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ca137e545c
to strengthen it and fix a rare case of incorrect behavior.
This is the incorrect behavior that's fixed:
if (invocation_id == 0)
patch_output[0] = invocation_id;
else if (invocation_id == 1)
patch_output[1] = invocation_id;
else
patch_output[2] = invocation_id;
The stored SSA defs are the same, but each invocation writes a different
value to different outputs, so they are not duplicated, but the code
incorrectly treated them as duplicated and removed [1] and [2].
The requirement for correctness is that if an output is duplicated,
it must have stores in the same blocks as the output it duplicates.
To fix the incorrect behavior, awareness of blocks is added to the algorithm,
which leads to the following new cases that are optimized:
1. Different blocks store different SSA defs, but equal in each block:
if (..) {
output[0] = a;
output[1] = a; // eliminated
} else {
output[0] = b;
output[1] = b; // eliminated
}
2. Different GS emit sections store different SSA defs, but equal in each
section:
output[0] = a;
output[1] = a; // eliminated
emit_vertex;
output[0] = b;
output[1] = b; // eliminated
emit_vertex;
3. A weird case that could be duplicated but is left alone due to
the counterexample above:
if (..)
output[0] = a;
else
output[1] = a;
Reviewed-by: Aitor Camacho <aitor@lunarg.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/41329>
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|---|---|---|
| .. | ||
| auxiliary | ||
| drivers | ||
| frontends | ||
| include | ||
| targets | ||
| tools | ||
| winsys | ||
| meson.build | ||
| README.portability | ||
CROSS-PLATFORM PORTABILITY GUIDELINES FOR GALLIUM3D
= General Considerations =
The frontend and winsys driver support a rather limited number of
platforms. However, the pipe drivers are meant to run in a wide number of
platforms. Hence the pipe drivers, the auxiliary modules, and all public
headers in general, should strictly follow these guidelines to ensure
= Compiler Support =
* Include the util/compiler.h.
* Cast explicitly when converting to integer types of smaller sizes.
* Cast explicitly when converting between float, double and integral types.
* Don't use named struct initializers.
* Don't use variable number of macro arguments. Use static inline functions
instead.
* Don't use C99 features.
= Standard Library =
* Avoid including standard library headers. Most standard library functions are
not available in Windows Kernel Mode. Use the appropriate p_*.h include.
== Memory Allocation ==
* Use MALLOC, CALLOC, FREE instead of the malloc, calloc, free functions.
* Use align_pointer() function defined in u_memory.h for aligning pointers
in a portable way.
== Debugging ==
* Use the functions/macros in p_debug.h.
* Don't include assert.h, call abort, printf, etc.
= Code Style =
== Inherantice in C ==
The main thing we do is mimic inheritance by structure containment.
Here's a silly made-up example:
/* base class */
struct buffer
{
int size;
void (*validate)(struct buffer *buf);
};
/* sub-class of bufffer */
struct texture_buffer
{
struct buffer base; /* the base class, MUST COME FIRST! */
int format;
int width, height;
};
Then, we'll typically have cast-wrapper functions to convert base-class
pointers to sub-class pointers where needed:
static inline struct vertex_buffer *vertex_buffer(struct buffer *buf)
{
return (struct vertex_buffer *) buf;
}
To create/init a sub-classed object:
struct buffer *create_texture_buffer(int w, int h, int format)
{
struct texture_buffer *t = malloc(sizeof(*t));
t->format = format;
t->width = w;
t->height = h;
t->base.size = w * h;
t->base.validate = tex_validate;
return &t->base;
}
Example sub-class method:
void tex_validate(struct buffer *buf)
{
struct texture_buffer *tb = texture_buffer(buf);
assert(tb->format);
assert(tb->width);
assert(tb->height);
}
Note that we typically do not use typedefs to make "class names"; we use
'struct whatever' everywhere.
Gallium's pipe_context and the subclassed psb_context, etc are prime examples
of this. There's also many examples in Mesa and the Mesa state tracker.