[feature] add an inner-malloc util function

Add a set of macros to help us deal with several mallocs back-to-back in
creators, while ensuring that pointers stay aligned properly.

See #45 for details. Related to the !68 cleanup.

include/Makefile.am

@@ -28,8 +28,9 @@ include_aml_tiling_HEADERS = \
 
 include_amlutilsdir=$(includedir)/aml/utils
 include_amlutils_HEADERS = \
-			   aml/utils/vector.h \
 			   aml/utils/bitmap.h \
-			   aml/utils/version.h \
-			   aml/utils/error.h
+			   aml/utils/error.h \
+			   aml/utils/inner-malloc.h \
+			   aml/utils/vector.h \
+			   aml/utils/version.h
 

include/aml.h

@@ -35,6 +35,7 @@
 
 #include "aml/utils/bitmap.h"
 #include "aml/utils/error.h"
+#include "aml/utils/inner-malloc.h"
 #include "aml/utils/vector.h"
 #include "aml/utils/version.h"
 

include/aml/utils/inner-malloc.h

+/*******************************************************************************
+ * Copyright 2019 UChicago Argonne, LLC.
+ * (c.f. AUTHORS, LICENSE)
+ *
+ * This file is part of the AML project.
+ * For more info, see https://xgitlab.cels.anl.gov/argo/aml
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+*******************************************************************************/
+
+#ifndef AML_INNER_MALLOC_H
+#define AML_INNER_MALLOC_H
+
+/**
+ * @defgroup aml_inner_malloc "AML Internal Allocation Management"
+ * @brief AML helper functions to handle inner allocations
+ * @{
+ *
+ * Set of macros to create properly sized allocations of our internal complex
+ * objects. In particular, help with the generic handle and implementation
+ * specific data allocation as a single allocation, with all pointer properly
+ * aligned.
+ *
+ * This code is all macros to handle the type specific logic we need.
+ **/
+
+/** Returns the allocation size required to handle two objects side-by-side.
+ *
+ * Use an anonymous struct to ask the compiler what size an allocation should be
+ * so that the second object is properly aligned too.
+ */
+#define AML_SIZEOF_ALIGNED(a, b) \
+	(sizeof(struct { a __e1; b __e2; }))
+
+/** Returns the offset of the second object when allocated side-by-side.
+ *
+ * Use the same anonymous struct trick to figure out what offset the pointer is
+ * at.
+ */
+#define AML_OFFSETOF_ALIGNED(a, b) \
+	(offsetof(struct { a __e1; b __e2; }, __e2))
+
+/** Allocate a pointer that can be used to contain two types.
+ *
+ **/
+#define AML_INNER_MALLOC_2(a, b) calloc(1, AML_SIZEOF_ALIGNED(a, b))
+
+/** Returns the next pointer after an AML_INNER_MALLOC.
+ *
+ * Can be used to iterate over the pointers we need, using the last two types as
+ * parameters.
+ **/
+#define AML_INNER_MALLOC_NEXTPTR(ptr, a, b) \
+	(void *)(((intptr_t) ptr) + AML_OFFSETOF_ALIGNED(a, b))
+
+/**
+ * @}
+ **/
+
+#endif //AML_INNER_MALLOC_H

tests/Makefile.am

@@ -8,8 +8,10 @@ if TEST_VALGRIND
 TESTS_ENVIRONMENT= @LIBTOOL@ --mode=execute @VALGRIND@ --tool=memcheck -q --leak-check=full
 endif
 
-UTILS_TESTS = utils/test_vector \
+UTILS_TESTS = \
 	      utils/test_bitmap \
+	      utils/test_inner_malloc \
+	      utils/test_vector \
 	      utils/test_version
 
 AREA_TESTS = \

tests/utils/test_inner_malloc.c

+/*******************************************************************************
+ * Copyright 2019 UChicago Argonne, LLC.
+ * (c.f. AUTHORS, LICENSE)
+ *
+ * This file is part of the AML project.
+ * For more info, see https://xgitlab.cels.anl.gov/argo/aml
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+*******************************************************************************/
+
+#include "aml.h"
+#include <assert.h>
+
+int main(void)
+{
+	assert(AML_SIZEOF_ALIGN_GENERIC(16, size_t) % 16 == 0);
+	assert(AML_SIZEOF_ALIGN_GENERIC(16, char) % 16 == 0);
+	assert(AML_SIZEOF_ALIGN_DEFAULT(struct aml_area) %
+		       AML_DEFAULT_INNER_MALLOC_ALIGN == 0);
+	intptr_t *ptr = AML_INNER_MALLOC_2(void *, void *);
+	assert(ptr != NULL);
+	void *b = AML_INNER_MALLOC_NEXTPTR(ptr, void *);
+	assert(b == &ptr[1]);
+	free(ptr);
+	return 0;
+}
+