//! Test command for testing the code generator pipeline

//!

//! The `compile` test command runs each function through the full code generator pipeline

use crate::subtest::{Context, SubTest, check_precise_output, run_filecheck};

use anyhow::Result;

use cranelift_codegen::ir;

use cranelift_reader::{TestCommand, TestOption};

use log::info;

use std::borrow::Cow;

struct TestCompile {

    /// Flag indicating that the text expectation, comments after the function,

    /// must be a precise 100% match on the compiled output of the function.

    /// This test assertion is also automatically-update-able to allow tweaking

    /// the code generator and easily updating all affected tests.

    precise_output: bool,

    /// Flag indicating that we expect compilation to fail, not succeed.

    expect_fail: bool,

}

pub fn subtest(parsed: &TestCommand) -> Result<Box<dyn SubTest>> {

    assert_eq!(parsed.command, "compile");

    let mut test = TestCompile {

        precise_output: false,

        expect_fail: false,

    };

    for option in parsed.options.iter() {

        match option {

            TestOption::Flag("precise-output") => test.precise_output = true,

            TestOption::Flag("expect-fail") => test.expect_fail = true,

            _ => anyhow::bail!("unknown option on {parsed}"),

        }

    }

    Ok(Box::new(test))

}

impl SubTest for TestCompile {

    fn name(&self) -> &'static str {

        "compile"

    }

    fn is_mutating(&self) -> bool {

        true

    }

    fn needs_isa(&self) -> bool {

        true

    }

    fn run(&self, func: Cow<ir::Function>, context: &Context) -> Result<()> {

        let isa = context.isa.expect("compile needs an ISA");

        let params = func.params.clone();

        let mut comp_ctx = cranelift_codegen::Context::for_function(func.into_owned());

        // With `MachBackend`s, we need to explicitly request disassembly results.

        comp_ctx.set_disasm(true);

        let compiled_code = comp_ctx.compile(isa, &mut Default::default());

        let compiled_code = if self.expect_fail {

            if compiled_code.is_ok() {

                anyhow::bail!("Expected compilation failure but compilation succeeded");

            }

            return Ok(());

        } else {

            compiled_code.map_err(|e| crate::pretty_anyhow_error(&e.func, e.inner))?

        };

        let total_size = compiled_code.code_info().total_size;

        let vcode = compiled_code.vcode.as_ref().unwrap();

        info!("Generated {total_size} bytes of code:\n{vcode}");

        if self.precise_output {

            let dis = match isa.triple().architecture {

                target_lexicon::Architecture::Pulley32 | target_lexicon::Architecture::Pulley64 => {

                    // Disable hexdumps/offsets to reduce the churn in these

                    // tests as instructions are encoded differently and/or

                    // their immediates change.

                    let mut disas =

                        pulley_interpreter::disas::Disassembler::new(compiled_code.buffer.data());

                    disas.hexdump(false).offsets(false);

                    pulley_interpreter::decode::Decoder::decode_all(&mut disas)?;

                    disas.disas().to_string()

                }

                _ => {

                    let cs = isa.to_capstone().map_err(|e| anyhow::format_err!("{e}"))?;

                    compiled_code.disassemble(Some(&params), &cs)?

                }

            };

            let actual = Vec::from_iter(

                std::iter::once("VCode:")

                    .chain(compiled_code.vcode.as_ref().unwrap().lines())

                    .chain(["", "Disassembled:"])

                    .chain(dis.lines()),

            );

            check_precise_output(&actual, context)

        } else {

            run_filecheck(&vcode, context)

        }

    }

}