phasm/compiler.py

@@ -361,6 +361,7 @@ def module(inp: ourlang.Module) -> wasm.Module:
     result.functions = [
         _generate____new_reference___(inp),
         _generate_stdlib_alloc___init__(inp),
+        _generate_stdlib_alloc___find_free_block__(inp),
         _generate_stdlib_alloc___alloc__(inp),
         _generate____access_bytes_index___(inp),
     ] + [
@@ -394,6 +395,9 @@ def _generate____new_reference___(mod: ourlang.Module) -> wasm.Function:
         ],
     )
 
+STDLIB_ALLOC__FREE_BLOCK = '0x08'
+STDLIB_ALLOC__UNALLOC_ADDR = '0x0C'
+
 def _generate_stdlib_alloc___init__(mod: ourlang.Module) -> wasm.Function:
     return wasm.Function(
         'stdlib.alloc.__init__',
@@ -411,15 +415,17 @@ def _generate_stdlib_alloc___init__(mod: ourlang.Module) -> wasm.Function:
             wasm.Statement('end'),
 
             wasm.Statement('i32.const', '0x04', comment='Reserved'),
-            wasm.Statement('i32.const', '0x000000'),
+            wasm.Statement('i32.const', '0x00000000'),
             wasm.Statement('i32.store'),
 
-            wasm.Statement('i32.const', '0x08', comment='Address of next free block'),
+            wasm.Statement('i32.const', STDLIB_ALLOC__FREE_BLOCK,
-            wasm.Statement('i32.const', '0x000000'),
+                comment='Address of next free block'),
+            wasm.Statement('i32.const', '0x00000000'),
             wasm.Statement('i32.store'),
 
-            wasm.Statement('i32.const', '0x0C', comment='Reserved'),
+            wasm.Statement('i32.const', STDLIB_ALLOC__UNALLOC_ADDR,
-            wasm.Statement('i32.const', '0x000000'),
+                comment='Address of first unallocated byte'),
+            wasm.Statement('i32.const', '0x10'),
             wasm.Statement('i32.store'),
 
             wasm.Statement('i32.const', '0x00', comment='Done setting up'),
@@ -428,6 +434,30 @@ def _generate_stdlib_alloc___init__(mod: ourlang.Module) -> wasm.Function:
         ],
     )
 
+def _generate_stdlib_alloc___find_free_block__(mod: ourlang.Module) -> wasm.Function:
+    return wasm.Function(
+        'stdlib.alloc.__find_free_block__',
+        'stdlib.alloc.__find_free_block__',
+        [
+            ('alloc_size', type_(mod.types['i32']), ),
+        ],
+        [
+            ('result', type_(mod.types['i32']), ),
+        ],
+        type_(mod.types['i32']),
+        [
+            wasm.Statement('i32.const', STDLIB_ALLOC__FREE_BLOCK),
+            wasm.Statement('i32.load'),
+            wasm.Statement('i32.const', '0x00000000'),
+            wasm.Statement('i32.eq'),
+            wasm.Statement('if'),
+            wasm.Statement('i32.const', '0x00000000'),
+            wasm.Statement('return'),
+            wasm.Statement('end'),
+            wasm.Statement('unreachable'),
+        ],
+    )
+
 def _generate_stdlib_alloc___alloc__(mod: ourlang.Module) -> wasm.Function:
     return wasm.Function(
         'stdlib.alloc.__alloc__',
@@ -444,15 +474,36 @@ def _generate_stdlib_alloc___alloc__(mod: ourlang.Module) -> wasm.Function:
             wasm.Statement('i32.load'),
             wasm.Statement('i32.const', '0xA1C0'),
             wasm.Statement('i32.ne'),
-            wasm.Statement('if', comment='Failed to set up'),
+            wasm.Statement('if', comment='Failed to set up or memory corruption'),
             wasm.Statement('unreachable'),
             wasm.Statement('end'),
 
-            # wasm.Statement('local.get', '$alloc_size'),
+            wasm.Statement('local.get', '$alloc_size'),
-            # wasm.Statement('call', '$stdlib.alloc.__find_space__'),
+            wasm.Statement('call', '$stdlib.alloc.__find_free_block__'),
-            wasm.Statement('i32.const', '0x16', comment='STUB'),
             wasm.Statement('local.set', '$result'),
 
+            # Check if there was a free block
+            wasm.Statement('local.get', '$result'),
+            wasm.Statement('i32.const', '0x00000000'),
+            wasm.Statement('i32.eq'),
+            wasm.Statement('if', comment='No free block found'),
+
+            # Use unallocated space
+            wasm.Statement('i32.const', STDLIB_ALLOC__UNALLOC_ADDR),
+
+            wasm.Statement('i32.const', STDLIB_ALLOC__UNALLOC_ADDR),
+            wasm.Statement('i32.load'),
+            wasm.Statement('local.tee', '$result'),
+
+            # Updated unalloc pointer (address already set on stack)
+            wasm.Statement('i32.const', '0x04'), # Struct size
+            wasm.Statement('i32.add'),
+            wasm.Statement('local.get', '$alloc_size'),
+            wasm.Statement('i32.add'),
+            wasm.Statement('i32.store', 'offset=0'),
+
+            wasm.Statement('end'),
+
             # Store block size
             wasm.Statement('local.get', '$result'),
             wasm.Statement('local.get', '$alloc_size'),

tests/integration/test_stdlib_alloc.py

@@ -54,7 +54,7 @@ def testEntry() -> u8:
         b'\xC0\xA1\x00\x00'
         b'\x00\x00\x00\x00'
         b'\x00\x00\x00\x00'
-        b'\x00\x00\x00\x00'
+        b'\x10\x00\x00\x00'
         b'\x10\x11\x12\x13' # Untouched because unused
     ) == memory[0:20]
 
@@ -93,8 +93,10 @@ def testEntry() -> u8:
     sys.stderr.write(f'{DASHES} Memory (pre run)  {DASHES}\n')
     _dump_memory(rtime.get_memory(0))
 
-    offset = rtime.find_function('stdlib.alloc.__init__')()
+    rtime.find_function('stdlib.alloc.__init__')()
-    offset = rtime.find_function('stdlib.alloc.__alloc__')(32)
+    offset0 = rtime.find_function('stdlib.alloc.__alloc__')(32)
+    offset1 = rtime.find_function('stdlib.alloc.__alloc__')(32)
+    offset2 = rtime.find_function('stdlib.alloc.__alloc__')(32)
 
     sys.stderr.write(f'{DASHES} Memory (pre run)  {DASHES}\n')
     _dump_memory(rtime.get_memory(0))
@@ -103,4 +105,8 @@ def testEntry() -> u8:
 
     assert b'\xC0\xA1\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00' == memory[0:12]
 
-    assert 0 == offset
+    assert 0x14 == offset0
+    assert 0x38 == offset1
+    assert 0x5C == offset2
+
+    assert False