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accept some differences for rustc_abi(assert_eq), so that we can test more things to be compatible

This commit is contained in:
Ralf Jung 2023-09-02 11:59:31 +02:00
parent 8922c0c541
commit c3e14edd8b
7 changed files with 449 additions and 64 deletions
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17
compiler/rustc_abi/src/lib.rs
View File

@ -1348,6 +1348,23 @@ impl Abi {
Abi::Uninhabited | Abi::Aggregate { .. } => Abi::Aggregate { sized: true },
}
}
pub fn eq_up_to_validity(&self, other: &Self) -> bool {
match (self, other) {
// Scalar, Vector, ScalarPair have `Scalar` in them where we ignore validity ranges.
// We do *not* ignore the sign since it matters for some ABIs (e.g. s390x).
(Abi::Scalar(l), Abi::Scalar(r)) => l.primitive() == r.primitive(),
(
Abi::Vector { element: element_l, count: count_l },
Abi::Vector { element: element_r, count: count_r },
) => element_l.primitive() == element_r.primitive() && count_l == count_r,
(Abi::ScalarPair(l1, l2), Abi::ScalarPair(r1, r2)) => {
l1.primitive() == r1.primitive() && l2.primitive() == r2.primitive()
}
// Everything else must be strictly identical.
_ => self == other,
}
}
}
#[derive(PartialEq, Eq, Hash, Clone, Debug)]

70
compiler/rustc_const_eval/src/interpret/terminator.rs
View File

@ -10,7 +10,7 @@ use rustc_middle::{
Instance, Ty,
},
};
use rustc_target::abi::call::{ArgAbi, ArgAttribute, ArgAttributes, FnAbi, PassMode};
use rustc_target::abi::call::{ArgAbi, FnAbi, PassMode};
use rustc_target::abi::{self, FieldIdx};
use rustc_target::spec::abi::Abi;
@ -291,32 +291,17 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
return true;
}
match (caller_layout.abi, callee_layout.abi) {
// If both sides have Scalar/Vector/ScalarPair ABI, we can easily directly compare them.
// Different valid ranges are okay (the validity check will complain if this leads to
// invalid transmutes). Different signs are *not* okay on some targets (e.g. `extern
// "C"` on `s390x` where small integers are passed zero/sign-extended in large
// registers), so we generally reject them to increase portability.
match caller_layout.abi {
// For Scalar/Vector/ScalarPair ABI, we directly compare them.
// NOTE: this is *not* a stable guarantee! It just reflects a property of our current
// ABIs. It's also fragile; the same pair of types might be considered ABI-compatible
// when used directly by-value but not considered compatible as a struct field or array
// element.
(abi::Abi::Scalar(caller), abi::Abi::Scalar(callee)) => {
caller.primitive() == callee.primitive()
abi::Abi::Scalar(..) | abi::Abi::ScalarPair(..) | abi::Abi::Vector { .. } => {
caller_layout.abi.eq_up_to_validity(&callee_layout.abi)
}
(
abi::Abi::Vector { element: caller_element, count: caller_count },
abi::Abi::Vector { element: callee_element, count: callee_count },
) => {
caller_element.primitive() == callee_element.primitive()
&& caller_count == callee_count
}
(abi::Abi::ScalarPair(caller1, caller2), abi::Abi::ScalarPair(callee1, callee2)) => {
caller1.primitive() == callee1.primitive()
&& caller2.primitive() == callee2.primitive()
}
(abi::Abi::Aggregate { .. }, abi::Abi::Aggregate { .. }) => {
// Aggregates are compatible only if they newtype-wrap the same type, or if they are both 1-ZST.
_ => {
// Everything else is compatible only if they newtype-wrap the same type, or if they are both 1-ZST.
// (The latter part is needed to ensure e.g. that `struct Zst` is compatible with `struct Wrap((), Zst)`.)
// This is conservative, but also means that our check isn't quite so heavily dependent on the `PassMode`,
// which means having ABI-compatibility on one target is much more likely to imply compatibility for other targets.
@ -329,9 +314,6 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
== self.unfold_transparent(callee_layout).ty
}
}
// What remains is `Abi::Uninhabited` (which can never be passed anyway) and
// mismatching ABIs, that should all be rejected.
_ => false,
}
}
@ -340,40 +322,6 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
caller_abi: &ArgAbi<'tcx, Ty<'tcx>>,
callee_abi: &ArgAbi<'tcx, Ty<'tcx>>,
) -> bool {
// When comparing the PassMode, we have to be smart about comparing the attributes.
let arg_attr_compat = |a1: &ArgAttributes, a2: &ArgAttributes| {
// There's only one regular attribute that matters for the call ABI: InReg.
// Everything else is things like noalias, dereferenceable, nonnull, ...
// (This also applies to pointee_size, pointee_align.)
if a1.regular.contains(ArgAttribute::InReg) != a2.regular.contains(ArgAttribute::InReg)
{
return false;
}
// We also compare the sign extension mode -- this could let the callee make assumptions
// about bits that conceptually were not even passed.
if a1.arg_ext != a2.arg_ext {
return false;
}
return true;
};
let mode_compat = || match (&caller_abi.mode, &callee_abi.mode) {
(PassMode::Ignore, PassMode::Ignore) => true, // can still be reached for the return type
(PassMode::Direct(a1), PassMode::Direct(a2)) => arg_attr_compat(a1, a2),
(PassMode::Pair(a1, b1), PassMode::Pair(a2, b2)) => {
arg_attr_compat(a1, a2) && arg_attr_compat(b1, b2)
}
(PassMode::Cast(c1, pad1), PassMode::Cast(c2, pad2)) => c1 == c2 && pad1 == pad2,
(
PassMode::Indirect { attrs: a1, extra_attrs: None, on_stack: s1 },
PassMode::Indirect { attrs: a2, extra_attrs: None, on_stack: s2 },
) => arg_attr_compat(a1, a2) && s1 == s2,
(
PassMode::Indirect { attrs: a1, extra_attrs: Some(e1), on_stack: s1 },
PassMode::Indirect { attrs: a2, extra_attrs: Some(e2), on_stack: s2 },
) => arg_attr_compat(a1, a2) && arg_attr_compat(e1, e2) && s1 == s2,
_ => false,
};
// Ideally `PassMode` would capture everything there is about argument passing, but that is
// not the case: in `FnAbi::llvm_type`, also parts of the layout and type information are
// used. So we need to check that *both* sufficiently agree to ensures the arguments are
@ -381,7 +329,9 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
// For instance, `layout_compat` is needed to reject `i32` vs `f32`, which is not reflected
// in `PassMode`. `mode_compat` is needed to reject `u8` vs `bool`, which have the same
// `abi::Primitive` but different `arg_ext`.
if self.layout_compat(caller_abi.layout, callee_abi.layout) && mode_compat() {
if self.layout_compat(caller_abi.layout, callee_abi.layout)
&& caller_abi.mode.eq_abi(&callee_abi.mode)
{
// Something went very wrong if our checks don't even imply that the layout is the same.
assert!(
caller_abi.layout.size == callee_abi.layout.size

4
compiler/rustc_passes/src/abi_test.rs
View File

@ -121,9 +121,7 @@ fn test_arg_abi_eq<'tcx>(
// Ideally we'd just compare the `mode`, but that is not enough -- for some modes LLVM will look
// at the type. Comparing the `mode` and `layout.abi` should catch basically everything though
// (except for tricky cases around unized types).
// This *is* overly strict (e.g. we compare the sign of integer `Primitive`s, or parts of `ArgAttributes` that do not affect ABI),
// but for the purpose of ensuring repr(transparent) ABI compatibility that is fine.
abi1.mode == abi2.mode && abi1.layout.abi == abi2.layout.abi
abi1.mode.eq_abi(&abi2.mode) && abi1.layout.abi.eq_up_to_validity(&abi2.layout.abi)
}
fn test_abi_eq<'tcx>(abi1: &'tcx FnAbi<'tcx, Ty<'tcx>>, abi2: &'tcx FnAbi<'tcx, Ty<'tcx>>) -> bool {

48
compiler/rustc_target/src/abi/call/mod.rs
View File

@ -55,6 +55,28 @@ pub enum PassMode {
Indirect { attrs: ArgAttributes, extra_attrs: Option<ArgAttributes>, on_stack: bool },
}
impl PassMode {
/// Checks if these two `PassMode` are equal enough to be considered "the same for all
/// function call ABIs".
pub fn eq_abi(&self, other: &Self) -> bool {
match (self, other) {
(PassMode::Ignore, PassMode::Ignore) => true, // can still be reached for the return type
(PassMode::Direct(a1), PassMode::Direct(a2)) => a1.eq_abi(a2),
(PassMode::Pair(a1, b1), PassMode::Pair(a2, b2)) => a1.eq_abi(a2) && b1.eq_abi(b2),
(PassMode::Cast(c1, pad1), PassMode::Cast(c2, pad2)) => c1.eq_abi(c2) && pad1 == pad2,
(
PassMode::Indirect { attrs: a1, extra_attrs: None, on_stack: s1 },
PassMode::Indirect { attrs: a2, extra_attrs: None, on_stack: s2 },
) => a1.eq_abi(a2) && s1 == s2,
(
PassMode::Indirect { attrs: a1, extra_attrs: Some(e1), on_stack: s1 },
PassMode::Indirect { attrs: a2, extra_attrs: Some(e2), on_stack: s2 },
) => a1.eq_abi(a2) && e1.eq_abi(e2) && s1 == s2,
_ => false,
}
}
}
// Hack to disable non_upper_case_globals only for the bitflags! and not for the rest
// of this module
pub use attr_impl::ArgAttribute;
@ -127,6 +149,24 @@ impl ArgAttributes {
pub fn contains(&self, attr: ArgAttribute) -> bool {
self.regular.contains(attr)
}
/// Checks if these two `ArgAttributes` are equal enough to be considered "the same for all
/// function call ABIs".
pub fn eq_abi(&self, other: &Self) -> bool {
// There's only one regular attribute that matters for the call ABI: InReg.
// Everything else is things like noalias, dereferenceable, nonnull, ...
// (This also applies to pointee_size, pointee_align.)
if self.regular.contains(ArgAttribute::InReg) != other.regular.contains(ArgAttribute::InReg)
{
return false;
}
// We also compare the sign extension mode -- this could let the callee make assumptions
// about bits that conceptually were not even passed.
if self.arg_ext != other.arg_ext {
return false;
}
return true;
}
}
#[derive(Copy, Clone, PartialEq, Eq, Hash, Debug, HashStable_Generic)]
@ -272,6 +312,14 @@ impl CastTarget {
acc.max(align)
})
}
/// Checks if these two `CastTarget` are equal enough to be considered "the same for all
/// function call ABIs".
pub fn eq_abi(&self, other: &Self) -> bool {
let CastTarget { prefix: prefix_l, rest: rest_l, attrs: attrs_l } = self;
let CastTarget { prefix: prefix_r, rest: rest_r, attrs: attrs_r } = other;
prefix_l == prefix_r && rest_l == rest_r && attrs_l.eq_abi(attrs_r)
}
}
/// Return value from the `homogeneous_aggregate` test function.

76
tests/ui/abi/compatibility.rs Normal file
View File

@ -0,0 +1,76 @@
// check-pass
#![feature(rustc_attrs)]
#![allow(unused, improper_ctypes_definitions)]
use std::num::NonZeroI32;
use std::ptr::NonNull;
macro_rules! assert_abi_compatible {
($name:ident, $t1:ty, $t2:ty) => {
mod $name {
use super::*;
// Test argument and return value, `Rust` and `C` ABIs.
#[rustc_abi(assert_eq)]
type TestRust = (fn($t1) -> $t1, fn($t2) -> $t2);
#[rustc_abi(assert_eq)]
type TestC = (extern "C" fn($t1) -> $t1, extern "C" fn($t2) -> $t2);
}
};
}
#[derive(Copy, Clone)]
struct Zst;
#[repr(C)]
struct ReprC1<T>(T);
#[repr(C)]
struct ReprC2Int<T>(i32, T);
#[repr(C)]
struct ReprC2Float<T>(f32, T);
#[repr(C)]
struct ReprC4<T>(T, T, T, T);
#[repr(C)]
struct ReprC4Mixed<T>(T, f32, i32, T);
#[repr(C)]
enum ReprCEnum<T> {
Variant1,
Variant2(T),
}
#[repr(C)]
union ReprCUnion<T: Copy> {
nothing: (),
something: T,
}
macro_rules! test_abi_compatible {
($name:ident, $t1:ty, $t2:ty) => {
mod $name {
use super::*;
assert_abi_compatible!(plain, $t1, $t2);
// We also do some tests with differences in fields of `repr(C)` types.
assert_abi_compatible!(repr_c_1, ReprC1<$t1>, ReprC1<$t2>);
assert_abi_compatible!(repr_c_2_int, ReprC2Int<$t1>, ReprC2Int<$t2>);
assert_abi_compatible!(repr_c_2_float, ReprC2Float<$t1>, ReprC2Float<$t2>);
assert_abi_compatible!(repr_c_4, ReprC4<$t1>, ReprC4<$t2>);
assert_abi_compatible!(repr_c_4mixed, ReprC4Mixed<$t1>, ReprC4Mixed<$t2>);
assert_abi_compatible!(repr_c_enum, ReprCEnum<$t1>, ReprCEnum<$t2>);
assert_abi_compatible!(repr_c_union, ReprCUnion<$t1>, ReprCUnion<$t2>);
}
};
}
// Compatibility of pointers is probably de-facto guaranteed,
// but that does not seem to be documented.
test_abi_compatible!(ptr_mut, *const i32, *mut i32);
test_abi_compatible!(ptr_pointee, *const i32, *const Vec<i32>);
test_abi_compatible!(ref_mut, &i32, &mut i32);
test_abi_compatible!(ref_ptr, &i32, *const i32);
test_abi_compatible!(box_ptr, Box<i32>, *const i32);
test_abi_compatible!(nonnull_ptr, NonNull<i32>, *const i32);
test_abi_compatible!(fn_fn, fn(), fn(i32) -> i32);
// Some further guarantees we will likely (have to) make.
test_abi_compatible!(zst_unit, Zst, ());
test_abi_compatible!(zst_array, Zst, [u8; 0]);
test_abi_compatible!(nonzero_int, NonZeroI32, i32);
fn main() {}

7
tests/ui/abi/debug.rs
View File

@ -38,3 +38,10 @@ type TestAbiEq = (fn(bool), fn(bool));
#[rustc_abi(assert_eq)]
type TestAbiNe = (fn(u8), fn(u32)); //~ ERROR: ABIs are not compatible
#[rustc_abi(assert_eq)]
type TestAbiNeFloat = (fn(f32), fn(u32)); //~ ERROR: ABIs are not compatible
// Sign matters on some targets (such as s390x), so let's make sure we never accept this.
#[rustc_abi(assert_eq)]
type TestAbiNeSign = (fn(i32), fn(u32)); //~ ERROR: ABIs are not compatible

291
tests/ui/abi/debug.stderr
View File

@ -508,5 +508,294 @@ error: ABIs are not compatible
LL | type TestAbiNe = (fn(u8), fn(u32));
| ^^^^^^^^^^^^^^
error: aborting due to 7 previous errors
error: ABIs are not compatible
left ABI = FnAbi {
args: [
ArgAbi {
layout: TyAndLayout {
ty: f32,
layout: Layout {
size: $SOME_SIZE,
align: AbiAndPrefAlign {
abi: $SOME_ALIGN,
pref: $SOME_ALIGN,
},
abi: Scalar(
Initialized {
value: F32,
valid_range: $FULL,
},
),
fields: Primitive,
largest_niche: None,
variants: Single {
index: 0,
},
max_repr_align: None,
unadjusted_abi_align: $SOME_ALIGN,
},
},
mode: Direct(
ArgAttributes {
regular: NoUndef,
arg_ext: None,
pointee_size: Size(0 bytes),
pointee_align: None,
},
),
},
],
ret: ArgAbi {
layout: TyAndLayout {
ty: (),
layout: Layout {
size: Size(0 bytes),
align: AbiAndPrefAlign {
abi: $SOME_ALIGN,
pref: $SOME_ALIGN,
},
abi: Aggregate {
sized: true,
},
fields: Arbitrary {
offsets: [],
memory_index: [],
},
largest_niche: None,
variants: Single {
index: 0,
},
max_repr_align: None,
unadjusted_abi_align: $SOME_ALIGN,
},
},
mode: Ignore,
},
c_variadic: false,
fixed_count: 1,
conv: Rust,
can_unwind: $SOME_BOOL,
}
right ABI = FnAbi {
args: [
ArgAbi {
layout: TyAndLayout {
ty: u32,
layout: Layout {
size: $SOME_SIZE,
align: AbiAndPrefAlign {
abi: $SOME_ALIGN,
pref: $SOME_ALIGN,
},
abi: Scalar(
Initialized {
value: Int(
I32,
false,
),
valid_range: $FULL,
},
),
fields: Primitive,
largest_niche: None,
variants: Single {
index: 0,
},
max_repr_align: None,
unadjusted_abi_align: $SOME_ALIGN,
},
},
mode: Direct(
ArgAttributes {
regular: NoUndef,
arg_ext: None,
pointee_size: Size(0 bytes),
pointee_align: None,
},
),
},
],
ret: ArgAbi {
layout: TyAndLayout {
ty: (),
layout: Layout {
size: Size(0 bytes),
align: AbiAndPrefAlign {
abi: $SOME_ALIGN,
pref: $SOME_ALIGN,
},
abi: Aggregate {
sized: true,
},
fields: Arbitrary {
offsets: [],
memory_index: [],
},
largest_niche: None,
variants: Single {
index: 0,
},
max_repr_align: None,
unadjusted_abi_align: $SOME_ALIGN,
},
},
mode: Ignore,
},
c_variadic: false,
fixed_count: 1,
conv: Rust,
can_unwind: $SOME_BOOL,
}
--> $DIR/debug.rs:43:1
|
LL | type TestAbiNeFloat = (fn(f32), fn(u32));
| ^^^^^^^^^^^^^^^^^^^
error: ABIs are not compatible
left ABI = FnAbi {
args: [
ArgAbi {
layout: TyAndLayout {
ty: i32,
layout: Layout {
size: $SOME_SIZE,
align: AbiAndPrefAlign {
abi: $SOME_ALIGN,
pref: $SOME_ALIGN,
},
abi: Scalar(
Initialized {
value: Int(
I32,
true,
),
valid_range: $FULL,
},
),
fields: Primitive,
largest_niche: None,
variants: Single {
index: 0,
},
max_repr_align: None,
unadjusted_abi_align: $SOME_ALIGN,
},
},
mode: Direct(
ArgAttributes {
regular: NoUndef,
arg_ext: None,
pointee_size: Size(0 bytes),
pointee_align: None,
},
),
},
],
ret: ArgAbi {
layout: TyAndLayout {
ty: (),
layout: Layout {
size: Size(0 bytes),
align: AbiAndPrefAlign {
abi: $SOME_ALIGN,
pref: $SOME_ALIGN,
},
abi: Aggregate {
sized: true,
},
fields: Arbitrary {
offsets: [],
memory_index: [],
},
largest_niche: None,
variants: Single {
index: 0,
},
max_repr_align: None,
unadjusted_abi_align: $SOME_ALIGN,
},
},
mode: Ignore,
},
c_variadic: false,
fixed_count: 1,
conv: Rust,
can_unwind: $SOME_BOOL,
}
right ABI = FnAbi {
args: [
ArgAbi {
layout: TyAndLayout {
ty: u32,
layout: Layout {
size: $SOME_SIZE,
align: AbiAndPrefAlign {
abi: $SOME_ALIGN,
pref: $SOME_ALIGN,
},
abi: Scalar(
Initialized {
value: Int(
I32,
false,
),
valid_range: $FULL,
},
),
fields: Primitive,
largest_niche: None,
variants: Single {
index: 0,
},
max_repr_align: None,
unadjusted_abi_align: $SOME_ALIGN,
},
},
mode: Direct(
ArgAttributes {
regular: NoUndef,
arg_ext: None,
pointee_size: Size(0 bytes),
pointee_align: None,
},
),
},
],
ret: ArgAbi {
layout: TyAndLayout {
ty: (),
layout: Layout {
size: Size(0 bytes),
align: AbiAndPrefAlign {
abi: $SOME_ALIGN,
pref: $SOME_ALIGN,
},
abi: Aggregate {
sized: true,
},
fields: Arbitrary {
offsets: [],
memory_index: [],
},
largest_niche: None,
variants: Single {
index: 0,
},
max_repr_align: None,
unadjusted_abi_align: $SOME_ALIGN,
},
},
mode: Ignore,
},
c_variadic: false,
fixed_count: 1,
conv: Rust,
can_unwind: $SOME_BOOL,
}
--> $DIR/debug.rs:47:1
|
LL | type TestAbiNeSign = (fn(i32), fn(u32));
| ^^^^^^^^^^^^^^^^^^
error: aborting due to 9 previous errors