add == and != for lists

compiler/gen/src/llvm/build.rs

@@ -2750,7 +2750,15 @@ fn run_low_level<'a, 'ctx, 'env>(
 
             let (elem, elem_layout) = load_symbol_and_layout(env, scope, &args[1]);
 
-            list_contains(env, parent, elem, elem_layout, list, list_layout)
+            list_contains(
+                env,
+                layout_ids,
+                parent,
+                elem,
+                elem_layout,
+                list,
+                list_layout,
+            )
         }
         ListWalk => {
             debug_assert_eq!(args.len(), 3);
@@ -2975,7 +2983,7 @@ fn run_low_level<'a, 'ctx, 'env>(
             let (lhs_arg, lhs_layout) = load_symbol_and_layout(env, scope, &args[0]);
             let (rhs_arg, rhs_layout) = load_symbol_and_layout(env, scope, &args[1]);
 
-            build_eq(env, lhs_arg, rhs_arg, lhs_layout, rhs_layout)
+            build_eq(env, layout_ids, lhs_arg, rhs_arg, lhs_layout, rhs_layout)
         }
         NotEq => {
             debug_assert_eq!(args.len(), 2);
@@ -2983,7 +2991,7 @@ fn run_low_level<'a, 'ctx, 'env>(
             let (lhs_arg, lhs_layout) = load_symbol_and_layout(env, scope, &args[0]);
             let (rhs_arg, rhs_layout) = load_symbol_and_layout(env, scope, &args[1]);
 
-            build_neq(env, lhs_arg, rhs_arg, lhs_layout, rhs_layout)
+            build_neq(env, layout_ids, lhs_arg, rhs_arg, lhs_layout, rhs_layout)
         }
         And => {
             // The (&&) operator

compiler/gen/src/llvm/build_list.rs

@@ -1003,6 +1003,7 @@ pub fn list_walk_backwards<'a, 'ctx, 'env>(
 /// List.contains : List elem, elem -> Bool
 pub fn list_contains<'a, 'ctx, 'env>(
     env: &Env<'a, 'ctx, 'env>,
+    layout_ids: &mut LayoutIds<'a>,
     parent: FunctionValue<'ctx>,
     elem: BasicValueEnum<'ctx>,
     elem_layout: &Layout<'a>,
@@ -1034,6 +1035,7 @@ pub fn list_contains<'a, 'ctx, 'env>(
 
     list_contains_help(
         env,
+        layout_ids,
         parent,
         length,
         list_ptr,
@@ -1045,6 +1047,7 @@ pub fn list_contains<'a, 'ctx, 'env>(
 
 pub fn list_contains_help<'a, 'ctx, 'env>(
     env: &Env<'a, 'ctx, 'env>,
+    layout_ids: &mut LayoutIds<'a>,
     parent: FunctionValue<'ctx>,
     length: IntValue<'ctx>,
     source_ptr: PointerValue<'ctx>,
@@ -1082,7 +1085,14 @@ pub fn list_contains_help<'a, 'ctx, 'env>(
 
     let current_elem = builder.build_load(current_elem_ptr, "load_elem");
 
-    let has_found = build_eq(env, current_elem, elem, list_elem_layout, elem_layout);
+    let has_found = build_eq(
+        env,
+        layout_ids,
+        current_elem,
+        elem,
+        list_elem_layout,
+        elem_layout,
+    );
 
     builder.build_store(bool_alloca, has_found.into_int_value());
 

compiler/gen/src/llvm/compare.rs

@@ -1,11 +1,16 @@
 use crate::llvm::build::Env;
+use crate::llvm::build::{set_name, FAST_CALL_CONV};
+use crate::llvm::build_list::{list_len, load_list_ptr};
 use crate::llvm::build_str::str_equal;
-use inkwell::values::{BasicValueEnum, IntValue};
-use inkwell::{FloatPredicate, IntPredicate};
-use roc_mono::layout::{Builtin, Layout};
+use crate::llvm::convert::{basic_type_from_layout, get_ptr_type};
+use inkwell::values::{BasicValueEnum, FunctionValue, IntValue, StructValue};
+use inkwell::{AddressSpace, FloatPredicate, IntPredicate};
+use roc_module::symbol::Symbol;
+use roc_mono::layout::{Builtin, Layout, LayoutIds};
 
 pub fn build_eq<'a, 'ctx, 'env>(
     env: &Env<'a, 'ctx, 'env>,
+    layout_ids: &mut LayoutIds<'a>,
     lhs_val: BasicValueEnum<'ctx>,
     rhs_val: BasicValueEnum<'ctx>,
     lhs_layout: &Layout<'a>,
@@ -45,6 +50,25 @@ pub fn build_eq<'a, 'ctx, 'env>(
                 (Builtin::Float64, Builtin::Float64) => float_cmp(FloatPredicate::OEQ, "eq_f64"),
                 (Builtin::Float32, Builtin::Float32) => float_cmp(FloatPredicate::OEQ, "eq_f32"),
                 (Builtin::Str, Builtin::Str) => str_equal(env, lhs_val, rhs_val),
+                (Builtin::EmptyList, Builtin::EmptyList) => {
+                    env.context.bool_type().const_int(1, false).into()
+                }
+                (Builtin::List(_, _), Builtin::EmptyList)
+                | (Builtin::EmptyList, Builtin::List(_, _)) => {
+                    unreachable!("the `==` operator makes sure its two arguments have the same type and thus layout")
+                }
+                (Builtin::List(_, elem1), Builtin::List(_, elem2)) => {
+                    debug_assert_eq!(elem1, elem2);
+
+                    build_list_eq(
+                        env,
+                        layout_ids,
+                        lhs_layout,
+                        elem1,
+                        lhs_val.into_struct_value(),
+                        rhs_val.into_struct_value(),
+                    )
+                }
                 (b1, b2) => {
                     todo!("Handle equals for builtin layouts {:?} == {:?}", b1, b2);
                 }
@@ -57,8 +81,206 @@ pub fn build_eq<'a, 'ctx, 'env>(
     }
 }
 
+fn build_list_eq<'a, 'ctx, 'env>(
+    env: &Env<'a, 'ctx, 'env>,
+    layout_ids: &mut LayoutIds<'a>,
+    list_layout: &Layout<'a>,
+    element_layout: &Layout<'a>,
+    list1: StructValue<'ctx>,
+    list2: StructValue<'ctx>,
+) -> BasicValueEnum<'ctx> {
+    let block = env.builder.get_insert_block().expect("to be in a function");
+    let di_location = env.builder.get_current_debug_location().unwrap();
+
+    let symbol = Symbol::LIST_EQ;
+    let fn_name = layout_ids
+        .get(symbol, &element_layout)
+        .to_symbol_string(symbol, &env.interns);
+
+    let function = match env.module.get_function(fn_name.as_str()) {
+        Some(function_value) => function_value,
+        None => {
+            let arena = env.arena;
+            let arg_type = basic_type_from_layout(arena, env.context, &list_layout, env.ptr_bytes);
+
+            let function_value = crate::llvm::refcounting::build_header_help(
+                env,
+                &fn_name,
+                env.context.bool_type().into(),
+                &[arg_type, arg_type],
+            );
+
+            build_list_eq_help(env, layout_ids, function_value, element_layout);
+
+            function_value
+        }
+    };
+
+    env.builder.position_at_end(block);
+    env.builder
+        .set_current_debug_location(env.context, di_location);
+    let call = env
+        .builder
+        .build_call(function, &[list1.into(), list2.into()], "list_eq");
+
+    call.set_call_convention(FAST_CALL_CONV);
+
+    call.try_as_basic_value().left().unwrap()
+}
+
+fn build_list_eq_help<'a, 'ctx, 'env>(
+    env: &Env<'a, 'ctx, 'env>,
+    layout_ids: &mut LayoutIds<'a>,
+    parent: FunctionValue<'ctx>,
+    element_layout: &Layout<'a>,
+) {
+    let ctx = env.context;
+    let builder = env.builder;
+
+    {
+        use inkwell::debug_info::AsDIScope;
+
+        let func_scope = parent.get_subprogram().unwrap();
+        let lexical_block = env.dibuilder.create_lexical_block(
+            /* scope */ func_scope.as_debug_info_scope(),
+            /* file */ env.compile_unit.get_file(),
+            /* line_no */ 0,
+            /* column_no */ 0,
+        );
+
+        let loc = env.dibuilder.create_debug_location(
+            ctx,
+            /* line */ 0,
+            /* column */ 0,
+            /* current_scope */ lexical_block.as_debug_info_scope(),
+            /* inlined_at */ None,
+        );
+        builder.set_current_debug_location(&ctx, loc);
+    }
+
+    // Add args to scope
+    let mut it = parent.get_param_iter();
+    let list1 = it.next().unwrap().into_struct_value();
+    let list2 = it.next().unwrap().into_struct_value();
+
+    set_name(list1.into(), Symbol::ARG_1.ident_string(&env.interns));
+    set_name(list1.into(), Symbol::ARG_2.ident_string(&env.interns));
+
+    let entry = ctx.append_basic_block(parent, "entry");
+    env.builder.position_at_end(entry);
+
+    let return_true = ctx.append_basic_block(parent, "return_true");
+    let return_false = ctx.append_basic_block(parent, "return_false");
+
+    // first, check whether the length is equal
+
+    let len1 = list_len(env.builder, list1);
+    let len2 = list_len(env.builder, list2);
+
+    let length_equal: IntValue =
+        env.builder
+            .build_int_compare(IntPredicate::EQ, len1, len2, "bounds_check");
+
+    let then_block = ctx.append_basic_block(parent, "then");
+
+    env.builder
+        .build_conditional_branch(length_equal, then_block, return_false);
+
+    {
+        // the length is equal; check elements pointwise
+        env.builder.position_at_end(then_block);
+
+        {
+            let builder = env.builder;
+            let element_type =
+                basic_type_from_layout(env.arena, env.context, element_layout, env.ptr_bytes);
+            let ptr_type = get_ptr_type(&element_type, AddressSpace::Generic);
+            let ptr1 = load_list_ptr(env.builder, list1, ptr_type);
+            let ptr2 = load_list_ptr(env.builder, list2, ptr_type);
+
+            // we know that len1 == len2
+            let end = len1;
+
+            // constant 1i64
+            let one = ctx.i64_type().const_int(1, false);
+
+            // allocate a stack slot for the current index
+            let index_alloca = builder.build_alloca(ctx.i64_type(), "index");
+            builder.build_store(index_alloca, ctx.i64_type().const_zero());
+
+            let loop_bb = ctx.append_basic_block(parent, "loop");
+            let body_bb = ctx.append_basic_block(parent, "body");
+            let increment_bb = ctx.append_basic_block(parent, "increment");
+
+            builder.build_unconditional_branch(loop_bb);
+            builder.position_at_end(loop_bb);
+
+            let curr_index = builder.build_load(index_alloca, "index").into_int_value();
+
+            // #index < end
+            let loop_end_cond =
+                builder.build_int_compare(IntPredicate::ULT, curr_index, end, "bounds_check");
+
+            builder.build_conditional_branch(loop_end_cond, body_bb, return_true);
+
+            builder.position_at_end(body_bb);
+
+            {
+                // loop body
+                let elem1 = {
+                    let elem_ptr =
+                        unsafe { builder.build_in_bounds_gep(ptr1, &[curr_index], "load_index") };
+                    builder.build_load(elem_ptr, "get_elem")
+                };
+
+                let elem2 = {
+                    let elem_ptr =
+                        unsafe { builder.build_in_bounds_gep(ptr2, &[curr_index], "load_index") };
+                    builder.build_load(elem_ptr, "get_elem")
+                };
+
+                let are_equal = build_eq(
+                    env,
+                    layout_ids,
+                    elem1,
+                    elem2,
+                    element_layout,
+                    element_layout,
+                )
+                .into_int_value();
+
+                builder.build_conditional_branch(are_equal, increment_bb, return_false);
+            }
+
+            {
+                env.builder.position_at_end(increment_bb);
+
+                let next_index = builder.build_int_add(curr_index, one, "nextindex");
+
+                builder.build_store(index_alloca, next_index);
+
+                // jump back to the top of the loop
+                builder.build_unconditional_branch(loop_bb);
+            }
+        }
+    }
+
+    {
+        env.builder.position_at_end(return_true);
+        env.builder
+            .build_return(Some(&env.context.bool_type().const_int(1, false)));
+    }
+
+    {
+        env.builder.position_at_end(return_false);
+        env.builder
+            .build_return(Some(&env.context.bool_type().const_int(0, false)));
+    }
+}
+
 pub fn build_neq<'a, 'ctx, 'env>(
     env: &Env<'a, 'ctx, 'env>,
+    layout_ids: &mut LayoutIds<'a>,
     lhs_val: BasicValueEnum<'ctx>,
     rhs_val: BasicValueEnum<'ctx>,
     lhs_layout: &Layout<'a>,
@@ -103,6 +325,29 @@ pub fn build_neq<'a, 'ctx, 'env>(
 
                     result.into()
                 }
+                (Builtin::EmptyList, Builtin::EmptyList) => {
+                    env.context.bool_type().const_int(0, false).into()
+                }
+                (Builtin::List(_, _), Builtin::EmptyList)
+                | (Builtin::EmptyList, Builtin::List(_, _)) => {
+                    unreachable!("the `==` operator makes sure its two arguments have the same type and thus layout")
+                }
+                (Builtin::List(_, elem1), Builtin::List(_, elem2)) => {
+                    debug_assert_eq!(elem1, elem2);
+
+                    let equal = build_list_eq(
+                        env,
+                        layout_ids,
+                        lhs_layout,
+                        elem1,
+                        lhs_val.into_struct_value(),
+                        rhs_val.into_struct_value(),
+                    );
+
+                    let not_equal: IntValue = env.builder.build_not(equal.into_int_value(), "not");
+
+                    not_equal.into()
+                }
                 (b1, b2) => {
                     todo!("Handle not equals for builtin layouts {:?} == {:?}", b1, b2);
                 }

compiler/gen/src/llvm/refcounting.rs

@@ -8,6 +8,7 @@ use bumpalo::collections::Vec;
 use inkwell::context::Context;
 use inkwell::debug_info::AsDIScope;
 use inkwell::module::Linkage;
+use inkwell::types::{AnyTypeEnum, BasicTypeEnum};
 use inkwell::values::{BasicValueEnum, FunctionValue, IntValue, PointerValue, StructValue};
 use inkwell::{AddressSpace, IntPredicate};
 use roc_module::symbol::Symbol;
@@ -993,12 +994,28 @@ pub fn build_header<'a, 'ctx, 'env>(
     fn_name: &str,
 ) -> FunctionValue<'ctx> {
     let arena = env.arena;
-    let context = &env.context;
-
     let arg_type = basic_type_from_layout(arena, env.context, &layout, env.ptr_bytes);
+    build_header_help(env, fn_name, env.context.void_type().into(), &[arg_type])
+}
 
-    // inc and dec return void
-    let fn_type = context.void_type().fn_type(&[arg_type], false);
+/// Build an increment or decrement function for a specific layout
+pub fn build_header_help<'a, 'ctx, 'env>(
+    env: &Env<'a, 'ctx, 'env>,
+    fn_name: &str,
+    return_type: AnyTypeEnum<'ctx>,
+    arguments: &[BasicTypeEnum<'ctx>],
+) -> FunctionValue<'ctx> {
+    use inkwell::types::AnyTypeEnum::*;
+    let fn_type = match return_type {
+        ArrayType(t) => t.fn_type(arguments, false),
+        FloatType(t) => t.fn_type(arguments, false),
+        FunctionType(_) => unreachable!("functions cannot return functions"),
+        IntType(t) => t.fn_type(arguments, false),
+        PointerType(t) => t.fn_type(arguments, false),
+        StructType(t) => t.fn_type(arguments, false),
+        VectorType(t) => t.fn_type(arguments, false),
+        VoidType(t) => t.fn_type(arguments, false),
+    };
 
     let fn_val = env
         .module

compiler/gen/tests/gen_list.rs

@@ -1703,4 +1703,40 @@ mod gen_list {
         assert_evals_to!("List.sum [ 1, 2, 3 ]", 6, i64);
         assert_evals_to!("List.sum [ 1.1, 2.2, 3.3 ]", 6.6, f64);
     }
+
+    #[test]
+    fn list_eq_empty() {
+        assert_evals_to!("[] == []", true, bool);
+        assert_evals_to!("[] != []", false, bool);
+    }
+
+    #[test]
+    fn list_eq_by_length() {
+        assert_evals_to!("[1] == []", false, bool);
+        assert_evals_to!("[] == [1]", false, bool);
+    }
+
+    #[test]
+    fn list_eq_compare_pointwise() {
+        assert_evals_to!("[1] == [1]", true, bool);
+        assert_evals_to!("[2] == [1]", false, bool);
+    }
+
+    #[test]
+    fn list_eq_nested() {
+        assert_evals_to!("[[1]] == [[1]]", true, bool);
+        assert_evals_to!("[[2]] == [[1]]", false, bool);
+    }
+
+    #[test]
+    fn list_neq_compare_pointwise() {
+        assert_evals_to!("[1] != [1]", false, bool);
+        assert_evals_to!("[2] != [1]", true, bool);
+    }
+
+    #[test]
+    fn list_neq_nested() {
+        assert_evals_to!("[[1]] != [[1]]", false, bool);
+        assert_evals_to!("[[2]] != [[1]]", true, bool);
+    }
 }

compiler/module/src/symbol.rs

@@ -738,6 +738,7 @@ define_builtins! {
         10 INC: "#inc" // internal function that increments the refcount
         11 DEC: "#dec" // internal function that increments the refcount
         12 ARG_CLOSURE: "#arg_closure" // symbol used to store the closure record
+        13 LIST_EQ: "#list_eq" // internal function that checks list equality
     }
     1 NUM: "Num" => {
         0 NUM_NUM: "Num" imported // the Num.Num type alias