shaderc/src/compiler/backend/mod.rs

#[cfg(test)]
mod tests;

use crate::compiler::Module;
use std::fmt::Write;
use std::fmt;

use super::StorageClass;

#[derive(Debug, PartialEq, Clone)]
pub enum Type {
    Pointer(Box<Type>, StorageClass),
    Vector(Box<Type>, u32),
    Float(u32),
    Int(u32),
    Unsigned(u32),
}

impl fmt::Display for Type {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match self {
            Type::Pointer(typ, storage_class) => {
                match storage_class {
                    StorageClass::Input => write!(f, "*{}i", typ),
                    StorageClass::Output => write!(f, "*{}o", typ),
                    StorageClass::Undefined => panic!("Bound a non-declared variable"),
                }
            },
            Type::Vector(typ, size) => write!(f, "v{}{}", size, typ),
            Type::Float(size) => write!(f, "f{}", size),
            Type::Int(size) => write!(f, "s{}", size),
            Type::Unsigned(size) => write!(f, "u{}", size),
        }
    }
}

pub fn parse_type(typ: String) -> Type {
    // pointers have the format *<t>i or *<t>o, for the storage class
    // floats have the format f<size>, so f32, f64...
    // ints have the format s<size>, so s32, s64...
    // unsigned ints have the format u<size>, so u32, u64...
    // So, *v4f32i is a pointer to a vector of 4 floats, with the storage class Input.
    // *v4f32o is a pointer to a vector of 4 floats, with the storage class Output.

    let c = typ.chars().next().unwrap();
    match c {
        '*' => {
            let mut chars = typ.chars();
            chars.next();
            let typ = chars.collect::<String>();
            let storage_class = match typ.chars().last().unwrap() {
                'i' => StorageClass::Input,
                'o' => StorageClass::Output,
                _ => panic!("Invalid storage class"),
            };
            let typ = typ.chars().take(typ.len() - 1).collect::<String>();
            Type::Pointer(Box::new(parse_type(typ)), storage_class)
        },
        'v' => {
            let mut chars = typ.chars();
            chars.next();
            let size = chars.next().unwrap().to_digit(10).unwrap();
            let typ = chars.collect::<String>();
            Type::Vector(Box::new(parse_type(typ)), size)
        },
        'f' => {
            let size = typ.chars().skip(1).collect::<String>().parse().unwrap();
            Type::Float(size)
        },
        's' => {
            let size = typ.chars().skip(1).collect::<String>().parse().unwrap();
            Type::Int(size)
        },
        'u' => {
            let size = typ.chars().skip(1).collect::<String>().parse().unwrap();
            Type::Unsigned(size)
        },
        _ => panic!("Invalid type"),
    }

}

fn emit_type(typ: Type, ops: &mut Vec<(String, String)>) {
    match typ {
        Type::Unsigned(size) => {
            ops.push((format!("%u{}", size).to_string(), format!("OpTypeInt {}", size)));
        },
        Type::Int(size) => {
            ops.push((format!("%s{}", size).to_string(), format!("OpTypeInt {}", size)));
        },
        Type::Float(size) => {
            ops.push((format!("%f{}", size).to_string(), format!("OpTypeFloat {}", size)));
        },
        Type::Vector(typ, size) => {
            emit_type(*typ.clone(), ops);
            let typ_id = format!("%{}", *typ.clone());
            ops.push((format!("%v{}{}", typ_id, size).to_string(), format!("OpTypeVector {} {}", typ_id, size)))
        },
        Type::Pointer(typ, storage_class) => {
            emit_type(*typ.clone(), ops);
            let typ_id = format!("%{}", *typ.clone());
            let storage_class = match storage_class {
                StorageClass::Input => "Input",
                StorageClass::Output => "Output",
                StorageClass::Undefined => panic!("Bound a non-declared variable"),
            };
            ops.push((format!("%{}{}", typ_id, storage_class).to_string(), format!("OpTypePointer {} {}", storage_class, typ_id)))
        },
    }
}

fn fix_name(name: &String) -> String {
    format!("%{}", name.clone().replace("-", "_"))
}

pub fn spirv_meta(module: Module) -> String {
    let mut spirv_asm = String::new();
    let mut ops: Vec<(Option<String>, Vec<String>)> = Vec::new();

    let capabilities: Vec<String> = module.capabilities.iter()
        .map(|c| format!("{:?}", c))
        .collect();
    for cap in capabilities {
        ops.push((None, vec!["OpCapability".to_string(), cap]));
    }

    let memory_model_address = match module.memory_model.addressing_model {
        crate::compiler::AddressingModel::Logical => "Logical",
        crate::compiler::AddressingModel::Physical32 => "Physical32",
        crate::compiler::AddressingModel::Physical64 => "Physical64",
        crate::compiler::AddressingModel::PhysicalStorageBuffer64 => "PhysicalStorageBuffer64",
    };
    let memory_model_model = match module.memory_model.memory_model {
        crate::compiler::MemoryModel::Simple => "Simple",
        crate::compiler::MemoryModel::GLSL450 => "GLSL450",
        crate::compiler::MemoryModel::OpenCL => "OpenCL",
        _ => todo!(),
    };
    ops.push((None, vec!["OpMemoryModel".to_string(), memory_model_address.to_string(), memory_model_model.to_string()]));

    for entry in module.entry_points {
        let exec_model = match entry.execution_model {
            crate::compiler::ExecutionModel::Fragment => "Fragment",
            crate::compiler::ExecutionModel::Vertex => "Vertex",
        };
        let name = entry.name;
        let interface: Vec<String> = entry.interface.iter()
            .map(|i| fix_name(&i.to_string()))
            .collect();
        let exec_mode = match entry.execution_mode {
            crate::compiler::ExecutionMode::OriginUpperLeft => "OriginUpperLeft",
        };
        ops.push((None, vec!["OpEntryPoint".to_string(), exec_model.to_string(), fix_name(&name), format!("\"{}\"", name), interface.join(" ")]));
        ops.push((None, vec!["OpExecutionMode".to_string(), fix_name(&name), exec_mode.to_string()]));
    }

    for global in module.globals {
        let name = fix_name(&global.name);
        let _typ = global.typ;
        let storage_class = match global.storage_class {
            crate::compiler::StorageClass::Input => "Input",
            crate::compiler::StorageClass::Output => "Output",
            crate::compiler::StorageClass::Undefined => panic!("Bound a non-declared variable"),
        };
        let typ_id = format!("%{}", _typ);
        let mut type_ops = Vec::new();
        emit_type(parse_type(_typ), &mut type_ops);
        for op in type_ops {
            ops.push((Some(op.0), vec![op.1]));
        }
        ops.push((Some(name.clone()), vec!["OpVariable".to_string(), typ_id.to_string(), storage_class.to_string()]));
        for dec in global.decorations {
            // Decorations have the format Location 0, or Builtin FragCoord
            let dec = match dec {
                crate::compiler::Decoration::Location(loc) => format!("Location {}", loc),
                crate::compiler::Decoration::BuiltIn(builtin) => {
                    let builtin = match builtin {
                        crate::compiler::BuiltinDecoration::FragCoord => "FragCoord",
                    };
                    format!("BuiltIn {}", builtin)
                },
            };
            ops.push((None, vec!["OpDecorate".to_string(), name.clone(), dec]));
        }
    }

    for op in ops {
        if op.0.is_some() {
            write!(spirv_asm, "{} = ", op.0.unwrap()).unwrap();
        }
        for arg in op.1 {
            write!(spirv_asm, "{} ", arg).unwrap();
        }
        writeln!(spirv_asm).unwrap();
    }
    spirv_asm
}