/
block.rs
261 lines (237 loc) · 12.3 KB
/
block.rs
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// 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::{BasicBlockRef, ValueRef};
use rustc::mir::repr as mir;
use trans::adt;
use trans::base;
use trans::build;
use trans::attributes;
use trans::common::{self, Block};
use trans::debuginfo::DebugLoc;
use trans::type_of;
use trans::type_::Type;
use super::MirContext;
use super::operand::OperandValue::{FatPtr, Immediate, Ref};
impl<'bcx, 'tcx> MirContext<'bcx, 'tcx> {
pub fn trans_block(&mut self, bb: mir::BasicBlock) {
debug!("trans_block({:?})", bb);
let mut bcx = self.bcx(bb);
let data = self.mir.basic_block_data(bb);
for statement in &data.statements {
bcx = self.trans_statement(bcx, statement);
}
debug!("trans_block: terminator: {:?}", data.terminator());
match *data.terminator() {
mir::Terminator::Goto { target } => {
build::Br(bcx, self.llblock(target), DebugLoc::None)
}
mir::Terminator::If { ref cond, targets: (true_bb, false_bb) } => {
let cond = self.trans_operand(bcx, cond);
let lltrue = self.llblock(true_bb);
let llfalse = self.llblock(false_bb);
build::CondBr(bcx, cond.immediate(), lltrue, llfalse, DebugLoc::None);
}
mir::Terminator::Switch { ref discr, ref adt_def, ref targets } => {
let discr_lvalue = self.trans_lvalue(bcx, discr);
let ty = discr_lvalue.ty.to_ty(bcx.tcx());
let repr = adt::represent_type(bcx.ccx(), ty);
let discr = adt::trans_get_discr(bcx, &repr, discr_lvalue.llval, None);
// The else branch of the Switch can't be hit, so branch to an unreachable
// instruction so LLVM knows that
let unreachable_blk = self.unreachable_block();
let switch = build::Switch(bcx, discr, unreachable_blk.llbb, targets.len());
assert_eq!(adt_def.variants.len(), targets.len());
for (adt_variant, target) in adt_def.variants.iter().zip(targets) {
let llval = adt::trans_case(bcx, &*repr, adt_variant.disr_val);
let llbb = self.llblock(*target);
build::AddCase(switch, llval, llbb)
}
}
mir::Terminator::SwitchInt { ref discr, switch_ty, ref values, ref targets } => {
let (otherwise, targets) = targets.split_last().unwrap();
let discr = build::Load(bcx, self.trans_lvalue(bcx, discr).llval);
let switch = build::Switch(bcx, discr, self.llblock(*otherwise), values.len());
for (value, target) in values.iter().zip(targets) {
let llval = self.trans_constval(bcx, value, switch_ty).immediate();
let llbb = self.llblock(*target);
build::AddCase(switch, llval, llbb)
}
}
mir::Terminator::Resume => {
let ps = self.get_personality_slot(bcx);
let lp = build::Load(bcx, ps);
base::call_lifetime_end(bcx, ps);
base::trans_unwind_resume(bcx, lp);
}
mir::Terminator::Return => {
let return_ty = bcx.monomorphize(&self.mir.return_ty);
base::build_return_block(bcx.fcx, bcx, return_ty, DebugLoc::None);
}
mir::Terminator::Call { ref func, ref args, ref kind } => {
// Create the callee. This will always be a fn ptr and hence a kind of scalar.
let callee = self.trans_operand(bcx, func);
let attrs = attributes::from_fn_type(bcx.ccx(), callee.ty);
let debugloc = DebugLoc::None;
// The arguments we'll be passing. Plus one to account for outptr, if used.
let mut llargs = Vec::with_capacity(args.len() + 1);
// Prepare the return value destination
let (ret_dest_ty, must_copy_dest) = if let Some(d) = kind.destination() {
let dest = self.trans_lvalue(bcx, d);
let ret_ty = dest.ty.to_ty(bcx.tcx());
if type_of::return_uses_outptr(bcx.ccx(), ret_ty) {
llargs.push(dest.llval);
(Some((dest, ret_ty)), false)
} else {
(Some((dest, ret_ty)), !common::type_is_zero_size(bcx.ccx(), ret_ty))
}
} else {
(None, false)
};
// Process the rest of the args.
for arg in args {
match self.trans_operand(bcx, arg).val {
Ref(llval) | Immediate(llval) => llargs.push(llval),
FatPtr(b, e) => {
llargs.push(b);
llargs.push(e);
}
}
}
// Many different ways to call a function handled here
match (base::avoid_invoke(bcx), kind) {
// The two cases below are the only ones to use LLVM’s `invoke`.
(false, &mir::CallKind::DivergingCleanup(cleanup)) => {
let cleanup = self.bcx(cleanup);
let landingpad = self.make_landing_pad(cleanup);
build::Invoke(bcx,
callee.immediate(),
&llargs[..],
self.unreachable_block().llbb,
landingpad.llbb,
Some(attrs),
debugloc);
},
(false, &mir::CallKind::ConvergingCleanup { ref targets, .. }) => {
let cleanup = self.bcx(targets.1);
let landingpad = self.make_landing_pad(cleanup);
let (target, postinvoke) = if must_copy_dest {
(bcx.fcx.new_block(false, "", None), Some(self.bcx(targets.0)))
} else {
(self.bcx(targets.0), None)
};
let invokeret = build::Invoke(bcx,
callee.immediate(),
&llargs[..],
target.llbb,
landingpad.llbb,
Some(attrs),
debugloc);
if let Some(postinvoketarget) = postinvoke {
// We translate the copy into a temoprary block. The temporary block is
// necessary because the current block has already been terminated (by
// `invoke`) and we cannot really translate into the target block
// because:
// * The target block may have more than a single precedesor;
// * Some LLVM insns cannot have a preceeding store insn (phi,
// cleanuppad), and adding/prepending the store now may render
// those other instructions invalid.
//
// NB: This approach still may break some LLVM code. For example if the
// target block starts with a `phi` (which may only match on immediate
// precedesors), it cannot know about this temporary block thus
// resulting in an invalid code:
//
// this:
// …
// %0 = …
// %1 = invoke to label %temp …
// temp:
// store ty %1, ty* %dest
// br label %actualtargetblock
// actualtargetblock: ; preds: %temp, …
// phi … [%this, …], [%0, …] ; ERROR: phi requires to match only on
// ; immediate precedesors
let (ret_dest, ret_ty) = ret_dest_ty
.expect("return destination and type not set");
base::store_ty(target, invokeret, ret_dest.llval, ret_ty);
build::Br(target, postinvoketarget.llbb, debugloc);
}
},
(_, &mir::CallKind::DivergingCleanup(_)) |
(_, &mir::CallKind::Diverging) => {
build::Call(bcx, callee.immediate(), &llargs[..], Some(attrs), debugloc);
build::Unreachable(bcx);
}
(_, k@&mir::CallKind::ConvergingCleanup { .. }) |
(_, k@&mir::CallKind::Converging { .. }) => {
// Bug #20046
let target = match *k {
mir::CallKind::ConvergingCleanup { targets, .. } => targets.0,
mir::CallKind::Converging { target, .. } => target,
_ => unreachable!()
};
let llret = build::Call(bcx,
callee.immediate(),
&llargs[..],
Some(attrs),
debugloc);
if must_copy_dest {
let (ret_dest, ret_ty) = ret_dest_ty
.expect("return destination and type not set");
base::store_ty(bcx, llret, ret_dest.llval, ret_ty);
}
build::Br(bcx, self.llblock(target), debugloc);
}
}
}
}
}
fn get_personality_slot(&mut self, bcx: Block<'bcx, 'tcx>) -> ValueRef {
let ccx = bcx.ccx();
if let Some(slot) = self.llpersonalityslot {
slot
} else {
let llretty = Type::struct_(ccx, &[Type::i8p(ccx), Type::i32(ccx)], false);
let slot = base::alloca(bcx, llretty, "personalityslot");
self.llpersonalityslot = Some(slot);
base::call_lifetime_start(bcx, slot);
slot
}
}
fn make_landing_pad(&mut self, cleanup: Block<'bcx, 'tcx>) -> Block<'bcx, 'tcx> {
let bcx = cleanup.fcx.new_block(true, "cleanup", None);
let ccx = bcx.ccx();
let llpersonality = bcx.fcx.eh_personality();
let llretty = Type::struct_(ccx, &[Type::i8p(ccx), Type::i32(ccx)], false);
let llretval = build::LandingPad(bcx, llretty, llpersonality, 1);
build::SetCleanup(bcx, llretval);
let slot = self.get_personality_slot(bcx);
build::Store(bcx, llretval, slot);
build::Br(bcx, cleanup.llbb, DebugLoc::None);
bcx
}
fn unreachable_block(&mut self) -> Block<'bcx, 'tcx> {
match self.unreachable_block {
Some(b) => b,
None => {
let bl = self.fcx.new_block(false, "unreachable", None);
build::Unreachable(bl);
self.unreachable_block = Some(bl);
bl
}
}
}
fn bcx(&self, bb: mir::BasicBlock) -> Block<'bcx, 'tcx> {
self.blocks[bb.index()]
}
fn llblock(&self, bb: mir::BasicBlock) -> BasicBlockRef {
self.blocks[bb.index()].llbb
}
}