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Pull out get_or_create landing pad to avoid issues with dynamic borrowck.

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Mark-Simulacrum 2016-12-12 15:08:12 -07:00 • committed by Mark Simulacrum
parent 48715a15ff
commit da971b7652
1 changed files with 73 additions and 60 deletions
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133
src/librustc_trans/cleanup.rs
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@ -242,6 +242,78 @@ impl<'blk, 'tcx> FunctionContext<'blk, 'tcx> {
self.scopes.borrow().iter().rev().any(|s| s.needs_invoke())
}
/// Creates a landing pad for the top scope, if one does not exist. The
/// landing pad will perform all cleanups necessary for an unwind and then
/// `resume` to continue error propagation:
///
/// landing_pad -> ... cleanups ... -> [resume]
///
/// (The cleanups and resume instruction are created by
/// `trans_cleanups_to_exit_scope()`, not in this function itself.)
fn get_or_create_landing_pad(&'blk self) -> BasicBlockRef {
let pad_bcx;
debug!("get_or_create_landing_pad");
// Check if a landing pad block exists; if not, create one.
{
let mut scopes = self.scopes.borrow_mut();
let last_scope = scopes.last_mut().unwrap();
match last_scope.cached_landing_pad {
Some(llbb) => return llbb,
None => {
let name = last_scope.block_name("unwind");
pad_bcx = self.build_new_block(&name[..]);
last_scope.cached_landing_pad = Some(pad_bcx.llbb());
}
}
};
let llpersonality = pad_bcx.fcx().eh_personality();
let val = if base::wants_msvc_seh(self.ccx.sess()) {
// A cleanup pad requires a personality function to be specified, so
// we do that here explicitly (happens implicitly below through
// creation of the landingpad instruction). We then create a
// cleanuppad instruction which has no filters to run cleanup on all
// exceptions.
pad_bcx.set_personality_fn(llpersonality);
let llretval = pad_bcx.cleanup_pad(None, &[]);
UnwindKind::CleanupPad(llretval)
} else {
// The landing pad return type (the type being propagated). Not sure
// what this represents but it's determined by the personality
// function and this is what the EH proposal example uses.
let llretty = Type::struct_(self.ccx,
&[Type::i8p(self.ccx), Type::i32(self.ccx)],
false);
// The only landing pad clause will be 'cleanup'
let llretval = pad_bcx.landing_pad(llretty, llpersonality, 1, pad_bcx.fcx().llfn);
// The landing pad block is a cleanup
pad_bcx.set_cleanup(llretval);
let addr = match self.landingpad_alloca.get() {
Some(addr) => addr,
None => {
let addr = base::alloca(&pad_bcx, common::val_ty(llretval), "");
Lifetime::Start.call(&pad_bcx, addr);
self.landingpad_alloca.set(Some(addr));
addr
}
};
pad_bcx.store(llretval, addr);
UnwindKind::LandingPad
};
// Generate the cleanup block and branch to it.
let cleanup_llbb = self.trans_cleanups_to_exit_scope(val);
val.branch(&pad_bcx, cleanup_llbb);
return pad_bcx.llbb();
}
/// Returns a basic block to branch to in the event of a panic. This block
/// will run the panic cleanups and eventually resume the exception that
/// caused the landing pad to be run.
@ -260,66 +332,7 @@ impl<'blk, 'tcx> FunctionContext<'blk, 'tcx> {
popped_scopes.push(self.pop_scope());
}
// Creates a landing pad for the top scope, if one does not exist. The
// landing pad will perform all cleanups necessary for an unwind and then
// `resume` to continue error propagation:
//
// landing_pad -> ... cleanups ... -> [resume]
//
// (The cleanups and resume instruction are created by
// `trans_cleanups_to_exit_scope()`, not in this function itself.)
let mut scopes = self.scopes.borrow_mut();
let last_scope = scopes.last_mut().unwrap();
let llbb = if let Some(llbb) = last_scope.cached_landing_pad {
llbb
} else {
let name = last_scope.block_name("unwind");
let pad_bcx = self.build_new_block(&name[..]);
last_scope.cached_landing_pad = Some(pad_bcx.llbb());
let llpersonality = pad_bcx.fcx().eh_personality();
let val = if base::wants_msvc_seh(self.ccx.sess()) {
// A cleanup pad requires a personality function to be specified, so
// we do that here explicitly (happens implicitly below through
// creation of the landingpad instruction). We then create a
// cleanuppad instruction which has no filters to run cleanup on all
// exceptions.
pad_bcx.set_personality_fn(llpersonality);
let llretval = pad_bcx.cleanup_pad(None, &[]);
UnwindKind::CleanupPad(llretval)
} else {
// The landing pad return type (the type being propagated). Not sure
// what this represents but it's determined by the personality
// function and this is what the EH proposal example uses.
let llretty = Type::struct_(self.ccx,
&[Type::i8p(self.ccx), Type::i32(self.ccx)],
false);
// The only landing pad clause will be 'cleanup'
let llretval = pad_bcx.landing_pad(llretty, llpersonality, 1,
pad_bcx.fcx().llfn);
// The landing pad block is a cleanup
pad_bcx.set_cleanup(llretval);
let addr = match self.landingpad_alloca.get() {
Some(addr) => addr,
None => {
let addr = base::alloca(&pad_bcx, common::val_ty(llretval), "");
Lifetime::Start.call(&pad_bcx, addr);
self.landingpad_alloca.set(Some(addr));
addr
}
};
pad_bcx.store(llretval, addr);
UnwindKind::LandingPad
};
// Generate the cleanup block and branch to it.
let cleanup_llbb = self.trans_cleanups_to_exit_scope(val);
val.branch(&pad_bcx, cleanup_llbb);
pad_bcx.llbb()
};
let llbb = self.get_or_create_landing_pad();
// Push the scopes we removed back on:
loop {