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Auto merge of #115045 - RalfJung:unwind-terminate-reason, r=davidtwco
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when terminating during unwinding, show the reason why

With this, the output on double-panic becomes something like that:
```
thread 'main' panicked at src/tools/miri/tests/fail/panic/double_panic.rs:15:5:
first
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
thread 'main' panicked at src/tools/miri/tests/fail/panic/double_panic.rs:10:9:
second
stack backtrace:
   0:           0xbe273a - std::backtrace_rs::backtrace::miri::trace_unsynchronized::<&mut [closure@std::sys_common::backtrace::_print_fmt::{closure#1}]>
                               at /home/r/src/rust/rustc.3/library/std/src/../../backtrace/src/backtrace/miri.rs:99:5
   1:           0xbe22e6 - std::backtrace_rs::backtrace::miri::trace::<&mut [closure@std::sys_common::backtrace::_print_fmt::{closure#1}]>
                               at /home/r/src/rust/rustc.3/library/std/src/../../backtrace/src/backtrace/miri.rs:62:14
   2:           0xbe1086 - std::backtrace_rs::backtrace::trace_unsynchronized::<[closure@std::sys_common::backtrace::_print_fmt::{closure#1}]>
                               at /home/r/src/rust/rustc.3/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   3:           0xba3afd - std::sys_common::backtrace::_print_fmt
                               at /home/r/src/rust/rustc.3/library/std/src/sys_common/backtrace.rs:67:5
   4:           0xba2471 - <std::sys_common::backtrace::_print::DisplayBacktrace as std::fmt::Display>::fmt
                               at /home/r/src/rust/rustc.3/library/std/src/sys_common/backtrace.rs:44:22
   5:           0xbcf754 - core::fmt::rt::Argument::<'_>::fmt
                               at /home/r/src/rust/rustc.3/library/core/src/fmt/rt.rs:138:9
   6:           0x9b8f81 - std::fmt::write
                               at /home/r/src/rust/rustc.3/library/core/src/fmt/mod.rs:1094:17
   7:           0x21391d - <std::sys::unix::stdio::Stderr as std::io::Write>::write_fmt
                               at /home/r/src/rust/rustc.3/library/std/src/io/mod.rs:1714:15
   8:           0xba37b1 - std::sys_common::backtrace::_print
                               at /home/r/src/rust/rustc.3/library/std/src/sys_common/backtrace.rs:47:5
   9:           0xba365b - std::sys_common::backtrace::print
                               at /home/r/src/rust/rustc.3/library/std/src/sys_common/backtrace.rs:34:9
  10:           0x143c67 - std::panic_hook_with_disk_dump::{closure#1}
                               at /home/r/src/rust/rustc.3/library/std/src/panicking.rs:278:22
  11:           0x144187 - std::panic_hook_with_disk_dump
                               at /home/r/src/rust/rustc.3/library/std/src/panicking.rs:312:9
  12:           0x143659 - std::panicking::default_hook
                               at /home/r/src/rust/rustc.3/library/std/src/panicking.rs:239:5
  13:           0x1482a7 - std::panicking::rust_panic_with_hook
                               at /home/r/src/rust/rustc.3/library/std/src/panicking.rs:729:13
  14:           0x1475d5 - std::rt::begin_panic::<&str>::{closure#0}
                               at /home/r/src/rust/rustc.3/library/std/src/panicking.rs:650:9
  15:           0xba496a - std::sys_common::backtrace::__rust_end_short_backtrace::<[closure@std::rt::begin_panic<&str>::{closure#0}], !>
                               at /home/r/src/rust/rustc.3/library/std/src/sys_common/backtrace.rs:170:18
  16:           0x147599 - std::rt::begin_panic::<&str>
                               at /home/r/src/rust/rustc.3/library/std/src/panicking.rs:649:12
  17:            0x31916 - <Foo as std::ops::Drop>::drop
                               at src/tools/miri/tests/fail/panic/double_panic.rs:10:9
  18:           0x1a2b5e - std::ptr::drop_in_place::<Foo> - shim(Some(Foo))
                               at /home/r/src/rust/rustc.3/library/core/src/ptr/mod.rs:497:1
  19:            0x202bf - main
                               at src/tools/miri/tests/fail/panic/double_panic.rs:16:1
  20:            0xcc6a8 - <fn() as std::ops::FnOnce<()>>::call_once - shim(fn())
                               at /home/r/src/rust/rustc.3/library/core/src/ops/function.rs:250:5
  21:           0xba47d9 - std::sys_common::backtrace::__rust_begin_short_backtrace::<fn(), ()>
                               at /home/r/src/rust/rustc.3/library/std/src/sys_common/backtrace.rs:154:18
  22:           0x141a6a - std::rt::lang_start::<()>::{closure#0}
                               at /home/r/src/rust/rustc.3/library/std/src/rt.rs:166:18
  23:            0xcca18 - std::ops::function::impls::<impl std::ops::FnOnce<()> for &dyn std::ops::Fn() -> i32 + std::marker::Sync + std::panic::RefUnwindSafe>::call_once
                               at /home/r/src/rust/rustc.3/library/core/src/ops/function.rs:284:13
  24:           0x146469 - std::panicking::try::do_call::<&dyn std::ops::Fn() -> i32 + std::marker::Sync + std::panic::RefUnwindSafe, i32>
                               at /home/r/src/rust/rustc.3/library/std/src/panicking.rs:524:40
  25:           0x145e09 - std::panicking::try::<i32, &dyn std::ops::Fn() -> i32 + std::marker::Sync + std::panic::RefUnwindSafe>
                               at /home/r/src/rust/rustc.3/library/std/src/panicking.rs:488:19
  26:            0x7b0ac - std::panic::catch_unwind::<&dyn std::ops::Fn() -> i32 + std::marker::Sync + std::panic::RefUnwindSafe, i32>
                               at /home/r/src/rust/rustc.3/library/std/src/panic.rs:142:14
  27:           0x14189b - std::rt::lang_start_internal::{closure#2}
                               at /home/r/src/rust/rustc.3/library/std/src/rt.rs:148:48
  28:           0x146481 - std::panicking::try::do_call::<[closure@std::rt::lang_start_internal::{closure#2}], isize>
                               at /home/r/src/rust/rustc.3/library/std/src/panicking.rs:524:40
  29:           0x145e2c - std::panicking::try::<isize, [closure@std::rt::lang_start_internal::{closure#2}]>
                               at /home/r/src/rust/rustc.3/library/std/src/panicking.rs:488:19
  30:            0x7b0d5 - std::panic::catch_unwind::<[closure@std::rt::lang_start_internal::{closure#2}], isize>
                               at /home/r/src/rust/rustc.3/library/std/src/panic.rs:142:14
  31:           0x1418b0 - std::rt::lang_start_internal
                               at /home/r/src/rust/rustc.3/library/std/src/rt.rs:148:20
  32:           0x141a97 - std::rt::lang_start::<()>
                               at /home/r/src/rust/rustc.3/library/std/src/rt.rs:165:17
thread 'main' panicked at /home/r/src/rust/rustc.3/library/core/src/panicking.rs:126:5:
panic in a destructor during cleanup
stack backtrace:
   0:           0xe9f6d7 - std::backtrace_rs::backtrace::miri::trace_unsynchronized::<&mut [closure@std::sys_common::backtrace::_print_fmt::{closure#1}]>
                               at /home/r/src/rust/rustc.3/library/std/src/../../backtrace/src/backtrace/miri.rs:99:5
   1:           0xe9f27d - std::backtrace_rs::backtrace::miri::trace::<&mut [closure@std::sys_common::backtrace::_print_fmt::{closure#1}]>
                               at /home/r/src/rust/rustc.3/library/std/src/../../backtrace/src/backtrace/miri.rs:62:14
   2:           0xe9e016 - std::backtrace_rs::backtrace::trace_unsynchronized::<[closure@std::sys_common::backtrace::_print_fmt::{closure#1}]>
                               at /home/r/src/rust/rustc.3/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   3:           0xba3afd - std::sys_common::backtrace::_print_fmt
                               at /home/r/src/rust/rustc.3/library/std/src/sys_common/backtrace.rs:67:5
   4:           0xba2471 - <std::sys_common::backtrace::_print::DisplayBacktrace as std::fmt::Display>::fmt
                               at /home/r/src/rust/rustc.3/library/std/src/sys_common/backtrace.rs:44:22
   5:           0xbcf754 - core::fmt::rt::Argument::<'_>::fmt
                               at /home/r/src/rust/rustc.3/library/core/src/fmt/rt.rs:138:9
   6:           0x9b8f81 - std::fmt::write
                               at /home/r/src/rust/rustc.3/library/core/src/fmt/mod.rs:1094:17
   7:           0x4d0895 - <std::sys::unix::stdio::Stderr as std::io::Write>::write_fmt
                               at /home/r/src/rust/rustc.3/library/std/src/io/mod.rs:1714:15
   8:           0xba37b1 - std::sys_common::backtrace::_print
                               at /home/r/src/rust/rustc.3/library/std/src/sys_common/backtrace.rs:47:5
   9:           0xba365b - std::sys_common::backtrace::print
                               at /home/r/src/rust/rustc.3/library/std/src/sys_common/backtrace.rs:34:9
  10:           0x400bd4 - std::panic_hook_with_disk_dump::{closure#1}
                               at /home/r/src/rust/rustc.3/library/std/src/panicking.rs:278:22
  11:           0x144187 - std::panic_hook_with_disk_dump
                               at /home/r/src/rust/rustc.3/library/std/src/panicking.rs:312:9
  12:           0x143659 - std::panicking::default_hook
                               at /home/r/src/rust/rustc.3/library/std/src/panicking.rs:239:5
  13:           0x1482a7 - std::panicking::rust_panic_with_hook
                               at /home/r/src/rust/rustc.3/library/std/src/panicking.rs:729:13
  14:           0x40403b - std::panicking::begin_panic_handler::{closure#0}
                               at /home/r/src/rust/rustc.3/library/std/src/panicking.rs:619:13
  15:           0xe618b3 - std::sys_common::backtrace::__rust_end_short_backtrace::<[closure@std::panicking::begin_panic_handler::{closure#0}], !>
                               at /home/r/src/rust/rustc.3/library/std/src/sys_common/backtrace.rs:170:18
  16:           0x403fc8 - std::panicking::begin_panic_handler
                               at /home/r/src/rust/rustc.3/library/std/src/panicking.rs:617:5
  17:           0xee23e9 - core::panicking::panic_nounwind_fmt
                               at /home/r/src/rust/rustc.3/library/core/src/panicking.rs:96:14
  18:           0xee29e6 - core::panicking::panic_nounwind
                               at /home/r/src/rust/rustc.3/library/core/src/panicking.rs:126:5
  19:           0xee365e - core::panicking::panic_in_cleanup
                               at /home/r/src/rust/rustc.3/library/core/src/panicking.rs:206:5
  20:            0x2028a - main
                               at src/tools/miri/tests/fail/panic/double_panic.rs:13:1
  21:           0x3895ee - <fn() as std::ops::FnOnce<()>>::call_once - shim(fn())
                               at /home/r/src/rust/rustc.3/library/core/src/ops/function.rs:250:5
  22:           0xe61725 - std::sys_common::backtrace::__rust_begin_short_backtrace::<fn(), ()>
                               at /home/r/src/rust/rustc.3/library/std/src/sys_common/backtrace.rs:154:18
  23:           0x3fe9aa - std::rt::lang_start::<()>::{closure#0}
                               at /home/r/src/rust/rustc.3/library/std/src/rt.rs:166:18
  24:           0x389962 - std::ops::function::impls::<impl std::ops::FnOnce<()> for &dyn std::ops::Fn() -> i32 + std::marker::Sync + std::panic::RefUnwindSafe>::call_once
                               at /home/r/src/rust/rustc.3/library/core/src/ops/function.rs:284:13
  25:           0x4033b9 - std::panicking::try::do_call::<&dyn std::ops::Fn() -> i32 + std::marker::Sync + std::panic::RefUnwindSafe, i32>
                               at /home/r/src/rust/rustc.3/library/std/src/panicking.rs:524:40
  26:           0x402d58 - std::panicking::try::<i32, &dyn std::ops::Fn() -> i32 + std::marker::Sync + std::panic::RefUnwindSafe>
                               at /home/r/src/rust/rustc.3/library/std/src/panicking.rs:488:19
  27:           0x337ff7 - std::panic::catch_unwind::<&dyn std::ops::Fn() -> i32 + std::marker::Sync + std::panic::RefUnwindSafe, i32>
                               at /home/r/src/rust/rustc.3/library/std/src/panic.rs:142:14
  28:           0x3fe7e7 - std::rt::lang_start_internal::{closure#2}
                               at /home/r/src/rust/rustc.3/library/std/src/rt.rs:148:48
  29:           0x4033d6 - std::panicking::try::do_call::<[closure@std::rt::lang_start_internal::{closure#2}], isize>
                               at /home/r/src/rust/rustc.3/library/std/src/panicking.rs:524:40
  30:           0x402d7f - std::panicking::try::<isize, [closure@std::rt::lang_start_internal::{closure#2}]>
                               at /home/r/src/rust/rustc.3/library/std/src/panicking.rs:488:19
  31:           0x338028 - std::panic::catch_unwind::<[closure@std::rt::lang_start_internal::{closure#2}], isize>
                               at /home/r/src/rust/rustc.3/library/std/src/panic.rs:142:14
  32:           0x1418b0 - std::rt::lang_start_internal
                               at /home/r/src/rust/rustc.3/library/std/src/rt.rs:148:20
  33:           0x3fe9dc - std::rt::lang_start::<()>
                               at /home/r/src/rust/rustc.3/library/std/src/rt.rs:165:17
thread caused non-unwinding panic. aborting.
```
If we also land #115020, the 2nd backtrace disappears, hopefully making the "panic in a destructor during cleanup" easier to see.

Fixes #114954.
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@bors
bors committed Aug 25, 2023
2 parents 4535d33 + df5a248 commit b60f7b5
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Showing 105 changed files with 491 additions and 307 deletions.
2 changes: 1 addition & 1 deletion compiler/rustc_borrowck/src/invalidation.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -202,7 +202,7 @@ impl<'cx, 'tcx> Visitor<'tcx> for InvalidationGenerator<'cx, 'tcx> {
}
}
TerminatorKind::Goto { target: _ }
| TerminatorKind::UnwindTerminate
| TerminatorKind::UnwindTerminate(_)
| TerminatorKind::Unreachable
| TerminatorKind::FalseEdge { real_target: _, imaginary_target: _ }
| TerminatorKind::FalseUnwind { real_target: _, unwind: _ } => {
Expand Down
4 changes: 2 additions & 2 deletions compiler/rustc_borrowck/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -770,7 +770,7 @@ impl<'cx, 'tcx, R> rustc_mir_dataflow::ResultsVisitor<'cx, 'tcx, R> for MirBorro
}

TerminatorKind::Goto { target: _ }
| TerminatorKind::UnwindTerminate
| TerminatorKind::UnwindTerminate(_)
| TerminatorKind::Unreachable
| TerminatorKind::UnwindResume
| TerminatorKind::Return
Expand Down Expand Up @@ -817,7 +817,7 @@ impl<'cx, 'tcx, R> rustc_mir_dataflow::ResultsVisitor<'cx, 'tcx, R> for MirBorro
}
}

TerminatorKind::UnwindTerminate
TerminatorKind::UnwindTerminate(_)
| TerminatorKind::Assert { .. }
| TerminatorKind::Call { .. }
| TerminatorKind::Drop { .. }
Expand Down
6 changes: 3 additions & 3 deletions compiler/rustc_borrowck/src/type_check/mod.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1334,7 +1334,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
match &term.kind {
TerminatorKind::Goto { .. }
| TerminatorKind::UnwindResume
| TerminatorKind::UnwindTerminate
| TerminatorKind::UnwindTerminate(_)
| TerminatorKind::Return
| TerminatorKind::GeneratorDrop
| TerminatorKind::Unreachable
Expand Down Expand Up @@ -1613,7 +1613,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
span_mirbug!(self, block_data, "resume on non-cleanup block!")
}
}
TerminatorKind::UnwindTerminate => {
TerminatorKind::UnwindTerminate(_) => {
if !is_cleanup {
span_mirbug!(self, block_data, "abort on non-cleanup block!")
}
Expand Down Expand Up @@ -1697,7 +1697,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
span_mirbug!(self, ctxt, "unwind on cleanup block")
}
}
UnwindAction::Unreachable | UnwindAction::Terminate => (),
UnwindAction::Unreachable | UnwindAction::Terminate(_) => (),
}
}

Expand Down
9 changes: 5 additions & 4 deletions compiler/rustc_codegen_cranelift/src/base.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -474,8 +474,8 @@ fn codegen_fn_body(fx: &mut FunctionCx<'_, '_, '_>, start_block: Block) {
*destination,
);
}
TerminatorKind::UnwindTerminate => {
codegen_panic_cannot_unwind(fx, source_info);
TerminatorKind::UnwindTerminate(reason) => {
codegen_unwind_terminate(fx, source_info, *reason);
}
TerminatorKind::UnwindResume => {
// FIXME implement unwinding
Expand Down Expand Up @@ -971,13 +971,14 @@ pub(crate) fn codegen_panic_nounwind<'tcx>(
codegen_panic_inner(fx, rustc_hir::LangItem::PanicNounwind, &args, source_info.span);
}

pub(crate) fn codegen_panic_cannot_unwind<'tcx>(
pub(crate) fn codegen_unwind_terminate<'tcx>(
fx: &mut FunctionCx<'_, '_, 'tcx>,
source_info: mir::SourceInfo,
reason: UnwindTerminateReason,
) {
let args = [];

codegen_panic_inner(fx, rustc_hir::LangItem::PanicCannotUnwind, &args, source_info.span);
codegen_panic_inner(fx, reason.lang_item(), &args, source_info.span);
}

fn codegen_panic_inner<'tcx>(
Expand Down
2 changes: 1 addition & 1 deletion compiler/rustc_codegen_cranelift/src/constant.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -551,7 +551,7 @@ pub(crate) fn mir_operand_get_const_val<'tcx>(
TerminatorKind::Goto { .. }
| TerminatorKind::SwitchInt { .. }
| TerminatorKind::UnwindResume
| TerminatorKind::UnwindTerminate
| TerminatorKind::UnwindTerminate(_)
| TerminatorKind::Return
| TerminatorKind::Unreachable
| TerminatorKind::Drop { .. }
Expand Down
2 changes: 1 addition & 1 deletion compiler/rustc_codegen_ssa/src/mir/analyze.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -285,7 +285,7 @@ pub fn cleanup_kinds(mir: &mir::Body<'_>) -> IndexVec<mir::BasicBlock, CleanupKi
match data.terminator().kind {
TerminatorKind::Goto { .. }
| TerminatorKind::UnwindResume
| TerminatorKind::UnwindTerminate
| TerminatorKind::UnwindTerminate(_)
| TerminatorKind::Return
| TerminatorKind::GeneratorDrop
| TerminatorKind::Unreachable
Expand Down
149 changes: 76 additions & 73 deletions compiler/rustc_codegen_ssa/src/mir/block.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -12,7 +12,7 @@ use crate::MemFlags;
use rustc_ast as ast;
use rustc_ast::{InlineAsmOptions, InlineAsmTemplatePiece};
use rustc_hir::lang_items::LangItem;
use rustc_middle::mir::{self, AssertKind, SwitchTargets};
use rustc_middle::mir::{self, AssertKind, SwitchTargets, UnwindTerminateReason};
use rustc_middle::ty::layout::{HasTyCtxt, LayoutOf, ValidityRequirement};
use rustc_middle::ty::print::{with_no_trimmed_paths, with_no_visible_paths};
use rustc_middle::ty::{self, Instance, Ty};
Expand Down Expand Up @@ -178,7 +178,7 @@ impl<'a, 'tcx> TerminatorCodegenHelper<'tcx> {
mir::UnwindAction::Cleanup(cleanup) => Some(self.llbb_with_cleanup(fx, cleanup)),
mir::UnwindAction::Continue => None,
mir::UnwindAction::Unreachable => None,
mir::UnwindAction::Terminate => {
mir::UnwindAction::Terminate(reason) => {
if fx.mir[self.bb].is_cleanup && base::wants_new_eh_instructions(fx.cx.tcx().sess) {
// MSVC SEH will abort automatically if an exception tries to
// propagate out from cleanup.
Expand All @@ -191,7 +191,7 @@ impl<'a, 'tcx> TerminatorCodegenHelper<'tcx> {

None
} else {
Some(fx.terminate_block())
Some(fx.terminate_block(reason))
}
}
};
Expand Down Expand Up @@ -264,7 +264,7 @@ impl<'a, 'tcx> TerminatorCodegenHelper<'tcx> {
) -> MergingSucc {
let unwind_target = match unwind {
mir::UnwindAction::Cleanup(cleanup) => Some(self.llbb_with_cleanup(fx, cleanup)),
mir::UnwindAction::Terminate => Some(fx.terminate_block()),
mir::UnwindAction::Terminate(reason) => Some(fx.terminate_block(reason)),
mir::UnwindAction::Continue => None,
mir::UnwindAction::Unreachable => None,
};
Expand Down Expand Up @@ -649,12 +649,13 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
helper: TerminatorCodegenHelper<'tcx>,
bx: &mut Bx,
terminator: &mir::Terminator<'tcx>,
reason: UnwindTerminateReason,
) {
let span = terminator.source_info.span;
self.set_debug_loc(bx, terminator.source_info);

// Obtain the panic entry point.
let (fn_abi, llfn) = common::build_langcall(bx, Some(span), LangItem::PanicCannotUnwind);
let (fn_abi, llfn) = common::build_langcall(bx, Some(span), reason.lang_item());

// Codegen the actual panic invoke/call.
let merging_succ = helper.do_call(
Expand Down Expand Up @@ -1229,8 +1230,8 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
MergingSucc::False
}

mir::TerminatorKind::UnwindTerminate => {
self.codegen_terminate_terminator(helper, bx, terminator);
mir::TerminatorKind::UnwindTerminate(reason) => {
self.codegen_terminate_terminator(helper, bx, terminator, reason);
MergingSucc::False
}

Expand Down Expand Up @@ -1579,79 +1580,81 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
})
}

fn terminate_block(&mut self) -> Bx::BasicBlock {
self.terminate_block.unwrap_or_else(|| {
let funclet;
let llbb;
let mut bx;
if base::wants_msvc_seh(self.cx.sess()) {
// This is a basic block that we're aborting the program for,
// notably in an `extern` function. These basic blocks are inserted
// so that we assert that `extern` functions do indeed not panic,
// and if they do we abort the process.
//
// On MSVC these are tricky though (where we're doing funclets). If
// we were to do a cleanuppad (like below) the normal functions like
// `longjmp` would trigger the abort logic, terminating the
// program. Instead we insert the equivalent of `catch(...)` for C++
// which magically doesn't trigger when `longjmp` files over this
// frame.
//
// Lots more discussion can be found on #48251 but this codegen is
// modeled after clang's for:
//
// try {
// foo();
// } catch (...) {
// bar();
// }
//
// which creates an IR snippet like
//
// cs_terminate:
// %cs = catchswitch within none [%cp_terminate] unwind to caller
// cp_terminate:
// %cp = catchpad within %cs [null, i32 64, null]
// ...

llbb = Bx::append_block(self.cx, self.llfn, "cs_terminate");
let cp_llbb = Bx::append_block(self.cx, self.llfn, "cp_terminate");

let mut cs_bx = Bx::build(self.cx, llbb);
let cs = cs_bx.catch_switch(None, None, &[cp_llbb]);

// The "null" here is actually a RTTI type descriptor for the
// C++ personality function, but `catch (...)` has no type so
// it's null. The 64 here is actually a bitfield which
// represents that this is a catch-all block.
bx = Bx::build(self.cx, cp_llbb);
let null =
bx.const_null(bx.type_ptr_ext(bx.cx().data_layout().instruction_address_space));
let sixty_four = bx.const_i32(64);
funclet = Some(bx.catch_pad(cs, &[null, sixty_four, null]));
} else {
llbb = Bx::append_block(self.cx, self.llfn, "terminate");
bx = Bx::build(self.cx, llbb);
fn terminate_block(&mut self, reason: UnwindTerminateReason) -> Bx::BasicBlock {
if let Some((cached_bb, cached_reason)) = self.terminate_block && reason == cached_reason {
return cached_bb;
}

let llpersonality = self.cx.eh_personality();
bx.filter_landing_pad(llpersonality);
let funclet;
let llbb;
let mut bx;
if base::wants_msvc_seh(self.cx.sess()) {
// This is a basic block that we're aborting the program for,
// notably in an `extern` function. These basic blocks are inserted
// so that we assert that `extern` functions do indeed not panic,
// and if they do we abort the process.
//
// On MSVC these are tricky though (where we're doing funclets). If
// we were to do a cleanuppad (like below) the normal functions like
// `longjmp` would trigger the abort logic, terminating the
// program. Instead we insert the equivalent of `catch(...)` for C++
// which magically doesn't trigger when `longjmp` files over this
// frame.
//
// Lots more discussion can be found on #48251 but this codegen is
// modeled after clang's for:
//
// try {
// foo();
// } catch (...) {
// bar();
// }
//
// which creates an IR snippet like
//
// cs_terminate:
// %cs = catchswitch within none [%cp_terminate] unwind to caller
// cp_terminate:
// %cp = catchpad within %cs [null, i32 64, null]
// ...

llbb = Bx::append_block(self.cx, self.llfn, "cs_terminate");
let cp_llbb = Bx::append_block(self.cx, self.llfn, "cp_terminate");

let mut cs_bx = Bx::build(self.cx, llbb);
let cs = cs_bx.catch_switch(None, None, &[cp_llbb]);

// The "null" here is actually a RTTI type descriptor for the
// C++ personality function, but `catch (...)` has no type so
// it's null. The 64 here is actually a bitfield which
// represents that this is a catch-all block.
bx = Bx::build(self.cx, cp_llbb);
let null =
bx.const_null(bx.type_ptr_ext(bx.cx().data_layout().instruction_address_space));
let sixty_four = bx.const_i32(64);
funclet = Some(bx.catch_pad(cs, &[null, sixty_four, null]));
} else {
llbb = Bx::append_block(self.cx, self.llfn, "terminate");
bx = Bx::build(self.cx, llbb);

funclet = None;
}
let llpersonality = self.cx.eh_personality();
bx.filter_landing_pad(llpersonality);

funclet = None;
}

self.set_debug_loc(&mut bx, mir::SourceInfo::outermost(self.mir.span));
self.set_debug_loc(&mut bx, mir::SourceInfo::outermost(self.mir.span));

let (fn_abi, fn_ptr) = common::build_langcall(&bx, None, LangItem::PanicCannotUnwind);
let fn_ty = bx.fn_decl_backend_type(&fn_abi);
let (fn_abi, fn_ptr) = common::build_langcall(&bx, None, reason.lang_item());
let fn_ty = bx.fn_decl_backend_type(&fn_abi);

let llret = bx.call(fn_ty, None, Some(&fn_abi), fn_ptr, &[], funclet.as_ref());
bx.do_not_inline(llret);
let llret = bx.call(fn_ty, None, Some(&fn_abi), fn_ptr, &[], funclet.as_ref());
bx.do_not_inline(llret);

bx.unreachable();
bx.unreachable();

self.terminate_block = Some(llbb);
llbb
})
self.terminate_block = Some((llbb, reason));
llbb
}

/// Get the backend `BasicBlock` for a MIR `BasicBlock`, either already
Expand Down
7 changes: 4 additions & 3 deletions compiler/rustc_codegen_ssa/src/mir/mod.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,7 @@ use rustc_index::IndexVec;
use rustc_middle::mir;
use rustc_middle::mir::interpret::ErrorHandled;
use rustc_middle::mir::traversal;
use rustc_middle::mir::UnwindTerminateReason;
use rustc_middle::ty::layout::{FnAbiOf, HasTyCtxt, TyAndLayout};
use rustc_middle::ty::{self, Instance, Ty, TyCtxt, TypeFoldable, TypeVisitableExt};
use rustc_target::abi::call::{FnAbi, PassMode};
Expand Down Expand Up @@ -83,8 +84,8 @@ pub struct FunctionCx<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> {
/// Cached unreachable block
unreachable_block: Option<Bx::BasicBlock>,

/// Cached terminate upon unwinding block
terminate_block: Option<Bx::BasicBlock>,
/// Cached terminate upon unwinding block and its reason
terminate_block: Option<(Bx::BasicBlock, UnwindTerminateReason)>,

/// The location where each MIR arg/var/tmp/ret is stored. This is
/// usually an `PlaceRef` representing an alloca, but not always:
Expand Down Expand Up @@ -174,7 +175,7 @@ pub fn codegen_mir<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
let mut start_bx = Bx::build(cx, start_llbb);

if mir.basic_blocks.iter().any(|bb| {
bb.is_cleanup || matches!(bb.terminator().unwind(), Some(mir::UnwindAction::Terminate))
bb.is_cleanup || matches!(bb.terminator().unwind(), Some(mir::UnwindAction::Terminate(_)))
}) {
start_bx.set_personality_fn(cx.eh_personality());
}
Expand Down
5 changes: 3 additions & 2 deletions compiler/rustc_const_eval/src/interpret/eval_context.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -756,16 +756,17 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
///
/// If `target` is `UnwindAction::Unreachable`, that indicates the function does not allow
/// unwinding, and doing so is UB.
#[cold] // usually we have normal returns, not unwinding
pub fn unwind_to_block(&mut self, target: mir::UnwindAction) -> InterpResult<'tcx> {
self.frame_mut().loc = match target {
mir::UnwindAction::Cleanup(block) => Left(mir::Location { block, statement_index: 0 }),
mir::UnwindAction::Continue => Right(self.frame_mut().body.span),
mir::UnwindAction::Unreachable => {
throw_ub_custom!(fluent::const_eval_unreachable_unwind);
}
mir::UnwindAction::Terminate => {
mir::UnwindAction::Terminate(reason) => {
self.frame_mut().loc = Right(self.frame_mut().body.span);
M::unwind_terminate(self)?;
M::unwind_terminate(self, reason)?;
// This might have pushed a new stack frame, or it terminated execution.
// Either way, `loc` will not be updated.
return Ok(());
Expand Down
11 changes: 9 additions & 2 deletions compiler/rustc_const_eval/src/interpret/machine.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -222,7 +222,10 @@ pub trait Machine<'mir, 'tcx: 'mir>: Sized {
fn panic_nounwind(_ecx: &mut InterpCx<'mir, 'tcx, Self>, msg: &str) -> InterpResult<'tcx>;

/// Called when unwinding reached a state where execution should be terminated.
fn unwind_terminate(_ecx: &mut InterpCx<'mir, 'tcx, Self>) -> InterpResult<'tcx>;
fn unwind_terminate(
ecx: &mut InterpCx<'mir, 'tcx, Self>,
reason: mir::UnwindTerminateReason,
) -> InterpResult<'tcx>;

/// Called for all binary operations where the LHS has pointer type.
///
Expand Down Expand Up @@ -462,6 +465,7 @@ pub trait Machine<'mir, 'tcx: 'mir>: Sized {

/// Called immediately after a stack frame got popped, but before jumping back to the caller.
/// The `locals` have already been destroyed!
#[inline(always)]
fn after_stack_pop(
_ecx: &mut InterpCx<'mir, 'tcx, Self>,
_frame: Frame<'mir, 'tcx, Self::Provenance, Self::FrameExtra>,
Expand Down Expand Up @@ -501,7 +505,10 @@ pub macro compile_time_machine(<$mir: lifetime, $tcx: lifetime>) {
}

#[inline(always)]
fn unwind_terminate(_ecx: &mut InterpCx<$mir, $tcx, Self>) -> InterpResult<$tcx> {
fn unwind_terminate(
_ecx: &mut InterpCx<$mir, $tcx, Self>,
_reason: mir::UnwindTerminateReason,
) -> InterpResult<$tcx> {
unreachable!("unwinding cannot happen during compile-time evaluation")
}

Expand Down

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