cc86964ab3
- cdsl.ast defines classes representing abstract syntax trees. - cdsl.xform defines classes for instruction transformations. - base.legalize defines legalization patterns.
130 lines
3.4 KiB
Python
130 lines
3.4 KiB
Python
"""
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Patterns for legalizing the `base` instruction set.
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The base Cretonne instruction set is 'fat', and many instructions don't have
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legal representations in a given target ISA. This module defines legalization
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patterns that describe how base instructions can be transformed to other base
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instructions that are legal.
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"""
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from __future__ import absolute_import
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from .instructions import iadd, iadd_cout, iadd_cin, iadd_carry
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from .instructions import isub, isub_bin, isub_bout, isub_borrow
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from .instructions import band, bor, bxor, isplit_lohi, iconcat_lohi
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from .instructions import icmp
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from cdsl.ast import Var
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from cdsl.xform import Rtl, XFormGroup
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narrow = XFormGroup('narrow', """
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Legalize instructions by narrowing.
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The transformations in the 'narrow' group work by expressing
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instructions in terms of smaller types. Operations on vector types are
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expressed in terms of vector types with fewer lanes, and integer
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operations are expressed in terms of smaller integer types.
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""")
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expand = XFormGroup('expand', """
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Legalize instructions by expansion.
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Rewrite instructions in terms of other instructions, generally
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operating on the same types as the original instructions.
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""")
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x = Var('x')
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y = Var('y')
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a = Var('a')
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a1 = Var('a1')
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a2 = Var('a2')
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b = Var('b')
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b1 = Var('b1')
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b2 = Var('b2')
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b_in = Var('b_in')
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c = Var('c')
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c1 = Var('c1')
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c2 = Var('c2')
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c_in = Var('c_in')
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xl = Var('xl')
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xh = Var('xh')
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yl = Var('yl')
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yh = Var('yh')
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al = Var('al')
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ah = Var('ah')
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narrow.legalize(
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a << iadd(x, y),
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Rtl(
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(xl, xh) << isplit_lohi(x),
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(yl, yh) << isplit_lohi(y),
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(al, c) << iadd_cout(xl, yl),
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ah << iadd_cin(xh, yh, c),
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a << iconcat_lohi(al, ah)
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))
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narrow.legalize(
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a << isub(x, y),
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Rtl(
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(xl, xh) << isplit_lohi(x),
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(yl, yh) << isplit_lohi(y),
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(al, b) << isub_bout(xl, yl),
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ah << isub_bin(xh, yh, b),
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a << iconcat_lohi(al, ah)
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))
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for bitop in [band, bor, bxor]:
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narrow.legalize(
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a << bitop(x, y),
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Rtl(
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(xl, xh) << isplit_lohi(x),
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(yl, yh) << isplit_lohi(y),
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al << bitop(xl, yl),
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ah << bitop(xh, yh),
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a << iconcat_lohi(al, ah)
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))
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# Expand integer operations with carry for RISC architectures that don't have
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# the flags.
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expand.legalize(
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(a, c) << iadd_cout(x, y),
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Rtl(
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a << iadd(x, y),
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c << icmp('IntCC::UnsignedLessThan', a, x)
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))
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expand.legalize(
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(a, b) << isub_bout(x, y),
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Rtl(
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a << isub(x, y),
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b << icmp('IntCC::UnsignedGreaterThan', a, x)
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))
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expand.legalize(
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a << iadd_cin(x, y, c),
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Rtl(
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a1 << iadd(x, y),
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a << iadd(a1, c)
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))
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expand.legalize(
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a << isub_bin(x, y, b),
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Rtl(
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a1 << isub(x, y),
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a << isub(a1, b)
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))
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expand.legalize(
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(a, c) << iadd_carry(x, y, c_in),
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Rtl(
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(a1, c1) << iadd_cout(x, y),
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(a, c2) << iadd_cout(a1, c_in),
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c << bor(c1, c2)
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))
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expand.legalize(
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(a, b) << isub_borrow(x, y, b_in),
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Rtl(
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(a1, b1) << isub_bout(x, y),
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(a, b2) << isub_bout(a1, b_in),
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b << bor(b1, b2)
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))
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