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75 lines
1.8 KiB
Python
75 lines
1.8 KiB
Python
from amaranth import *
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from amaranth.asserts import *
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from .. import pfv
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__all__ = ["IAForwardCheck", "IAForwardCover"]
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class IAForwardCheck(Elaboratable):
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"""IA forward check.
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Given two instructions retiring in order, check that the NIA of the first matches the CIA
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of the second.
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"""
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def __init__(self):
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self.pre = Signal()
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self.post = Signal()
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self.pfv = pfv.Interface()
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def elaborate(self, platform):
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m = Module()
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pred_order = AnyConst(self.pfv.order.width)
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pred_stb = Signal()
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pred_nia = Signal.like(self.pfv.nia)
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with m.If(self.pfv.stb & (self.pfv.order == pred_order)):
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m.d.sync += [
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pred_stb.eq(1),
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pred_nia.eq(self.pfv.nia)
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]
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with m.If(self.post):
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m.d.sync += [
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Assume(self.pfv.stb),
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Assume(self.pfv.order == pred_order + 1),
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Assume(self.pfv.order > 0),
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Assert(pred_stb.implies(self.pfv.cia == pred_nia)),
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]
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return m
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class IAForwardCover(Elaboratable):
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def __init__(self):
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self.pre = Signal()
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self.post = Signal()
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self.pfv = pfv.Interface()
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def elaborate(self, platform):
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m = Module()
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insn_count = Signal(range(4))
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pred_branch = Signal()
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with m.If(self.pfv.stb):
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m.d.sync += [
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insn_count .eq(insn_count + 1),
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pred_branch.eq(self.pfv.nia != (self.pfv.cia + 4)),
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]
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cover_1 = Signal()
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cover_2 = Signal()
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m.d.comb += [
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cover_1.eq((insn_count > 1) & pred_branch),
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cover_2.eq(cover_1 & self.pfv.stb),
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Cover(cover_1),
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Cover(cover_2),
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]
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return m
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