9dbb8c25c5
Add support for implicit type conversions to ISLE. This feature allows the DSL user to register to the compiler that a particular term (used as a constructor or extractor) converts from one type to another. The compiler will then *automatically* insert this term whenever a type mismatch involving that specific pair of types occurs. This significantly cleans up many uses of the ISLE DSL. For example, when defining the compiler backends, we often have newtypes like `Gpr` around `Reg` (signifying a particular type of register); we can define a conversion from Gpr to Reg automatically. Conversions can also have side-effects, as long as these side-effects are idempotent. For example, `put_value_in_reg` in a compiler backend has the effect of marking the value as used, causing codegen to produce it, and assigns a register to the value; but multiple invocations of this will return the same register for the same value. Thus it is safe to use it as an implicit conversion that may be invoked multiple times. This is documented in the ISLE-Cranelift integration document. This PR also adds some testing infrastructure to the ISLE compiler, checking that "pass" tests pass through the DSL compiler, "fail" tests do not, and "link" tests are able to generate code and link that code with corresponding Rust code.
97 lines
3.4 KiB
Common Lisp
97 lines
3.4 KiB
Common Lisp
;;;; Type Definitions ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; Declare that we are using the `i32` primitive type from Rust.
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(type i32 (primitive i32))
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;; Our high-level, RISC-y input IR.
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(type HighLevelInst
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(enum (Add (a Value) (b Value))
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(Load (addr Value))
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(Const (c i32))))
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;; A value in our high-level IR is a Rust `Copy` type. Values are either defined
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;; by an instruction, or are a basic block argument.
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(type Value (primitive Value))
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;; Our low-level, CISC-y machine instructions.
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(type LowLevelInst
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(enum (Add (mode AddrMode))
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(Load (offset i32) (addr Reg))
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(Const (c i32))))
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;; Different kinds of addressing modes for operands to our low-level machine
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;; instructions.
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(type AddrMode
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(enum
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;; Both operands in registers.
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(RegReg (a Reg) (b Reg))
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;; The destination/first operand is a register; the second operand is in
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;; memory at `[b + offset]`.
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(RegMem (a Reg) (b Reg) (offset i32))
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;; The destination/first operand is a register, second operand is an
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;; immediate.
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(RegImm (a Reg) (imm i32))))
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;; The register type is a Rust `Copy` type.
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(type Reg (primitive Reg))
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;;;; Rules ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; Declare our top-level lowering function. We will attach rules to this
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;; declaration for lowering various patterns of `HighLevelInst` inputs.
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(decl lower (HighLevelInst) LowLevelInst)
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;; Simple rule for lowering constants.
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(rule (lower (HighLevelInst.Const c))
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(LowLevelInst.Const c))
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;; Declare an external constructor that puts a high-level `Value` into a
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;; low-level `Reg`.
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(decl put_in_reg (Value) Reg)
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(extern constructor put_in_reg put_in_reg)
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;; Simple rule for lowering adds.
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(rule (lower (HighLevelInst.Add a b))
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(LowLevelInst.Add
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(AddrMode.RegReg (put_in_reg a) (put_in_reg b))))
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;; Simple rule for lowering loads.
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(rule (lower (HighLevelInst.Load addr))
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(LowLevelInst.Load 0 (put_in_reg addr)))
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;; Declare an external extractor for extracting the instruction that defined a
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;; given operand value.
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(decl inst_result (HighLevelInst) Value)
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(extern extractor inst_result inst_result)
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;; Rule to sink loads into adds.
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(rule (lower (HighLevelInst.Add a (inst_result (HighLevelInst.Load addr))))
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(LowLevelInst.Add
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(AddrMode.RegMem (put_in_reg a)
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(put_in_reg addr)
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0)))
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;; Rule to sink a load of a base address with a static offset into a single add.
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(rule (lower (HighLevelInst.Add
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a
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(inst_result (HighLevelInst.Load
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(inst_result (HighLevelInst.Add
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base
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(inst_result (HighLevelInst.Const offset))))))))
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(LowLevelInst.Add
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(AddrMode.RegMem (put_in_reg a)
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(put_in_reg base)
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offset)))
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;; Rule for sinking an immediate into an add.
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(rule (lower (HighLevelInst.Add a (inst_result (HighLevelInst.Const c))))
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(LowLevelInst.Add
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(AddrMode.RegImm (put_in_reg a) c)))
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;; Rule for lowering loads of a base address with a static offset.
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(rule (lower (HighLevelInst.Load
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(inst_result (HighLevelInst.Add
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base
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(inst_result (HighLevelInst.Const offset))))))
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(LowLevelInst.Load offset (put_in_reg base)))
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