Author: Richard Plangger <[email protected]>
Branch: vecopt-merge
Changeset: r79121:571344b0097d
Date: 2015-08-21 16:14 +0200
http://bitbucket.org/pypy/pypy/changeset/571344b0097d/
Log: docu vectorize.py
diff --git a/rpython/jit/metainterp/optimizeopt/vectorize.py
b/rpython/jit/metainterp/optimizeopt/vectorize.py
--- a/rpython/jit/metainterp/optimizeopt/vectorize.py
+++ b/rpython/jit/metainterp/optimizeopt/vectorize.py
@@ -299,12 +299,13 @@
return unroll_count-1 # it is already unrolled once
def find_adjacent_memory_refs(self):
- """ the pre pass already builds a hash of memory references and the
- operations. Since it is in SSA form there are no array indices.
- If there are two array accesses in the unrolled loop
- i0,i1 and i1 = int_add(i0,c), then i0 = i0 + 0, i1 = i0 + 1.
- They are represented as a linear combination: i*c/d + e, i is a
variable,
- all others are integers that are calculated in reverse direction"""
+ """ The pre pass already builds a hash of memory references and the
+ operations. Since it is in SSA form there are no array indices.
+ If there are two array accesses in the unrolled loop
+ i0,i1 and i1 = int_add(i0,c), then i0 = i0 + 0, i1 = i0 + 1.
+ They are represented as a linear combination: i*c/d + e, i is a
variable,
+ all others are integers that are calculated in reverse direction
+ """
loop = self.loop
operations = loop.operations
@@ -328,6 +329,9 @@
self.packset.add_pack(pair)
def extend_packset(self):
+ """ Follow dependency chains to find more candidates to put into
+ pairs.
+ """
pack_count = self.packset.pack_count()
while True:
for pack in self.packset.packs:
@@ -375,11 +379,11 @@
def combine_packset(self):
""" Combination is done iterating the packs that have
- a sorted op index of the first operation (= left).
- If a pack is marked as 'full', the next pack that is
- encountered having the full_pack.right == pack.left,
- the pack is removed. This is because the packs have
- intersecting edges.
+ a sorted op index of the first operation (= left).
+ If a pack is marked as 'full', the next pack that is
+ encountered having the full_pack.right == pack.left,
+ the pack is removed. This is because the packs have
+ intersecting edges.
"""
if len(self.packset.packs) == 0:
raise NotAVectorizeableLoop()
@@ -445,7 +449,6 @@
for pack in self.packset.packs:
pack.update_pack_of_nodes()
-
if not we_are_translated():
# some test cases check the accumulation variables
self.packset.accum_vars = {}
@@ -470,6 +473,10 @@
assert False
def schedule(self, vector=False, sched_data=None):
+ """ Scheduling the trace and emitting vector operations
+ for packed instructions.
+ """
+
self.clear_newoperations()
if sched_data is None:
sched_data = VecScheduleData(self.cpu.vector_register_size,
@@ -520,7 +527,7 @@
def prepend_invariant_operations(self, sched_data):
""" Add invariant operations to the trace loop. returns the operation
list
- as first argument and a second a boolean value. it is true if any
inva
+ as first argument and a second a boolean value.
"""
oplist = self._newoperations
@@ -552,6 +559,11 @@
return oplist
def analyse_index_calculations(self):
+ """ Tries to move guarding instructions an all the instructions that
+ need to be computed for the guard to the loop header. This ensures
+ that guards fail 'early' and relax dependencies. Without this
+ step vectorization would not be possible!
+ """
ee_pos = self.loop.find_first_index(rop.GUARD_EARLY_EXIT)
if len(self.loop.operations) <= 2 or ee_pos == -1:
raise NotAVectorizeableLoop()
@@ -627,6 +639,10 @@
class CostModel(object):
+ """ Utility to estimate the savings for the new trace loop.
+ The main reaons to have this is of frequent unpack instructions,
+ and the missing ability (by design) to detect not vectorizable loops.
+ """
def __init__(self, threshold, vec_reg_size):
self.threshold = threshold
self.vec_reg_size = vec_reg_size
@@ -657,7 +673,6 @@
return self.savings >= 0
class X86_CostModel(CostModel):
-
def record_pack_savings(self, pack, times):
cost, benefit_factor = (1,1)
node = pack.operations[0]
@@ -693,7 +708,9 @@
self.record_vector_pack(src, index, count)
def isomorphic(l_op, r_op):
- """ Subject of definition """
+ """ Subject of definition, here it is equal operation.
+ See limintations (vectorization.rst).
+ """
if l_op.getopnum() == r_op.getopnum():
return True
return False
@@ -716,6 +733,8 @@
self.packs.append(pack)
def can_be_packed(self, lnode, rnode, origin_pack, forward):
+ """ Check to ensure that two nodes might be packed into a Pair.
+ """
if isomorphic(lnode.getoperation(), rnode.getoperation()):
if lnode.independent(rnode):
if forward and isinstance(origin_pack, AccumPair):
@@ -782,8 +801,9 @@
return False
def combine(self, i, j):
- """ combine two packs. it is assumed that the attribute self.packs
- is not iterated when calling this method. """
+ """ Combine two packs. it is assumed that the attribute self.packs
+ is not iterated when calling this method.
+ """
pack_i = self.packs[i]
pack_j = self.packs[j]
operations = pack_i.operations
@@ -893,6 +913,4 @@
# rename the variable with the box
sched_data.setvector_of_box(accum.getoriginalbox(), 0, result) #
prevent it from expansion
renamer.start_renaming(accum.getoriginalbox(), result)
- if not we_are_translated():
- print "renaming accum", accum.getoriginalbox(), "->", result
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