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Rollup merge of #59560 - matthewjasper:mir-generation-cleanup, r=oli-obk

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MIR generation cleanup

* Handle the case where the body of a constant is a subtype of the type of the constant (see `mir_static_subtype.rs`).
* Move the evaluation of `ExprKind::Use` into `into.rs`, saving an unnecessary copy.
This commit is contained in:
Mazdak Farrokhzad 2019-04-25 03:05:19 +02:00 committed by GitHub
commit 5440cf1cb6
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GPG Key ID: 4AEE18F83AFDEB23
10 changed files with 69 additions and 31 deletions
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5
src/librustc_mir/build/expr/as_rvalue.rs
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@ -150,10 +150,6 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
let source = unpack!(block = this.as_operand(block, scope, source));
block.and(Rvalue::Cast(CastKind::Misc, source, expr.ty))
}
ExprKind::Use { source } => {
let source = unpack!(block = this.as_operand(block, scope, source));
block.and(Rvalue::Use(source))
}
ExprKind::Pointer { cast, source } => {
let source = unpack!(block = this.as_operand(block, scope, source));
block.and(Rvalue::Cast(CastKind::Pointer(cast), source, expr.ty))
@ -363,6 +359,7 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
| ExprKind::Match { .. }
| ExprKind::If { .. }
| ExprKind::NeverToAny { .. }
| ExprKind::Use { .. }
| ExprKind::Loop { .. }
| ExprKind::LogicalOp { .. }
| ExprKind::Call { .. }

2
src/librustc_mir/build/expr/category.rs
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@ -48,6 +48,7 @@ impl Category {
| ExprKind::If { .. }
| ExprKind::Match { .. }
| ExprKind::NeverToAny { .. }
| ExprKind::Use { .. }
| ExprKind::Call { .. } => Some(Category::Rvalue(RvalueFunc::Into)),
ExprKind::Array { .. }
@ -58,7 +59,6 @@ impl Category {
| ExprKind::Binary { .. }
| ExprKind::Box { .. }
| ExprKind::Cast { .. }
| ExprKind::Use { .. }
| ExprKind::Pointer { .. }
| ExprKind::Repeat { .. }
| ExprKind::Borrow { .. }

4
src/librustc_mir/build/expr/into.rs
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@ -327,6 +327,9 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
success.unit()
}
}
ExprKind::Use { source } => {
this.into(destination, block, source)
}
// These cases don't actually need a destination
ExprKind::Assign { .. }
@ -379,7 +382,6 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
| ExprKind::Binary { .. }
| ExprKind::Box { .. }
| ExprKind::Cast { .. }
| ExprKind::Use { .. }
| ExprKind::Pointer { .. }
| ExprKind::Repeat { .. }
| ExprKind::Borrow { .. }

33
src/librustc_mir/build/mod.rs
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@ -147,7 +147,21 @@ pub fn mir_build<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> Mir<'t
build::construct_fn(cx, id, arguments, safety, abi,
return_ty, yield_ty, return_ty_span, body)
} else {
build::construct_const(cx, body_id, return_ty_span)
// Get the revealed type of this const. This is *not* the adjusted
// type of its body, which may be a subtype of this type. For
// example:
//
// fn foo(_: &()) {}
// static X: fn(&'static ()) = foo;
//
// The adjusted type of the body of X is `for<'a> fn(&'a ())` which
// is not the same as the type of X. We need the type of the return
// place to be the type of the constant because NLL typeck will
// equate them.
let return_ty = cx.tables().node_type(id);
build::construct_const(cx, body_id, return_ty, return_ty_span)
};
// Convert the Mir to global types.
@ -730,16 +744,25 @@ fn construct_fn<'a, 'gcx, 'tcx, A>(hir: Cx<'a, 'gcx, 'tcx>,
fn construct_const<'a, 'gcx, 'tcx>(
hir: Cx<'a, 'gcx, 'tcx>,
body_id: hir::BodyId,
ty_span: Span,
const_ty: Ty<'tcx>,
const_ty_span: Span,
) -> Mir<'tcx> {
let tcx = hir.tcx();
let ast_expr = &tcx.hir().body(body_id).value;
let ty = hir.tables().expr_ty_adjusted(ast_expr);
let owner_id = tcx.hir().body_owner(body_id);
let span = tcx.hir().span(owner_id);
let mut builder = Builder::new(hir, span, 0, Safety::Safe, ty, ty_span, vec![], vec![]);
let mut builder = Builder::new(
hir,
span,
0,
Safety::Safe,
const_ty,
const_ty_span,
vec![],
vec![],
);
let mut block = START_BLOCK;
let ast_expr = &tcx.hir().body(body_id).value;
let expr = builder.hir.mirror(ast_expr);
unpack!(block = builder.into_expr(&Place::RETURN_PLACE, block, expr));

3
src/librustc_mir/interpret/step.rs
View File

@ -259,8 +259,7 @@ impl<'a, 'mir, 'tcx, M: Machine<'a, 'mir, 'tcx>> InterpretCx<'a, 'mir, 'tcx, M>
)?;
}
Cast(kind, ref operand, cast_ty) => {
debug_assert_eq!(self.monomorphize(cast_ty)?, dest.layout.ty);
Cast(kind, ref operand, _) => {
let src = self.eval_operand(operand, None)?;
self.cast(src, kind, dest)?;
}

2
src/librustc_typeck/check/mod.rs
View File

@ -866,6 +866,8 @@ fn typeck_tables_of<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
fcx.check_expr_coercable_to_type(&body.value, revealed_ty);
fcx.write_ty(id, revealed_ty);
fcx
};

8
src/librustc_typeck/check/writeback.rs
View File

@ -42,6 +42,14 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
for arg in &body.arguments {
wbcx.visit_node_id(arg.pat.span, arg.hir_id);
}
// Type only exists for constants and statics, not functions.
match self.tcx.hir().body_owner_kind(item_id) {
hir::BodyOwnerKind::Const | hir::BodyOwnerKind::Static(_) => {
let item_hir_id = self.tcx.hir().node_to_hir_id(item_id);
wbcx.visit_node_id(body.value.span, item_hir_id);
}
hir::BodyOwnerKind::Closure | hir::BodyOwnerKind::Fn => (),
}
wbcx.visit_body(body);
wbcx.visit_upvar_capture_map();
wbcx.visit_upvar_list_map();

21
src/test/mir-opt/array-index-is-temporary.rs
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@ -18,25 +18,24 @@ fn main() {
// START rustc.main.EraseRegions.after.mir
// bb0: {
// ...
// _6 = &mut _2;
// _5 = &mut (*_6);
// _4 = move _5 as *mut usize (Misc);
// _3 = move _4;
// _5 = &mut _2;
// _4 = &mut (*_5);
// _3 = move _4 as *mut usize (Misc);
// ...
// _8 = _3;
// _7 = const foo(move _8) -> bb1;
// _7 = _3;
// _6 = const foo(move _7) -> bb1;
// }
//
// bb1: {
// ...
// _9 = _2;
// _10 = Len(_1);
// _11 = Lt(_9, _10);
// assert(move _11, "index out of bounds: the len is move _10 but the index is _9") -> bb2;
// _8 = _2;
// _9 = Len(_1);
// _10 = Lt(_8, _9);
// assert(move _10, "index out of bounds: the len is move _9 but the index is _8") -> bb2;
// }
//
// bb2: {
// _1[_9] = move _7;
// _1[_8] = move _6;
// ...
// return;
// }

14
src/test/mir-opt/retag.rs
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@ -75,18 +75,18 @@ fn main() {
// _10 = move _8;
// Retag(_10);
// ...
// _15 = &mut (*_10);
// Retag(_15);
// _14 = move _15 as *mut i32 (Misc);
// Retag([raw] _14);
// _13 = &mut (*_10);
// Retag(_13);
// _12 = move _13 as *mut i32 (Misc);
// Retag([raw] _12);
// ...
// _18 = move _19(move _20) -> bb2;
// _16 = move _17(move _18) -> bb2;
// }
//
// bb2: {
// Retag(_18);
// Retag(_16);
// ...
// _22 = const Test::foo_shr(move _23, move _25) -> bb3;
// _20 = const Test::foo_shr(move _21, move _23) -> bb3;
// }
//
// bb3: {

8
src/test/run-pass/mir/mir_static_subtype.rs Normal file
View File

@ -0,0 +1,8 @@
// Test that subtyping the body of a static doesn't cause an ICE.
fn foo(_ : &()) {}
static X: fn(&'static ()) = foo;
fn main() {
let _ = X;
}