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Auto merge of #115372 - RalfJung:abi-assert-eq, r=davidtwco

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add rustc_abi(assert_eq) to test some guaranteed or at least highly expected ABI compatibility guarantees

This new repr(transparent) test is super useful, it would have found https://github.com/rust-lang/rust/issues/115336 and found https://github.com/rust-lang/rust/issues/115404, https://github.com/rust-lang/rust/issues/115481, https://github.com/rust-lang/rust/issues/115509.
This commit is contained in:
bors 2023-09-08 11:56:08 +00:00
commit cd71a37f32
17 changed files with 1305 additions and 175 deletions
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78
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
@ -381,13 +329,11 @@ 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() {
// 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
&& caller_abi.layout.align.abi == callee_abi.layout.align.abi
&& caller_abi.layout.is_sized() == callee_abi.layout.is_sized()
);
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 imply layout ABI compatibility.
assert!(caller_abi.layout.eq_abi(&callee_abi.layout));
return true;
} else {
trace!(