From 57d6a6f5889cc26edba024675b5af017b8c4a8b0 Mon Sep 17 00:00:00 2001 From: Oli Scherer Date: Mon, 10 Jul 2023 14:26:24 +0000 Subject: [PATCH] Only call `mir_const_qualif` if absolutely necessary --- compiler/rustc_mir_transform/src/lib.rs | 26 ++++++++++++++++++++++--- 1 file changed, 23 insertions(+), 3 deletions(-) diff --git a/compiler/rustc_mir_transform/src/lib.rs b/compiler/rustc_mir_transform/src/lib.rs index 9aaa54110bdfe..68b8911824c2e 100644 --- a/compiler/rustc_mir_transform/src/lib.rs +++ b/compiler/rustc_mir_transform/src/lib.rs @@ -20,6 +20,7 @@ extern crate tracing; #[macro_use] extern crate rustc_middle; +use hir::ConstContext; use required_consts::RequiredConstsVisitor; use rustc_const_eval::util; use rustc_data_structures::fx::FxIndexSet; @@ -251,8 +252,13 @@ fn mir_const_qualif(tcx: TyCtxt<'_>, def: LocalDefId) -> ConstQualifs { let const_kind = tcx.hir().body_const_context(def); // No need to const-check a non-const `fn`. - if const_kind.is_none() { - return Default::default(); + match const_kind { + Some(ConstContext::Const { .. } | ConstContext::Static(_)) + | Some(ConstContext::ConstFn) => {} + None => span_bug!( + tcx.def_span(def), + "`mir_const_qualif` should only be called on const fns and const items" + ), } // N.B., this `borrow()` is guaranteed to be valid (i.e., the value @@ -317,7 +323,21 @@ fn mir_promoted( // Ensure that we compute the `mir_const_qualif` for constants at // this point, before we steal the mir-const result. // Also this means promotion can rely on all const checks having been done. - let const_qualifs = tcx.mir_const_qualif(def); + + let const_qualifs = match tcx.def_kind(def) { + DefKind::Fn | DefKind::AssocFn | DefKind::Closure + if tcx.constness(def) == hir::Constness::Const + || tcx.is_const_default_method(def.to_def_id()) => + { + tcx.mir_const_qualif(def) + } + DefKind::AssocConst + | DefKind::Const + | DefKind::Static(_) + | DefKind::InlineConst + | DefKind::AnonConst => tcx.mir_const_qualif(def), + _ => ConstQualifs::default(), + }; let mut body = tcx.mir_const(def).steal(); if let Some(error_reported) = const_qualifs.tainted_by_errors { body.tainted_by_errors = Some(error_reported);