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Commit 912f7a6

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veluca93veluca93
committed
Emit error when calling/declaring functions with unavailable vectors.
On some architectures, vector types may have a different ABI when relevant target features are enabled. As discussed in rust-lang/lang-team#235, this turns out to very easily lead to unsound code. This commit makes it an error to declare or call functions using those vector types in a context in which the corresponding target features are disabled, if using an ABI for which the difference is relevant.
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‎Cargo.lock

Copy file name to clipboardExpand all lines: Cargo.lock
+1Lines changed: 1 addition & 0 deletions
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@@ -4470,6 +4470,7 @@ dependencies = [
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name = "rustc_monomorphize"
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version = "0.0.0"
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dependencies = [
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"rustc_abi",
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"rustc_data_structures",
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"rustc_errors",
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"rustc_fluent_macro",

‎compiler/rustc_monomorphize/Cargo.toml

Copy file name to clipboardExpand all lines: compiler/rustc_monomorphize/Cargo.toml
+1Lines changed: 1 addition & 0 deletions
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@@ -5,6 +5,7 @@ edition = "2021"
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[dependencies]
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# tidy-alphabetical-start
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rustc_abi = { path = "../rustc_abi" }
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rustc_data_structures = { path = "../rustc_data_structures" }
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rustc_errors = { path = "../rustc_errors" }
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rustc_fluent_macro = { path = "../rustc_fluent_macro" }

‎compiler/rustc_monomorphize/messages.ftl

Copy file name to clipboardExpand all lines: compiler/rustc_monomorphize/messages.ftl
+7Lines changed: 7 additions & 0 deletions
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@@ -1,3 +1,10 @@
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monomorphize_abi_error_disabled_vector_type_call =
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ABI error: this function call uses a {$required_feature} vector type, which is not enabled in the caller
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.help = consider enabling it globally (-C target-feature=+{$required_feature}) or locally (#[target_feature(enable="{$required_feature}")])
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monomorphize_abi_error_disabled_vector_type_def =
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ABI error: this function definition uses a {$required_feature} vector type, which is not enabled
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.help = consider enabling it globally (-C target-feature=+{$required_feature}) or locally (#[target_feature(enable="{$required_feature}")])
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monomorphize_couldnt_dump_mono_stats =
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unexpected error occurred while dumping monomorphization stats: {$error}
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‎compiler/rustc_monomorphize/src/collector.rs

Copy file name to clipboardExpand all lines: compiler/rustc_monomorphize/src/collector.rs
+3Lines changed: 3 additions & 0 deletions
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@@ -205,6 +205,7 @@
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//! this is not implemented however: a mono item will be produced
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//! regardless of whether it is actually needed or not.
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mod abi_check;
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mod move_check;
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use rustc_data_structures::sync::{par_for_each_in, LRef, MTLock};
@@ -762,6 +763,7 @@ impl<'a, 'tcx> MirVisitor<'tcx> for MirUsedCollector<'a, 'tcx> {
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self.used_mentioned_items.insert(MentionedItem::Fn(callee_ty));
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let callee_ty = self.monomorphize(callee_ty);
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self.check_fn_args_move_size(callee_ty, args, *fn_span, location);
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abi_check::check_call_site_abi(tcx, callee_ty, *fn_span, self.body.source.instance);
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visit_fn_use(self.tcx, callee_ty, true, source, &mut self.used_items)
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}
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mir::TerminatorKind::Drop { ref place, .. } => {
@@ -1199,6 +1201,7 @@ fn collect_items_of_instance<'tcx>(
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mentioned_items: &mut MonoItems<'tcx>,
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mode: CollectionMode,
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) {
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abi_check::check_instance_abi(tcx, instance);
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let body = tcx.instance_mir(instance.def);
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// Naively, in "used" collection mode, all functions get added to *both* `used_items` and
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// `mentioned_items`. Mentioned items processing will then notice that they have already been

‎compiler/rustc_monomorphize/src/collector/abi_check.rs

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+111Lines changed: 111 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,111 @@
1+
use rustc_abi::Abi;
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use rustc_middle::ty::{self, Instance, InstanceKind, ParamEnv, Ty, TyCtxt};
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use rustc_span::{def_id::DefId, Span, Symbol};
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use rustc_target::abi::call::{FnAbi, PassMode};
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use crate::errors::{AbiErrorDisabledVectorTypeCall, AbiErrorDisabledVectorTypeDef};
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const SSE_FEATURES: &'static [&'static str] = &["sse", "sse2", "ssse3", "sse3", "sse4.1", "sse4.2"];
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const AVX_FEATURES: &'static [&'static str] = &["avx", "avx2", "f16c", "fma"];
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const AVX512_FEATURES: &'static [&'static str] = &[
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"avx512f",
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"avx512bw",
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"avx512cd",
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"avx512er",
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"avx512pf",
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"avx512vl",
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"avx512dq",
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"avx512ifma",
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"avx512vbmi",
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"avx512vnni",
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"avx512bitalg",
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"avx512vpopcntdq",
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"avx512bf16",
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"avx512vbmi2",
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];
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fn do_check_abi<'tcx>(
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tcx: TyCtxt<'tcx>,
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abi: &FnAbi<'tcx, Ty<'tcx>>,
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target_feature_def: DefId,
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emit_err: impl Fn(&'static str),
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) {
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// FIXME: add support for other architectures
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if tcx.sess.target.arch != "x86" && tcx.sess.target.arch != "x86_64" {
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return;
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}
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let codegen_attrs = tcx.codegen_fn_attrs(target_feature_def);
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for arg_abi in abi.args.iter().chain(std::iter::once(&abi.ret)) {
39+
let size = arg_abi.layout.size;
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if matches!(arg_abi.layout.abi, Abi::Vector { .. })
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&& matches!(arg_abi.mode, PassMode::Direct(_))
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{
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let features: &[_] = match size.bits() {
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x if x <= 128 => &[SSE_FEATURES, AVX_FEATURES, AVX512_FEATURES],
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x if x <= 256 => &[AVX_FEATURES, AVX512_FEATURES],
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x if x <= 512 => &[AVX512_FEATURES],
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_ => {
48+
panic!("Unknown vector size for x86: {}; arg = {:?}", size.bits(), arg_abi)
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}
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};
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let required_feature = features.iter().map(|x| x.iter()).flatten().next().unwrap();
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if !features.iter().map(|x| x.iter()).flatten().any(|feature| {
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let required_feature_sym = Symbol::intern(feature);
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tcx.sess.unstable_target_features.contains(&required_feature_sym)
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|| codegen_attrs.target_features.contains(&required_feature_sym)
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}) {
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emit_err(required_feature);
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}
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}
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}
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}
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/// Checks that the ABI of a given instance of a function does not contain vector-passed arguments
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/// or return values for which the corresponding target feature is not enabled.
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pub fn check_instance_abi<'tcx>(tcx: TyCtxt<'tcx>, instance: Instance<'tcx>) {
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let param_env = ParamEnv::reveal_all();
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let Ok(abi) = tcx.fn_abi_of_instance(param_env.and((instance, ty::List::empty()))) else {
68+
// An error will be reported during codegen if we cannot determine the ABI of this
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// function.
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return;
71+
};
72+
do_check_abi(tcx, abi, instance.def_id(), |required_feature| {
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tcx.dcx().emit_err(AbiErrorDisabledVectorTypeDef {
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span: tcx.def_span(instance.def_id()),
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required_feature,
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});
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})
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}
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/// Checks that a call expression does not try to pass a vector-passed argument which requires a
81+
/// target feature that the caller does not have, as doing so causes UB because of ABI mismatch.
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pub fn check_call_site_abi<'tcx>(
83+
tcx: TyCtxt<'tcx>,
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ty: Ty<'tcx>,
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span: Span,
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caller: InstanceKind<'tcx>,
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) {
88+
let param_env = ParamEnv::reveal_all();
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let callee_abi = match *ty.kind() {
90+
ty::FnPtr(sig) => tcx.fn_abi_of_fn_ptr(param_env.and((sig, ty::List::empty()))),
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ty::FnDef(def_id, args) => {
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// Intrinsics are handled separately by the compiler.
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if tcx.intrinsic(def_id).is_some() {
94+
return;
95+
}
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let instance = ty::Instance::expect_resolve(tcx, param_env, def_id, args, span);
97+
tcx.fn_abi_of_instance(param_env.and((instance, ty::List::empty())))
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}
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_ => {
100+
panic!("Invalid function call");
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}
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};
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let Ok(callee_abi) = callee_abi else {
105+
// ABI failed to compute; this will not get through codegen.
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return;
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};
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do_check_abi(tcx, callee_abi, caller.def_id(), |required_feature| {
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tcx.dcx().emit_err(AbiErrorDisabledVectorTypeCall { span, required_feature });
110+
})
111+
}

‎compiler/rustc_monomorphize/src/errors.rs

Copy file name to clipboardExpand all lines: compiler/rustc_monomorphize/src/errors.rs
+18Lines changed: 18 additions & 0 deletions
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@@ -91,3 +91,21 @@ pub struct StartNotFound;
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pub struct UnknownCguCollectionMode<'a> {
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pub mode: &'a str,
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}
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#[derive(Diagnostic)]
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#[diag(monomorphize_abi_error_disabled_vector_type_def)]
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#[help]
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pub struct AbiErrorDisabledVectorTypeDef<'a> {
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#[primary_span]
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pub span: Span,
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pub required_feature: &'a str,
102+
}
103+
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#[derive(Diagnostic)]
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#[diag(monomorphize_abi_error_disabled_vector_type_call)]
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#[help]
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pub struct AbiErrorDisabledVectorTypeCall<'a> {
108+
#[primary_span]
109+
pub span: Span,
110+
pub required_feature: &'a str,
111+
}

‎tests/ui/simd-abi-checks.rs

Copy file name to clipboard
+55Lines changed: 55 additions & 0 deletions
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@@ -0,0 +1,55 @@
1+
//@ only-x86_64
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//@ build-fail
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#![feature(avx512_target_feature)]
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#![feature(portable_simd)]
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#![allow(improper_ctypes_definitions)]
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use std::arch::x86_64::*;
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unsafe extern "C" fn f(_: __m256) {
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//~^ ABI error: this function definition uses a avx vector type, which is not enabled
12+
todo!()
13+
}
14+
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unsafe extern "C" fn g() -> __m256 {
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//~^ ABI error: this function definition uses a avx vector type, which is not enabled
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todo!()
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}
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20+
#[target_feature(enable = "avx")]
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unsafe extern "C" fn favx(_: __m256) {
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todo!()
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}
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#[target_feature(enable = "avx")]
26+
unsafe extern "C" fn gavx() -> __m256 {
27+
todo!()
28+
}
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fn as_f64x8(d: __m512d) -> std::simd::f64x8 {
31+
unsafe { std::mem::transmute(d) }
32+
}
33+
34+
unsafe fn test() {
35+
let arg = std::mem::transmute([0.0f64; 8]);
36+
as_f64x8(arg);
37+
}
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fn main() {
40+
unsafe {
41+
f(g());
42+
//~^ ERROR ABI error: this function call uses a avx vector type, which is not enabled in the caller
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//~| ERROR ABI error: this function call uses a avx vector type, which is not enabled in the caller
44+
}
45+
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unsafe {
47+
favx(gavx());
48+
//~^ ERROR ABI error: this function call uses a avx vector type, which is not enabled in the caller
49+
//~| ERROR ABI error: this function call uses a avx vector type, which is not enabled in the caller
50+
}
51+
52+
unsafe {
53+
test();
54+
}
55+
}

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