On Fri, Feb 24, 2023 at 11:02:07AM +0100, Jakub Jelinek via Gcc-patches wrote:
> Maybe this would work, vl_relative even could be vl_embed.
> Because vl_embed I believe is used in two spots, part of
> auto_vec where it is followed by m_data and on heap or GGC
> allocated memory where vec<..., vl_embed> is followed by
> further storage for the vector.
So roughtly something like below? Except I get weird crashes with it
in the gen* tools. And we'd need to adjust the gdb python hooks
which also use m_vecdata.
--- gcc/vec.h.jj 2023-01-02 09:32:32.177143804 +0100
+++ gcc/vec.h 2023-02-24 11:19:37.900157177 +0100
@@ -586,8 +586,8 @@ public:
unsigned allocated (void) const { return m_vecpfx.m_alloc; }
unsigned length (void) const { return m_vecpfx.m_num; }
bool is_empty (void) const { return m_vecpfx.m_num == 0; }
- T *address (void) { return m_vecdata; }
- const T *address (void) const { return m_vecdata; }
+ T *address (void) { return (T *) (this + 1); }
+ const T *address (void) const { return (const T *) (this + 1); }
T *begin () { return address (); }
const T *begin () const { return address (); }
T *end () { return address () + length (); }
@@ -629,10 +629,9 @@ public:
friend struct va_gc_atomic;
friend struct va_heap;
- /* FIXME - These fields should be private, but we need to cater to
+ /* FIXME - This field should be private, but we need to cater to
compilers that have stricter notions of PODness for types. */
- vec_prefix m_vecpfx;
- T m_vecdata[1];
+ alignas (T) alignas (vec_prefix) vec_prefix m_vecpfx;
};
@@ -879,7 +878,7 @@ inline const T &
vec<T, A, vl_embed>::operator[] (unsigned ix) const
{
gcc_checking_assert (ix < m_vecpfx.m_num);
- return m_vecdata[ix];
+ return address ()[ix];
}
template<typename T, typename A>
@@ -887,7 +886,7 @@ inline T &
vec<T, A, vl_embed>::operator[] (unsigned ix)
{
gcc_checking_assert (ix < m_vecpfx.m_num);
- return m_vecdata[ix];
+ return address ()[ix];
}
@@ -929,7 +928,7 @@ vec<T, A, vl_embed>::iterate (unsigned i
{
if (ix < m_vecpfx.m_num)
{
- *ptr = m_vecdata[ix];
+ *ptr = address ()[ix];
return true;
}
else
@@ -955,7 +954,7 @@ vec<T, A, vl_embed>::iterate (unsigned i
{
if (ix < m_vecpfx.m_num)
{
- *ptr = CONST_CAST (T *, &m_vecdata[ix]);
+ *ptr = CONST_CAST (T *, &address ()[ix]);
return true;
}
else
@@ -978,7 +977,7 @@ vec<T, A, vl_embed>::copy (ALONE_MEM_STA
{
vec_alloc (new_vec, len PASS_MEM_STAT);
new_vec->embedded_init (len, len);
- vec_copy_construct (new_vec->address (), m_vecdata, len);
+ vec_copy_construct (new_vec->address (), address (), len);
}
return new_vec;
}
@@ -1018,7 +1017,7 @@ inline T *
vec<T, A, vl_embed>::quick_push (const T &obj)
{
gcc_checking_assert (space (1));
- T *slot = &m_vecdata[m_vecpfx.m_num++];
+ T *slot = &address ()[m_vecpfx.m_num++];
*slot = obj;
return slot;
}
@@ -1031,7 +1030,7 @@ inline T &
vec<T, A, vl_embed>::pop (void)
{
gcc_checking_assert (length () > 0);
- return m_vecdata[--m_vecpfx.m_num];
+ return address ()[--m_vecpfx.m_num];
}
@@ -1056,7 +1055,7 @@ vec<T, A, vl_embed>::quick_insert (unsig
{
gcc_checking_assert (length () < allocated ());
gcc_checking_assert (ix <= length ());
- T *slot = &m_vecdata[ix];
+ T *slot = &address ()[ix];
memmove (slot + 1, slot, (m_vecpfx.m_num++ - ix) * sizeof (T));
*slot = obj;
}
@@ -1071,7 +1070,7 @@ inline void
vec<T, A, vl_embed>::ordered_remove (unsigned ix)
{
gcc_checking_assert (ix < length ());
- T *slot = &m_vecdata[ix];
+ T *slot = &address ()[ix];
memmove (slot, slot + 1, (--m_vecpfx.m_num - ix) * sizeof (T));
}
@@ -1118,7 +1117,7 @@ inline void
vec<T, A, vl_embed>::unordered_remove (unsigned ix)
{
gcc_checking_assert (ix < length ());
- m_vecdata[ix] = m_vecdata[--m_vecpfx.m_num];
+ address ()[ix] = address ()[--m_vecpfx.m_num];
}
@@ -1130,7 +1129,7 @@ inline void
vec<T, A, vl_embed>::block_remove (unsigned ix, unsigned len)
{
gcc_checking_assert (ix + len <= length ());
- T *slot = &m_vecdata[ix];
+ T *slot = &address ()[ix];
m_vecpfx.m_num -= len;
memmove (slot, slot + len, (m_vecpfx.m_num - ix) * sizeof (T));
}
@@ -1309,7 +1308,7 @@ vec<T, A, vl_embed>::embedded_size (unsi
vec, vec_embedded>::type vec_stdlayout;
static_assert (sizeof (vec_stdlayout) == sizeof (vec), "");
static_assert (alignof (vec_stdlayout) == alignof (vec), "");
- return offsetof (vec_stdlayout, m_vecdata) + alloc * sizeof (T);
+ return sizeof (vec_stdlayout) + alloc * sizeof (T);
}
@@ -1476,10 +1475,10 @@ public:
{ return m_vec ? m_vec->length () : 0; }
T *address (void)
- { return m_vec ? m_vec->m_vecdata : NULL; }
+ { return m_vec ? m_vec->address () : NULL; }
const T *address (void) const
- { return m_vec ? m_vec->m_vecdata : NULL; }
+ { return m_vec ? m_vec->address () : NULL; }
T *begin () { return address (); }
const T *begin () const { return address (); }
@@ -1584,7 +1583,7 @@ public:
private:
vec<T, va_heap, vl_embed> m_auto;
- T m_data[MAX (N - 1, 1)];
+ unsigned char m_data[MAX (N - 1, 1)];
};
/* auto_vec is a sub class of vec whose storage is released when it is
Jakub
