speedup bumpptr_alloc

Don't use three individual expensive TSD variables.
Externalize and inline bump_up.

1 files changed, 51 insertions, 0 deletions

diff --git a/src/bump_alloc.h b/src/bump_alloc.h
new file mode 100644
index 0000000..300feef
--- /dev/null
+++ b/src/bump_alloc.h
@@ -0,0 +1,51 @@
+#include <assert.h>
+#include <stddef.h>   /* NULL, size_t */
+#include <stdint.h>   /* uintptr_t */
+#include <sys/mman.h> /* mmap */
+
+#ifndef MEMSIZE
+#define MEMSIZE 1024*4*1024*1024l
+#endif
+
+#define unlikely(x)     __builtin_expect((x),0)
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef struct bumpptr {
+	uintptr_t end;
+	uintptr_t ptr;
+} bumpptr_t;
+
+__thread bumpptr_t* tsd = NULL;
+
+static inline void* bump_up(size_t size, size_t align) {
+	assert(align % 2 == 0);
+
+	if (unlikely(tsd == NULL)) {
+		void* mem_start = mmap(NULL, MEMSIZE, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
+		if(mem_start == MAP_FAILED) {
+			perror("mmap");
+			return NULL;
+		}
+		tsd = (bumpptr_t*)mem_start;
+		tsd->ptr = (uintptr_t)mem_start + sizeof(bumpptr_t);
+		tsd->end = (uintptr_t)mem_start + MEMSIZE;
+	}
+
+	// align ptr;
+	uintptr_t aligned = (tsd->ptr + align - 1) & ~(align - 1);
+
+	uintptr_t new_ptr = aligned + size;
+	if (new_ptr > tsd->end)
+		return NULL;
+	else {
+		tsd->ptr = new_ptr;
+		return (void*)aligned;
+	}
+}
+
+#ifdef __cplusplus
+}
+#endif