Convert some H5MM calls to standard C equivalents

src/H5MM.c

@@ -54,63 +54,6 @@
 /* Local Variables */
 /*******************/
 
-/*-------------------------------------------------------------------------
- * Function: H5MM_malloc
- *
- * Purpose: Similar to the C89 version of malloc().
- *
- * On size of 0, we return a NULL pointer instead of the
- * standard-allowed 'special' pointer since that's more
- * difficult to check as a return value. This is still
- * considered an error condition since allocations of zero
- * bytes usually indicate problems.
- *
- * Return: Success: Pointer to new memory
- * Failure: NULL
- *-------------------------------------------------------------------------
- */
-void *
-H5MM_malloc(size_t size)
-{
- void *ret_value = NULL;
-
- /* Use FUNC_ENTER_NOAPI_NOINIT_NOERR here to avoid performance issues */
- FUNC_ENTER_NOAPI_NOINIT_NOERR
-
- ret_value = HDmalloc(size);
-
- FUNC_LEAVE_NOAPI(ret_value)
-} /* end H5MM_malloc() */
-
-/*-------------------------------------------------------------------------
- * Function: H5MM_calloc
- *
- * Purpose: Similar to the C89 version of calloc(), except this
- * routine just takes a 'size' parameter.
- *
- * On size of 0, we return a NULL pointer instead of the
- * standard-allowed 'special' pointer since that's more
- * difficult to check as a return value. This is still
- * considered an error condition since allocations of zero
- * bytes usually indicate problems.
- *
- * Return: Success: Pointer to new memory
- * Failure: NULL
- *-------------------------------------------------------------------------
- */
-void *
-H5MM_calloc(size_t size)
-{
- void *ret_value = NULL;
-
- /* Use FUNC_ENTER_NOAPI_NOINIT_NOERR here to avoid performance issues */
- FUNC_ENTER_NOAPI_NOINIT_NOERR
-
- ret_value = HDcalloc(1, size);
-
- FUNC_LEAVE_NOAPI(ret_value)
-} /* end H5MM_calloc() */
-
 /*-------------------------------------------------------------------------
  * Function: H5MM_realloc
  *
@@ -282,34 +225,3 @@ H5MM_xfree_const(const void *mem)
 
  FUNC_LEAVE_NOAPI(NULL)
 } /* end H5MM_xfree_const() */
-
-/*-------------------------------------------------------------------------
- * Function: H5MM_memcpy
- *
- * Purpose: Like memcpy(3) but with sanity checks on the parameters,
- * particularly buffer overlap.
- *
- * Return: Success: pointer to dest
- * Failure: NULL
- *-------------------------------------------------------------------------
- */
-void *
-H5MM_memcpy(void *dest, const void *src, size_t n)
-{
- void *ret = NULL;
-
- /* Use FUNC_ENTER_NOAPI_NOINIT_NOERR here to avoid performance issues */
- FUNC_ENTER_NOAPI_NOINIT_NOERR
-
- HDassert(dest);
- HDassert(src);
-
- /* Check for buffer overlap */
- HDassert((char *)dest >= (const char *)src + n || (const char *)src >= (char *)dest + n);
-
- /* Copy */
- ret = HDmemcpy(dest, src, n);
-
- FUNC_LEAVE_NOAPI(ret)
-
-} /* end H5MM_memcpy() */

src/H5MMprivate.h

@@ -26,19 +26,26 @@
 /* Private headers needed by this file */
 #include "H5private.h"
 
-#define H5MM_free(Z) HDfree(Z)
+#define H5MM_calloc(Z) HDcalloc(1, Z)
+#define H5MM_free(Z) HDfree(Z)
+#define H5MM_malloc(Z) HDmalloc(Z)
+/* The void * casts are required to avoid tripping over undefined behavior if
+ * we are copying to/from poorly aliased pointers. As an example, this can
+ * happen in the type conversion code if a mis-aligned user buffer is passed
+ * to H5Tconvert and then cast to a type that assumes alignment. The casts
+ * will prevent the compiler from doing things like using SSE for the
+ * memcpy, which has strong alignment constraints.
+ */
+#define H5MM_memcpy(D, S, N) HDmemcpy((void *)D, (void *)S, N)
 
 /*
  * Library prototypes...
  */
-H5_DLL void *H5MM_malloc(size_t size) H5_ATTR_MALLOC;
-H5_DLL void *H5MM_calloc(size_t size) H5_ATTR_MALLOC;
 H5_DLL void *H5MM_realloc(void *mem, size_t size);
 H5_DLL char *H5MM_xstrdup(const char *s);
 H5_DLL char *H5MM_strdup(const char *s);
 H5_DLL char *H5MM_strndup(const char *s, size_t n);
 H5_DLL void *H5MM_xfree(void *mem);
 H5_DLL void *H5MM_xfree_const(const void *mem);
-H5_DLL void *H5MM_memcpy(void *dest, const void *src, size_t n);
 
 #endif /* H5MMprivate_H */

src/H5Tconv.c

@@ -887,7 +887,17 @@ done:
 /* Macro defining action on source data which needs to be aligned (before main action) */
 #define H5T_CONV_LOOP_PRE_SALIGN(ST) \
  { \
- H5MM_memcpy(&src_aligned, src, sizeof(ST)); \
+ /* The uint8_t * cast is required to avoid tripping over undefined behavior. \
+ * \
+ * The typed pointer arrives via a void pointer, which may have any alignement. \
+ * We then cast it to a pointer to a type that is assumed to be aligned, which \
+ * is undefined behavior (section 6.3.2.3 paragraph 7 of the C99 standard). \
+ * In the past this hasn't caused many problems, but in some cases (e.g. \
+ * converting long doubles on macOS), an optimizing compiler might do the \
+ * wrong thing (in the macOS case, the conversion uses SSE, which has stricter \
+ * requirements about alignment). \
+ */ \
+ H5MM_memcpy(&src_aligned, (uint8_t *)src, sizeof(ST)); \
  }
 
 /* Macro defining action on source data which doesn't need to be aligned (before main action) */
@@ -919,7 +929,17 @@ done:
 /* Macro defining action on destination data which needs to be aligned (after main action) */
 #define H5T_CONV_LOOP_POST_DALIGN(DT) \
  { \
- H5MM_memcpy(dst, &dst_aligned, sizeof(DT)); \
+ /* The uint8_t * cast is required to avoid tripping over undefined behavior. \
+ * \
+ * The typed pointer arrives via a void pointer, which may have any alignement. \
+ * We then cast it to a pointer to a type that is assumed to be aligned, which \
+ * is undefined behavior (section 6.3.2.3 paragraph 7 of the C99 standard). \
+ * In the past this hasn't caused many problems, but in some cases (e.g. \
+ * converting long doubles on macOS), an optimizing compiler might do the \
+ * wrong thing (in the macOS case, the conversion uses SSE, which has stricter \
+ * requirements about alignment). \
+ */ \
+ H5MM_memcpy((uint8_t *)dst, &dst_aligned, sizeof(DT)); \
  }
 
 /* Macro defining action on destination data which doesn't need to be aligned (after main action) */