Quoting Jason Ekstrand (2018-03-07 06:34:52)
> The original string map assumed that the mapping from strings to
> entrypoints was a bijection. This will not be true the moment we
> add entrypoint aliasing. This reworks things to be an arbitrary map
> from strings to non-negative signed integers. The old one also had a
> potential bug if we ever had a hash collision because it didn't do the
> strcmp inside the lookup loop. While we're at it, we break things out
> into a helpful class.
>
> Reviewed-by: Lionel Landwerlin <lionel.g.landwer...@intel.com>
> Reviewed-by: Samuel Iglesias Gonsálvez <sigles...@igalia.com>
> ---
> src/intel/vulkan/anv_entrypoints_gen.py | 188
> +++++++++++++++++---------------
> 1 file changed, 103 insertions(+), 85 deletions(-)
>
> diff --git a/src/intel/vulkan/anv_entrypoints_gen.py
> b/src/intel/vulkan/anv_entrypoints_gen.py
> index 34ffedb..dc0f0e9 100644
> --- a/src/intel/vulkan/anv_entrypoints_gen.py
> +++ b/src/intel/vulkan/anv_entrypoints_gen.py
> @@ -115,9 +115,10 @@ TEMPLATE_C = Template(u"""\
>
> #include "anv_private.h"
>
> -struct anv_entrypoint {
> +struct string_map_entry {
> uint32_t name;
> uint32_t hash;
> + uint32_t num;
> };
>
> /* We use a big string constant to avoid lots of reloctions from the entry
> @@ -126,17 +127,60 @@ struct anv_entrypoint {
> */
>
> static const char strings[] =
> -% for e in entrypoints:
> - "${e.name}\\0"
> +% for s in strmap.sorted_strings:
> + "${s.string}\\0"
> % endfor
> ;
>
> -static const struct anv_entrypoint entrypoints[] = {
> -% for e in entrypoints:
> - [${e.num}] = { ${offsets[e.num]}, ${'{:0=#8x}'.format(e.get_c_hash())}
> }, /* ${e.name} */
> +static const struct string_map_entry string_map_entries[] = {
> +% for s in strmap.sorted_strings:
> + { ${s.offset}, ${'{:0=#8x}'.format(s.hash)}, ${s.num} }, /* ${s.string}
> */
> % endfor
> };
>
> +/* Hash table stats:
> + * size ${len(strmap.sorted_strings)} entries
> + * collisions entries:
> +% for i in xrange(10):
> + * ${i}${'+' if i == 9 else ' '} ${strmap.collisions[i]}
> +% endfor
> + */
> +
> +#define none 0xffff
> +static const uint16_t string_map[${strmap.hash_size}] = {
> +% for e in strmap.mapping:
> + ${ '{:0=#6x}'.format(e) if e >= 0 else 'none' },
> +% endfor
> +};
> +
> +static int
> +string_map_lookup(const char *str)
> +{
> + static const uint32_t prime_factor = ${strmap.prime_factor};
> + static const uint32_t prime_step = ${strmap.prime_step};
> + const struct string_map_entry *e;
> + uint32_t hash, h;
> + uint16_t i;
> + const char *p;
> +
> + hash = 0;
> + for (p = str; *p; p++)
> + hash = hash * prime_factor + *p;
> +
> + h = hash;
> + while (1) {
> + i = string_map[h & ${strmap.hash_mask}];
> + if (i == none)
> + return -1;
> + e = &string_map_entries[i];
> + if (e->hash == hash && strcmp(str, strings + e->name) == 0)
> + return e->num;
> + h += prime_step;
> + }
> +
> + return -1;
> +}
> +
> /* Weak aliases for all potential implementations. These will resolve to
> * NULL if they're not defined, which lets the resolve_entrypoint() function
> * either pick the correct entry point.
> @@ -275,54 +319,10 @@ anv_resolve_entrypoint(const struct gen_device_info
> *devinfo, uint32_t index)
> return anv_dispatch_table.entrypoints[index];
> }
>
> -/* Hash table stats:
> - * size ${hash_size} entries
> - * collisions entries:
> -% for i in xrange(10):
> - * ${i}${'+' if i == 9 else ''} ${collisions[i]}
> -% endfor
> - */
> -
> -#define none ${'{:#x}'.format(none)}
> -static const uint16_t map[] = {
> -% for i in xrange(0, hash_size, 8):
> - % for j in xrange(i, i + 8):
> - ## This is 6 because the 0x is counted in the length
> - % if mapping[j] & 0xffff == 0xffff:
> - none,
> - % else:
> - ${'{:0=#6x}'.format(mapping[j] & 0xffff)},
> - % endif
> - % endfor
> -% endfor
> -};
> -
> int
> anv_get_entrypoint_index(const char *name)
> {
> - static const uint32_t prime_factor = ${prime_factor};
> - static const uint32_t prime_step = ${prime_step};
> - const struct anv_entrypoint *e;
> - uint32_t hash, h, i;
> - const char *p;
> -
> - hash = 0;
> - for (p = name; *p; p++)
> - hash = hash * prime_factor + *p;
> -
> - h = hash;
> - do {
> - i = map[h & ${hash_mask}];
> - if (i == none)
> - return -1;
> - e = &entrypoints[i];
> - h += prime_step;
> - } while (e->hash != hash);
> -
> - if (strcmp(name, strings + e->name) != 0)
> - return -1;
> -
> - return i;
> + return string_map_lookup(name);
> }
>
> void *
> @@ -334,7 +334,6 @@ anv_lookup_entrypoint(const struct gen_device_info
> *devinfo, const char *name)
> return anv_resolve_entrypoint(devinfo, idx);
> }""", output_encoding='utf-8')
>
> -NONE = 0xffff
> HASH_SIZE = 256
> U32_MASK = 2**32 - 1
> HASH_MASK = HASH_SIZE - 1
> @@ -342,11 +341,54 @@ HASH_MASK = HASH_SIZE - 1
> PRIME_FACTOR = 5024183
> PRIME_STEP = 19
>
> -
> -def cal_hash(name):
> - """Calculate the same hash value that Mesa will calculate in C."""
> - return functools.reduce(
> - lambda h, c: (h * PRIME_FACTOR + ord(c)) & U32_MASK, name, 0)
> +class StringIntMapEntry(object):
> + def __init__(self, string, num):
> + self.string = string
> + self.num = num
> +
> + # Calculate the same hash value that we will calculate in C.
> + h = 0
> + for c in string:
> + h = ((h * PRIME_FACTOR) + ord(c)) & U32_MASK
> + self.hash = h
why no love for my use of reduce?
> +
> + self.offset = None
> +
This needs a __hash__ method,
def __hash__(self):
return self.hash
is probably sufficient
> +class StringIntMap(object):
> + def __init__(self):
> + self.baked = False
> + self.strings = dict()
can we add all of the instance attributes in the constructor please? just set
them to None or something?
> +
> + def add_string(self, string, num):
> + assert not self.baked
> + assert string not in self.strings
> + assert num >= 0 and num < 2**31
> + self.strings[string] = StringIntMapEntry(string, num)
> +
> + def bake(self):
> + self.sorted_strings = \
> + sorted(self.strings.values(), key=lambda x: x.string)
> + offset = 0
> + for entry in self.sorted_strings:
> + entry.offset = offset
> + offset += len(entry.string) + 1
how about:
self.offset = sum(len(e.string) + 1 for e in self.sorted_strings)
> +
> + # Save off some values that we'll need in C
> + self.hash_size = HASH_SIZE
> + self.hash_mask = HASH_SIZE - 1
> + self.prime_factor = PRIME_FACTOR
> + self.prime_step = PRIME_STEP
> +
> + self.mapping = [-1] * self.hash_size
> + self.collisions = [0] * 10
> + for idx, s in enumerate(self.sorted_strings):
> + level = 0
> + h = s.hash
> + while self.mapping[h & self.hash_mask] >= 0:
> + h = h + PRIME_STEP
> + level = level + 1
> + self.collisions[min(level, 9)] += 1
> + self.mapping[h & self.hash_mask] = idx
>
> EntrypointParam = namedtuple('EntrypointParam', 'type name decl')
>
> @@ -372,9 +414,6 @@ class Entrypoint(object):
> def call_params(self):
> return ', '.join(p.name for p in self.params)
>
> - def get_c_hash(self):
> - return cal_hash(self.name)
> -
> def get_entrypoints(doc, entrypoints_to_defines, start_index):
> """Extract the entry points from the registry."""
> entrypoints = OrderedDict()
> @@ -443,36 +482,15 @@ def get_entrypoints_defines(doc):
>
> def gen_code(entrypoints):
> """Generate the C code."""
> - i = 0
> - offsets = []
> - for e in entrypoints:
> - offsets.append(i)
> - i += len(e.name) + 1
>
> - mapping = [NONE] * HASH_SIZE
> - collisions = [0] * 10
> + strmap = StringIntMap()
> for e in entrypoints:
> - level = 0
> - h = e.get_c_hash()
> - while mapping[h & HASH_MASK] != NONE:
> - h = h + PRIME_STEP
> - level = level + 1
> - if level > 9:
> - collisions[9] += 1
> - else:
> - collisions[level] += 1
> - mapping[h & HASH_MASK] = e.num
> + strmap.add_string(e.name, e.num)
> + strmap.bake()
>
> return TEMPLATE_C.render(entrypoints=entrypoints,
> LAYERS=LAYERS,
> - offsets=offsets,
> - collisions=collisions,
> - mapping=mapping,
> - hash_mask=HASH_MASK,
> - prime_step=PRIME_STEP,
> - prime_factor=PRIME_FACTOR,
> - none=NONE,
> - hash_size=HASH_SIZE,
> + strmap=strmap,
> filename=os.path.basename(__file__))
>
>
> --
> 2.5.0.400.gff86faf
>
> _______________________________________________
> mesa-dev mailing list
> mesa-dev@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/mesa-dev
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