bjoernager/rust
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Auto merge of #120675 - oli-obk:intrinsics3.0, r=pnkfelix

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Add a scheme for moving away from `extern "rust-intrinsic"` entirely

All `rust-intrinsic`s can become free functions now, either with a fallback body, or with a dummy body and an attribute, requiring backends to actually implement the intrinsic.

This PR demonstrates the dummy-body scheme with the `vtable_size` intrinsic.

cc https://github.com/rust-lang/rust/issues/63585

follow-up to #120500

MCP at https://github.com/rust-lang/compiler-team/issues/720
This commit is contained in:
bors 2024-03-05 00:13:01 +00:00
commit 2eeff462b7
31 changed files with 207 additions and 51 deletions
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4
compiler/rustc_codegen_ssa/src/back/symbol_export.rs
View file

@ -81,6 +81,10 @@ fn reachable_non_generics_provider(tcx: TyCtxt<'_>, _: LocalCrate) -> DefIdMap<S
return library.kind.is_statically_included().then_some(def_id);
}
if tcx.intrinsic(def_id).is_some_and(|i| i.must_be_overridden) {
return None;
}
// Only consider nodes that actually have exported symbols.
match tcx.def_kind(def_id) {
DefKind::Fn | DefKind::Static(_) => {}

59
compiler/rustc_codegen_ssa/src/mir/block.rs
View file

@ -12,12 +12,12 @@ use crate::MemFlags;
use rustc_ast as ast;
use rustc_ast::{InlineAsmOptions, InlineAsmTemplatePiece};
use rustc_hir::lang_items::LangItem;
use rustc_middle::mir::{self, AssertKind, SwitchTargets, UnwindTerminateReason};
use rustc_middle::mir::{self, AssertKind, BasicBlock, SwitchTargets, UnwindTerminateReason};
use rustc_middle::ty::layout::{HasTyCtxt, LayoutOf, ValidityRequirement};
use rustc_middle::ty::print::{with_no_trimmed_paths, with_no_visible_paths};
use rustc_middle::ty::{self, Instance, Ty};
use rustc_session::config::OptLevel;
use rustc_span::{source_map::Spanned, sym, Span, Symbol};
use rustc_span::{source_map::Spanned, sym, Span};
use rustc_target::abi::call::{ArgAbi, FnAbi, PassMode, Reg};
use rustc_target::abi::{self, HasDataLayout, WrappingRange};
use rustc_target::spec::abi::Abi;
@ -680,7 +680,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
&mut self,
helper: &TerminatorCodegenHelper<'tcx>,
bx: &mut Bx,
intrinsic: Option<Symbol>,
intrinsic: Option<ty::IntrinsicDef>,
instance: Option<Instance<'tcx>>,
source_info: mir::SourceInfo,
target: Option<mir::BasicBlock>,
@ -690,7 +690,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
// Emit a panic or a no-op for `assert_*` intrinsics.
// These are intrinsics that compile to panics so that we can get a message
// which mentions the offending type, even from a const context.
let panic_intrinsic = intrinsic.and_then(|s| ValidityRequirement::from_intrinsic(s));
let panic_intrinsic = intrinsic.and_then(|i| ValidityRequirement::from_intrinsic(i.name));
if let Some(requirement) = panic_intrinsic {
let ty = instance.unwrap().args.type_at(0);
@ -826,14 +826,20 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
// The arguments we'll be passing. Plus one to account for outptr, if used.
let arg_count = fn_abi.args.len() + fn_abi.ret.is_indirect() as usize;
if intrinsic == Some(sym::caller_location) {
if matches!(intrinsic, Some(ty::IntrinsicDef { name: sym::caller_location, .. })) {
return if let Some(target) = target {
let location =
self.get_caller_location(bx, mir::SourceInfo { span: fn_span, ..source_info });
let mut llargs = Vec::with_capacity(arg_count);
let ret_dest =
self.make_return_dest(bx, destination, &fn_abi.ret, &mut llargs, true, true);
let ret_dest = self.make_return_dest(
bx,
destination,
&fn_abi.ret,
&mut llargs,
intrinsic,
Some(target),
);
assert_eq!(llargs, []);
if let ReturnDest::IndirectOperand(tmp, _) = ret_dest {
location.val.store(bx, tmp);
@ -846,7 +852,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
}
let instance = match intrinsic {
None | Some(sym::drop_in_place) => instance,
None | Some(ty::IntrinsicDef { name: sym::drop_in_place, .. }) => instance,
Some(intrinsic) => {
let mut llargs = Vec::with_capacity(1);
let ret_dest = self.make_return_dest(
@ -854,8 +860,8 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
destination,
&fn_abi.ret,
&mut llargs,
true,
target.is_some(),
Some(intrinsic),
target,
);
let dest = match ret_dest {
_ if fn_abi.ret.is_indirect() => llargs[0],
@ -873,7 +879,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
// The indices passed to simd_shuffle in the
// third argument must be constant. This is
// checked by the type-checker.
if i == 2 && intrinsic == sym::simd_shuffle {
if i == 2 && intrinsic.name == sym::simd_shuffle {
if let mir::Operand::Constant(constant) = &arg.node {
let (llval, ty) = self.simd_shuffle_indices(bx, constant);
return OperandRef {
@ -903,14 +909,33 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
MergingSucc::False
};
}
Err(instance) => Some(instance),
Err(instance) => {
if intrinsic.must_be_overridden {
span_bug!(
span,
"intrinsic {} must be overridden by codegen backend, but isn't",
intrinsic.name,
);
}
Some(instance)
}
}
}
};
let mut llargs = Vec::with_capacity(arg_count);
let destination = target.as_ref().map(|&target| {
(self.make_return_dest(bx, destination, &fn_abi.ret, &mut llargs, false, true), target)
(
self.make_return_dest(
bx,
destination,
&fn_abi.ret,
&mut llargs,
None,
Some(target),
),
target,
)
});
// Split the rust-call tupled arguments off.
@ -1643,10 +1668,10 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
dest: mir::Place<'tcx>,
fn_ret: &ArgAbi<'tcx, Ty<'tcx>>,
llargs: &mut Vec<Bx::Value>,
is_intrinsic: bool,
has_target: bool,
intrinsic: Option<ty::IntrinsicDef>,
target: Option<BasicBlock>,
) -> ReturnDest<'tcx, Bx::Value> {
if !has_target {
if target.is_none() {
return ReturnDest::Nothing;
}
// If the return is ignored, we can just return a do-nothing `ReturnDest`.
@ -1667,7 +1692,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
tmp.storage_live(bx);
llargs.push(tmp.llval);
ReturnDest::IndirectOperand(tmp, index)
} else if is_intrinsic {
} else if intrinsic.is_some() {
// Currently, intrinsics always need a location to store
// the result, so we create a temporary `alloca` for the
// result.