41b74b11b4
Supersedes https://github.com/rust-lang/rust/pull/30517 Fixes https://github.com/rust-lang/rust/issues/29575 cc @luqmana r? @nikomatsakis
301 lines
14 KiB
Rust
301 lines
14 KiB
Rust
// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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use llvm::{BasicBlockRef, ValueRef};
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use rustc::middle::ty;
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use rustc::mir::repr as mir;
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use syntax::abi::Abi;
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use trans::adt;
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use trans::attributes;
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use trans::base;
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use trans::build;
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use trans::common::{self, Block};
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use trans::debuginfo::DebugLoc;
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use trans::foreign;
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use trans::type_of;
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use trans::type_::Type;
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use trans::Disr;
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use super::MirContext;
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use super::operand::OperandValue::{FatPtr, Immediate, Ref};
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impl<'bcx, 'tcx> MirContext<'bcx, 'tcx> {
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pub fn trans_block(&mut self, bb: mir::BasicBlock) {
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debug!("trans_block({:?})", bb);
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let mut bcx = self.bcx(bb);
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let data = self.mir.basic_block_data(bb);
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for statement in &data.statements {
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bcx = self.trans_statement(bcx, statement);
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}
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debug!("trans_block: terminator: {:?}", data.terminator());
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match *data.terminator() {
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mir::Terminator::Goto { target } => {
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build::Br(bcx, self.llblock(target), DebugLoc::None)
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}
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mir::Terminator::If { ref cond, targets: (true_bb, false_bb) } => {
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let cond = self.trans_operand(bcx, cond);
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let lltrue = self.llblock(true_bb);
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let llfalse = self.llblock(false_bb);
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build::CondBr(bcx, cond.immediate(), lltrue, llfalse, DebugLoc::None);
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}
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mir::Terminator::Switch { ref discr, ref adt_def, ref targets } => {
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let discr_lvalue = self.trans_lvalue(bcx, discr);
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let ty = discr_lvalue.ty.to_ty(bcx.tcx());
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let repr = adt::represent_type(bcx.ccx(), ty);
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let discr = adt::trans_get_discr(bcx, &repr, discr_lvalue.llval, None);
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// The else branch of the Switch can't be hit, so branch to an unreachable
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// instruction so LLVM knows that
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let unreachable_blk = self.unreachable_block();
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let switch = build::Switch(bcx, discr, unreachable_blk.llbb, targets.len());
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assert_eq!(adt_def.variants.len(), targets.len());
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for (adt_variant, target) in adt_def.variants.iter().zip(targets) {
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let llval = adt::trans_case(bcx, &*repr, Disr::from(adt_variant.disr_val));
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let llbb = self.llblock(*target);
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build::AddCase(switch, llval, llbb)
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}
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}
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mir::Terminator::SwitchInt { ref discr, switch_ty, ref values, ref targets } => {
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let (otherwise, targets) = targets.split_last().unwrap();
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let discr = build::Load(bcx, self.trans_lvalue(bcx, discr).llval);
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let switch = build::Switch(bcx, discr, self.llblock(*otherwise), values.len());
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for (value, target) in values.iter().zip(targets) {
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let llval = self.trans_constval(bcx, value, switch_ty).immediate();
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let llbb = self.llblock(*target);
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build::AddCase(switch, llval, llbb)
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}
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}
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mir::Terminator::Resume => {
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let ps = self.get_personality_slot(bcx);
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let lp = build::Load(bcx, ps);
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base::call_lifetime_end(bcx, ps);
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base::trans_unwind_resume(bcx, lp);
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}
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mir::Terminator::Return => {
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let return_ty = bcx.monomorphize(&self.mir.return_ty);
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base::build_return_block(bcx.fcx, bcx, return_ty, DebugLoc::None);
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}
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mir::Terminator::Call { ref func, ref args, ref kind } => {
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// Create the callee. This will always be a fn ptr and hence a kind of scalar.
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let callee = self.trans_operand(bcx, func);
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let attrs = attributes::from_fn_type(bcx.ccx(), callee.ty);
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let debugloc = DebugLoc::None;
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// The arguments we'll be passing. Plus one to account for outptr, if used.
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let mut llargs = Vec::with_capacity(args.len() + 1);
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// Types of the arguments. We do not preallocate, because this vector is only
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// filled when `is_foreign` is `true` and foreign calls are minority of the cases.
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let mut arg_tys = Vec::new();
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// Foreign-ABI functions are translated differently
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let is_foreign = if let ty::TyBareFn(_, ref f) = callee.ty.sty {
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// We do not translate intrinsics here (they shouldn’t be functions)
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assert!(f.abi != Abi::RustIntrinsic && f.abi != Abi::PlatformIntrinsic);
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f.abi != Abi::Rust && f.abi != Abi::RustCall
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} else {
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false
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};
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// Prepare the return value destination
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let (ret_dest_ty, must_copy_dest) = if let Some(d) = kind.destination() {
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let dest = self.trans_lvalue(bcx, d);
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let ret_ty = dest.ty.to_ty(bcx.tcx());
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if !is_foreign && type_of::return_uses_outptr(bcx.ccx(), ret_ty) {
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llargs.push(dest.llval);
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(Some((dest, ret_ty)), false)
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} else {
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(Some((dest, ret_ty)), !common::type_is_zero_size(bcx.ccx(), ret_ty))
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}
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} else {
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(None, false)
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};
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// Process the rest of the args.
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for arg in args {
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let operand = self.trans_operand(bcx, arg);
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match operand.val {
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Ref(llval) | Immediate(llval) => llargs.push(llval),
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FatPtr(b, e) => {
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llargs.push(b);
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llargs.push(e);
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}
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}
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if is_foreign {
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arg_tys.push(operand.ty);
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}
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}
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// Many different ways to call a function handled here
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match (is_foreign, base::avoid_invoke(bcx), kind) {
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// The two cases below are the only ones to use LLVM’s `invoke`.
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(false, false, &mir::CallKind::DivergingCleanup(cleanup)) => {
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let cleanup = self.bcx(cleanup);
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let landingpad = self.make_landing_pad(cleanup);
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let unreachable_blk = self.unreachable_block();
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build::Invoke(bcx,
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callee.immediate(),
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&llargs[..],
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unreachable_blk.llbb,
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landingpad.llbb,
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Some(attrs),
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debugloc);
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},
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(false, false, &mir::CallKind::ConvergingCleanup { ref targets, .. }) => {
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let cleanup = self.bcx(targets.1);
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let landingpad = self.make_landing_pad(cleanup);
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let (target, postinvoke) = if must_copy_dest {
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(bcx.fcx.new_block(false, "", None), Some(self.bcx(targets.0)))
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} else {
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(self.bcx(targets.0), None)
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};
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let invokeret = build::Invoke(bcx,
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callee.immediate(),
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&llargs[..],
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target.llbb,
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landingpad.llbb,
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Some(attrs),
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debugloc);
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if let Some(postinvoketarget) = postinvoke {
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// We translate the copy into a temoprary block. The temporary block is
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// necessary because the current block has already been terminated (by
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// `invoke`) and we cannot really translate into the target block
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// because:
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// * The target block may have more than a single precedesor;
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// * Some LLVM insns cannot have a preceeding store insn (phi,
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// cleanuppad), and adding/prepending the store now may render
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// those other instructions invalid.
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//
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// NB: This approach still may break some LLVM code. For example if the
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// target block starts with a `phi` (which may only match on immediate
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// precedesors), it cannot know about this temporary block thus
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// resulting in an invalid code:
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//
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// this:
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// …
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// %0 = …
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// %1 = invoke to label %temp …
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// temp:
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// store ty %1, ty* %dest
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// br label %actualtargetblock
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// actualtargetblock: ; preds: %temp, …
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// phi … [%this, …], [%0, …] ; ERROR: phi requires to match only on
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// ; immediate precedesors
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let (ret_dest, ret_ty) = ret_dest_ty
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.expect("return destination and type not set");
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base::store_ty(target, invokeret, ret_dest.llval, ret_ty);
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build::Br(target, postinvoketarget.llbb, debugloc);
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}
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},
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(false, _, &mir::CallKind::DivergingCleanup(_)) |
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(false, _, &mir::CallKind::Diverging) => {
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build::Call(bcx, callee.immediate(), &llargs[..], Some(attrs), debugloc);
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build::Unreachable(bcx);
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}
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(false, _, k@&mir::CallKind::ConvergingCleanup { .. }) |
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(false, _, k@&mir::CallKind::Converging { .. }) => {
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// FIXME: Bug #20046
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let target = match *k {
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mir::CallKind::ConvergingCleanup { targets, .. } => targets.0,
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mir::CallKind::Converging { target, .. } => target,
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_ => unreachable!()
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};
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let llret = build::Call(bcx,
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callee.immediate(),
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&llargs[..],
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Some(attrs),
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debugloc);
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if must_copy_dest {
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let (ret_dest, ret_ty) = ret_dest_ty
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.expect("return destination and type not set");
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base::store_ty(bcx, llret, ret_dest.llval, ret_ty);
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}
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build::Br(bcx, self.llblock(target), debugloc);
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}
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// Foreign functions
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(true, _, k) => {
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let (dest, _) = ret_dest_ty
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.expect("return destination is not set");
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bcx = foreign::trans_native_call(bcx,
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callee.ty,
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callee.immediate(),
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dest.llval,
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&llargs[..],
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arg_tys,
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debugloc);
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match *k {
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mir::CallKind::ConvergingCleanup { targets, .. } =>
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build::Br(bcx, self.llblock(targets.0), debugloc),
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mir::CallKind::Converging { target, .. } =>
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build::Br(bcx, self.llblock(target), debugloc),
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_ => ()
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};
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},
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}
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}
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}
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}
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fn get_personality_slot(&mut self, bcx: Block<'bcx, 'tcx>) -> ValueRef {
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let ccx = bcx.ccx();
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if let Some(slot) = self.llpersonalityslot {
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slot
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} else {
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let llretty = Type::struct_(ccx, &[Type::i8p(ccx), Type::i32(ccx)], false);
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let slot = base::alloca(bcx, llretty, "personalityslot");
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self.llpersonalityslot = Some(slot);
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base::call_lifetime_start(bcx, slot);
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slot
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}
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}
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fn make_landing_pad(&mut self, cleanup: Block<'bcx, 'tcx>) -> Block<'bcx, 'tcx> {
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let bcx = cleanup.fcx.new_block(true, "cleanup", None);
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let ccx = bcx.ccx();
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let llpersonality = bcx.fcx.eh_personality();
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let llretty = Type::struct_(ccx, &[Type::i8p(ccx), Type::i32(ccx)], false);
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let llretval = build::LandingPad(bcx, llretty, llpersonality, 1);
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build::SetCleanup(bcx, llretval);
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let slot = self.get_personality_slot(bcx);
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build::Store(bcx, llretval, slot);
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build::Br(bcx, cleanup.llbb, DebugLoc::None);
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bcx
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}
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fn unreachable_block(&mut self) -> Block<'bcx, 'tcx> {
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match self.unreachable_block {
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Some(b) => b,
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None => {
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let bl = self.fcx.new_block(false, "unreachable", None);
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build::Unreachable(bl);
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self.unreachable_block = Some(bl);
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bl
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}
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}
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}
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fn bcx(&self, bb: mir::BasicBlock) -> Block<'bcx, 'tcx> {
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self.blocks[bb.index()]
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}
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fn llblock(&self, bb: mir::BasicBlock) -> BasicBlockRef {
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self.blocks[bb.index()].llbb
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}
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}
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