[Mesa-dev] [PATCH 04/56] anv/entrypoints: Generalize the string map a bit
Dylan Baker
dylan at pnwbakers.com
Thu Mar 8 04:13:25 UTC 2018
You sent out a 56 patch series and didn't even wait 12 hours before pushing it?
Quoting Jason Ekstrand (2018-03-07 19:56:21)
> You're 4.5 hours too late, I'm afraid. I'd be happy to take some patches
> though. :-)
>
> On Wed, Mar 7, 2018 at 4:42 PM, Dylan Baker <dylan at pnwbakers.com> wrote:
>
> 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.landwerlin at intel.com>
> > Reviewed-by: Samuel Iglesias Gonsálvez <siglesias at 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 at lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/mesa-dev
>
>
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