Rename to struct rbimpl_size_overflow_tag

This struct is used for addition not only for multiplication, so
remove the word `mul`, and make the member names more descriptive.

Author: nobu

gc.c

@@ -484,31 +484,31 @@ rb_malloc_grow_capa(size_t current, size_t type_size)
     return new_capacity;
 }
 
-static inline struct rbimpl_size_mul_overflow_tag
+static inline struct rbimpl_size_overflow_tag
 size_mul_add_overflow(size_t x, size_t y, size_t z) /* x * y + z */
 {
-    struct rbimpl_size_mul_overflow_tag t = rbimpl_size_mul_overflow(x, y);
-    struct rbimpl_size_mul_overflow_tag u = rbimpl_size_add_overflow(t.right, z);
-    return (struct rbimpl_size_mul_overflow_tag) { t.left || u.left, u.right };
+    struct rbimpl_size_overflow_tag t = rbimpl_size_mul_overflow(x, y);
+    struct rbimpl_size_overflow_tag u = rbimpl_size_add_overflow(t.result, z);
+    return (struct rbimpl_size_overflow_tag) { t.overflowed || u.overflowed, u.result };
 }
 
-static inline struct rbimpl_size_mul_overflow_tag
+static inline struct rbimpl_size_overflow_tag
 size_mul_add_mul_overflow(size_t x, size_t y, size_t z, size_t w) /* x * y + z * w */
 {
-    struct rbimpl_size_mul_overflow_tag t = rbimpl_size_mul_overflow(x, y);
-    struct rbimpl_size_mul_overflow_tag u = rbimpl_size_mul_overflow(z, w);
-    struct rbimpl_size_mul_overflow_tag v = rbimpl_size_add_overflow(t.right, u.right);
-    return (struct rbimpl_size_mul_overflow_tag) { t.left || u.left || v.left, v.right };
+    struct rbimpl_size_overflow_tag t = rbimpl_size_mul_overflow(x, y);
+    struct rbimpl_size_overflow_tag u = rbimpl_size_mul_overflow(z, w);
+    struct rbimpl_size_overflow_tag v = rbimpl_size_add_overflow(t.result, u.result);
+    return (struct rbimpl_size_overflow_tag) { t.overflowed || u.overflowed || v.overflowed, v.result };
 }
 
 PRINTF_ARGS(NORETURN(static void gc_raise(VALUE, const char*, ...)), 2, 3);
 
 static inline size_t
 size_mul_or_raise(size_t x, size_t y, VALUE exc)
 {
-    struct rbimpl_size_mul_overflow_tag t = rbimpl_size_mul_overflow(x, y);
-    if (LIKELY(!t.left)) {
-        return t.right;
+    struct rbimpl_size_overflow_tag t = rbimpl_size_mul_overflow(x, y);
+    if (LIKELY(!t.overflowed)) {
+        return t.result;
     }
     else if (rb_during_gc()) {
         rb_memerror();          /* or...? */
@@ -532,9 +532,9 @@ rb_size_mul_or_raise(size_t x, size_t y, VALUE exc)
 static inline size_t
 size_mul_add_or_raise(size_t x, size_t y, size_t z, VALUE exc)
 {
-    struct rbimpl_size_mul_overflow_tag t = size_mul_add_overflow(x, y, z);
-    if (LIKELY(!t.left)) {
-        return t.right;
+    struct rbimpl_size_overflow_tag t = size_mul_add_overflow(x, y, z);
+    if (LIKELY(!t.overflowed)) {
+        return t.result;
     }
     else if (rb_during_gc()) {
         rb_memerror();          /* or...? */
@@ -559,9 +559,9 @@ rb_size_mul_add_or_raise(size_t x, size_t y, size_t z, VALUE exc)
 static inline size_t
 size_mul_add_mul_or_raise(size_t x, size_t y, size_t z, size_t w, VALUE exc)
 {
-    struct rbimpl_size_mul_overflow_tag t = size_mul_add_mul_overflow(x, y, z, w);
-    if (LIKELY(!t.left)) {
-        return t.right;
+    struct rbimpl_size_overflow_tag t = size_mul_add_mul_overflow(x, y, z, w);
+    if (LIKELY(!t.overflowed)) {
+        return t.result;
     }
     else if (rb_during_gc()) {
         rb_memerror();          /* or...? */
@@ -5372,11 +5372,11 @@ ruby_mimcalloc(size_t num, size_t size)
 {
     void *mem;
 #if CALC_EXACT_MALLOC_SIZE
-    struct rbimpl_size_mul_overflow_tag t = rbimpl_size_mul_overflow(num, size);
-    if (UNLIKELY(t.left)) {
+    struct rbimpl_size_overflow_tag t = rbimpl_size_mul_overflow(num, size);
+    if (UNLIKELY(t.overflowed)) {
         return NULL;
     }
-    size = t.right + sizeof(struct malloc_obj_info);
+    size = t.result + sizeof(struct malloc_obj_info);
     mem = calloc1(size);
     if (!mem) {
         return NULL;

include/ruby/internal/memory.h

@@ -408,17 +408,18 @@ typedef uint128_t DSIZE_T;
 /**
  * @private
  *
- * This is an implementation detail of rbimpl_size_mul_overflow().
+ * This is an implementation detail of rbimpl_size_mul_overflow() and
+ * rbimpl_size_add_overflow().
  *
  * @internal
  *
  * Expecting  this struct  to be  eliminated  by function  inlinings.  This  is
  * nothing more than std::variant<std::size_t> if  we could use recent C++, but
  * reality is we cannot.
  */
-struct rbimpl_size_mul_overflow_tag {
-    bool left;                  /**< Whether overflow happened or not. */
-    size_t right;               /**< Multiplication result. */
+struct rbimpl_size_overflow_tag {
+    bool overflowed;            /**< Whether overflow happened or not. */
+    size_t result;              /**< Calculation result. */
 };
 
 RBIMPL_SYMBOL_EXPORT_BEGIN()
@@ -572,46 +573,46 @@ RBIMPL_ATTR_CONST()
  *
  * @param[in]  x  Arbitrary value.
  * @param[in]  y  Arbitrary value.
- * @return     `{ left, right }`,  where `left` is whether there  is an integer
- *             overflow or not,  and `right` is a  (possibly overflowed) result
- *             of `x` * `y`.
+ * @return     `{ overflowed, result }`, where  `overflowed` is whether there is
+ *             an  integer  overflow  or  not,   and  `result`  is  a  (possibly
+ *             overflowed) result of `x` * `y`.
  *
  * @internal
  *
  * This is in fact also an implementation detail of ruby_xmalloc2() etc.
  */
-static inline struct rbimpl_size_mul_overflow_tag
+static inline struct rbimpl_size_overflow_tag
 rbimpl_size_mul_overflow(size_t x, size_t y)
 {
-    struct rbimpl_size_mul_overflow_tag ret = { false,  0, };
+    struct rbimpl_size_overflow_tag ret = { false,  0, };
 
 #if defined(ckd_mul)
-    ret.left = ckd_mul(&ret.right, x, y);
+    ret.overflowed = ckd_mul(&ret.result, x, y);
 
 #elif RBIMPL_HAS_BUILTIN(__builtin_mul_overflow)
-    ret.left = __builtin_mul_overflow(x, y, &ret.right);
+    ret.overflowed = __builtin_mul_overflow(x, y, &ret.result);
 
 #elif defined(DSIZE_T)
     RB_GNUC_EXTENSION DSIZE_T dx = x;
     RB_GNUC_EXTENSION DSIZE_T dy = y;
     RB_GNUC_EXTENSION DSIZE_T dz = dx * dy;
-    ret.left  = dz > SIZE_MAX;
-    ret.right = RBIMPL_CAST((size_t)dz);
+    ret.overflowed  = dz > SIZE_MAX;
+    ret.result = RBIMPL_CAST((size_t)dz);
 
 #elif defined(_MSC_VER) && defined(_M_AMD64)
     unsigned __int64 dp = 0;
     unsigned __int64 dz = _umul128(x, y, &dp);
-    ret.left  = RBIMPL_CAST((bool)dp);
-    ret.right = RBIMPL_CAST((size_t)dz);
+    ret.overflowed  = RBIMPL_CAST((bool)dp);
+    ret.result = RBIMPL_CAST((size_t)dz);
 
 #elif defined(_MSC_VER) && defined(_M_ARM64)
-    ret.left  = __umulh(x, y) != 0;
-    ret.right = x * y;
+    ret.overflowed  = __umulh(x, y) != 0;
+    ret.result = x * y;
 
 #else
     /* https://wiki.sei.cmu.edu/confluence/display/c/INT30-C.+Ensure+that+unsigned+integer+operations+do+not+wrap */
-    ret.left  = (y != 0) && (x > SIZE_MAX / y);
-    ret.right = x * y;
+    ret.overflowed  = (y != 0) && (x > SIZE_MAX / y);
+    ret.result = x * y;
 #endif
 
     return ret;
@@ -635,11 +636,11 @@ rbimpl_size_mul_overflow(size_t x, size_t y)
 static inline size_t
 rbimpl_size_mul_or_raise(size_t x, size_t y)
 {
-    struct rbimpl_size_mul_overflow_tag size =
+    struct rbimpl_size_overflow_tag size =
         rbimpl_size_mul_overflow(x, y);
 
-    if (RB_LIKELY(! size.left)) {
-        return size.right;
+    if (RB_LIKELY(! size.overflowed)) {
+        return size.result;
     }
     else {
         ruby_malloc_size_overflow(x, y);
@@ -662,33 +663,33 @@ RBIMPL_ATTR_CONST()
  *
  * @param[in]  x  Arbitrary value.
  * @param[in]  y  Arbitrary value.
- * @return     `{ left, right }`,  where `left` is whether there  is an integer
- *             overflow or not,  and `right` is a  (possibly overflowed) result
- *             of `x` + `y`.
+ * @return     `{ overflowed, result }`, where  `overflowed` is whether there is
+ *             an  integer  overflow  or  not,   and  `result`  is  a  (possibly
+ *             overflowed) result of `x` + `y`.
  *
  * @internal
  */
-static inline struct rbimpl_size_mul_overflow_tag
+static inline struct rbimpl_size_overflow_tag
 rbimpl_size_add_overflow(size_t x, size_t y)
 {
-    struct rbimpl_size_mul_overflow_tag ret = { false,  0, };
+    struct rbimpl_size_overflow_tag ret = { false,  0, };
 
 #if defined(ckd_add)
-    ret.left = ckd_add(&ret.right, x, y);
+    ret.overflowed = ckd_add(&ret.result, x, y);
 
 #elif RBIMPL_HAS_BUILTIN(__builtin_add_overflow)
-    ret.left = __builtin_add_overflow(x, y, &ret.right);
+    ret.overflowed = __builtin_add_overflow(x, y, &ret.result);
 
 #elif defined(DSIZE_T)
     RB_GNUC_EXTENSION DSIZE_T dx = x;
     RB_GNUC_EXTENSION DSIZE_T dy = y;
     RB_GNUC_EXTENSION DSIZE_T dz = dx + dy;
-    ret.left = dz > SIZE_MAX;
-    ret.right = (size_t)dz;
+    ret.overflowed = dz > SIZE_MAX;
+    ret.result = (size_t)dz;
 
 #else
-    ret.right = x + y;
-    ret.left = ret.right < y;
+    ret.result = x + y;
+    ret.overflowed = ret.result < y;
 
 #endif
 
@@ -710,11 +711,11 @@ rbimpl_size_add_overflow(size_t x, size_t y)
 static inline size_t
 rbimpl_size_add_or_raise(size_t x, size_t y)
 {
-    struct rbimpl_size_mul_overflow_tag size =
+    struct rbimpl_size_overflow_tag size =
         rbimpl_size_add_overflow(x, y);
 
-    if (RB_LIKELY(!size.left)) {
-        return size.right;
+    if (RB_LIKELY(!size.overflowed)) {
+        return size.result;
     }
     else {
         ruby_malloc_add_size_overflow(x, y);

io_buffer.c

@@ -1527,8 +1527,8 @@ VALUE rb_io_buffer_free_locked(VALUE self)
 static bool
 size_sum_is_bigger_than(size_t a, size_t b, size_t x)
 {
-    struct rbimpl_size_mul_overflow_tag size = rbimpl_size_add_overflow(a, b);
-    return size.left || size.right > x;
+    struct rbimpl_size_overflow_tag size = rbimpl_size_add_overflow(a, b);
+    return size.overflowed || size.result > x;
 }
 
 // Validate that access to the buffer is within bounds, assuming you want to