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Remove -Z no-landing-pads flag #70175

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Apr 30, 2020
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5 changes: 4 additions & 1 deletion src/librustc_codegen_llvm/attributes.rs
Original file line number Diff line number Diff line change
@@ -13,6 +13,7 @@ use rustc_middle::ty::query::Providers;
use rustc_middle::ty::{self, TyCtxt};
use rustc_session::config::{OptLevel, Sanitizer};
use rustc_session::Session;
use rustc_target::spec::PanicStrategy;

use crate::attributes;
use crate::llvm::AttributePlace::Function;
@@ -270,7 +271,9 @@ pub fn from_fn_attrs(cx: &CodegenCx<'ll, 'tcx>, llfn: &'ll Value, instance: ty::
//
// You can also find more info on why Windows is whitelisted here in:
// https://bugzilla.mozilla.org/show_bug.cgi?id=1302078
if !cx.sess().no_landing_pads() || cx.sess().target.target.options.requires_uwtable {
if cx.sess().panic_strategy() == PanicStrategy::Unwind
|| cx.sess().target.target.options.requires_uwtable
{
attributes::emit_uwtable(llfn, true);
}

3 changes: 2 additions & 1 deletion src/librustc_codegen_llvm/intrinsic.rs
Original file line number Diff line number Diff line change
@@ -22,6 +22,7 @@ use rustc_middle::ty::{self, Ty};
use rustc_middle::{bug, span_bug};
use rustc_span::Span;
use rustc_target::abi::{self, HasDataLayout, LayoutOf, Primitive};
use rustc_target::spec::PanicStrategy;

use std::cmp::Ordering;
use std::iter;
@@ -804,7 +805,7 @@ fn try_intrinsic(
catch_func: &'ll Value,
dest: &'ll Value,
) {
if bx.sess().no_landing_pads() {
if bx.sess().panic_strategy() == PanicStrategy::Abort {
bx.call(try_func, &[data], None);
// Return 0 unconditionally from the intrinsic call;
// we can never unwind.
4 changes: 2 additions & 2 deletions src/librustc_codegen_ssa/back/write.rs
Original file line number Diff line number Diff line change
@@ -36,7 +36,7 @@ use rustc_session::Session;
use rustc_span::hygiene::ExpnId;
use rustc_span::source_map::SourceMap;
use rustc_span::symbol::{sym, Symbol};
use rustc_target::spec::MergeFunctions;
use rustc_target::spec::{MergeFunctions, PanicStrategy};

use std::any::Any;
use std::fs;
@@ -1021,7 +1021,7 @@ fn start_executing_work<B: ExtraBackendMethods>(
crate_types: sess.crate_types.borrow().clone(),
each_linked_rlib_for_lto,
lto: sess.lto(),
no_landing_pads: sess.no_landing_pads(),
no_landing_pads: sess.panic_strategy() == PanicStrategy::Abort,
fewer_names: sess.fewer_names(),
save_temps: sess.opts.cg.save_temps,
opts: Arc::new(sess.opts.clone()),
1 change: 0 additions & 1 deletion src/librustc_interface/tests.rs
Original file line number Diff line number Diff line change
@@ -546,7 +546,6 @@ fn test_debugging_options_tracking_hash() {
tracked!(new_llvm_pass_manager, true);
tracked!(no_codegen, true);
tracked!(no_generate_arange_section, true);
tracked!(no_landing_pads, true);
tracked!(no_link, true);
tracked!(no_profiler_runtime, true);
tracked!(osx_rpath_install_name, true);
3 changes: 2 additions & 1 deletion src/librustc_mir/transform/generator.rs
Original file line number Diff line number Diff line change
@@ -68,6 +68,7 @@ use rustc_middle::ty::subst::SubstsRef;
use rustc_middle::ty::GeneratorSubsts;
use rustc_middle::ty::{self, AdtDef, Ty, TyCtxt};
use rustc_target::abi::VariantIdx;
use rustc_target::spec::PanicStrategy;
use std::borrow::Cow;
use std::iter;

@@ -978,7 +979,7 @@ fn can_return<'tcx>(tcx: TyCtxt<'tcx>, body: &Body<'tcx>) -> bool {

fn can_unwind<'tcx>(tcx: TyCtxt<'tcx>, body: &Body<'tcx>) -> bool {
// Nothing can unwind when landing pads are off.
if tcx.sess.no_landing_pads() {
if tcx.sess.panic_strategy() == PanicStrategy::Abort {
return false;
}

3 changes: 2 additions & 1 deletion src/librustc_mir/transform/no_landing_pads.rs
Original file line number Diff line number Diff line change
@@ -5,6 +5,7 @@ use crate::transform::{MirPass, MirSource};
use rustc_middle::mir::visit::MutVisitor;
use rustc_middle::mir::*;
use rustc_middle::ty::TyCtxt;
use rustc_target::spec::PanicStrategy;

pub struct NoLandingPads<'tcx> {
tcx: TyCtxt<'tcx>,
@@ -23,7 +24,7 @@ impl<'tcx> MirPass<'tcx> for NoLandingPads<'tcx> {
}

pub fn no_landing_pads<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
if tcx.sess.no_landing_pads() {
if tcx.sess.panic_strategy() == PanicStrategy::Abort {
NoLandingPads::new(tcx).visit_body(body);
}
}
3 changes: 2 additions & 1 deletion src/librustc_mir/transform/remove_noop_landing_pads.rs
Original file line number Diff line number Diff line change
@@ -3,14 +3,15 @@ use crate::util::patch::MirPatch;
use rustc_index::bit_set::BitSet;
use rustc_middle::mir::*;
use rustc_middle::ty::TyCtxt;
use rustc_target::spec::PanicStrategy;

/// A pass that removes noop landing pads and replaces jumps to them with
/// `None`. This is important because otherwise LLVM generates terrible
/// code for these.
pub struct RemoveNoopLandingPads;

pub fn remove_noop_landing_pads<'tcx>(tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
if tcx.sess.no_landing_pads() {
if tcx.sess.panic_strategy() == PanicStrategy::Abort {
return;
}
debug!("remove_noop_landing_pads({:?})", body);
5 changes: 0 additions & 5 deletions src/librustc_mir_build/build/mod.rs
Original file line number Diff line number Diff line change
@@ -533,11 +533,6 @@ fn should_abort_on_panic(tcx: TyCtxt<'_>, fn_def_id: LocalDefId, _abi: Abi) -> b
return false;
}

// We cannot add landing pads, so don't add one.
if tcx.sess.no_landing_pads() {
return false;
}

// This is a special case: some functions have a C abi but are meant to
// unwind anyway. Don't stop them.
match unwind_attr {
2 changes: 0 additions & 2 deletions src/librustc_session/options.rs
Original file line number Diff line number Diff line change
@@ -878,8 +878,6 @@ options! {DebuggingOptions, DebuggingSetter, basic_debugging_options,
"omit DWARF address ranges that give faster lookups"),
no_interleave_lints: bool = (false, parse_no_flag, [UNTRACKED],
"execute lints separately; allows benchmarking individual lints"),
no_landing_pads: bool = (false, parse_no_flag, [TRACKED],
"omit landing pads for unwinding"),
no_leak_check: bool = (false, parse_no_flag, [UNTRACKED],
"disable the 'leak check' for subtyping; unsound, but useful for tests"),
no_link: bool = (false, parse_no_flag, [TRACKED],
3 changes: 0 additions & 3 deletions src/librustc_session/session.rs
Original file line number Diff line number Diff line change
@@ -540,9 +540,6 @@ impl Session {
self.opts.debugging_opts.fewer_names || !more_names
}

pub fn no_landing_pads(&self) -> bool {
self.opts.debugging_opts.no_landing_pads || self.panic_strategy() == PanicStrategy::Abort
}
pub fn unstable_options(&self) -> bool {
self.opts.debugging_opts.unstable_options
}
3 changes: 2 additions & 1 deletion src/test/mir-opt/generator-tiny.rs
Original file line number Diff line number Diff line change
@@ -1,7 +1,8 @@
//! Tests that generators that cannot return or unwind don't have unnecessary
//! panic branches.
// compile-flags: -Zno-landing-pads
// compile-flags: -C panic=abort
// no-prefer-dynamic

#![feature(generators, generator_trait)]

Original file line number Diff line number Diff line change
@@ -1,78 +1,78 @@
// MIR for `main::{{closure}}#0` 0 generator_resume
// generator_layout = GeneratorLayout { field_tys: [HasDrop], variant_fields: [[], [], [], [_0]], storage_conflicts: BitMatrix { num_rows: 1, num_columns: 1, words: [1], marker: PhantomData } }

fn main::{{closure}}#0(_1: std::pin::Pin<&mut [generator@$DIR/generator-tiny.rs:18:16: 24:6 {u8, HasDrop, ()}]>, _2: u8) -> std::ops::GeneratorState<(), ()> {
debug _x => _10; // in scope 0 at $DIR/generator-tiny.rs:18:17: 18:19
let mut _0: std::ops::GeneratorState<(), ()>; // return place in scope 0 at $DIR/generator-tiny.rs:18:16: 24:6
let _3: HasDrop; // in scope 0 at $DIR/generator-tiny.rs:19:13: 19:15
let mut _4: !; // in scope 0 at $DIR/generator-tiny.rs:20:9: 23:10
let mut _5: (); // in scope 0 at $DIR/generator-tiny.rs:18:16: 24:6
let _6: u8; // in scope 0 at $DIR/generator-tiny.rs:21:13: 21:18
let mut _7: (); // in scope 0 at $DIR/generator-tiny.rs:21:13: 21:18
let _8: (); // in scope 0 at $DIR/generator-tiny.rs:22:13: 22:21
let mut _9: (); // in scope 0 at $DIR/generator-tiny.rs:18:25: 18:25
let _10: u8; // in scope 0 at $DIR/generator-tiny.rs:18:17: 18:19
let mut _11: isize; // in scope 0 at $DIR/generator-tiny.rs:18:16: 24:6
fn main::{{closure}}#0(_1: std::pin::Pin<&mut [generator@$DIR/generator-tiny.rs:19:16: 25:6 {u8, HasDrop, ()}]>, _2: u8) -> std::ops::GeneratorState<(), ()> {
debug _x => _10; // in scope 0 at $DIR/generator-tiny.rs:19:17: 19:19
let mut _0: std::ops::GeneratorState<(), ()>; // return place in scope 0 at $DIR/generator-tiny.rs:19:16: 25:6
let _3: HasDrop; // in scope 0 at $DIR/generator-tiny.rs:20:13: 20:15
let mut _4: !; // in scope 0 at $DIR/generator-tiny.rs:21:9: 24:10
let mut _5: (); // in scope 0 at $DIR/generator-tiny.rs:19:16: 25:6
let _6: u8; // in scope 0 at $DIR/generator-tiny.rs:22:13: 22:18
let mut _7: (); // in scope 0 at $DIR/generator-tiny.rs:22:13: 22:18
let _8: (); // in scope 0 at $DIR/generator-tiny.rs:23:13: 23:21
let mut _9: (); // in scope 0 at $DIR/generator-tiny.rs:19:25: 19:25
let _10: u8; // in scope 0 at $DIR/generator-tiny.rs:19:17: 19:19
let mut _11: isize; // in scope 0 at $DIR/generator-tiny.rs:19:16: 25:6
scope 1 {
debug _d => (((*(_1.0: &mut [generator@$DIR/generator-tiny.rs:18:16: 24:6 {u8, HasDrop, ()}])) as variant#3).0: HasDrop); // in scope 1 at $DIR/generator-tiny.rs:19:13: 19:15
debug _d => (((*(_1.0: &mut [generator@$DIR/generator-tiny.rs:19:16: 25:6 {u8, HasDrop, ()}])) as variant#3).0: HasDrop); // in scope 1 at $DIR/generator-tiny.rs:20:13: 20:15
}

bb0: {
_11 = discriminant((*(_1.0: &mut [generator@$DIR/generator-tiny.rs:18:16: 24:6 {u8, HasDrop, ()}]))); // scope 0 at $DIR/generator-tiny.rs:18:16: 24:6
switchInt(move _11) -> [0u32: bb1, 3u32: bb5, otherwise: bb6]; // scope 0 at $DIR/generator-tiny.rs:18:16: 24:6
_11 = discriminant((*(_1.0: &mut [generator@$DIR/generator-tiny.rs:19:16: 25:6 {u8, HasDrop, ()}]))); // scope 0 at $DIR/generator-tiny.rs:19:16: 25:6
switchInt(move _11) -> [0u32: bb1, 3u32: bb5, otherwise: bb6]; // scope 0 at $DIR/generator-tiny.rs:19:16: 25:6
}

bb1: {
_10 = move _2; // scope 0 at $DIR/generator-tiny.rs:18:16: 24:6
nop; // scope 0 at $DIR/generator-tiny.rs:19:13: 19:15
(((*(_1.0: &mut [generator@$DIR/generator-tiny.rs:18:16: 24:6 {u8, HasDrop, ()}])) as variant#3).0: HasDrop) = HasDrop; // scope 0 at $DIR/generator-tiny.rs:19:18: 19:25
StorageLive(_4); // scope 1 at $DIR/generator-tiny.rs:20:9: 23:10
goto -> bb2; // scope 1 at $DIR/generator-tiny.rs:20:9: 23:10
_10 = move _2; // scope 0 at $DIR/generator-tiny.rs:19:16: 25:6
nop; // scope 0 at $DIR/generator-tiny.rs:20:13: 20:15
(((*(_1.0: &mut [generator@$DIR/generator-tiny.rs:19:16: 25:6 {u8, HasDrop, ()}])) as variant#3).0: HasDrop) = HasDrop; // scope 0 at $DIR/generator-tiny.rs:20:18: 20:25
StorageLive(_4); // scope 1 at $DIR/generator-tiny.rs:21:9: 24:10
goto -> bb2; // scope 1 at $DIR/generator-tiny.rs:21:9: 24:10
}

bb2: {
StorageLive(_6); // scope 1 at $DIR/generator-tiny.rs:21:13: 21:18
StorageLive(_7); // scope 1 at $DIR/generator-tiny.rs:21:13: 21:18
_7 = (); // scope 1 at $DIR/generator-tiny.rs:21:13: 21:18
_0 = std::ops::GeneratorState::<(), ()>::Yielded(move _7); // scope 1 at $DIR/generator-tiny.rs:21:13: 21:18
discriminant((*(_1.0: &mut [generator@$DIR/generator-tiny.rs:18:16: 24:6 {u8, HasDrop, ()}]))) = 3; // scope 1 at $DIR/generator-tiny.rs:21:13: 21:18
return; // scope 1 at $DIR/generator-tiny.rs:21:13: 21:18
StorageLive(_6); // scope 1 at $DIR/generator-tiny.rs:22:13: 22:18
StorageLive(_7); // scope 1 at $DIR/generator-tiny.rs:22:13: 22:18
_7 = (); // scope 1 at $DIR/generator-tiny.rs:22:13: 22:18
_0 = std::ops::GeneratorState::<(), ()>::Yielded(move _7); // scope 1 at $DIR/generator-tiny.rs:22:13: 22:18
discriminant((*(_1.0: &mut [generator@$DIR/generator-tiny.rs:19:16: 25:6 {u8, HasDrop, ()}]))) = 3; // scope 1 at $DIR/generator-tiny.rs:22:13: 22:18
return; // scope 1 at $DIR/generator-tiny.rs:22:13: 22:18
}

bb3: {
StorageDead(_7); // scope 1 at $DIR/generator-tiny.rs:21:17: 21:18
StorageDead(_6); // scope 1 at $DIR/generator-tiny.rs:21:18: 21:19
StorageLive(_8); // scope 1 at $DIR/generator-tiny.rs:22:13: 22:21
_8 = const callee() -> bb4; // scope 1 at $DIR/generator-tiny.rs:22:13: 22:21
StorageDead(_7); // scope 1 at $DIR/generator-tiny.rs:22:17: 22:18
StorageDead(_6); // scope 1 at $DIR/generator-tiny.rs:22:18: 22:19
StorageLive(_8); // scope 1 at $DIR/generator-tiny.rs:23:13: 23:21
_8 = const callee() -> bb4; // scope 1 at $DIR/generator-tiny.rs:23:13: 23:21
// ty::Const
// + ty: fn() {callee}
// + val: Value(Scalar(<ZST>))
// mir::Constant
// + span: $DIR/generator-tiny.rs:22:13: 22:19
// + span: $DIR/generator-tiny.rs:23:13: 23:19
// + literal: Const { ty: fn() {callee}, val: Value(Scalar(<ZST>)) }
}

bb4: {
StorageDead(_8); // scope 1 at $DIR/generator-tiny.rs:22:21: 22:22
_5 = const (); // scope 1 at $DIR/generator-tiny.rs:20:14: 23:10
StorageDead(_8); // scope 1 at $DIR/generator-tiny.rs:23:21: 23:22
_5 = const (); // scope 1 at $DIR/generator-tiny.rs:21:14: 24:10
// ty::Const
// + ty: ()
// + val: Value(Scalar(<ZST>))
// mir::Constant
// + span: $DIR/generator-tiny.rs:20:14: 23:10
// + span: $DIR/generator-tiny.rs:21:14: 24:10
// + literal: Const { ty: (), val: Value(Scalar(<ZST>)) }
goto -> bb2; // scope 1 at $DIR/generator-tiny.rs:20:9: 23:10
goto -> bb2; // scope 1 at $DIR/generator-tiny.rs:21:9: 24:10
}

bb5: {
StorageLive(_4); // scope 0 at $DIR/generator-tiny.rs:18:16: 24:6
StorageLive(_6); // scope 0 at $DIR/generator-tiny.rs:18:16: 24:6
StorageLive(_7); // scope 0 at $DIR/generator-tiny.rs:18:16: 24:6
_6 = move _2; // scope 0 at $DIR/generator-tiny.rs:18:16: 24:6
goto -> bb3; // scope 0 at $DIR/generator-tiny.rs:18:16: 24:6
StorageLive(_4); // scope 0 at $DIR/generator-tiny.rs:19:16: 25:6
StorageLive(_6); // scope 0 at $DIR/generator-tiny.rs:19:16: 25:6
StorageLive(_7); // scope 0 at $DIR/generator-tiny.rs:19:16: 25:6
_6 = move _2; // scope 0 at $DIR/generator-tiny.rs:19:16: 25:6
goto -> bb3; // scope 0 at $DIR/generator-tiny.rs:19:16: 25:6
}

bb6: {
unreachable; // scope 0 at $DIR/generator-tiny.rs:18:16: 24:6
unreachable; // scope 0 at $DIR/generator-tiny.rs:19:16: 25:6
}
}
27 changes: 0 additions & 27 deletions src/test/run-fail/mir_codegen_no_landing_pads.rs

This file was deleted.

27 changes: 0 additions & 27 deletions src/test/run-fail/mir_codegen_no_landing_pads_diverging.rs

This file was deleted.