Add bump allocator

3 files changed, 55 insertions, 2 deletions

diff --git a/runtime/build.py b/runtime/build.py
index bd55dbf4..927eaf20 100644
--- a/runtime/build.py
+++ b/runtime/build.py
@@ -30,7 +30,7 @@ targets = [
 ]
 
 
-gcs = ["mark-and-sweep"]
+gcs = ["bump", "mark-and-sweep"]
 
 
 def main():
diff --git a/runtime/meson_options.txt b/runtime/meson_options.txt
index f8e34764..1bec2d79 100644
--- a/runtime/meson_options.txt
+++ b/runtime/meson_options.txt
@@ -1,4 +1,4 @@
-option('gc', type : 'combo', choices : ['mark-and-sweep'], value : 'mark-and-sweep')
+option('gc', type : 'combo', choices : ['bump', 'mark-and-sweep'], value : 'mark-and-sweep')
 
 # In production, we only want to collect periodically, but we currently always
 # collect by default to hopefully surface errors more quickly.
diff --git a/runtime/src/shed/gc/bump/gc.c b/runtime/src/shed/gc/bump/gc.c
new file mode 100644
index 00000000..e61e5d89
--- /dev/null
+++ b/runtime/src/shed/gc/bump/gc.c
@@ -0,0 +1,53 @@
+#include <unistd.h>
+
+#include "../../../patio/patio.h"
+#include "../../gc.h"
+
+#define MAX(a,b) (((a)>(b))?(a):(b))
+
+void* ptr = NULL;
+intptr_t remaining = 0;
+
+void shed__runtime__gc_init(void) {
+    ptr = sbrk(0);
+
+    intptr_t remainder = (intptr_t) ptr % sizeof(PatioInt);
+    if (remainder != 0) {
+        intptr_t increment = sizeof(PatioInt) - remainder;
+        // TODO: check for -1 from sbrk
+        sbrk(increment);
+
+        ptr += increment;
+    }
+}
+
+void* shed__runtime__gc_alloc(size_t size, uint32_t runtime_type_tag) {
+    // TODO: call init (once) from generated code
+    if (ptr == NULL) {
+        shed__runtime__gc_init();
+    }
+
+    if (size % sizeof(PatioInt) != 0) {
+        size = size + (sizeof(PatioInt) - size % sizeof(PatioInt));
+    }
+
+    if (remaining < size) {
+        // TODO: what should we grow by?
+        intptr_t increment = MAX(1024 * 1024, size);
+        // TODO: check for -1 from sbrk
+        sbrk(increment);
+
+        remaining += increment;
+    }
+
+    struct ShedGcObjectHeader* object = ptr;
+    ptr += size;
+    remaining -= size;
+
+    object->runtime_type_tag = runtime_type_tag;
+
+    return object;
+}
+
+void shed__runtime__gc_collect() {
+}