figured out basic runtime

docs/dev/backend/approach.md

@@ -1 +0,0 @@
-This has been the hardest to figure out. I found that LLVM as an abstraction is not good enough. So I am just writing my abstraction I guess. I am implementing my DSL to emit a JSON that closely mirrors LLVM.

src/backend/dsl.scm → src/backend/brilisp.scm

@@ -101,6 +101,8 @@
         (else (error "unknown instruction: " instr))))
 
 (bril '(
+    (bril-define ((print int) (n int)))
+
     (bril-define ((add5 int) (n int))
         (set (five int) (const 5))
         (set (sum int) (add n five))
@@ -109,6 +111,7 @@
     (bril-define ((main int))
         (set (a int) (const 9))
         (set (b int) (call add5 a))
+        (set (tmp int) (call print b))
         (ret b)
     )
 ))

src/backend/llvm.py

@@ -45,11 +45,13 @@ def gen_function(self, fn):
         self.func_symtab = {}
         # Create the function skeleton from the prototype.
         func = self.gen_function_prototype(fn)
-        # Create the entry BB in the function and set the builder to it.
-        bb_entry = func.append_basic_block("entry")
-        self.builder = ir.IRBuilder(bb_entry)
-        retval = self.gen_instructions(fn.instrs)
-        self.builder.ret(retval)
+
+        if fn.instrs:
+            # Create the entry BB in the function and set the builder to it.
+            bb_entry = func.append_basic_block("entry")
+            self.builder = ir.IRBuilder(bb_entry)
+            retval = self.gen_instructions(fn.instrs)
+            self.builder.ret(retval)
         return func
 
     def gen_function_prototype(self, fn):

src/backend/run.sh

@@ -0,0 +1,8 @@
+tmp_in=$(mktemp --suffix '.ll')
+tmp_out=$(mktemp --suffix '.out')
+
+cp /dev/stdin $tmp_in
+clang $tmp_in runtime.c -o $tmp_out -Wno-override-module
+$tmp_out
+
+rm $tmp_in $tmp_out

src/backend/runtime.c

@@ -0,0 +1,6 @@
+#include <stdio.h>
+
+int print(int x){
+    printf("%d\n", x);
+    return x;
+}