Auto merge of #108012 - compiler-errors:issue-107999, r=oli-obk

Don't ICE in `might_permit_raw_init` if reference is polymorphic

Emitting optimized MIR for a polymorphic function may require computing layout of a type that isn't (yet) known. This happens in the instcombine pass, for example. Let's fail gracefully in that condition.

cc `@saethlin`
fixes #107999

Author: bors

compiler/rustc_codegen_cranelift/src/intrinsics/mod.rs

@@ -640,7 +640,8 @@ fn codegen_regular_intrinsic_call<'tcx>(
         sym::assert_inhabited | sym::assert_zero_valid | sym::assert_mem_uninitialized_valid => {
             intrinsic_args!(fx, args => (); intrinsic);
 
-            let layout = fx.layout_of(substs.type_at(0));
+            let ty = substs.type_at(0);
+            let layout = fx.layout_of(ty);
             if layout.abi.is_uninhabited() {
                 with_no_trimmed_paths!({
                     crate::base::codegen_panic_nounwind(
@@ -653,7 +654,10 @@ fn codegen_regular_intrinsic_call<'tcx>(
             }
 
             if intrinsic == sym::assert_zero_valid
-                && !fx.tcx.permits_zero_init(fx.param_env().and(layout))
+                && !fx
+                    .tcx
+                    .permits_zero_init(fx.param_env().and(ty))
+                    .expect("expected to have layout during codegen")
             {
                 with_no_trimmed_paths!({
                     crate::base::codegen_panic_nounwind(
@@ -669,7 +673,10 @@ fn codegen_regular_intrinsic_call<'tcx>(
             }
 
             if intrinsic == sym::assert_mem_uninitialized_valid
-                && !fx.tcx.permits_uninit_init(fx.param_env().and(layout))
+                && !fx
+                    .tcx
+                    .permits_uninit_init(fx.param_env().and(ty))
+                    .expect("expected to have layout during codegen")
             {
                 with_no_trimmed_paths!({
                     crate::base::codegen_panic_nounwind(

compiler/rustc_codegen_ssa/src/mir/block.rs

@@ -674,8 +674,14 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
             let layout = bx.layout_of(ty);
             let do_panic = match intrinsic {
                 Inhabited => layout.abi.is_uninhabited(),
-                ZeroValid => !bx.tcx().permits_zero_init(bx.param_env().and(layout)),
-                MemUninitializedValid => !bx.tcx().permits_uninit_init(bx.param_env().and(layout)),
+                ZeroValid => !bx
+                    .tcx()
+                    .permits_zero_init(bx.param_env().and(ty))
+                    .expect("expected to have layout during codegen"),
+                MemUninitializedValid => !bx
+                    .tcx()
+                    .permits_uninit_init(bx.param_env().and(ty))
+                    .expect("expected to have layout during codegen"),
             };
             Some(if do_panic {
                 let msg_str = with_no_visible_paths!({

compiler/rustc_const_eval/src/interpret/intrinsics.rs

@@ -448,7 +448,10 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 }
 
                 if intrinsic_name == sym::assert_zero_valid {
-                    let should_panic = !self.tcx.permits_zero_init(self.param_env.and(layout));
+                    let should_panic = !self
+                        .tcx
+                        .permits_zero_init(self.param_env.and(ty))
+                        .map_err(|_| err_inval!(TooGeneric))?;
 
                     if should_panic {
                         M::abort(
@@ -462,7 +465,10 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 }
 
                 if intrinsic_name == sym::assert_mem_uninitialized_valid {
-                    let should_panic = !self.tcx.permits_uninit_init(self.param_env.and(layout));
+                    let should_panic = !self
+                        .tcx
+                        .permits_uninit_init(self.param_env.and(ty))
+                        .map_err(|_| err_inval!(TooGeneric))?;
 
                     if should_panic {
                         M::abort(

compiler/rustc_const_eval/src/lib.rs

@@ -59,11 +59,8 @@ pub fn provide(providers: &mut Providers) {
         const_eval::deref_mir_constant(tcx, param_env, value)
     };
     providers.permits_uninit_init = |tcx, param_env_and_ty| {
-        let (param_env, ty) = param_env_and_ty.into_parts();
-        util::might_permit_raw_init(tcx, param_env, ty, InitKind::UninitMitigated0x01Fill)
-    };
-    providers.permits_zero_init = |tcx, param_env_and_ty| {
-        let (param_env, ty) = param_env_and_ty.into_parts();
-        util::might_permit_raw_init(tcx, param_env, ty, InitKind::Zero)
+        util::might_permit_raw_init(tcx, param_env_and_ty, InitKind::UninitMitigated0x01Fill)
     };
+    providers.permits_zero_init =
+        |tcx, param_env_and_ty| util::might_permit_raw_init(tcx, param_env_and_ty, InitKind::Zero);
 }

compiler/rustc_const_eval/src/util/might_permit_raw_init.rs

@@ -1,5 +1,5 @@
-use rustc_middle::ty::layout::{LayoutCx, LayoutOf, TyAndLayout};
-use rustc_middle::ty::{ParamEnv, TyCtxt};
+use rustc_middle::ty::layout::{LayoutCx, LayoutError, LayoutOf, TyAndLayout};
+use rustc_middle::ty::{ParamEnv, ParamEnvAnd, Ty, TyCtxt};
 use rustc_session::Limit;
 use rustc_target::abi::{Abi, FieldsShape, InitKind, Scalar, Variants};
 
@@ -20,15 +20,14 @@ use crate::interpret::{InterpCx, MemoryKind, OpTy};
 /// to the full uninit check).
 pub fn might_permit_raw_init<'tcx>(
     tcx: TyCtxt<'tcx>,
-    param_env: ParamEnv<'tcx>,
-    ty: TyAndLayout<'tcx>,
+    param_env_and_ty: ParamEnvAnd<'tcx, Ty<'tcx>>,
     kind: InitKind,
-) -> bool {
+) -> Result<bool, LayoutError<'tcx>> {
     if tcx.sess.opts.unstable_opts.strict_init_checks {
-        might_permit_raw_init_strict(ty, tcx, kind)
+        might_permit_raw_init_strict(tcx.layout_of(param_env_and_ty)?, tcx, kind)
     } else {
-        let layout_cx = LayoutCx { tcx, param_env };
-        might_permit_raw_init_lax(ty, &layout_cx, kind)
+        let layout_cx = LayoutCx { tcx, param_env: param_env_and_ty.param_env };
+        might_permit_raw_init_lax(tcx.layout_of(param_env_and_ty)?, &layout_cx, kind)
     }
 }
 
@@ -38,7 +37,7 @@ fn might_permit_raw_init_strict<'tcx>(
     ty: TyAndLayout<'tcx>,
     tcx: TyCtxt<'tcx>,
     kind: InitKind,
-) -> bool {
+) -> Result<bool, LayoutError<'tcx>> {
     let machine = CompileTimeInterpreter::new(
         Limit::new(0),
         /*can_access_statics:*/ false,
@@ -65,7 +64,7 @@ fn might_permit_raw_init_strict<'tcx>(
     // This does *not* actually check that references are dereferenceable, but since all types that
     // require dereferenceability also require non-null, we don't actually get any false negatives
     // due to this.
-    cx.validate_operand(&ot).is_ok()
+    Ok(cx.validate_operand(&ot).is_ok())
 }
 
 /// Implements the 'lax' (default) version of the `might_permit_raw_init` checks; see that function for
@@ -74,7 +73,7 @@ fn might_permit_raw_init_lax<'tcx>(
     this: TyAndLayout<'tcx>,
     cx: &LayoutCx<'tcx, TyCtxt<'tcx>>,
     init_kind: InitKind,
-) -> bool {
+) -> Result<bool, LayoutError<'tcx>> {
     let scalar_allows_raw_init = move |s: Scalar| -> bool {
         match init_kind {
             InitKind::Zero => {
@@ -103,20 +102,20 @@ fn might_permit_raw_init_lax<'tcx>(
     };
     if !valid {
         // This is definitely not okay.
-        return false;
+        return Ok(false);
     }
 
     // Special magic check for references and boxes (i.e., special pointer types).
     if let Some(pointee) = this.ty.builtin_deref(false) {
-        let pointee = cx.layout_of(pointee.ty).expect("need to be able to compute layouts");
+        let pointee = cx.layout_of(pointee.ty)?;
         // We need to ensure that the LLVM attributes `aligned` and `dereferenceable(size)` are satisfied.
         if pointee.align.abi.bytes() > 1 {
             // 0x01-filling is not aligned.
-            return false;
+            return Ok(false);
         }
         if pointee.size.bytes() > 0 {
             // A 'fake' integer pointer is not sufficiently dereferenceable.
-            return false;
+            return Ok(false);
         }
     }
 
@@ -129,9 +128,9 @@ fn might_permit_raw_init_lax<'tcx>(
         }
         FieldsShape::Arbitrary { offsets, .. } => {
             for idx in 0..offsets.len() {
-                if !might_permit_raw_init_lax(this.field(cx, idx), cx, init_kind) {
+                if !might_permit_raw_init_lax(this.field(cx, idx), cx, init_kind)? {
                     // We found a field that is unhappy with this kind of initialization.
-                    return false;
+                    return Ok(false);
                 }
             }
         }
@@ -148,5 +147,5 @@ fn might_permit_raw_init_lax<'tcx>(
         }
     }
 
-    true
+    Ok(true)
 }

compiler/rustc_middle/src/query/mod.rs

@@ -2143,12 +2143,12 @@ rustc_queries! {
         separate_provide_extern
     }
 
-    query permits_uninit_init(key: ty::ParamEnvAnd<'tcx, TyAndLayout<'tcx>>) -> bool {
-        desc { "checking to see if `{}` permits being left uninit", key.value.ty }
+    query permits_uninit_init(key: ty::ParamEnvAnd<'tcx, Ty<'tcx>>) -> Result<bool, ty::layout::LayoutError<'tcx>> {
+        desc { "checking to see if `{}` permits being left uninit", key.value }
     }
 
-    query permits_zero_init(key: ty::ParamEnvAnd<'tcx, TyAndLayout<'tcx>>) -> bool {
-        desc { "checking to see if `{}` permits being left zeroed", key.value.ty }
+    query permits_zero_init(key: ty::ParamEnvAnd<'tcx, Ty<'tcx>>) -> Result<bool, ty::layout::LayoutError<'tcx>> {
+        desc { "checking to see if `{}` permits being left zeroed", key.value }
     }
 
     query compare_impl_const(

compiler/rustc_middle/src/ty/query.rs

@@ -30,7 +30,6 @@ use crate::traits::specialization_graph;
 use crate::traits::{self, ImplSource};
 use crate::ty::context::TyCtxtFeed;
 use crate::ty::fast_reject::SimplifiedType;
-use crate::ty::layout::TyAndLayout;
 use crate::ty::subst::{GenericArg, SubstsRef};
 use crate::ty::util::AlwaysRequiresDrop;
 use crate::ty::GeneratorDiagnosticData;

compiler/rustc_mir_transform/src/instcombine.rs

@@ -6,7 +6,8 @@ use rustc_middle::mir::{
     BinOp, Body, Constant, ConstantKind, LocalDecls, Operand, Place, ProjectionElem, Rvalue,
     SourceInfo, Statement, StatementKind, Terminator, TerminatorKind, UnOp,
 };
-use rustc_middle::ty::{self, layout::TyAndLayout, ParamEnv, ParamEnvAnd, SubstsRef, Ty, TyCtxt};
+use rustc_middle::ty::layout::LayoutError;
+use rustc_middle::ty::{self, ParamEnv, ParamEnvAnd, SubstsRef, Ty, TyCtxt};
 use rustc_span::symbol::{sym, Symbol};
 
 pub struct InstCombine;
@@ -230,38 +231,41 @@ impl<'tcx> InstCombineContext<'tcx, '_> {
 
         // Check this is a foldable intrinsic before we query the layout of our generic parameter
         let Some(assert_panics) = intrinsic_assert_panics(intrinsic_name) else { return; };
-        let Ok(layout) = self.tcx.layout_of(self.param_env.and(ty)) else { return; };
-        if assert_panics(self.tcx, self.param_env.and(layout)) {
-            // If we know the assert panics, indicate to later opts that the call diverges
-            *target = None;
-        } else {
-            // If we know the assert does not panic, turn the call into a Goto
-            terminator.kind = TerminatorKind::Goto { target: *target_block };
+        match assert_panics(self.tcx, self.param_env.and(ty)) {
+            // We don't know the layout, don't touch the assertion
+            Err(_) => {}
+            Ok(true) => {
+                // If we know the assert panics, indicate to later opts that the call diverges
+                *target = None;
+            }
+            Ok(false) => {
+                // If we know the assert does not panic, turn the call into a Goto
+                terminator.kind = TerminatorKind::Goto { target: *target_block };
+            }
         }
     }
 }
 
 fn intrinsic_assert_panics<'tcx>(
     intrinsic_name: Symbol,
-) -> Option<fn(TyCtxt<'tcx>, ParamEnvAnd<'tcx, TyAndLayout<'tcx>>) -> bool> {
+) -> Option<fn(TyCtxt<'tcx>, ParamEnvAnd<'tcx, Ty<'tcx>>) -> Result<bool, LayoutError<'tcx>>> {
     fn inhabited_predicate<'tcx>(
-        _tcx: TyCtxt<'tcx>,
-        param_env_and_layout: ParamEnvAnd<'tcx, TyAndLayout<'tcx>>,
-    ) -> bool {
-        let (_param_env, layout) = param_env_and_layout.into_parts();
-        layout.abi.is_uninhabited()
+        tcx: TyCtxt<'tcx>,
+        param_env_and_ty: ParamEnvAnd<'tcx, Ty<'tcx>>,
+    ) -> Result<bool, LayoutError<'tcx>> {
+        Ok(tcx.layout_of(param_env_and_ty)?.abi.is_uninhabited())
     }
     fn zero_valid_predicate<'tcx>(
         tcx: TyCtxt<'tcx>,
-        param_env_and_layout: ParamEnvAnd<'tcx, TyAndLayout<'tcx>>,
-    ) -> bool {
-        !tcx.permits_zero_init(param_env_and_layout)
+        param_env_and_ty: ParamEnvAnd<'tcx, Ty<'tcx>>,
+    ) -> Result<bool, LayoutError<'tcx>> {
+        Ok(!tcx.permits_zero_init(param_env_and_ty)?)
     }
     fn mem_uninitialized_valid_predicate<'tcx>(
         tcx: TyCtxt<'tcx>,
-        param_env_and_layout: ParamEnvAnd<'tcx, TyAndLayout<'tcx>>,
-    ) -> bool {
-        !tcx.permits_uninit_init(param_env_and_layout)
+        param_env_and_ty: ParamEnvAnd<'tcx, Ty<'tcx>>,
+    ) -> Result<bool, LayoutError<'tcx>> {
+        Ok(!tcx.permits_uninit_init(param_env_and_ty)?)
     }
 
     match intrinsic_name {

tests/mir-opt/dont_yeet_assert.generic.InstCombine.diff

@@ -0,0 +1,23 @@
+- // MIR for `generic` before InstCombine
++ // MIR for `generic` after InstCombine
+  
+  fn generic() -> () {
+      let mut _0: ();                      // return place in scope 0 at $DIR/dont_yeet_assert.rs:+0:21: +0:21
+      let _1: ();                          // in scope 0 at $DIR/dont_yeet_assert.rs:+1:5: +1:61
+  
+      bb0: {
+          StorageLive(_1);                 // scope 0 at $DIR/dont_yeet_assert.rs:+1:5: +1:61
+          _1 = assert_mem_uninitialized_valid::<&T>() -> bb1; // scope 0 at $DIR/dont_yeet_assert.rs:+1:5: +1:61
+                                           // mir::Constant
+                                           // + span: $DIR/dont_yeet_assert.rs:10:5: 10:59
+                                           // + user_ty: UserType(0)
+                                           // + literal: Const { ty: extern "rust-intrinsic" fn() {assert_mem_uninitialized_valid::<&T>}, val: Value(<ZST>) }
+      }
+  
+      bb1: {
+          StorageDead(_1);                 // scope 0 at $DIR/dont_yeet_assert.rs:+1:61: +1:62
+          _0 = const ();                   // scope 0 at $DIR/dont_yeet_assert.rs:+0:21: +2:2
+          return;                          // scope 0 at $DIR/dont_yeet_assert.rs:+2:2: +2:2
+      }
+  }
+  

tests/mir-opt/dont_yeet_assert.rs

@@ -0,0 +1,11 @@
+// compile-flags: --crate-type=lib
+// unit-test: InstCombine
+
+#![feature(core_intrinsics)]
+
+// Want to make sure this assertion isn't compiled away in generic code.
+
+// EMIT_MIR dont_yeet_assert.generic.InstCombine.diff
+pub fn generic<T>() {
+    core::intrinsics::assert_mem_uninitialized_valid::<&T>();
+}