//! Routines for manipulating the control-flow graph.

use crate::build::CFG;
use rustc::mir::*;

impl<'tcx> CFG<'tcx> {
    pub fn block_data(&self, blk: BasicBlock) -> &BasicBlockData<'tcx> {
        &self.basic_blocks[blk]
    }

    pub fn block_data_mut(&mut self, blk: BasicBlock) -> &mut BasicBlockData<'tcx> {
        &mut self.basic_blocks[blk]
    }

    // llvm.org/PR32488 makes this function use an excess of stack space. Mark
    // it as #[inline(never)] to keep rustc's stack use in check.
    #[inline(never)]
    pub fn start_new_block(&mut self) -> BasicBlock {
        self.basic_blocks.push(BasicBlockData::new(None))
    }

    pub fn start_new_cleanup_block(&mut self) -> BasicBlock {
        let bb = self.start_new_block();
        self.block_data_mut(bb).is_cleanup = true;
        bb
    }

    pub fn push(&mut self, block: BasicBlock, statement: Statement<'tcx>) {
        debug!("push({:?}, {:?})", block, statement);
        self.block_data_mut(block).statements.push(statement);
    }

    pub fn push_assign(&mut self,
                       block: BasicBlock,
                       source_info: SourceInfo,
                       place: &Place<'tcx>,
                       rvalue: Rvalue<'tcx>) {
        self.push(block, Statement {
            source_info,
            kind: StatementKind::Assign(box(place.clone(), rvalue))
        });
    }

    pub fn push_assign_constant(&mut self,
                                block: BasicBlock,
                                source_info: SourceInfo,
                                temp: &Place<'tcx>,
                                constant: Constant<'tcx>) {
        self.push_assign(block, source_info, temp,
                         Rvalue::Use(Operand::Constant(box constant)));
    }

    pub fn push_assign_unit(&mut self,
                            block: BasicBlock,
                            source_info: SourceInfo,
                            place: &Place<'tcx>) {
        self.push_assign(block, source_info, place, Rvalue::Aggregate(
            box AggregateKind::Tuple, vec![]
        ));
    }

    pub fn terminate(&mut self,
                     block: BasicBlock,
                     source_info: SourceInfo,
                     kind: TerminatorKind<'tcx>) {
        debug!("terminating block {:?} <- {:?}", block, kind);
        debug_assert!(self.block_data(block).terminator.is_none(),
                      "terminate: block {:?}={:?} already has a terminator set",
                      block,
                      self.block_data(block));
        self.block_data_mut(block).terminator = Some(Terminator {
            source_info,
            kind,
        });
    }
}