Replace check_mul_overflow_size_t with __builtin_mul_overflow

Checked on x86_64-linux-gnu and i686-linux-gnu.

	* malloc/alloc_buffer_alloc_array.c (__libc_alloc_buffer_alloc_array):
	Use __builtin_mul_overflow in place of check_mul_overflow_size_t.
	* malloc/dynarray_emplace_enlarge.c (__libc_dynarray_emplace_enlarge):
	Likewise.
	* malloc/dynarray_resize.c (__libc_dynarray_resize): Likewise.
	* malloc/reallocarray.c (__libc_reallocarray): Likewise.
	* malloc/malloc-internal.h (check_mul_overflow_size_t): Remove
	function.
	* support/blob_repeat.c (check_mul_overflow_size_t,
	(minimum_stride_size, support_blob_repeat_allocate): Likewise.

5 files changed, 5 insertions, 30 deletions

diff --git a/malloc/alloc_buffer_alloc_array.c b/malloc/alloc_buffer_alloc_array.c
index 1dd098a..7505422 100644
--- a/malloc/alloc_buffer_alloc_array.c
+++ b/malloc/alloc_buffer_alloc_array.c
@@ -17,7 +17,6 @@
    <http://www.gnu.org/licenses/>.  */
 
 #include <alloc_buffer.h>
-#include <malloc-internal.h>
 #include <libc-pointer-arith.h>
 
 void *
@@ -28,7 +27,7 @@ __libc_alloc_buffer_alloc_array (struct alloc_buffer *buf, size_t element_size,
   /* The caller asserts that align is a power of two.  */
   size_t aligned = ALIGN_UP (current, align);
   size_t size;
-  bool overflow = check_mul_overflow_size_t (element_size, count, &size);
+  bool overflow = __builtin_mul_overflow (element_size, count, &size);
   size_t new_current = aligned + size;
   if (!overflow                /* Multiplication did not overflow.  */
       && aligned >= current    /* No overflow in align step.  */
diff --git a/malloc/dynarray_emplace_enlarge.c b/malloc/dynarray_emplace_enlarge.c
index 0408271..aa8f5fa 100644
--- a/malloc/dynarray_emplace_enlarge.c
+++ b/malloc/dynarray_emplace_enlarge.c
@@ -18,7 +18,6 @@
 
 #include <dynarray.h>
 #include <errno.h>
-#include <malloc-internal.h>
 #include <stdlib.h>
 #include <string.h>
 
@@ -52,7 +51,7 @@ __libc_dynarray_emplace_enlarge (struct dynarray_header *list,
     }
 
   size_t new_size;
-  if (check_mul_overflow_size_t (new_allocated, element_size, &new_size))
+  if (__builtin_mul_overflow (new_allocated, element_size, &new_size))
     return false;
   void *new_array;
   if (list->array == scratch)
diff --git a/malloc/dynarray_resize.c b/malloc/dynarray_resize.c
index 0bfca1b..0205cf7 100644
--- a/malloc/dynarray_resize.c
+++ b/malloc/dynarray_resize.c
@@ -18,7 +18,6 @@
 
 #include <dynarray.h>
 #include <errno.h>
-#include <malloc-internal.h>
 #include <stdlib.h>
 #include <string.h>
 
@@ -38,7 +37,7 @@ __libc_dynarray_resize (struct dynarray_header *list, size_t size,
      over-allocation here.  */
 
   size_t new_size_bytes;
-  if (check_mul_overflow_size_t (size, element_size, &new_size_bytes))
+  if (__builtin_mul_overflow (size, element_size, &new_size_bytes))
     {
       /* Overflow.  */
       __set_errno (ENOMEM);
diff --git a/malloc/malloc-internal.h b/malloc/malloc-internal.h
index 9cee0fb..70d5b38 100644
--- a/malloc/malloc-internal.h
+++ b/malloc/malloc-internal.h
@@ -74,24 +74,4 @@ void __malloc_fork_unlock_child (void) attribute_hidden;
 /* Called as part of the thread shutdown sequence.  */
 void __malloc_arena_thread_freeres (void) attribute_hidden;
 
-/* Set *RESULT to LEFT * RIGHT.  Return true if the multiplication
-   overflowed.  */
-static inline bool
-check_mul_overflow_size_t (size_t left, size_t right, size_t *result)
-{
-#if __GNUC__ >= 5
-  return __builtin_mul_overflow (left, right, result);
-#else
-  /* size_t is unsigned so the behavior on overflow is defined.  */
-  *result = left * right;
-  size_t half_size_t = ((size_t) 1) << (8 * sizeof (size_t) / 2);
-  if (__glibc_unlikely ((left | right) >= half_size_t))
-    {
-      if (__glibc_unlikely (right != 0 && *result / right != left))
-        return true;
-    }
-  return false;
-#endif
-}
-
 #endif /* _MALLOC_INTERNAL_H */
diff --git a/malloc/reallocarray.c b/malloc/reallocarray.c
index 319eccd..3264230 100644
--- a/malloc/reallocarray.c
+++ b/malloc/reallocarray.c
@@ -18,19 +18,17 @@
 
 #include <errno.h>
 #include <malloc.h>
-#include <malloc/malloc-internal.h>
 
 void *
 __libc_reallocarray (void *optr, size_t nmemb, size_t elem_size)
 {
   size_t bytes;
-  if (check_mul_overflow_size_t (nmemb, elem_size, &bytes))
+  if (__builtin_mul_overflow (nmemb, elem_size, &bytes))
     {
       __set_errno (ENOMEM);
       return 0;
     }
-  else
-    return realloc (optr, bytes);
+  return realloc (optr, bytes);
 }
 libc_hidden_def (__libc_reallocarray)