From 07eeed7cffb916dda7ab531b01c5de92bbbf0ea4 Mon Sep 17 00:00:00 2001
From: janis <janis@nirgendwo.xyz>
Date: Mon, 3 Nov 2025 16:35:46 +0100
Subject: [PATCH] can do very cool stuff!

---
 lang/src/codegen.asm  | 86 ++++++++++++++++++++++++++-----------------
 lang/tests/codegen.rs |  2 +-
 2 files changed, 53 insertions(+), 35 deletions(-)

diff --git a/lang/src/codegen.asm b/lang/src/codegen.asm
index 142f2b7..46b0906 100644
--- a/lang/src/codegen.asm
+++ b/lang/src/codegen.asm
@@ -1310,7 +1310,6 @@ codegen_expr:
     jmp .done
 
 .gen_op:
-
     mov rdi, [rsp + 8]          ; &function_ctx
     mov rsi, [rsp]              ; ctx
     lea rsi, [rsi + 8]          ; &ctx.text
@@ -1844,25 +1843,40 @@ codegen_binary_op_rm64_rm64:
     push rbx
 
     ; dst [32..48]
-    sub rsp, 48
+    sub rsp, 56
     mov [rsp], rdi              ; *function_ctx
     mov [rsp + 8], rsi          ; *text
     mov [rsp + 16], rdx         ; lhs
     mov [rsp + 24], rcx         ; rhs
     mov [rsp + 32], r8          ; op
 
-    ; if lhs.kind == REGISTER || lhs.kind < ADDRESS && rhs.kind == REGISTER {
+    ; match (lhs.kind, rhs.kind) {
     cmp byte [rdx + 0], OPERAND_REGISTER
-    je .simple
+    sete al
+    cmp byte [rcx + 0], OPERAND_RBP_PVALUE
+    setb bl
+    test al, bl
+    jnz .simple
+    ;   (REGISTER, kind < RBP_PVALUE) => simple
     cmp byte [rdx + 0], OPERAND_RBP_PVALUE
     setb al
     cmp byte [rcx + 0], OPERAND_REGISTER
     sete bl
     test al, bl
-    jne .simple
-    jmp .complex
+    jnz .simple
+    ; (kind < RBP_PVALUE, REGISTER) => simple
+    test al, al
+    jnz .rax_lhs
+    ;   (kind < RBP_PVALUE, _) => rax_lhs
+    cmp byte [rdx + 0], OPERAND_RBP_PVALUE
+    jb .rax_rhs
+    ;   (_, kind < RBP_PVALUE) => rax_rhs
+    jmp .rax_dst
+    ;   (_, _) => rax_dst
+    ; }
+    
 .simple:
-    ;   op lhs, rhs
+    ; { op lhs, rhs; lhs }
     lea rdi, [rsp + 32]         ; op
     call strlen
     mov rdi, [rsp + 8]          ; *text
@@ -1898,11 +1912,9 @@ codegen_binary_op_rm64_rm64:
     mov rax, [rbx]
     mov rdx, [rbx + 8]
     jmp .epilogue
-    ; } else {
-.complex:
-    ;   if lhs.kind < RBP_PVALUE {
-    cmp byte [rdx + 0], OPERAND_RBP_PVALUE
-    jae .check_rhs
+
+.rax_lhs:
+    ; { mov rax, rhs; op lhs, rax; lhs }
 
     ;     mov rax, rhs
     mov rdi, [rsp + 8]          ; *text
@@ -1928,14 +1940,13 @@ codegen_binary_op_rm64_rm64:
     mov rdx, [rbx + 8]
     jmp .epilogue
 
-.check_rhs:
-    ;   } else if rhs.kind < RBP_PVALUE {
-    cmp byte [rcx + 0], OPERAND_RBP_PVALUE
-    jae .allocate_dst
+.rax_rhs:
+    ; { mov rax, lhs; op rax, rhs; mov rhs, rax; rhs }
+
     ;     mov rax, lhs
     mov rdi, [rsp + 8]          ; *text
     lea rsi, [rel OPERAND_RAX]
-    mov rdx, [rsp + 16]         ; lhs
+    mov rdx, [rsp + 16]         ; rhs
     call codegen_move_dst_src
 
     ;     op rax, rhs
@@ -1945,34 +1956,30 @@ codegen_binary_op_rm64_rm64:
     mov rcx, [rsp + 32]         ; op
     call codegen_binary_op_unchecked
 
-    ;     mov rhs, rax
-    mov rdi, [rsp + 8]          ; *text
-    mov rsi, [rsp + 24]         ; rhs
-    lea rdx, [rel OPERAND_RAX]
-    call codegen_move_dst_src
-
-    ;     free lhs
+    ;   free lhs
     mov rdi, [rsp]              ; *function_ctx
-    mov rsi, [rsp + 16]         ; rhs
+    mov rsi, [rsp + 16]         ; lhs
     call codegen_free_operand
 
-    ;     ret rhs
+    ;   ret rhs
     mov rbx, [rsp + 24]         ; rhs
     mov rax, [rbx]
     mov rdx, [rbx + 8]
     jmp .epilogue
-    ;   } else {
-.allocate_dst:
+
+.rax_dst:
+    ; { dst = allocate_value; mov dst, lhs; mov rax, rhs; op dst, rax; dst }
+
     ;     dst = allocate_value
     mov rdi, [rsp]              ; *function_ctx
     mov rsi, 8                  ; width = 8
     call codegen_allocate_value
-    mov [rsp + 32], rax         ; dst
-    mov [rsp + 40], rdx
-    
+    mov [rsp + 40], rax         ; dst
+    mov [rsp + 48], rdx
+
     ;     mov dst, lhs
     mov rdi, [rsp + 8]          ; *text
-    lea rsi, [rsp + 32]         ; dst
+    lea rsi, [rsp + 40]         ; dst
     mov rdx, [rsp + 16]         ; lhs
     call codegen_move_dst_src
 
@@ -1984,18 +1991,29 @@ codegen_binary_op_rm64_rm64:
 
     ;     op dst, rax
     mov rdi, [rsp + 8]          ; *text
-    lea rsi, [rsp + 32]         ; dst
+    lea rsi, [rsp + 40]         ; dst
     lea rdx, [rel OPERAND_RAX]  ; rax
     mov rcx, [rsp + 32]         ; op
     call codegen_binary_op_unchecked
 
+    ;   free rhs
+    mov rdi, [rsp]              ; *function_ctx
+    mov rsi, [rsp + 24]         ; lhs
+    call codegen_free_operand
+
+    ;   free lhs
+    mov rdi, [rsp]              ; *function_ctx
+    mov rsi, [rsp + 16]         ; lhs
+    call codegen_free_operand
+
     ;     ret dst
     mov rax, [rsp + 32]         ; dst
     mov rdx, [rsp + 40]
     ;   }
 
+
 .epilogue:
-    add rsp, 48
+    add rsp, 56
     pop rbx
     pop rbp
     ret
diff --git a/lang/tests/codegen.rs b/lang/tests/codegen.rs
index 0188e24..f36a75d 100644
--- a/lang/tests/codegen.rs
+++ b/lang/tests/codegen.rs
@@ -93,7 +93,7 @@ fn main() {
 
     print_ast(
         b"fn main(a: u32) -> void {
-    return 2 * 3 + 4 * 5 + a;
+    return 5 + &a;
     }",
         |ast| unsafe { parse_func(ast) },
     );