,7 @@ use rustc_hir::HirId;
use rustc_middle::query::plumbing::CyclePlaceholder;
use rustc_middle::ty::print::with_forced_trimmed_paths;
use rustc_middle::ty::util::IntTypeExt;
use rustc_middle::ty::{self, IsSuggestable, Ty, TyCtxt, TypeVisitableExt};
use rustc_middle::ty::{self, Article, IsSuggestable, Ty, TyCtxt, TypeVisitableExt};
use rustc_middle::{bug, span_bug};
use rustc_span::symbol::Ident;
use rustc_span::{Span, DUMMY_SP};
Expand All @@ -34,6 +34,20 @@ fn anon_const_type_of<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> Ty<'tcx> {
let parent_node_id = tcx.parent_hir_id(hir_id);
let parent_node = tcx.hir_node(parent_node_id);

let find_sym_fn = |&(op, op_sp)| match op {
hir::InlineAsmOperand::SymFn { anon_const } if anon_const.hir_id == hir_id => {
Some((anon_const, op_sp))
}
_ => None,
};

let find_const = |&(op, op_sp)| match op {
hir::InlineAsmOperand::Const { anon_const } if anon_const.hir_id == hir_id => {
Some((anon_const, op_sp))
}
_ => None,
};

match parent_node {
// Anon consts "inside" the type system.
Node::ConstArg(&ConstArg {
Expand All @@ -45,13 +59,51 @@ fn anon_const_type_of<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> Ty<'tcx> {
// Anon consts outside the type system.
Node::Expr(&Expr { kind: ExprKind::InlineAsm(asm), .. })
| Node::Item(&Item { kind: ItemKind::GlobalAsm(asm), .. })
if asm.operands.iter().any(|(op, _op_sp)| match op {
hir::InlineAsmOperand::Const { anon_const }
| hir::InlineAsmOperand::SymFn { anon_const } => anon_const.hir_id == hir_id,
_ => false,
}) =>
if let Some((anon_const, op_sp)) = asm.operands.iter().find_map(find_sym_fn) =>
{
tcx.typeck(def_id).node_type(hir_id)
let ty = tcx.typeck(def_id).node_type(hir_id);

match ty.kind() {
ty::Error(_) => ty,
ty::FnDef(..) => ty,
_ => {
let guar = tcx
.dcx()
.struct_span_err(op_sp, "invalid `sym` operand")
.with_span_label(
tcx.def_span(anon_const.def_id),
format!("is {} `{}`", ty.kind().article(), ty),
)
.with_help("`sym` operands must refer to either a function or a static")
.emit();

Ty::new_error(tcx, guar)
}
}
}
Node::Expr(&Expr { kind: ExprKind::InlineAsm(asm), .. })
| Node::Item(&Item { kind: ItemKind::GlobalAsm(asm), .. })
if let Some((anon_const, op_sp)) = asm.operands.iter().find_map(find_const) =>
{
let ty = tcx.typeck(def_id).node_type(hir_id);

match ty.kind() {
ty::Error(_) => ty,
ty::Int(_) | ty::Uint(_) => ty,
_ => {
let guar = tcx
.dcx()
.struct_span_err(op_sp, "invalid type for `const` operand")
.with_span_label(
tcx.def_span(anon_const.def_id),
format!("is {} `{}`", ty.kind().article(), ty),
)
.with_help("`const` operands must be of an integer type")
.emit();

Ty::new_error(tcx, guar)
}
}
}
Node::Variant(Variant { disr_expr: Some(ref e), .. }) if e.hir_id == hir_id => {
tcx.adt_def(tcx.hir().get_parent_item(hir_id)).repr().discr_type().to_ty(tcx)
Expand Down
9 changes: 4 additions & 5 deletions compiler/rustc_hir_typeck/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -265,11 +265,10 @@ fn infer_type_if_missing<'tcx>(fcx: &FnCtxt<'_, 'tcx>, node: Node<'tcx>) -> Opti
Node::Expr(&hir::Expr { kind: hir::ExprKind::InlineAsm(asm), span, .. })
| Node::Item(&hir::Item { kind: hir::ItemKind::GlobalAsm(asm), span, .. }) => {
asm.operands.iter().find_map(|(op, _op_sp)| match op {
hir::InlineAsmOperand::Const { anon_const } if anon_const.hir_id == id => {
// Inline assembly constants must be integers.
Some(fcx.next_int_var())
}
hir::InlineAsmOperand::SymFn { anon_const } if anon_const.hir_id == id => {
hir::InlineAsmOperand::Const { anon_const }
| hir::InlineAsmOperand::SymFn { anon_const }
if anon_const.hir_id == id =>
{
Some(fcx.next_ty_var(span))
}
_ => None,
Expand Down
18 changes: 0 additions & 18 deletions tests/ui/asm/aarch64/type-check-2.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -15,15 +15,6 @@ fn main() {
unsafe {
// Inputs must be initialized

// Sym operands must point to a function or static

const C: i32 = 0;
static S: i32 = 0;
asm!("{}", sym S);
asm!("{}", sym main);
asm!("{}", sym C);
//~^ ERROR invalid `sym` operand

// Register operands must be Copy

asm!("{:v}", in(vreg) SimdNonCopy(0.0, 0.0, 0.0, 0.0));
Expand Down Expand Up @@ -65,12 +56,3 @@ fn main() {
asm!("{}", in(reg) u);
}
}

// Sym operands must point to a function or static

const C: i32 = 0;
static S: i32 = 0;
global_asm!("{}", sym S);
global_asm!("{}", sym main);
global_asm!("{}", sym C);
//~^ ERROR invalid `sym` operand
34 changes: 9 additions & 25 deletions tests/ui/asm/aarch64/type-check-2.stderr
View file
Original file line number Diff line number Diff line change
@@ -1,37 +1,21 @@
error: invalid `sym` operand
--> $DIR/type-check-2.rs:75:19
|
LL | global_asm!("{}", sym C);
| ^^^^^ is an `i32`
|
= help: `sym` operands must refer to either a function or a static

error: invalid `sym` operand
--> $DIR/type-check-2.rs:24:20
|
LL | asm!("{}", sym C);
| ^^^^^ is an `i32`
|
= help: `sym` operands must refer to either a function or a static

error: arguments for inline assembly must be copyable
--> $DIR/type-check-2.rs:29:31
--> $DIR/type-check-2.rs:20:31
|
LL | asm!("{:v}", in(vreg) SimdNonCopy(0.0, 0.0, 0.0, 0.0));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: `SimdNonCopy` does not implement the Copy trait

error: cannot use value of type `{closure@$DIR/type-check-2.rs:41:28: 41:36}` for inline assembly
--> $DIR/type-check-2.rs:41:28
error: cannot use value of type `{closure@$DIR/type-check-2.rs:32:28: 32:36}` for inline assembly
--> $DIR/type-check-2.rs:32:28
|
LL | asm!("{}", in(reg) |x: i32| x);
| ^^^^^^^^^^
|
= note: only integers, floats, SIMD vectors, pointers and function pointers can be used as arguments for inline assembly

error: cannot use value of type `Vec<i32>` for inline assembly
--> $DIR/type-check-2.rs:43:28
--> $DIR/type-check-2.rs:34:28
|
LL | asm!("{}", in(reg) vec![0]);
| ^^^^^^^
Expand All @@ -40,36 +24,36 @@ LL | asm!("{}", in(reg) vec![0]);
= note: this error originates in the macro `vec` (in Nightly builds, run with -Z macro-backtrace for more info)

error: cannot use value of type `(i32, i32, i32)` for inline assembly
--> $DIR/type-check-2.rs:45:28
--> $DIR/type-check-2.rs:36:28
|
LL | asm!("{}", in(reg) (1, 2, 3));
| ^^^^^^^^^
|
= note: only integers, floats, SIMD vectors, pointers and function pointers can be used as arguments for inline assembly

error: cannot use value of type `[i32; 3]` for inline assembly
--> $DIR/type-check-2.rs:47:28
--> $DIR/type-check-2.rs:38:28
|
LL | asm!("{}", in(reg) [1, 2, 3]);
| ^^^^^^^^^
|
= note: only integers, floats, SIMD vectors, pointers and function pointers can be used as arguments for inline assembly

error: cannot use value of type `fn() {main}` for inline assembly
--> $DIR/type-check-2.rs:55:31
--> $DIR/type-check-2.rs:46:31
|
LL | asm!("{}", inout(reg) f);
| ^
|
= note: only integers, floats, SIMD vectors, pointers and function pointers can be used as arguments for inline assembly

error: cannot use value of type `&mut i32` for inline assembly
--> $DIR/type-check-2.rs:58:31
--> $DIR/type-check-2.rs:49:31
|
LL | asm!("{}", inout(reg) r);
| ^
|
= note: only integers, floats, SIMD vectors, pointers and function pointers can be used as arguments for inline assembly

error: aborting due to 9 previous errors
error: aborting due to 7 previous errors

51 changes: 51 additions & 0 deletions tests/ui/asm/invalid-const-operand.rs
View file
Original file line number Diff line number Diff line change
@@ -0,0 +1,51 @@
//@ needs-asm-support
//@ ignore-nvptx64
//@ ignore-spirv

#![feature(asm_const)]

use std::arch::{asm, global_asm};

// Const operands must be integers and must be constants.

global_asm!("{}", const 0);
global_asm!("{}", const 0i32);
global_asm!("{}", const 0i128);
global_asm!("{}", const 0f32);
//~^ ERROR invalid type for `const` operand
global_asm!("{}", const 0 as *mut u8);
//~^ ERROR invalid type for `const` operand

fn main() {
unsafe {
// Const operands must be integers and must be constants.

asm!("{}", const 0);
asm!("{}", const 0i32);
asm!("{}", const 0i128);
asm!("{}", const 0f32);
//~^ ERROR invalid type for `const` operand
asm!("{}", const 0 as *mut u8);
//~^ ERROR invalid type for `const` operand
asm!("{}", const &0);
//~^ ERROR invalid type for `const` operand

// Constants must be... constant

let x = 0;
const fn const_foo(x: i32) -> i32 {
x
}
const fn const_bar<T>(x: T) -> T {
x
}
asm!("{}", const x);
//~^ ERROR attempt to use a non-constant value in a constant
asm!("{}", const const_foo(0));
asm!("{}", const const_foo(x));
//~^ ERROR attempt to use a non-constant value in a constant
asm!("{}", const const_bar(0));
asm!("{}", const const_bar(x));
//~^ ERROR attempt to use a non-constant value in a constant
}
}
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