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Rollup merge of #132729 - bjorn3:fn_abi_extra_sanity_checks, r=compiler-errors

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Make fn_abi_sanity_check a bit stricter

The Rust ABI must ignore all ZST arguments, all ignored arguments must be either ZST or uninhabited. And finally ScalarPair should never be passed as PassMode::Direct.
This commit is contained in:
Matthias Krüger 2024-11-07 18:19:38 +01:00 committed by GitHub
commit bf0de1f308
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1 changed files with 51 additions and 30 deletions
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45
compiler/rustc_ty_utils/src/abi.rs
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@ -463,21 +463,41 @@ fn fn_arg_sanity_check<'tcx>(
arg: &ArgAbi<'tcx, Ty<'tcx>>,
) {
let tcx = cx.tcx();
if spec_abi == ExternAbi::Rust
|| spec_abi == ExternAbi::RustCall
|| spec_abi == ExternAbi::RustCold
{
if arg.layout.is_zst() {
// Casting closures to function pointers depends on ZST closure types being
// omitted entirely in the calling convention.
assert!(arg.is_ignore());
}
if let PassMode::Indirect { on_stack, .. } = arg.mode {
assert!(!on_stack, "rust abi shouldn't use on_stack");
}
}
match &arg.mode {
PassMode::Ignore => {}
PassMode::Ignore => {
assert!(arg.layout.is_zst() || arg.layout.is_uninhabited());
}
PassMode::Direct(_) => {
// Here the Rust type is used to determine the actual ABI, so we have to be very
// careful. Scalar/ScalarPair is fine, since backends will generally use
// `layout.abi` and ignore everything else. We should just reject `Aggregate`
// entirely here, but some targets need to be fixed first.
if matches!(arg.layout.backend_repr, BackendRepr::Memory { .. }) {
// careful. Scalar/Vector is fine, since backends will generally use
// `layout.backend_repr` and ignore everything else. We should just reject
//`Aggregate` entirely here, but some targets need to be fixed first.
match arg.layout.backend_repr {
BackendRepr::Uninhabited
| BackendRepr::Scalar(_)
| BackendRepr::Vector { .. } => {}
BackendRepr::ScalarPair(..) => {
panic!("`PassMode::Direct` used for ScalarPair type {}", arg.layout.ty)
}
BackendRepr::Memory { sized } => {
// For an unsized type we'd only pass the sized prefix, so there is no universe
// in which we ever want to allow this.
assert!(
arg.layout.is_sized(),
"`PassMode::Direct` for unsized type in ABI: {:#?}",
fn_abi
);
assert!(sized, "`PassMode::Direct` for unsized type in ABI: {:#?}", fn_abi);
// This really shouldn't happen even for sized aggregates, since
// `immediate_llvm_type` will use `layout.fields` to turn this Rust type into an
// LLVM type. This means all sorts of Rust type details leak into the ABI.
@ -497,9 +517,10 @@ fn fn_arg_sanity_check<'tcx>(
);
}
}
}
PassMode::Pair(_, _) => {
// Similar to `Direct`, we need to make sure that backends use `layout.abi` and
// ignore the rest of the layout.
// Similar to `Direct`, we need to make sure that backends use `layout.backend_repr`
// and ignore the rest of the layout.
assert!(
matches!(arg.layout.backend_repr, BackendRepr::ScalarPair(..)),
"PassMode::Pair for type {}",