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Rollup merge of #119365 - nbdd0121:asm-goto, r=Amanieu

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Add asm goto support to `asm!`

Tracking issue: #119364

This PR implements asm-goto support, using the syntax described in "future possibilities" section of [RFC2873](https://rust-lang.github.io/rfcs/2873-inline-asm.html#asm-goto).

Currently I have only implemented the `label` part, not the `fallthrough` part (i.e. fallthrough is implicit). This doesn't reduce the expressive though, since you can use label-break to get arbitrary control flow or simply set a value and rely on jump threading optimisation to get the desired control flow. I can add that later if deemed necessary.

r? ``@Amanieu``
cc ``@ojeda``
This commit is contained in:
Matthias Krüger 2024-03-08 08:19:17 +01:00 • committed by GitHub
commit d774fbea7c
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76 changed files with 857 additions and 200 deletions
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6
compiler/rustc_const_eval/src/interpret/machine.rs
View file

@ -374,11 +374,17 @@ pub trait Machine<'mir, 'tcx: 'mir>: Sized {
kind: Option<MemoryKind<Self::MemoryKind>>,
) -> InterpResult<'tcx, Cow<'b, Allocation<Self::Provenance, Self::AllocExtra, Self::Bytes>>>;
/// Evaluate the inline assembly.
///
/// This should take care of jumping to the next block (one of `targets`) when asm goto
/// is triggered, `targets[0]` when the assembly falls through, or diverge in case of
/// `InlineAsmOptions::NORETURN` being set.
fn eval_inline_asm(
_ecx: &mut InterpCx<'mir, 'tcx, Self>,
_template: &'tcx [InlineAsmTemplatePiece],
_operands: &[mir::InlineAsmOperand<'tcx>],
_options: InlineAsmOptions,
_targets: &[mir::BasicBlock],
) -> InterpResult<'tcx> {
throw_unsup_format!("inline assembly is not supported")
}

12
compiler/rustc_const_eval/src/interpret/terminator.rs
View file

@ -1,6 +1,5 @@
use std::borrow::Cow;
use rustc_ast::ast::InlineAsmOptions;
use rustc_middle::{
mir,
ty::{
@ -224,15 +223,8 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
terminator.kind
),
InlineAsm { template, ref operands, options, destination, .. } => {
M::eval_inline_asm(self, template, operands, options)?;
if options.contains(InlineAsmOptions::NORETURN) {
throw_ub_custom!(fluent::const_eval_noreturn_asm_returned);
}
self.go_to_block(
destination
.expect("InlineAsm terminators without noreturn must have a destination"),
)
InlineAsm { template, ref operands, options, ref targets, .. } => {
M::eval_inline_asm(self, template, operands, options, targets)?;
}
}

6
compiler/rustc_const_eval/src/transform/validate.rs
View file

@ -471,9 +471,9 @@ impl<'a, 'tcx> Visitor<'tcx> for CfgChecker<'a, 'tcx> {
self.check_edge(location, *real_target, EdgeKind::Normal);
self.check_unwind_edge(location, *unwind);
}
TerminatorKind::InlineAsm { destination, unwind, .. } => {
if let Some(destination) = destination {
self.check_edge(location, *destination, EdgeKind::Normal);
TerminatorKind::InlineAsm { targets, unwind, .. } => {
for &target in targets {
self.check_edge(location, target, EdgeKind::Normal);
}
self.check_unwind_edge(location, *unwind);
}