Files
wasmtime/lib/cretonne/meta/base/legalize.py
Jakob Stoklund Olesen d76280afba Add expansion patterns for large immediates.
Expand foo_imm into iconst + foo.
2016-11-10 15:55:54 -08:00

138 lines
3.6 KiB
Python

"""
Patterns for legalizing the `base` instruction set.
The base Cretonne instruction set is 'fat', and many instructions don't have
legal representations in a given target ISA. This module defines legalization
patterns that describe how base instructions can be transformed to other base
instructions that are legal.
"""
from __future__ import absolute_import
from .instructions import iadd, iadd_cout, iadd_cin, iadd_carry, iadd_imm
from .instructions import isub, isub_bin, isub_bout, isub_borrow
from .instructions import band, bor, bxor, isplit_lohi, iconcat_lohi
from .instructions import icmp, iconst
from cdsl.ast import Var
from cdsl.xform import Rtl, XFormGroup
narrow = XFormGroup('narrow', """
Legalize instructions by narrowing.
The transformations in the 'narrow' group work by expressing
instructions in terms of smaller types. Operations on vector types are
expressed in terms of vector types with fewer lanes, and integer
operations are expressed in terms of smaller integer types.
""")
expand = XFormGroup('expand', """
Legalize instructions by expansion.
Rewrite instructions in terms of other instructions, generally
operating on the same types as the original instructions.
""")
x = Var('x')
y = Var('y')
a = Var('a')
a1 = Var('a1')
a2 = Var('a2')
b = Var('b')
b1 = Var('b1')
b2 = Var('b2')
b_in = Var('b_in')
c = Var('c')
c1 = Var('c1')
c2 = Var('c2')
c_in = Var('c_in')
xl = Var('xl')
xh = Var('xh')
yl = Var('yl')
yh = Var('yh')
al = Var('al')
ah = Var('ah')
narrow.legalize(
a << iadd(x, y),
Rtl(
(xl, xh) << isplit_lohi(x),
(yl, yh) << isplit_lohi(y),
(al, c) << iadd_cout(xl, yl),
ah << iadd_cin(xh, yh, c),
a << iconcat_lohi(al, ah)
))
narrow.legalize(
a << isub(x, y),
Rtl(
(xl, xh) << isplit_lohi(x),
(yl, yh) << isplit_lohi(y),
(al, b) << isub_bout(xl, yl),
ah << isub_bin(xh, yh, b),
a << iconcat_lohi(al, ah)
))
for bitop in [band, bor, bxor]:
narrow.legalize(
a << bitop(x, y),
Rtl(
(xl, xh) << isplit_lohi(x),
(yl, yh) << isplit_lohi(y),
al << bitop(xl, yl),
ah << bitop(xh, yh),
a << iconcat_lohi(al, ah)
))
# Expand integer operations with carry for RISC architectures that don't have
# the flags.
expand.legalize(
(a, c) << iadd_cout(x, y),
Rtl(
a << iadd(x, y),
c << icmp('IntCC::UnsignedLessThan', a, x)
))
expand.legalize(
(a, b) << isub_bout(x, y),
Rtl(
a << isub(x, y),
b << icmp('IntCC::UnsignedGreaterThan', a, x)
))
expand.legalize(
a << iadd_cin(x, y, c),
Rtl(
a1 << iadd(x, y),
a << iadd(a1, c)
))
expand.legalize(
a << isub_bin(x, y, b),
Rtl(
a1 << isub(x, y),
a << isub(a1, b)
))
expand.legalize(
(a, c) << iadd_carry(x, y, c_in),
Rtl(
(a1, c1) << iadd_cout(x, y),
(a, c2) << iadd_cout(a1, c_in),
c << bor(c1, c2)
))
expand.legalize(
(a, b) << isub_borrow(x, y, b_in),
Rtl(
(a1, b1) << isub_bout(x, y),
(a, b2) << isub_bout(a1, b_in),
b << bor(b1, b2)
))
# Expansions for immediates that are too large.
expand.legalize(
a << iadd_imm(x, y),
Rtl(
a1 << iconst(y),
a << iadd(x, a1)
))