Auto merge of #52597 - oli-obk:promotion_simplify, r=nagisa

Promoteds are statics and statics have a place, not just a value

r? @eddyb

This makes everything around promoteds a little simpler

src/librustc/ich/impls_mir.rs

@@ -302,6 +302,9 @@ impl<'a, 'gcx> HashStable<StableHashingContext<'a>> for mir::Place<'gcx> {
             mir::Place::Static(ref statik) => {
                 statik.hash_stable(hcx, hasher);
             }
+            mir::Place::Promoted(ref promoted) => {
+                promoted.hash_stable(hcx, hasher);
+            }
             mir::Place::Projection(ref place_projection) => {
                 place_projection.hash_stable(hcx, hasher);
             }
@@ -527,22 +530,6 @@ impl_stable_hash_for!(enum mir::NullOp {
 
 impl_stable_hash_for!(struct mir::Constant<'tcx> { span, ty, literal });
 
-impl<'a, 'gcx> HashStable<StableHashingContext<'a>> for mir::Literal<'gcx> {
-    fn hash_stable<W: StableHasherResult>(&self,
-                                          hcx: &mut StableHashingContext<'a>,
-                                          hasher: &mut StableHasher<W>) {
-        mem::discriminant(self).hash_stable(hcx, hasher);
-        match *self {
-            mir::Literal::Value { ref value } => {
-                value.hash_stable(hcx, hasher);
-            }
-            mir::Literal::Promoted { index } => {
-                index.hash_stable(hcx, hasher);
-            }
-        }
-    }
-}
-
 impl_stable_hash_for!(struct mir::Location { block, statement_index });
 
 impl_stable_hash_for!(struct mir::BorrowCheckResult<'tcx> {

src/librustc/mir/mod.rs

@@ -1701,6 +1701,9 @@ pub enum Place<'tcx> {
     /// static or static mut variable
     Static(Box<Static<'tcx>>),
 
+    /// Constant code promoted to an injected static
+    Promoted(Box<(Promoted, Ty<'tcx>)>),
+
     /// projection out of a place (access a field, deref a pointer, etc)
     Projection(Box<PlaceProjection<'tcx>>),
 }
@@ -1810,6 +1813,7 @@ impl<'tcx> Debug for Place<'tcx> {
                 ty::tls::with(|tcx| tcx.item_path_str(def_id)),
                 ty
             ),
+            Promoted(ref promoted) => write!(fmt, "({:?}: {:?})", promoted.0, promoted.1),
             Projection(ref data) => match data.elem {
                 ProjectionElem::Downcast(ref adt_def, index) => {
                     write!(fmt, "({:?} as {})", data.base, adt_def.variants[index].name)
@@ -1910,9 +1914,7 @@ impl<'tcx> Operand<'tcx> {
         Operand::Constant(box Constant {
             span,
             ty,
-            literal: Literal::Value {
-                value: ty::Const::zero_sized(tcx, ty),
-            },
+            literal: ty::Const::zero_sized(tcx, ty),
         })
     }
 
@@ -2200,38 +2202,15 @@ impl<'tcx> Debug for Rvalue<'tcx> {
 pub struct Constant<'tcx> {
     pub span: Span,
     pub ty: Ty<'tcx>,
-    pub literal: Literal<'tcx>,
+    pub literal: &'tcx ty::Const<'tcx>,
 }
 
 newtype_index!(Promoted { DEBUG_FORMAT = "promoted[{}]" });
 
-#[derive(Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
-pub enum Literal<'tcx> {
-    Value {
-        value: &'tcx ty::Const<'tcx>,
-    },
-    Promoted {
-        // Index into the `promoted` vector of `Mir`.
-        index: Promoted,
-    },
-}
-
 impl<'tcx> Debug for Constant<'tcx> {
     fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
-        write!(fmt, "{:?}", self.literal)
-    }
-}
-
-impl<'tcx> Debug for Literal<'tcx> {
-    fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
-        use self::Literal::*;
-        match *self {
-            Value { value } => {
-                write!(fmt, "const ")?;
-                fmt_const_val(fmt, value)
-            }
-            Promoted { index } => write!(fmt, "{:?}", index),
-        }
+        write!(fmt, "const ")?;
+        fmt_const_val(fmt, self.literal)
     }
 }
 
@@ -2918,20 +2897,3 @@ impl<'tcx> TypeFoldable<'tcx> for Constant<'tcx> {
         self.ty.visit_with(visitor) || self.literal.visit_with(visitor)
     }
 }
-
-impl<'tcx> TypeFoldable<'tcx> for Literal<'tcx> {
-    fn super_fold_with<'gcx: 'tcx, F: TypeFolder<'gcx, 'tcx>>(&self, folder: &mut F) -> Self {
-        match *self {
-            Literal::Value { value } => Literal::Value {
-                value: value.fold_with(folder),
-            },
-            Literal::Promoted { index } => Literal::Promoted { index },
-        }
-    }
-    fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
-        match *self {
-            Literal::Value { value } => value.visit_with(visitor),
-            Literal::Promoted { .. } => false,
-        }
-    }
-}

src/librustc/mir/tcx.rs

@@ -113,6 +113,7 @@ impl<'tcx> Place<'tcx> {
         match *self {
             Place::Local(index) =>
                 PlaceTy::Ty { ty: local_decls.local_decls()[index].ty },
+            Place::Promoted(ref data) => PlaceTy::Ty { ty: data.1 },
             Place::Static(ref data) =>
                 PlaceTy::Ty { ty: data.ty },
             Place::Projection(ref proj) =>

src/librustc/mir/visit.rs

@@ -191,12 +191,6 @@ macro_rules! make_mir_visitor {
                 self.super_constant(constant, location);
             }
 
-            fn visit_literal(&mut self,
-                             literal: & $($mutability)* Literal<'tcx>,
-                             location: Location) {
-                self.super_literal(literal, location);
-            }
-
             fn visit_def_id(&mut self,
                             def_id: & $($mutability)* DefId,
                             _: Location) {
@@ -648,6 +642,9 @@ macro_rules! make_mir_visitor {
                     Place::Static(ref $($mutability)* static_) => {
                         self.visit_static(static_, context, location);
                     }
+                    Place::Promoted(ref $($mutability)* promoted) => {
+                        self.visit_ty(& $($mutability)* promoted.1, TyContext::Location(location));
+                    },
                     Place::Projection(ref $($mutability)* proj) => {
                         self.visit_projection(proj, context, location);
                     }
@@ -748,18 +745,7 @@ macro_rules! make_mir_visitor {
 
                 self.visit_span(span);
                 self.visit_ty(ty, TyContext::Location(location));
-                self.visit_literal(literal, location);
-            }
-
-            fn super_literal(&mut self,
-                             literal: & $($mutability)* Literal<'tcx>,
-                             location: Location) {
-                match *literal {
-                    Literal::Value { ref $($mutability)* value } => {
-                        self.visit_const(value, location);
-                    }
-                    Literal::Promoted { index: _ } => {}
-                }
+                self.visit_const(literal, location);
             }
 
             fn super_def_id(&mut self, _def_id: & $($mutability)* DefId) {

src/librustc_codegen_llvm/consts.rs

@@ -242,9 +242,11 @@ pub fn get_static(cx: &CodegenCx, def_id: DefId) -> ValueRef {
     g
 }
 
-pub fn codegen_static<'a, 'tcx>(cx: &CodegenCx<'a, 'tcx>,
-                                def_id: DefId,
-                                is_mutable: bool) {
+pub fn codegen_static<'a, 'tcx>(
+    cx: &CodegenCx<'a, 'tcx>,
+    def_id: DefId,
+    is_mutable: bool,
+) {
     unsafe {
         let attrs = cx.tcx.codegen_fn_attrs(def_id);
 

src/librustc_codegen_llvm/mir/block.rs

@@ -507,14 +507,40 @@ impl<'a, 'tcx> FunctionCx<'a, 'tcx> {
                         // promotes any complex rvalues to constants.
                         if i == 2 && intrinsic.unwrap().starts_with("simd_shuffle") {
                             match *arg {
+                                // The shuffle array argument is usually not an explicit constant,
+                                // but specified directly in the code. This means it gets promoted
+                                // and we can then extract the value by evaluating the promoted.
+                                mir::Operand::Copy(mir::Place::Promoted(box(index, ty))) |
+                                mir::Operand::Move(mir::Place::Promoted(box(index, ty))) => {
+                                    let param_env = ty::ParamEnv::reveal_all();
+                                    let cid = mir::interpret::GlobalId {
+                                        instance: self.instance,
+                                        promoted: Some(index),
+                                    };
+                                    let c = bx.tcx().const_eval(param_env.and(cid));
+                                    let (llval, ty) = self.simd_shuffle_indices(
+                                        &bx,
+                                        terminator.source_info.span,
+                                        ty,
+                                        c,
+                                    );
+                                    return OperandRef {
+                                        val: Immediate(llval),
+                                        layout: bx.cx.layout_of(ty),
+                                    };
+
+                                },
                                 mir::Operand::Copy(_) |
                                 mir::Operand::Move(_) => {
                                     span_bug!(span, "shuffle indices must be constant");
                                 }
                                 mir::Operand::Constant(ref constant) => {
+                                    let c = self.eval_mir_constant(&bx, constant);
                                     let (llval, ty) = self.simd_shuffle_indices(
                                         &bx,
-                                        constant,
+                                        constant.span,
+                                        constant.ty,
+                                        c,
                                     );
                                     return OperandRef {
                                         val: Immediate(llval),

src/librustc_codegen_llvm/mir/constant.rs

@@ -25,6 +25,7 @@ use consts;
 use type_of::LayoutLlvmExt;
 use type_::Type;
 use syntax::ast::Mutability;
+use syntax::codemap::Span;
 
 use super::super::callee;
 use super::FunctionCx;
@@ -117,13 +118,12 @@ pub fn const_alloc_to_llvm(cx: &CodegenCx, alloc: &Allocation) -> ValueRef {
 
 pub fn codegen_static_initializer<'a, 'tcx>(
     cx: &CodegenCx<'a, 'tcx>,
-    def_id: DefId)
-    -> Result<(ValueRef, &'tcx Allocation), Lrc<ConstEvalErr<'tcx>>>
-{
+    def_id: DefId,
+) -> Result<(ValueRef, &'tcx Allocation), Lrc<ConstEvalErr<'tcx>>> {
     let instance = ty::Instance::mono(cx.tcx, def_id);
     let cid = GlobalId {
         instance,
-        promoted: None
+        promoted: None,
     };
     let param_env = ty::ParamEnv::reveal_all();
     let static_ = cx.tcx.const_eval(param_env.and(cid))?;
@@ -161,28 +161,19 @@ impl<'a, 'tcx> FunctionCx<'a, 'tcx> {
         bx: &Builder<'a, 'tcx>,
         constant: &mir::Constant<'tcx>,
     ) -> Result<&'tcx ty::Const<'tcx>, Lrc<ConstEvalErr<'tcx>>> {
-        match constant.literal {
-            mir::Literal::Promoted { index } => {
-                let param_env = ty::ParamEnv::reveal_all();
-                let cid = mir::interpret::GlobalId {
-                    instance: self.instance,
-                    promoted: Some(index),
-                };
-                bx.tcx().const_eval(param_env.and(cid))
-            }
-            mir::Literal::Value { value } => {
-                Ok(self.monomorphize(&value))
-            }
-        }.and_then(|c| self.fully_evaluate(bx, c))
+        let c = self.monomorphize(&constant.literal);
+        self.fully_evaluate(bx, c)
     }
 
     /// process constant containing SIMD shuffle indices
     pub fn simd_shuffle_indices(
         &mut self,
         bx: &Builder<'a, 'tcx>,
-        constant: &mir::Constant<'tcx>,
+        span: Span,
+        ty: Ty<'tcx>,
+        constant: Result<&'tcx ty::Const<'tcx>, Lrc<ConstEvalErr<'tcx>>>,
     ) -> (ValueRef, Ty<'tcx>) {
-        self.eval_mir_constant(bx, constant)
+        constant
             .and_then(|c| {
                 let field_ty = c.ty.builtin_index().unwrap();
                 let fields = match c.ty.sty {
@@ -217,11 +208,11 @@ impl<'a, 'tcx> FunctionCx<'a, 'tcx> {
             })
             .unwrap_or_else(|e| {
                 e.report_as_error(
-                    bx.tcx().at(constant.span),
+                    bx.tcx().at(span),
                     "could not evaluate shuffle_indices at compile time",
                 );
                 // We've errored, so we don't have to produce working code.
-                let ty = self.monomorphize(&constant.ty);
+                let ty = self.monomorphize(&ty);
                 let llty = bx.cx.layout_of(ty).llvm_type(bx.cx);
                 (C_undef(llty), ty)
             })

src/librustc_codegen_llvm/mir/operand.rs

@@ -8,7 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-use llvm::{ValueRef, LLVMConstInBoundsGEP};
+use llvm::ValueRef;
 use rustc::mir::interpret::ConstEvalErr;
 use rustc::mir;
 use rustc::mir::interpret::ConstValue;
@@ -22,14 +22,12 @@ use common::{CodegenCx, C_undef, C_usize};
 use builder::{Builder, MemFlags};
 use value::Value;
 use type_of::LayoutLlvmExt;
-use type_::Type;
-use consts;
 
 use std::fmt;
 use std::ptr;
 
 use super::{FunctionCx, LocalRef};
-use super::constant::{scalar_to_llvm, const_alloc_to_llvm};
+use super::constant::scalar_to_llvm;
 use super::place::PlaceRef;
 
 /// The representation of a Rust value. The enum variant is in fact
@@ -139,16 +137,7 @@ impl<'a, 'tcx> OperandRef<'tcx> {
                 OperandValue::Pair(a_llval, b_llval)
             },
             ConstValue::ByRef(alloc, offset) => {
-                let init = const_alloc_to_llvm(bx.cx, alloc);
-                let base_addr = consts::addr_of(bx.cx, init, layout.align, "byte_str");
-
-                let llval = unsafe { LLVMConstInBoundsGEP(
-                    consts::bitcast(base_addr, Type::i8p(bx.cx)),
-                    &C_usize(bx.cx, offset.bytes()),
-                    1,
-                )};
-                let llval = consts::bitcast(llval, layout.llvm_type(bx.cx).ptr_to());
-                return Ok(PlaceRef::new_sized(llval, layout, alloc.align).load(bx));
+                return Ok(PlaceRef::from_const_alloc(bx, layout, alloc, offset).load(bx));
             },
         };
 
@@ -409,20 +398,12 @@ impl<'a, 'tcx> FunctionCx<'a, 'tcx> {
                 self.eval_mir_constant(bx, constant)
                     .and_then(|c| OperandRef::from_const(bx, c))
                     .unwrap_or_else(|err| {
-                        match constant.literal {
-                            mir::Literal::Promoted { .. } => {
-                                // this is unreachable as long as runtime
-                                // and compile-time agree on values
-                                // With floats that won't always be true
-                                // so we generate an abort below
-                            },
-                            mir::Literal::Value { .. } => {
-                                err.report_as_error(
-                                    bx.tcx().at(constant.span),
-                                    "could not evaluate constant operand",
-                                );
-                            },
-                        }
+                        err.report_as_error(
+                            bx.tcx().at(constant.span),
+                            "could not evaluate constant operand",
+                        );
+                        // Allow RalfJ to sleep soundly knowing that even refactorings that remove
+                        // the above error (or silence it under some conditions) will not cause UB
                         let fnname = bx.cx.get_intrinsic(&("llvm.trap"));
                         bx.call(fnname, &[], None);
                         // We've errored, so we don't have to produce working code.