03793b71a7
This PR removes "argument polarity": the feature of ISLE extractors that lets them take inputs aside from the value to be matched. Cases that need this expressivity have been subsumed by #4072 with if-let clauses; we can now finally remove this misfeature of the language, which has caused significant confusion and has always felt like a bit of a hack. This PR (i) removes the feature from the ISLE compiler; (ii) removes it from the reference documentation; and (iii) refactors away all uses of the feature in our three existing backends written in ISLE.
65 lines
1.7 KiB
Common Lisp
65 lines
1.7 KiB
Common Lisp
(type Opcode extern (enum
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Iadd
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Isub
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Load
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Store))
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(type Inst (primitive Inst))
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(type InstInput (primitive InstInput))
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(type Reg (primitive Reg))
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(type u32 (primitive u32))
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(decl Op (Opcode) Inst)
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(extern extractor infallible Op get_opcode)
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(decl InstInputs2 (InstInput InstInput) Inst)
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(extern extractor infallible InstInputs2 get_inst_inputs_2)
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(decl Producer (Inst) InstInput)
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(extern extractor Producer get_input_producer)
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(decl UseInput (InstInput) Reg)
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(extern constructor UseInput put_input_in_reg)
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(type MachInst (enum
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(Add (a Reg) (b Reg))
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(Add3 (a Reg) (b Reg) (c Reg))
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(Sub (a Reg) (b Reg))))
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(decl Lower (Inst) MachInst)
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;; Extractors that give syntax sugar for (Iadd ra rb), etc.
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;;
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;; Note that this is somewhat simplistic: it directly connects inputs to
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;; MachInst regs; really we'd want to return a VReg or InstInput that we can use
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;; another extractor to connect to another (producer) inst.
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;;
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;; Also, note that while it looks a little indirect, a verification effort could
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;; define equivalences across the `rule` LHS/RHS pairs, and the types ensure that
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;; we are dealing (at the semantic level) with pure value equivalences of
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;; "terms", not arbitrary side-effecting calls.
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(decl Iadd (InstInput InstInput) Inst)
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(decl Isub (InstInput InstInput) Inst)
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(extractor
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(Iadd a b)
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(and
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(Op (Opcode.Iadd))
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(InstInputs2 a b)))
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(extractor
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(Isub a b)
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(and
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(Op (Opcode.Isub))
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(InstInputs2 a b)))
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;; Now the nice syntax-sugar that "end-user" backend authors can write:
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(rule
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(Lower (Iadd ra rb))
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(MachInst.Add (UseInput ra) (UseInput rb)))
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(rule
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(Lower (Iadd (Producer (Iadd ra rb)) rc))
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(MachInst.Add3 (UseInput ra) (UseInput rb) (UseInput rc)))
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(rule
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(Lower (Isub ra rb))
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(MachInst.Sub (UseInput ra) (UseInput rb)))
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