From c8c6598f17128b3ac1ec3573dc54876d24cc7a77 Mon Sep 17 00:00:00 2001 From: "Celina G. Val" Date: Wed, 12 Jun 2024 16:01:38 -0700 Subject: [PATCH] Unify intrinsics body handling in StableMIR rust-lang/rust#120675 introduced a new mechanism to declare intrinsics which will potentially replace the rust-intrinsic ABI. The new mechanism introduces a placeholder body and mark the intrinsic with #[rustc_intrinsic_must_be_overridden]. In practice, this means that backends should not generate code for the placeholder, and shim the intrinsic. The new annotation is an internal compiler implementation, and it doesn't need to be exposed to StableMIR users. In this PR, intrinsics marked with `rustc_intrinsic_must_be_overridden` are handled the same way as intrinsics that do not have a body. --- compiler/rustc_smir/src/rustc_smir/context.rs | 16 +++++--------- compiler/rustc_smir/src/rustc_smir/mod.rs | 21 +++++++++++++++++-- compiler/stable_mir/src/compiler_interface.rs | 4 ---- compiler/stable_mir/src/ty.rs | 7 ++++++- .../stable-mir/check_intrinsics.rs | 19 ++++++++++------- 5 files changed, 42 insertions(+), 25 deletions(-) diff --git a/compiler/rustc_smir/src/rustc_smir/context.rs b/compiler/rustc_smir/src/rustc_smir/context.rs index a8688c88601c5..64174981b79a3 100644 --- a/compiler/rustc_smir/src/rustc_smir/context.rs +++ b/compiler/rustc_smir/src/rustc_smir/context.rs @@ -63,9 +63,10 @@ impl<'tcx> Context for TablesWrapper<'tcx> { } fn has_body(&self, def: DefId) -> bool { - let tables = self.0.borrow(); - let def_id = tables[def]; - tables.tcx.is_mir_available(def_id) + let mut tables = self.0.borrow_mut(); + let tcx = tables.tcx; + let def_id = def.internal(&mut *tables, tcx); + tables.item_has_body(def_id) } fn foreign_modules(&self, crate_num: CrateNum) -> Vec { @@ -322,13 +323,6 @@ impl<'tcx> Context for TablesWrapper<'tcx> { tcx.intrinsic(def_id).unwrap().name.to_string() } - fn intrinsic_must_be_overridden(&self, def: IntrinsicDef) -> bool { - let mut tables = self.0.borrow_mut(); - let tcx = tables.tcx; - let def_id = def.0.internal(&mut *tables, tcx); - tcx.intrinsic_raw(def_id).unwrap().must_be_overridden - } - fn closure_sig(&self, args: &GenericArgs) -> PolyFnSig { let mut tables = self.0.borrow_mut(); let tcx = tables.tcx; @@ -515,7 +509,7 @@ impl<'tcx> Context for TablesWrapper<'tcx> { let mut tables = self.0.borrow_mut(); let instance = tables.instances[def]; tables - .has_body(instance) + .instance_has_body(instance) .then(|| BodyBuilder::new(tables.tcx, instance).build(&mut *tables)) } diff --git a/compiler/rustc_smir/src/rustc_smir/mod.rs b/compiler/rustc_smir/src/rustc_smir/mod.rs index d13e780332632..89f9adfcfd663 100644 --- a/compiler/rustc_smir/src/rustc_smir/mod.rs +++ b/compiler/rustc_smir/src/rustc_smir/mod.rs @@ -51,9 +51,13 @@ impl<'tcx> Tables<'tcx> { self.mir_consts.create_or_fetch(constant) } - pub(crate) fn has_body(&self, instance: Instance<'tcx>) -> bool { + /// Return whether the instance as a body available. + /// + /// Items and intrinsics may have a body available from its definition. + /// Shims body may be generated depending on their type. + pub(crate) fn instance_has_body(&self, instance: Instance<'tcx>) -> bool { let def_id = instance.def_id(); - self.tcx.is_mir_available(def_id) + self.item_has_body(def_id) || !matches!( instance.def, ty::InstanceDef::Virtual(..) @@ -61,6 +65,19 @@ impl<'tcx> Tables<'tcx> { | ty::InstanceDef::Item(..) ) } + + /// Return whether the item has a body defined by the user. + /// + /// Note that intrinsics may have a placeholder body that shouldn't be used in practice. + /// In StableMIR, we handle this case as if the body is not available. + pub(crate) fn item_has_body(&self, def_id: DefId) -> bool { + let must_override = if let Some(intrinsic) = self.tcx.intrinsic(def_id) { + intrinsic.must_be_overridden + } else { + false + }; + !must_override && self.tcx.is_mir_available(def_id) + } } /// Build a stable mir crate from a given crate number. diff --git a/compiler/stable_mir/src/compiler_interface.rs b/compiler/stable_mir/src/compiler_interface.rs index 085dfd9ea8909..3e138e3c2e04e 100644 --- a/compiler/stable_mir/src/compiler_interface.rs +++ b/compiler/stable_mir/src/compiler_interface.rs @@ -94,10 +94,6 @@ pub trait Context { /// Retrieve the plain function name of an intrinsic. fn intrinsic_name(&self, def: IntrinsicDef) -> Symbol; - /// Returns whether the intrinsic has no meaningful body and all backends - /// need to shim all calls to it. - fn intrinsic_must_be_overridden(&self, def: IntrinsicDef) -> bool; - /// Retrieve the closure signature for the given generic arguments. fn closure_sig(&self, args: &GenericArgs) -> PolyFnSig; diff --git a/compiler/stable_mir/src/ty.rs b/compiler/stable_mir/src/ty.rs index bcbe87f7303b3..cdf1b0641ff3f 100644 --- a/compiler/stable_mir/src/ty.rs +++ b/compiler/stable_mir/src/ty.rs @@ -658,6 +658,11 @@ impl FnDef { with(|ctx| ctx.has_body(self.0).then(|| ctx.mir_body(self.0))) } + // Check if the function body is available. + pub fn has_body(&self) -> bool { + with(|ctx| ctx.has_body(self.0)) + } + /// Get the information of the intrinsic if this function is a definition of one. pub fn as_intrinsic(&self) -> Option { with(|cx| cx.intrinsic(self.def_id())) @@ -684,7 +689,7 @@ impl IntrinsicDef { /// Returns whether the intrinsic has no meaningful body and all backends /// need to shim all calls to it. pub fn must_be_overridden(&self) -> bool { - with(|cx| cx.intrinsic_must_be_overridden(*self)) + with(|cx| !cx.has_body(self.0)) } } diff --git a/tests/ui-fulldeps/stable-mir/check_intrinsics.rs b/tests/ui-fulldeps/stable-mir/check_intrinsics.rs index 7e247ce0c75d2..d7f37f36681bd 100644 --- a/tests/ui-fulldeps/stable-mir/check_intrinsics.rs +++ b/tests/ui-fulldeps/stable-mir/check_intrinsics.rs @@ -55,16 +55,19 @@ fn test_intrinsics() -> ControlFlow<()> { /// /// If by any chance this test breaks because you changed how an intrinsic is implemented, please /// update the test to invoke a different intrinsic. +/// +/// In StableMIR, we only expose intrinsic body if they are not marked with +/// `rustc_intrinsic_must_be_overridden`. fn check_instance(instance: &Instance) { assert_eq!(instance.kind, InstanceKind::Intrinsic); let name = instance.intrinsic_name().unwrap(); if instance.has_body() { let Some(body) = instance.body() else { unreachable!("Expected a body") }; assert!(!body.blocks.is_empty()); - assert_matches!(name.as_str(), "likely" | "vtable_size"); + assert_eq!(&name, "likely"); } else { assert!(instance.body().is_none()); - assert_eq!(&name, "size_of_val"); + assert_matches!(name.as_str(), "size_of_val" | "vtable_size"); } } @@ -75,11 +78,13 @@ fn check_def(fn_def: FnDef) { let name = intrinsic.fn_name(); match name.as_str() { - "likely" | "size_of_val" => { + "likely" => { assert!(!intrinsic.must_be_overridden()); + assert!(fn_def.has_body()); } - "vtable_size" => { + "vtable_size" | "size_of_val" => { assert!(intrinsic.must_be_overridden()); + assert!(!fn_def.has_body()); } _ => unreachable!("Unexpected intrinsic: {}", name), } @@ -96,9 +101,9 @@ impl<'a> MirVisitor for CallsVisitor<'a> { TerminatorKind::Call { func, .. } => { let TyKind::RigidTy(RigidTy::FnDef(def, args)) = func.ty(self.locals).unwrap().kind() - else { - return; - }; + else { + return; + }; self.calls.push((def, args.clone())); } _ => {}