Functions without explicit return statements

forge_core/src/compiler/ast_nodes/block.rs

@@ -69,6 +69,7 @@ mod test {
                 "peekr", // Push the addr of x
                 "swap 12", // The asm body, which swaps 12 behind it and stores it there
                 "storew",
+                "popr", "pop", "ret 0" // Implicit void return
             ]
                 .join("\n")
         )
@@ -109,6 +110,7 @@ mod test {
                 "popr", // Blow away old frame ptr
                 "pop",
                 "ret",
+                "popr", "pop", "ret 0" // Implicit void return
             ]
                 .join("\n")
         );

forge_core/src/compiler/ast_nodes/call.rs

@@ -17,6 +17,9 @@ impl Compilable for Call {
         }
 
         // Now we increment the frame ptr to right after the current frame:
+        // todo this messes with recursive calls: we're hard-coding the frame size _right now,_
+        // which may increase later with later vardecls in the fn, which could be _executed_ before
+        // this call is. We need to store the top of the frame at runtime somehow.
         sig.emit("peekr");
         let frame_size = sig.frame_size();
         if frame_size > 0 {
@@ -31,29 +34,13 @@ impl Compilable for Call {
         //sig.emit("loadw frame");
         //sig.emit("pushr");
 
-        // todo this makes arrays not work. we can no longer statically compute the frame size, we
-        // need to have the frame size stored at runtime somehow, probably rstack. This will mean
-        // every fn will stick the frame ptr it's given in the rstack in its preamble, and that any
-        // vardecl will increment that ptr (that the top of the rstack is the end of the current
-        // frame, essentially). Returns also need to popr/pop before doing the actual ret.
-        // todo also for that matter, that means that the frame ptr no longer needs to be a global
-        // symbol: have it be stored in the rstack and passed as the first param in a call. So the
-        // calling convention is, push the args, push the new fn's frame ptr (current top-of-frame+1),
-        // call. The receiving fn puts its frame ptr into the rstack, dups it there, puts the args
-        // (it knows its own arity) into its frame, and then every vardecl grabs the 2nd thing from r,
-        // increments it by whatever, and puts it back.
-        // todo in fact, a larger refactor would just store the frame size as the first thing in the
-        // frame, to make vardecls faster
-
         // Do the call:
         sig.emit("call");
 
         // And this is where we'll return to. The function has popped its args and left a word on
         // the stack as a return value, which someone else will deal with (this is the word that
-        // this expr::call will end up evaluating to). But before we're done, we need to restore
-        // our frame pointer:
-        //sig.emit("popr");
-        //sig.emit("storew frame");
+        // this expr::call will end up evaluating to). What's left on our rstack now is our frame ptr,
+        // which is what we want.
 
         // And we're finished!
         Ok(())
@@ -82,6 +69,7 @@ mod test {
                 "push _forge_gensym_1", // evaluating target (this fn)
                 "call", // Actually make the call
                 "pop", // expr-as-statement drops the evaluated value
+                "popr", "pop", "ret 0" // Implicit void return
             ]
                 .join("\n")
         );

forge_core/src/compiler/ast_nodes/conditional.rs

@@ -43,7 +43,9 @@ mod test {
                 "push 1",
                 "peekr",
                 "storew", // The branch, x = 1
-                "#end"]
+                "#end",
+                "popr", "pop", "ret 0" // Implicit void return
+            ]
                 .join("\n")
         );
     }
@@ -69,7 +71,9 @@ mod test {
                 "push 7",
                 "peekr",
                 "storew", // x = 7
-                "#end"]
+                "#end",
+                "popr", "pop", "ret 0" // Implicit void return
+            ]
                 .join("\n")
         )
     }

forge_core/src/compiler/ast_nodes/expr.rs

@@ -166,6 +166,7 @@ mod test {
                 "peekr",
                 "add 3", // the address of y (frame + 3) and put gensym_4 in it
                 "storew",
+                "popr", "pop", "ret 0" // Implicit void return
             ]
                 .join("\n")
         )
@@ -184,6 +185,7 @@ mod test {
                 "peekr",
                 "add 3", // the address of y (frame + 3) and put the addr of x (frame) in it
                 "storew",
+                "popr", "pop", "ret 0" // Implicit void return
             ]
                 .join("\n")
         )
@@ -203,6 +205,7 @@ mod test {
                 "loadw", // Then load the value at 3
                 "push 1000", // Push the addr 1000, for the lvalue
                 "storew", // Store whatever's at 3 to 1000
+                "popr", "pop", "ret 0" // Implicit void return
             ]
                 .join("\n")
         )
@@ -219,6 +222,7 @@ mod test {
                 "add", // Add 3 to that address
                 "peekr", // Store it in the first var
                 "storew",
+                "popr", "pop", "ret 0" // Implicit void return
             ]
                 .join("\n")
         )

forge_core/src/compiler/ast_nodes/function.rs

@@ -1,4 +1,4 @@
-use crate::ast::{Function, Location};
+use crate::ast::{Function, Location, Return};
 use crate::compiler::compilable::Compilable;
 use crate::compiler::compiled_fn::CompiledFn;
 use crate::compiler::CompileError;
@@ -26,6 +26,10 @@ impl Compilable for Function {
         // Compile the body, storing all of it in the CompiledFn we just created / added
         self.body.process(state, Some(&mut sig), loc)?;
 
+        // This fn probably has a return statement... but it's not required. As a final catch just
+        // in case we fall through to this point, we'll generate a void return and compile it:
+        Return(None).process(state, Some(&mut sig), loc)?;
+
         // This can't fail because if it were a dupe name, adding the global would have failed
         state.functions.insert(self.name.clone(), sig);
 
@@ -58,6 +62,7 @@ mod test {
                 "peekr", // Calculate the lvalue
                 "add 3",       // "b" arg is frame + 3
                 "storew",      // Finally store
+                "popr", "pop", "ret 0" // Implicit void return
             ]
                 .join("\n")
         )

forge_core/src/compiler/ast_nodes/repeat_loop.rs

@@ -132,6 +132,7 @@ mod test {
                 "popr", // toss old frame ptr
                 "pop",
                 "ret",
+                "popr", "pop", "ret 0" // Implicit void return
             ]
                 .join("\n")
         );
@@ -173,6 +174,7 @@ mod test {
                 "popr", // Toss old frame ptr
                 "pop",
                 "ret",
+                "popr", "pop", "ret 0" // Implicit void return
             ].join("\n")
         );
     }

forge_core/src/compiler/ast_nodes/return.rs

@@ -52,6 +52,7 @@ mod test {
                 "popr", // Toss frame ptr
                 "pop",
                 "ret", // Return that
+                "popr", "pop", "ret 0" // Implicit void return
             ]
                 .join("\n")
         );
@@ -74,6 +75,7 @@ mod test {
                 "pop",
                 "ret 0", // Default return value, for an expr-less return
                 "#end",
+                "popr", "pop", "ret 0" // Implicit void return
             ]
                 .join("\n")
         );

forge_core/src/compiler/ast_nodes/var_decl.rs

@@ -48,6 +48,7 @@ mod test {
                 "mul",         // b * 2 evaluated
                 "peekr", // Loading "a" as an lvalue
                 "storew",      // doing the assignment
+                "popr", "pop", "ret 0" // Implicit void return
             ]
                 .join("\n")
         )

forge_core/src/compiler/ast_nodes/while_loop.rs

@@ -58,7 +58,8 @@ mod test {
                 "peekr",
                 "add 3",
                 "storew", // c = c + 1
-                "#end" // End the loop body
+                "#end", // End the loop body
+                "popr", "pop", "ret 0" // Implicit void return
             ]
                 .join("\n")
         );

forge_core/src/compiler/mod.rs

@@ -79,6 +79,7 @@ mod test {
             "popr",
             "pop",
             "ret",
+            "popr", "pop", "ret 0", // Implicit void return
             "stack: .db 0",
         ].join("\n"));
 
@@ -96,6 +97,38 @@ mod test {
             "popr",
             "pop",
             "ret",
+            "popr", "pop", "ret 0", // Implicit void return
+            "stack: .db 0",
+        ].join("\n"))
+    }
+
+    #[test]
+    fn test_global_vars() {
+
+    }
+
+    #[test]
+    fn test_no_return() {
+        let asm = build_boot("fn foo() { } fn main() { foo(); }".into()).unwrap();
+        assert_eq!(asm.join("\n"), vec![
+            ".org 0x400",
+            "push stack",
+            "call _forge_gensym_2",
+            "hlt",
+            "_forge_gensym_1:", // fn foo()
+            "pushr", // capture frame ptr
+            "popr", // drop it and ret
+            "pop",
+            "ret 0",
+            "_forge_gensym_2:", // fn main()
+            "pushr", // capture frame ptr
+            "peekr", // prep frame ptr to send to foo
+            "push _forge_gensym_1", // load foo
+            "call", // call it
+            "pop", // Throw away its return value
+            "popr", // drop frame ptr and ret
+            "pop",
+            "ret 0",
             "stack: .db 0",
         ].join("\n"))
     }