Method insert_phi_value

crates/rustc_codegen_spirv/src/linker/mem2reg.rs:441–476

Returns the phi definition.

(&mut self, block: usize, from_block: usize)

impl Renamer<'_> {
    // Returns the phi definition.
    fn insert_phi_value(&mut self, block: usize, from_block: usize) -> Word {
        let from_block_label = self.blocks[from_block].label_id().unwrap();
        let phi_defs = &self.phi_defs;
        let existing_phi = self.blocks[block].instructions.iter_mut().find(|inst| {
            inst.class.opcode == Op::Phi && phi_defs.contains(&inst.result_id.unwrap())
        });
        let top_def = top_stack_or_undef(
            self.header,
            self.types_global_values,
            &self.stack,
            self.base_var_type,
        );
        match existing_phi {
            None => {
                let new_id = id(self.header);
                self.blocks[block].instructions.insert(
                    0,
                    Instruction::new(
                        Op::Phi,
                        Some(self.base_var_type),
                        Some(new_id),
                        vec![Operand::IdRef(top_def), Operand::IdRef(from_block_label)],
                    ),
                );
                self.phi_defs.insert(new_id);
                new_id
            }
            Some(existing_phi) => {
                existing_phi.operands.extend_from_slice(&[
                    Operand::IdRef(top_def),
                    Operand::IdRef(from_block_label),
                ]);
                existing_phi.result_id.unwrap()
            }
        }
    }

    fn rename(&mut self, block: usize, from_block: Option<usize>) {
        let original_stack = self.stack.len();