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Auto merge of #123444 - saethlin:const-eval-inline-cycles, r=tmiasko
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Teach MIR inliner query cycle avoidance about const_eval_select

Fixes #122659

r? tmiasko
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bors committed Apr 5, 2024
2 parents 3d7e881 + b0b7c86 commit c0ddaef
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Showing 2 changed files with 32 additions and 4 deletions.
18 changes: 14 additions & 4 deletions compiler/rustc_mir_transform/src/inline/cycle.rs
Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,7 @@ use rustc_middle::mir::TerminatorKind;
use rustc_middle::ty::TypeVisitableExt;
use rustc_middle::ty::{self, GenericArgsRef, InstanceDef, TyCtxt};
use rustc_session::Limit;
use rustc_span::sym;

// FIXME: check whether it is cheaper to precompute the entire call graph instead of invoking
// this query ridiculously often.
Expand Down Expand Up @@ -164,11 +165,20 @@ pub(crate) fn mir_inliner_callees<'tcx>(
let mut calls = FxIndexSet::default();
for bb_data in body.basic_blocks.iter() {
let terminator = bb_data.terminator();
if let TerminatorKind::Call { func, .. } = &terminator.kind {
if let TerminatorKind::Call { func, args: call_args, .. } = &terminator.kind {
let ty = func.ty(&body.local_decls, tcx);
let call = match ty.kind() {
ty::FnDef(def_id, args) => (*def_id, *args),
_ => continue,
let ty::FnDef(def_id, generic_args) = ty.kind() else {
continue;
};
let call = if tcx.is_intrinsic(*def_id, sym::const_eval_select) {
let func = &call_args[2].node;
let ty = func.ty(&body.local_decls, tcx);
let ty::FnDef(def_id, generic_args) = ty.kind() else {
continue;
};
(*def_id, *generic_args)
} else {
(*def_id, *generic_args)
};
calls.insert(call);
}
Expand Down
18 changes: 18 additions & 0 deletions tests/ui/mir/const_eval_select_cycle.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,18 @@
// Regression test for #122659
//@ build-pass
//@ compile-flags: -O --crate-type=lib

#![feature(core_intrinsics)]
#![feature(const_eval_select)]

use std::intrinsics::const_eval_select;

#[inline]
pub const fn f() {
const_eval_select((), g, g)
}

#[inline]
pub const fn g() {
const_eval_select((), f, f)
}

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