Method is_block_basic

cranelift/codegen/src/ir/function.rs:310–324

Checks that the specified block can be encoded as a basic block. On error, returns the first invalid instruction and an error message.

(&self, block: Block)

    ///
    /// On error, returns the first invalid instruction and an error message.
    pub fn is_block_basic(&self, block: Block) -> Result<(), (Inst, &'static str)> {
        let dfg = &self.dfg;
        let inst_iter = self.layout.block_insts(block);

        // Ignore all instructions prior to the first branch.
        let mut inst_iter = inst_iter.skip_while(|&inst| !dfg.insts[inst].opcode().is_branch());

        if let Some(_branch) = inst_iter.next() {
            if let Some(next) = inst_iter.next() {
                return Err((next, "post-terminator instruction"));
            }
        }

        Ok(())
    }

    /// Returns an iterator over the blocks succeeding the given block.
    pub fn block_successors(&self, block: Block) -> impl DoubleEndedIterator<Item = Block> + '_ {