From 9e09767e23a4edb6b31540195bfe885f83e080d7 Mon Sep 17 00:00:00 2001
From: bd <bdunahu@operationnull.com>
Date: Tue, 28 Jan 2025 14:39:47 -0500
Subject: [Ongoing] Rewrite frontend to use Flex/Bison

This is a merge of another experiment, so the changes are large:

- separated "modules" directory into frontend/backend
  - adjusted module names and moved files for this to happen
- removed modules lexer & parser
- removed all the unit tests (most were outdated)
- added Bison, flex, and C development tools to manifest.scm
- added lexer.l, a source file used by the flex utility with a functioning lexing implementation
- added parser.y, a source file used by the bison utility with a functioning parser implementation
- added node.c and node.h, which parser.y uses to construct an AST of a C source file (up to binary ops)
- added driver.c, a Guile-C interface that provides a module to scheme programs
- added a Makefile to make all of this
- added stuff to .gitignore
---
 src/backend/generator/allocate.scm  | 16 ++++++++++++++++
 src/backend/generator/assembly.scm  | 18 ++++++++++++++++++
 src/backend/generator/driver.scm    |  9 +++++++++
 src/backend/generator/expansion.scm | 23 +++++++++++++++++++++++
 4 files changed, 66 insertions(+)
 create mode 100644 src/backend/generator/allocate.scm
 create mode 100644 src/backend/generator/assembly.scm
 create mode 100644 src/backend/generator/driver.scm
 create mode 100644 src/backend/generator/expansion.scm

(limited to 'src/backend/generator')

diff --git a/src/backend/generator/allocate.scm b/src/backend/generator/allocate.scm
new file mode 100644
index 0000000..0d417db
--- /dev/null
+++ b/src/backend/generator/allocate.scm
@@ -0,0 +1,16 @@
+(define-module (backend generator allocate)
+  #:use-module (backend utils assign-stack)
+  #:export (expansion->allocate))
+
+
+(define (expansion->allocate ast)
+  (define (allocate n)
+    (cond
+     ((null? n) n)
+     ((eq? (car n) 'tmp)
+      (list 'stack (make-location (cadr n))))
+     ((list? (car n))
+      (cons (allocate (car n)) (allocate (cdr n))))
+     (#t
+      (cons (car n) (allocate (cdr n))))))
+  (allocate ast))
diff --git a/src/backend/generator/assembly.scm b/src/backend/generator/assembly.scm
new file mode 100644
index 0000000..8a110f3
--- /dev/null
+++ b/src/backend/generator/assembly.scm
@@ -0,0 +1,18 @@
+(define-module (backend generator assembly)
+  #:use-module (backend ast ir)
+  #:use-module (backend utils assign-stack)
+  #:use-module (backend utils merge-instructions)
+  #:export (instrs
+            mov))
+
+
+(define (instrs lst)
+  (cons 'list (cons (list 'alloc (abs (get-frame-size)))
+                    (merge-instr lst))))
+
+(define (mov src dst)
+  (if (and (eq? 'stack (car dst))
+           (eq? 'stack (car src)))
+      (append (list (list 'mov src (reg "r10d")))
+              (list (list 'mov (reg "r10d") dst)))
+      (list 'mov src dst)))
diff --git a/src/backend/generator/driver.scm b/src/backend/generator/driver.scm
new file mode 100644
index 0000000..6625388
--- /dev/null
+++ b/src/backend/generator/driver.scm
@@ -0,0 +1,9 @@
+(define-module (backend generator driver)
+  #:use-module (backend generator allocate)
+  #:export (tacky->assembly))
+
+
+(define (tacky->assembly n)
+  (eval (expansion->allocate
+         (eval n (resolve-module '(backend generator expansion))))
+        (resolve-module '(backend generator assembly))))
diff --git a/src/backend/generator/expansion.scm b/src/backend/generator/expansion.scm
new file mode 100644
index 0000000..9fe2e0a
--- /dev/null
+++ b/src/backend/generator/expansion.scm
@@ -0,0 +1,23 @@
+(define-module (backend generator expansion)
+  #:use-module (backend ast ir)
+  #:use-module (backend utils merge-instructions)
+  #:export (instrs
+            not
+            neg
+            ret))
+
+
+(define (instrs lst)
+  #f
+  (list 'instrs (cons 'list (merge-instr lst))))
+
+(define (not src dst) (unary 'not src dst))
+(define (neg src dst) (unary 'neg src dst))
+
+(define (ret src)
+  (list (list 'mov src (list 'reg "eax"))
+        (list 'ret)))
+
+(define (unary op src dst)
+  (list (list 'mov src dst)
+        (list op dst)))
-- 
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