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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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39
compiler/rustc_codegen_llvm/src/abi.rs
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@ -340,15 +340,50 @@ impl<'ll, 'tcx> FnAbiLlvmExt<'ll, 'tcx> for FnAbi<'tcx, Ty<'tcx>> {
};
for arg in args {
// Note that the exact number of arguments pushed here is carefully synchronized with
// code all over the place, both in the codegen_llvm and codegen_ssa crates. That's how
// other code then knows which LLVM argument(s) correspond to the n-th Rust argument.
let llarg_ty = match &arg.mode {
PassMode::Ignore => continue,
PassMode::Direct(_) => arg.layout.immediate_llvm_type(cx),
PassMode::Direct(_) => {
// ABI-compatible Rust types have the same `layout.abi` (up to validity ranges),
// and for Scalar ABIs the LLVM type is fully determined by `layout.abi`,
// guarnateeing that we generate ABI-compatible LLVM IR. Things get tricky for
// aggregates...
if matches!(arg.layout.abi, abi::Abi::Aggregate { .. }) {
// This really shouldn't happen, 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. However wasm sadly *does*
// currently use this mode so we have to allow it -- but we absolutely
// shouldn't let any more targets do that.
// (Also see <https://github.com/rust-lang/rust/issues/115666>.)
assert!(
matches!(&*cx.tcx.sess.target.arch, "wasm32" | "wasm64"),
"`PassMode::Direct` for aggregates only allowed on wasm targets\nProblematic type: {:#?}",
arg.layout,
);
}
arg.layout.immediate_llvm_type(cx)
}
PassMode::Pair(..) => {
// ABI-compatible Rust types have the same `layout.abi` (up to validity ranges),
// so for ScalarPair we can easily be sure that we are generating ABI-compatible
// LLVM IR.
assert!(
matches!(arg.layout.abi, abi::Abi::ScalarPair(..)),
"PassMode::Pair for type {}",
arg.layout.ty
);
llargument_tys.push(arg.layout.scalar_pair_element_llvm_type(cx, 0, true));
llargument_tys.push(arg.layout.scalar_pair_element_llvm_type(cx, 1, true));
continue;
}
PassMode::Indirect { attrs: _, extra_attrs: Some(_), on_stack: _ } => {
assert!(arg.layout.is_unsized());
// Construct the type of a (wide) pointer to `ty`, and pass its two fields.
// Any two ABI-compatible unsized types have the same metadata type and
// moreover the same metadata value leads to the same dynamic size and
// alignment, so this respects ABI compatibility.
let ptr_ty = Ty::new_mut_ptr(cx.tcx, arg.layout.ty);
let ptr_layout = cx.layout_of(ptr_ty);
llargument_tys.push(ptr_layout.scalar_pair_element_llvm_type(cx, 0, true));
@ -360,6 +395,8 @@ impl<'ll, 'tcx> FnAbiLlvmExt<'ll, 'tcx> for FnAbi<'tcx, Ty<'tcx>> {
if *pad_i32 {
llargument_tys.push(Reg::i32().llvm_type(cx));
}
// Compute the LLVM type we use for this function from the cast type.
// We assume here that ABI-compatible Rust types have the same cast type.
cast.llvm_type(cx)
}
PassMode::Indirect { attrs: _, extra_attrs: None, on_stack: _ } => cx.type_ptr(),