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[MIR] implement zero-on-move #31449
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[MIR] implement zero-on-move #31449
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,104 @@ | ||
| // Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT | ||
| // file at the top-level directory of this distribution and at | ||
| // http://rust-lang.org/COPYRIGHT. | ||
| // | ||
| // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or | ||
| // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license | ||
| // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your | ||
| // option. This file may not be copied, modified, or distributed | ||
| // except according to those terms. | ||
|
|
||
| use llvm::ValueRef; | ||
| use rustc::middle::ty::Ty; | ||
| use rustc::mir::repr as mir; | ||
| use trans::adt; | ||
| use trans::base; | ||
| use trans::build; | ||
| use trans::common::{self, Block}; | ||
| use trans::debuginfo::DebugLoc; | ||
| use trans::glue; | ||
| use trans::machine; | ||
| use trans::type_of; | ||
| use trans::type_::Type; | ||
|
|
||
| use super::{MirContext, TempRef}; | ||
|
|
||
| impl<'bcx, 'tcx> MirContext<'bcx, 'tcx> { | ||
| pub fn trans_drop(&mut self, | ||
| bcx: Block<'bcx, 'tcx>, | ||
| value: &mir::Lvalue<'tcx>, | ||
| target: mir::BasicBlock, | ||
| unwind: Option<mir::BasicBlock>) { | ||
| let lvalue = self.trans_lvalue(bcx, value); | ||
| let ty = lvalue.ty.to_ty(bcx.tcx()); | ||
| // Double check for necessity to drop | ||
| if !glue::type_needs_drop(bcx.tcx(), ty) { | ||
| build::Br(bcx, self.llblock(target), DebugLoc::None); | ||
| return; | ||
| } | ||
| let drop_fn = glue::get_drop_glue(bcx.ccx(), ty); | ||
| let drop_ty = glue::get_drop_glue_type(bcx.ccx(), ty); | ||
| let llvalue = if drop_ty != ty { | ||
| build::PointerCast(bcx, lvalue.llval, | ||
| type_of::type_of(bcx.ccx(), drop_ty).ptr_to()) | ||
| } else { | ||
| lvalue.llval | ||
| }; | ||
| if let Some(unwind) = unwind { | ||
| // block cannot be cleanup in this case, so a regular block is fine | ||
| let intermediate_bcx = bcx.fcx.new_block("", None); | ||
| let uwbcx = self.bcx(unwind); | ||
| let unwind = self.make_landing_pad(uwbcx); | ||
| // FIXME: it could be possible to do zeroing before invoking here if the drop glue | ||
| // didn’t code in the checks inside itself. | ||
| build::Invoke(bcx, | ||
| drop_fn, | ||
| &[llvalue], | ||
| intermediate_bcx.llbb, | ||
| unwind.llbb, | ||
| None, | ||
| DebugLoc::None); | ||
| // FIXME: perhaps we also should fill inside failed branch? We do not want to re-drop a | ||
| // failed drop again by mistake. (conflicts with MSVC SEH if we don’t want to introduce | ||
| // a heap of hacks) | ||
| self.drop_fill(intermediate_bcx, lvalue.llval, ty); | ||
| build::Br(intermediate_bcx, self.llblock(target), DebugLoc::None); | ||
| } else { | ||
| build::Call(bcx, drop_fn, &[llvalue], None, DebugLoc::None); | ||
| self.drop_fill(bcx, lvalue.llval, ty); | ||
| build::Br(bcx, self.llblock(target), DebugLoc::None); | ||
| } | ||
| } | ||
|
|
||
| pub fn drop_fill(&mut self, bcx: Block<'bcx, 'tcx>, value: ValueRef, ty: Ty<'tcx>) { | ||
| let llty = type_of::type_of(bcx.ccx(), ty); | ||
| let llptr = build::PointerCast(bcx, value, Type::i8(bcx.ccx()).ptr_to()); | ||
| let filling = common::C_u8(bcx.ccx(), adt::DTOR_DONE); | ||
| let size = machine::llsize_of(bcx.ccx(), llty); | ||
| let align = common::C_u32(bcx.ccx(), machine::llalign_of_min(bcx.ccx(), llty)); | ||
| base::call_memset(&build::B(bcx), llptr, filling, size, align, false); | ||
| } | ||
|
|
||
| pub fn set_operand_dropped(&mut self, | ||
| bcx: Block<'bcx, 'tcx>, | ||
| operand: &mir::Operand<'tcx>) { | ||
| match *operand { | ||
| mir::Operand::Constant(_) => return, | ||
| mir::Operand::Consume(ref lvalue) => { | ||
| if let mir::Lvalue::Temp(idx) = *lvalue { | ||
| if let TempRef::Operand(..) = self.temps[idx as usize] { | ||
| return // we do not handle these, should we? | ||
| } | ||
| } | ||
| let lvalue = self.trans_lvalue(bcx, lvalue); | ||
| let ty = lvalue.ty.to_ty(bcx.tcx()); | ||
| if !glue::type_needs_drop(bcx.tcx(), ty) || | ||
| common::type_is_fat_ptr(bcx.tcx(), ty) { | ||
| return | ||
| } else { | ||
| self.drop_fill(bcx, lvalue.llval, ty); | ||
| } | ||
| } | ||
| } | ||
| } | ||
| } | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
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@@ -196,6 +196,7 @@ mod analyze; | |
| mod block; | ||
| mod constant; | ||
| mod did; | ||
| mod drop; | ||
| mod lvalue; | ||
| mod operand; | ||
| mod rvalue; | ||
|
|
||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,43 @@ | ||
| // Copyright 2016 The Rust Project Developers. See the COPYRIGHT | ||
| // file at the top-level directory of this distribution and at | ||
| // http://rust-lang.org/COPYRIGHT. | ||
| // | ||
| // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or | ||
| // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license | ||
| // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your | ||
| // option. This file may not be copied, modified, or distributed | ||
| // except according to those terms. | ||
| #![feature(rustc_attrs)] | ||
| // error-pattern:drop 1 | ||
| // error-pattern:drop 2 | ||
| use std::io::{self, Write}; | ||
|
|
||
|
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||
| /// Structure which will not allow to be dropped twice. | ||
| struct Droppable<'a>(&'a mut bool, u32); | ||
| impl<'a> Drop for Droppable<'a> { | ||
| fn drop(&mut self) { | ||
| if *self.0 { | ||
| writeln!(io::stderr(), "{} dropped twice", self.1); | ||
| ::std::process::exit(1); | ||
| } | ||
| writeln!(io::stderr(), "drop {}", self.1); | ||
| *self.0 = true; | ||
| } | ||
| } | ||
|
|
||
| #[rustc_mir] | ||
| fn mir(){ | ||
| let mut b1 = false; | ||
| let mut b2 = false; | ||
| let x = Droppable(&mut b1, 1); | ||
| let y = Droppable(&mut b2, 2); | ||
| let mut z = x; | ||
| let k = y; | ||
| z = k; | ||
| } | ||
|
|
||
| fn main() { | ||
| mir(); | ||
| panic!(); | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,40 @@ | ||
| // Copyright 2016 The Rust Project Developers. See the COPYRIGHT | ||
| // file at the top-level directory of this distribution and at | ||
| // http://rust-lang.org/COPYRIGHT. | ||
| // | ||
| // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or | ||
| // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license | ||
| // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your | ||
| // option. This file may not be copied, modified, or distributed | ||
| // except according to those terms. | ||
| #![feature(rustc_attrs)] | ||
| // error-pattern:drop 1 | ||
| use std::io::{self, Write}; | ||
|
|
||
|
|
||
| /// Structure which will not allow to be dropped twice. | ||
| struct Droppable<'a>(&'a mut bool, u32); | ||
| impl<'a> Drop for Droppable<'a> { | ||
| fn drop(&mut self) { | ||
| if *self.0 { | ||
| writeln!(io::stderr(), "{} dropped twice", self.1); | ||
| ::std::process::exit(1); | ||
| } | ||
| writeln!(io::stderr(), "drop {}", self.1); | ||
| *self.0 = true; | ||
| } | ||
| } | ||
|
|
||
| #[rustc_mir] | ||
| fn mir(d: Droppable){ | ||
| loop { | ||
| let x = d; | ||
| break; | ||
| } | ||
| } | ||
|
|
||
| fn main() { | ||
| let mut d1 = false; | ||
| mir(Droppable(&mut d1, 1)); | ||
| panic!(); | ||
| } |
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This also feels seriously hacky to me, but I don’t see an obvious way to dropflag-fill a
OperandValue::Immediate.There was a problem hiding this comment.
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You could use an out-of-line drop flag for these