From d017ebe096ee310bfe73431dbd4a54a4350c6243 Mon Sep 17 00:00:00 2001
From: "Johan B.W. de Vries" <info@jbwdevries.nl>
Date: Sun, 25 May 2025 14:42:31 +0200
Subject: [PATCH] Support tail calls

---
 phasm/compiler.py | 24 +++++++++++++++++-------
 1 file changed, 17 insertions(+), 7 deletions(-)

diff --git a/phasm/compiler.py b/phasm/compiler.py
index 4eaf1b2..cc7aa1e 100644
--- a/phasm/compiler.py
+++ b/phasm/compiler.py
@@ -369,21 +369,31 @@ def expression(wgn: WasmGenerator, mod: ourlang.Module, inp: ourlang.Expression)
 
     raise NotImplementedError(expression, inp)
 
-def statement_return(wgn: WasmGenerator, mod: ourlang.Module, inp: ourlang.StatementReturn) -> None:
+def statement_return(wgn: WasmGenerator, mod: ourlang.Module, fun: ourlang.Function, inp: ourlang.StatementReturn) -> None:
     """
     Compile: Return statement
     """
+    # Support tail calls
+    # https://github.com/WebAssembly/tail-call
+    # These help a lot with some functional programming techniques
+    if isinstance(inp.value, ourlang.FunctionCall) and inp.value.function is fun:
+        for arg in inp.value.arguments:
+            expression(wgn, mod, arg)
+
+        wgn.add_statement('return_call', '${}'.format(inp.value.function.name))
+        return
+
     expression(wgn, mod, inp.value)
     wgn.return_()
 
-def statement_if(wgn: WasmGenerator, mod: ourlang.Module, inp: ourlang.StatementIf) -> None:
+def statement_if(wgn: WasmGenerator, mod: ourlang.Module, fun: ourlang.Function, inp: ourlang.StatementIf) -> None:
     """
     Compile: If statement
     """
     expression(wgn, mod, inp.test)
     with wgn.if_():
         for stat in inp.statements:
-            statement(wgn, mod, stat)
+            statement(wgn, mod, fun, stat)
 
         if inp.else_statements:
             raise NotImplementedError
@@ -391,16 +401,16 @@ def statement_if(wgn: WasmGenerator, mod: ourlang.Module, inp: ourlang.Statement
             # for stat in inp.else_statements:
             #     statement(wgn, stat)
 
-def statement(wgn: WasmGenerator, mod: ourlang.Module, inp: ourlang.Statement) -> None:
+def statement(wgn: WasmGenerator, mod: ourlang.Module, fun: ourlang.Function, inp: ourlang.Statement) -> None:
     """
     Compile: any statement
     """
     if isinstance(inp, ourlang.StatementReturn):
-        statement_return(wgn, mod, inp)
+        statement_return(wgn, mod, fun, inp)
         return
 
     if isinstance(inp, ourlang.StatementIf):
-        statement_if(wgn, mod, inp)
+        statement_if(wgn, mod, fun, inp)
         return
 
     if isinstance(inp, ourlang.StatementPass):
@@ -443,7 +453,7 @@ def function(mod: ourlang.Module, inp: ourlang.Function) -> wasm.Function:
         _generate_struct_constructor(wgn, inp)
     else:
         for stat in inp.statements:
-            statement(wgn, mod, stat)
+            statement(wgn, mod, inp, stat)
 
     return wasm.Function(
         inp.name,