first attempt at List.replace in the dev backend

compiler/gen_dev/src/generic64/aarch64.rs

@@ -282,7 +282,7 @@ impl CallConv<AArch64GeneralReg, AArch64FloatReg, AArch64Assembler> for AArch64C
             AArch64Call,
         >,
         _dst: &Symbol,
-        _args: &'a [Symbol],
+        _args: &[Symbol],
         _arg_layouts: &[Layout<'a>],
         _ret_layout: &Layout<'a>,
     ) {

compiler/gen_dev/src/generic64/mod.rs

@@ -3,7 +3,7 @@ use crate::{
     Relocation,
 };
 use bumpalo::collections::Vec;
-use roc_builtins::bitcode::{FloatWidth, IntWidth};
+use roc_builtins::bitcode::{self, FloatWidth, IntWidth};
 use roc_collections::all::MutMap;
 use roc_error_macros::internal_error;
 use roc_module::symbol::{Interns, Symbol};
@@ -78,7 +78,7 @@ pub trait CallConv<GeneralReg: RegTrait, FloatReg: RegTrait, ASM: Assembler<Gene
         buf: &mut Vec<'a, u8>,
         storage_manager: &mut StorageManager<'a, GeneralReg, FloatReg, ASM, Self>,
         dst: &Symbol,
-        args: &'a [Symbol],
+        args: &[Symbol],
         arg_layouts: &[Layout<'a>],
         // ret_layout is needed because if it is a complex type, we pass a pointer as the first arg.
         ret_layout: &Layout<'a>,
@@ -495,7 +495,7 @@ impl<
         &mut self,
         dst: &Symbol,
         fn_name: String,
-        args: &'a [Symbol],
+        args: &[Symbol],
         arg_layouts: &[Layout<'a>],
         ret_layout: &Layout<'a>,
     ) {
@@ -636,7 +636,7 @@ impl<
     fn build_jump(
         &mut self,
         id: &JoinPointId,
-        args: &'a [Symbol],
+        args: &[Symbol],
         arg_layouts: &[Layout<'a>],
         _ret_layout: &Layout<'a>,
     ) {
@@ -897,6 +897,7 @@ impl<
     fn build_list_len(&mut self, dst: &Symbol, list: &Symbol) {
         self.storage_manager.list_len(&mut self.buf, dst, list);
     }
+
     fn build_list_get_unsafe(
         &mut self,
         dst: &Symbol,
@@ -931,6 +932,129 @@ impl<
         );
     }
 
+    fn build_list_replace_unsafe(
+        &mut self,
+        dst: &Symbol,
+        args: &'a [Symbol],
+        arg_layouts: &[Layout<'a>],
+        ret_layout: &Layout<'a>,
+    ) {
+        // We want to delegate to the zig builtin, but it takes some extra parameters.
+        // Firstly, it takes the alignment of the list.
+        // Secondly, it takes the stack size of an element.
+        // Thirdly, it takes a pointer that it will write the output element to.
+        let list = args[0];
+        let list_layout = arg_layouts[0];
+        let index = args[1];
+        let index_layout = arg_layouts[1];
+        let elem = args[2];
+        let elem_layout = arg_layouts[2];
+
+        let u32_layout = &Layout::Builtin(Builtin::Int(IntWidth::U32));
+        let list_alignment = list_layout.alignment_bytes(self.storage_manager.target_info());
+        self.load_literal(
+            &Symbol::DEV_TMP,
+            &u32_layout,
+            &Literal::Int(list_alignment as i128),
+        );
+
+        // Have to pass the input element by pointer, so put it on the stack and load it's address.
+        self.storage_manager
+            .ensure_symbol_on_stack(&mut self.buf, &elem);
+        let u64_layout = &Layout::Builtin(Builtin::Int(IntWidth::U64));
+        let (new_elem_offset, _) = self.storage_manager.stack_offset_and_size(&elem);
+        // Load address of output element into register.
+        let reg = self
+            .storage_manager
+            .claim_general_reg(&mut self.buf, &Symbol::DEV_TMP2);
+        ASM::add_reg64_reg64_imm32(&mut self.buf, reg, CC::BASE_PTR_REG, new_elem_offset);
+
+        // Load the elements size.
+        let elem_stack_size = elem_layout.stack_size(self.storage_manager.target_info());
+        self.load_literal(
+            &Symbol::DEV_TMP3,
+            &u64_layout,
+            &Literal::Int(elem_stack_size as i128),
+        );
+
+        // Setup the return location.
+        let base_offset = self.storage_manager.claim_stack_area(
+            &dst,
+            ret_layout.stack_size(self.storage_manager.target_info()),
+        );
+
+        let ret_fields = if let Layout::Struct { field_layouts, .. } = ret_layout {
+            field_layouts
+        } else {
+            internal_error!(
+                "Expected replace to return a struct instead found: {:?}",
+                ret_layout
+            )
+        };
+
+        // Only return list and old element.
+        debug_assert_eq!(ret_fields.len(), 2);
+
+        let (out_list_offset, out_elem_offset) = if ret_fields[0] == elem_layout {
+            (
+                base_offset + ret_fields[0].stack_size(self.storage_manager.target_info()) as i32,
+                base_offset,
+            )
+        } else {
+            (
+                base_offset,
+                base_offset + ret_fields[0].stack_size(self.storage_manager.target_info()) as i32,
+            )
+        };
+
+        // Load address of output element into register.
+        let reg = self
+            .storage_manager
+            .claim_general_reg(&mut self.buf, &Symbol::DEV_TMP4);
+        ASM::add_reg64_reg64_imm32(&mut self.buf, reg, CC::BASE_PTR_REG, out_elem_offset);
+
+        let lowlevel_args = bumpalo::vec![
+        in self.env.arena;
+            list,
+            Symbol::DEV_TMP,
+            index,
+            Symbol::DEV_TMP2,
+            Symbol::DEV_TMP3,
+            Symbol::DEV_TMP4,
+         ];
+        let lowlevel_arg_layouts = bumpalo::vec![
+        in self.env.arena;
+                list_layout,
+                *u32_layout,
+                index_layout,
+                *u64_layout,
+                *u64_layout,
+                *u64_layout,
+        ];
+
+        self.build_fn_call(
+            &Symbol::DEV_TMP5,
+            bitcode::LIST_REPLACE.to_string(),
+            &lowlevel_args,
+            &lowlevel_arg_layouts,
+            &list_layout,
+        );
+        self.free_symbol(&Symbol::DEV_TMP);
+        self.free_symbol(&Symbol::DEV_TMP2);
+        self.free_symbol(&Symbol::DEV_TMP3);
+        self.free_symbol(&Symbol::DEV_TMP4);
+
+        // Copy from list to the output record.
+        self.storage_manager.copy_symbol_to_stack_offset(
+            &mut self.buf,
+            out_list_offset,
+            &Symbol::DEV_TMP5,
+            &list_layout,
+        );
+
+        self.free_symbol(&Symbol::DEV_TMP5);
+    }
+
     fn build_ptr_cast(&mut self, dst: &Symbol, src: &Symbol) {
         // We may not strictly need an instruction here.
         // What's important is to load the value, and for src and dest to have different Layouts.

compiler/gen_dev/src/generic64/storage.rs

@@ -806,6 +806,28 @@ impl<
         }
     }
 
+    pub fn ensure_symbol_on_stack(&mut self, buf: &mut Vec<'a, u8>, sym: &Symbol) {
+        match self.remove_storage_for_sym(sym) {
+            Reg(reg_storage) => {
+                let base_offset = self.claim_stack_size(8);
+                match reg_storage {
+                    General(reg) => ASM::mov_base32_reg64(buf, base_offset, reg),
+                    Float(reg) => ASM::mov_base32_freg64(buf, base_offset, reg),
+                }
+                self.symbol_storage_map.insert(
+                    *sym,
+                    Stack(Primitive {
+                        base_offset,
+                        reg: Some(reg_storage),
+                    }),
+                );
+            }
+            x => {
+                self.symbol_storage_map.insert(*sym, x);
+            }
+        }
+    }
+
     /// Frees `wanted_reg` which is currently owned by `sym` by making sure the value is loaded on the stack.
     /// Note, used and free regs are expected to be updated outside of this function.
     fn free_to_stack(
@@ -960,7 +982,7 @@ impl<
         &mut self,
         buf: &mut Vec<'a, u8>,
         id: &JoinPointId,
-        args: &'a [Symbol],
+        args: &[Symbol],
         arg_layouts: &[Layout<'a>],
     ) {
         // TODO: remove was use here and for current_storage to deal with borrow checker.

compiler/gen_dev/src/generic64/x86_64.rs

@@ -267,7 +267,7 @@ impl CallConv<X86_64GeneralReg, X86_64FloatReg, X86_64Assembler> for X86_64Syste
             X86_64SystemV,
         >,
         dst: &Symbol,
-        args: &'a [Symbol],
+        args: &[Symbol],
         arg_layouts: &[Layout<'a>],
         ret_layout: &Layout<'a>,
     ) {
@@ -693,7 +693,7 @@ impl CallConv<X86_64GeneralReg, X86_64FloatReg, X86_64Assembler> for X86_64Windo
             X86_64WindowsFastcall,
         >,
         dst: &Symbol,
-        args: &'a [Symbol],
+        args: &[Symbol],
         arg_layouts: &[Layout<'a>],
         ret_layout: &Layout<'a>,
     ) {

compiler/gen_dev/src/lib.rs

@@ -233,7 +233,7 @@ trait Backend<'a> {
     fn build_jump(
         &mut self,
         id: &JoinPointId,
-        args: &'a [Symbol],
+        args: &[Symbol],
         arg_layouts: &[Layout<'a>],
         ret_layout: &Layout<'a>,
     );
@@ -571,17 +571,18 @@ trait Backend<'a> {
                 debug_assert_eq!(
                     2,
                     args.len(),
-                    "ListLen: expected to have exactly two arguments"
+                    "ListGetUnsafe: expected to have exactly two arguments"
                 );
                 self.build_list_get_unsafe(sym, &args[0], &args[1], ret_layout)
             }
-            LowLevel::ListSet => self.build_fn_call(
-                sym,
-                bitcode::LIST_SET.to_string(),
-                args,
-                arg_layouts,
-                ret_layout,
-            ),
+            LowLevel::ListReplaceUnsafe => {
+                debug_assert_eq!(
+                    3,
+                    args.len(),
+                    "ListReplaceUnsafe: expected to have exactly three arguments"
+                );
+                self.build_list_replace_unsafe(sym, args, arg_layouts, ret_layout)
+            }
             LowLevel::StrConcat => self.build_fn_call(
                 sym,
                 bitcode::STR_CONCAT.to_string(),
@@ -643,7 +644,7 @@ trait Backend<'a> {
                 self.build_eq(sym, &args[0], &Symbol::DEV_TMP, &arg_layouts[0]);
                 self.free_symbol(&Symbol::DEV_TMP)
             }
-            Symbol::LIST_GET | Symbol::LIST_SET => {
+            Symbol::LIST_GET | Symbol::LIST_SET | Symbol::LIST_REPLACE => {
                 // TODO: This is probably simple enough to be worth inlining.
                 let layout_id = LayoutIds::default().get(func_sym, ret_layout);
                 let fn_name = self.symbol_to_string(func_sym, layout_id);
@@ -661,7 +662,7 @@ trait Backend<'a> {
         &mut self,
         dst: &Symbol,
         fn_name: String,
-        args: &'a [Symbol],
+        args: &[Symbol],
         arg_layouts: &[Layout<'a>],
         ret_layout: &Layout<'a>,
     );
@@ -728,6 +729,16 @@ trait Backend<'a> {
         index: &Symbol,
         ret_layout: &Layout<'a>,
     );
+
+    /// build_list_replace_unsafe returns the old element and new list with the list having the new element inserted.
+    fn build_list_replace_unsafe(
+        &mut self,
+        dst: &Symbol,
+        args: &'a [Symbol],
+        arg_layouts: &[Layout<'a>],
+        ret_layout: &Layout<'a>,
+    );
+
     /// build_refcount_getptr loads the pointer to the reference count of src into dst.
     fn build_ptr_cast(&mut self, dst: &Symbol, src: &Symbol);
 

compiler/module/src/symbol.rs

@@ -883,6 +883,10 @@ define_builtins! {
 
         // used in dev backend
         26 DEV_TMP: "#dev_tmp"
+        27 DEV_TMP2: "#dev_tmp2"
+        28 DEV_TMP3: "#dev_tmp3"
+        29 DEV_TMP4: "#dev_tmp4"
+        30 DEV_TMP5: "#dev_tmp5"
     }
     1 NUM: "Num" => {
         0 NUM_NUM: "Num" imported // the Num.Num type alias