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Bug 1523996 - part 5 - bulk-read/write adjacent POD fields in IPDL-defined structs; r=Alex_Gaynor

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Now that fields are packed nicely, we can take advantage of the
contiguous layout of POD fields and read/write all the POD fields of a
given size in a single read/write call.  For many structs, this should
have little or no effect, but for large structs such as LoadInfoArgs,
this reduces the number of function calls by ~50%.

Differential Revision: https://phabricator.services.mozilla.com/D22001

--HG--
extra : moz-landing-system : lando
This commit is contained in:
Nathan Froyd 2019-03-06 13:59:57 +00:00
parent c5829037f6
commit 14c0cbba56
1 changed files with 72 additions and 19 deletions
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91
ipc/ipdl/ipdl/lower.py
View File

@ -1901,6 +1901,47 @@ class _ParamTraits():
block.addstmts(cls.writeSentinel(msgvar, sentinelKey))
return block
@classmethod
def bulkSentinelKey(cls, fields):
return ' | '.join(f.basename for f in fields)
@classmethod
def checkedBulkWrite(cls, size, fields):
block = Block()
first = fields[0]
block.addstmts([
StmtExpr(ExprCall(ExprSelect(cls.msgvar, '->', 'WriteBytes'),
args=[ExprAddrOf(ExprCall(first.getMethod(thisexpr=cls.var,
sel='.'))),
ExprLiteral.Int(size * len(fields))]))
])
block.addstmts(cls.writeSentinel(cls.msgvar, cls.bulkSentinelKey(fields)))
return block
@classmethod
def checkedBulkRead(cls, size, fields):
block = Block()
first = fields[0]
readbytes = ExprCall(ExprSelect(cls.msgvar, '->', 'ReadBytesInto'),
args=[cls.itervar,
ExprAddrOf(ExprCall(first.getMethod(thisexpr=cls.var,
sel='->'))),
ExprLiteral.Int(size * len(fields))])
ifbad = StmtIf(ExprNot(readbytes))
errmsg = 'Error bulk reading fields from %s' % first.ipdltype.name()
ifbad.addifstmts([cls.fatalError(errmsg),
StmtReturn.FALSE])
block.addstmt(ifbad)
block.addstmts(cls.readSentinel(cls.msgvar,
cls.itervar,
cls.bulkSentinelKey(fields),
errfnSentinel()(errmsg)))
return block
@classmethod
def checkedRead(cls, ipdltype, var,
msgvar, itervar, errfn,
@ -2078,27 +2119,39 @@ class _ParamTraits():
write = []
read = []
# The iteration order here doesn't particularly matter, but we choose
# member order for ideally better cache performance.
for f in sd.fields_member_order():
writefield = cls.checkedWrite(f.ipdltype,
get('.', f),
cls.msgvar,
sentinelKey=f.basename,
actor=cls.actor)
readfield = cls._checkedRead(f.ipdltype,
ExprAddrOf(get('->', f)), f.basename,
'\'' + f.getMethod().name + '\' ' +
'(' + f.ipdltype.name() + ') member of ' +
'\'' + structtype.name() + '\'')
for (size, fields) in itertools.groupby(sd.fields_member_order(),
lambda f: pod_size(f.ipdltype)):
fields = list(fields)
# Wrap the read/write in a side check if the field is special.
if f.special:
writefield = cls.ifsideis(f.side, writefield)
readfield = cls.ifsideis(f.side, readfield)
if size == pod_size_sentinel:
for f in fields:
writefield = cls.checkedWrite(f.ipdltype,
get('.', f),
cls.msgvar,
sentinelKey=f.basename,
actor=cls.actor)
readfield = cls._checkedRead(f.ipdltype,
ExprAddrOf(get('->', f)), f.basename,
'\'' + f.getMethod().name + '\' ' +
'(' + f.ipdltype.name() + ') member of ' +
'\'' + structtype.name() + '\'')
write.append(writefield)
read.append(readfield)
# Wrap the read/write in a side check if the field is special.
if f.special:
writefield = cls.ifsideis(f.side, writefield)
readfield = cls.ifsideis(f.side, readfield)
write.append(writefield)
read.append(readfield)
else:
for f in fields:
assert not f.special
writefield = cls.checkedBulkWrite(size, fields)
readfield = cls.checkedBulkRead(size, fields)
write.append(writefield)
read.append(readfield)
read.append(StmtReturn.TRUE)