Files
wasmtime/lib/cretonne/meta/base/legalize.py
Jakob Stoklund Olesen 421a88123d Add Intel encodings for the icmp instruction.
This instruction returns a `b1` value which is represented as the output
of a setCC instruction which is the low 8 bits of a GPR register. Use a
cmp+setCC macro recipe to encode this. That is not ideal, but we can't
represent CPU flags yet.
2017-07-19 11:30:15 -07:00

154 lines
3.9 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 .immediates import intcc
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, iconcat
from .instructions import icmp, icmp_imm
from .instructions import iconst, bint
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')
b_int = Var('b_int')
c = Var('c')
c1 = Var('c1')
c2 = Var('c2')
c_in = Var('c_in')
c_int = Var('c_int')
xl = Var('xl')
xh = Var('xh')
yl = Var('yl')
yh = Var('yh')
al = Var('al')
ah = Var('ah')
cc = Var('cc')
narrow.legalize(
a << iadd(x, y),
Rtl(
(xl, xh) << isplit(x),
(yl, yh) << isplit(y),
(al, c) << iadd_cout(xl, yl),
ah << iadd_cin(xh, yh, c),
a << iconcat(al, ah)
))
narrow.legalize(
a << isub(x, y),
Rtl(
(xl, xh) << isplit(x),
(yl, yh) << isplit(y),
(al, b) << isub_bout(xl, yl),
ah << isub_bin(xh, yh, b),
a << iconcat(al, ah)
))
for bitop in [band, bor, bxor]:
narrow.legalize(
a << bitop(x, y),
Rtl(
(xl, xh) << isplit(x),
(yl, yh) << isplit(y),
al << bitop(xl, yl),
ah << bitop(xh, yh),
a << iconcat(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.ult, a, x)
))
expand.legalize(
(a, b) << isub_bout(x, y),
Rtl(
a << isub(x, y),
b << icmp(intcc.ugt, a, x)
))
expand.legalize(
a << iadd_cin(x, y, c),
Rtl(
a1 << iadd(x, y),
c_int << bint(c),
a << iadd(a1, c_int)
))
expand.legalize(
a << isub_bin(x, y, b),
Rtl(
a1 << isub(x, y),
b_int << bint(b),
a << isub(a1, b_int)
))
expand.legalize(
(a, c) << iadd_carry(x, y, c_in),
Rtl(
(a1, c1) << iadd_cout(x, y),
c_int << bint(c_in),
(a, c2) << iadd_cout(a1, c_int),
c << bor(c1, c2)
))
expand.legalize(
(a, b) << isub_borrow(x, y, b_in),
Rtl(
(a1, b1) << isub_bout(x, y),
b_int << bint(b_in),
(a, b2) << isub_bout(a1, b_int),
b << bor(b1, b2)
))
# Expansions for immediate operands that are out of range.
expand.legalize(
a << iadd_imm(x, y),
Rtl(
a1 << iconst(y),
a << iadd(x, a1)
))
expand.legalize(
a << icmp_imm(cc, x, y),
Rtl(
a1 << iconst(y),
a << icmp(cc, x, a1)
))