[Mesa-dev] [RFC PATCH] util/ralloc: make mem_ctx parameter const for all r*alloc functions
Nicolai Hähnle
nhaehnle at gmail.com
Thu Nov 2 15:46:02 UTC 2017
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 <gw.fossdev at gmail.com>
> ---
> 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<TYPE *>(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 size size to allocate (max 32 bits)
> */
> -void *linear_alloc_parent(void *ralloc_ctx, unsigned size);
> +void *linear_alloc_parent(const void *ralloc_ctx, unsigned size);
>
> /**
> * Same as linear_alloc_child, but also clears memory.
> */
> -void *linear_zalloc_child(void *parent, unsigned size);
> +void *linear_zalloc_child(const void *parent, unsigned size);
>
> /**
> * Same as linear_alloc_parent, but also clears memory.
> */
> -void *linear_zalloc_parent(void *ralloc_ctx, unsigned size);
> +void *linear_zalloc_parent(const void *ralloc_ctx, unsigned size);
>
> /**
> * Free the linear parent node. This will free all child nodes too.
> @@ -505,12 +506,12 @@ void linear_free_parent(void *ptr);
> /**
> * Same as ralloc_steal, but steals the linear parent node.
> */
> -void ralloc_steal_linear_parent(void *new_ralloc_ctx, void *ptr);
> +void ralloc_steal_linear_parent(const void *new_ralloc_ctx, void *ptr);
>
> /**
> * Return the ralloc parent of the linear parent node.
> */
> -void *ralloc_parent_of_linear_parent(void *ptr);
> +void *ralloc_parent_of_linear_parent(const void *ptr);
>
> /**
> * Same as realloc except that the linear allocator doesn't free child nodes,
>
--
Lerne, wie die Welt wirklich ist,
Aber vergiss niemals, wie sie sein sollte.
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