Re: [Mesa-dev] [RFC PATCH] util/ralloc: make mem_ctx parameter const for all r*alloc functions
This one got lost ...
Am Donnerstag, den 02.11.2017, 16:46 +0100 schrieb Nicolai Hähnle:
> On 26.10.2017 13:02, Gert Wollny wrote:
> > r(z)alloc_size and get_header both take a "const void *" for
> > mem_ctx,
> > but most of the other functions take a "void *" and also the "new"
> > operator in DECLARE_ALLOC_CXX_OPERATORS_TEMPLATE. The latter makes
> > it
> > impossible to copy-construct from a constant declared
> > class variable my using its mem_ctx like
> >
> > void f(const someclass *p)
> > {
> > someclass *q = new(p) someclass(*p);
> > ...
> > }
> >
> > and one has to write
> >
> > someclass *q = ralloc(p, someclass);
> > *q = *p;
> >
> > With this patch declare the mem_ctx parameters as "const void *"
> > for all relevant functions so that a more C++ like deep copy of
> > pointers to classes can be used.
>
> Well... the const-ness indicates that you're not going to modify an
> object, but you *are* modifying it here by adding child objects to
> it.
The key function where the ctx object is actually changed by adding a
child is
void *
ralloc_size(const void *ctx, size_t size);
so the const-ness is already violated. Actually, most of the r(z)alloc
functions take "const void *ctx", if it wasn't like this I would never
have proposed a patch that works around const-correctness.
> Admittedly there are some weird corner cases with const, but I don't
> think this is the right call.
In any case the proposed patch would only be convenience that makes
some c++ code more c++-ish ...
Best,
Gert
>
> Cheers,
> Nicolai
>
>
> >
> > Signed-off-by: Gert Wollny
> > ---
> > Submitter has no write access to mesa-git.
> >
> > src/util/ralloc.c | 14 +++---
> > src/util/ralloc.h | 15 ---
> > 2 files changed, 15 insertions(+), 14 deletions(-)
> >
> > diff --git a/src/util/ralloc.c b/src/util/ralloc.c
> > index 42cfa2e391..cd6bbfa9d4 100644
> > --- a/src/util/ralloc.c
> > +++ b/src/util/ralloc.c
> > @@ -597,7 +597,7 @@ typedef struct linear_size_chunk
> > linear_size_chunk;
> >
> > /* Allocate the linear buffer with its header. */
> > static linear_header *
> > -create_linear_node(void *ralloc_ctx, unsigned min_size)
> > +create_linear_node(const void *ralloc_ctx, unsigned min_size)
> > {
> > linear_header *node;
> >
> > @@ -622,7 +622,7 @@ create_linear_node(void *ralloc_ctx, unsigned
> > min_size)
> > }
> >
> > void *
> > -linear_alloc_child(void *parent, unsigned size)
> > +linear_alloc_child(const void *parent, unsigned size)
> > {
> > linear_header *first = LINEAR_PARENT_TO_HEADER(parent);
> > linear_header *latest = first->latest;
> > @@ -657,7 +657,7 @@ linear_alloc_child(void *parent, unsigned size)
> > }
> >
> > void *
> > -linear_alloc_parent(void *ralloc_ctx, unsigned size)
> > +linear_alloc_parent(const void *ralloc_ctx, unsigned size)
> > {
> > linear_header *node;
> >
> > @@ -676,7 +676,7 @@ linear_alloc_parent(void *ralloc_ctx, unsigned
> > size)
> > }
> >
> > void *
> > -linear_zalloc_child(void *parent, unsigned size)
> > +linear_zalloc_child(const void *parent, unsigned size)
> > {
> > void *ptr = linear_alloc_child(parent, size);
> >
> > @@ -686,7 +686,7 @@ linear_zalloc_child(void *parent, unsigned
> > size)
> > }
> >
> > void *
> > -linear_zalloc_parent(void *parent, unsigned size)
> > +linear_zalloc_parent(const void *parent, unsigned size)
> > {
> > void *ptr = linear_alloc_parent(parent, size);
> >
> > @@ -717,7 +717,7 @@ linear_free_parent(void *ptr)
> > }
> >
> > void
> > -ralloc_steal_linear_parent(void *new_ralloc_ctx, void *ptr)
> > +ralloc_steal_linear_parent(const void *new_ralloc_ctx, void *ptr)
> > {
> > linear_header *node;
> >
> > @@ -737,7 +737,7 @@ ralloc_steal_linear_parent(void
> > *new_ralloc_ctx, void *ptr)
> > }
> >
> > void *
> > -ralloc_parent_of_linear_parent(void *ptr)
> > +ralloc_parent_of_linear_parent(const void *ptr)
> > {
> > linear_header *node = LINEAR_PARENT_TO_HEADER(ptr);
> > #ifdef DEBUG
> > diff --git a/src/util/ralloc.h b/src/util/ralloc.h
> > index 05ae8f8407..e5c7993eb5 100644
> > --- a/src/util/ralloc.h
> > +++ b/src/util/ralloc.h
> > @@ -355,6 +355,7 @@ bool ralloc_asprintf_rewrite_tail(char **str,
> > size_t *start,
> > PRINTFLIKE(3, 4);
> >
> > /**
> > +
> > * Rewrite the tail of an existing string, starting at a given
> > index.
> > *
> > * Overwrites the contents of *str starting at \p start with
> > newly formatted
> > @@ -433,7 +434,7 @@
> > private:
> > \
> > reinterpret_cast(p)-
> > >~TYPE(); \
> > }
> > \
> >
> > public:
> > \
> > -
Re: [Mesa-dev] [RFC PATCH] util/ralloc: make mem_ctx parameter const for all r*alloc functions
On 26.10.2017 13:02, Gert Wollny wrote:
r(z)alloc_size and get_header both take a "const void *" for mem_ctx,
but most of the other functions take a "void *" and also the "new"
operator in DECLARE_ALLOC_CXX_OPERATORS_TEMPLATE. The latter makes it
impossible to copy-construct from a constant declared
class variable my using its mem_ctx like
void f(const someclass *p)
{
someclass *q = new(p) someclass(*p);
...
}
and one has to write
someclass *q = ralloc(p, someclass);
*q = *p;
With this patch declare the mem_ctx parameters as "const void *" for all
relevant functions so that a more C++ like deep copy of pointers to
classes can be used.
Well... the const-ness indicates that you're not going to modify an
object, but you *are* modifying it here by adding child objects to it.
Admittedly there are some weird corner cases with const, but I don't
think this is the right call.
Cheers,
Nicolai
Signed-off-by: Gert Wollny
---
Submitter has no write access to mesa-git.
src/util/ralloc.c | 14 +++---
src/util/ralloc.h | 15 ---
2 files changed, 15 insertions(+), 14 deletions(-)
diff --git a/src/util/ralloc.c b/src/util/ralloc.c
index 42cfa2e391..cd6bbfa9d4 100644
--- a/src/util/ralloc.c
+++ b/src/util/ralloc.c
@@ -597,7 +597,7 @@ typedef struct linear_size_chunk linear_size_chunk;
/* Allocate the linear buffer with its header. */
static linear_header *
-create_linear_node(void *ralloc_ctx, unsigned min_size)
+create_linear_node(const void *ralloc_ctx, unsigned min_size)
{
linear_header *node;
@@ -622,7 +622,7 @@ create_linear_node(void *ralloc_ctx, unsigned min_size)
}
void *
-linear_alloc_child(void *parent, unsigned size)
+linear_alloc_child(const void *parent, unsigned size)
{
linear_header *first = LINEAR_PARENT_TO_HEADER(parent);
linear_header *latest = first->latest;
@@ -657,7 +657,7 @@ linear_alloc_child(void *parent, unsigned size)
}
void *
-linear_alloc_parent(void *ralloc_ctx, unsigned size)
+linear_alloc_parent(const void *ralloc_ctx, unsigned size)
{
linear_header *node;
@@ -676,7 +676,7 @@ linear_alloc_parent(void *ralloc_ctx, unsigned size)
}
void *
-linear_zalloc_child(void *parent, unsigned size)
+linear_zalloc_child(const void *parent, unsigned size)
{
void *ptr = linear_alloc_child(parent, size);
@@ -686,7 +686,7 @@ linear_zalloc_child(void *parent, unsigned size)
}
void *
-linear_zalloc_parent(void *parent, unsigned size)
+linear_zalloc_parent(const void *parent, unsigned size)
{
void *ptr = linear_alloc_parent(parent, size);
@@ -717,7 +717,7 @@ linear_free_parent(void *ptr)
}
void
-ralloc_steal_linear_parent(void *new_ralloc_ctx, void *ptr)
+ralloc_steal_linear_parent(const void *new_ralloc_ctx, void *ptr)
{
linear_header *node;
@@ -737,7 +737,7 @@ ralloc_steal_linear_parent(void *new_ralloc_ctx, void *ptr)
}
void *
-ralloc_parent_of_linear_parent(void *ptr)
+ralloc_parent_of_linear_parent(const void *ptr)
{
linear_header *node = LINEAR_PARENT_TO_HEADER(ptr);
#ifdef DEBUG
diff --git a/src/util/ralloc.h b/src/util/ralloc.h
index 05ae8f8407..e5c7993eb5 100644
--- a/src/util/ralloc.h
+++ b/src/util/ralloc.h
@@ -355,6 +355,7 @@ bool ralloc_asprintf_rewrite_tail(char **str, size_t *start,
PRINTFLIKE(3, 4);
/**
+
* Rewrite the tail of an existing string, starting at a given index.
*
* Overwrites the contents of *str starting at \p start with newly formatted
@@ -433,7 +434,7 @@ private:
\
reinterpret_cast(p)->~TYPE(); \
} \
public: \
- static void* operator new(size_t size, void *mem_ctx) \
+ static void* operator new(size_t size, const void *mem_ctx) \
{ \
void *p = ALLOC_FUNC(mem_ctx, size); \
assert(p != NULL); \
@@ -474,7 +475,7 @@ public:
\
* \param parent parent node of the linear allocator
* \param size size to allocate (max 32 bits)
*/
-void *linear_alloc_child(void *parent, unsigned size);
+void *linear_alloc_child(const void *parent, unsigned size);
/**
* Allocate a parent node that will hold linear buffers. The returned
@@ -484,17 +485,17 @@ void *linear_alloc_child(void *parent, unsigned size);
* \param ralloc_ctx ralloc context, must not be NULL
* \param sizesize to allocate (max 32 bits)
*/
-void *linear_alloc_parent(void *ralloc_ctx, unsigned size);
+void
