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ISLE: remove all uses of argument polarity, and remove it from the language. (#4091)

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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.
This commit is contained in:
Chris Fallin
2022-05-02 09:52:12 -07:00
committed by GitHub
parent c7e2c21bb2
commit 03793b71a7
21 changed files with 2123 additions and 2464 deletions
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16
cranelift/codegen/src/isa/x64/inst.isle
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@@ -793,8 +793,8 @@
;; A helper to both check that the `Imm64` and `Offset32` values sum to less
;; than 32-bits AND return this summed `u32` value. Also, the `Imm64` will be
;; zero-extended from `Type` up to 64 bits. This is useful for `to_amode`.
(decl sum_extend_fits_in_32_bits (Type Imm64 u32) Offset32)
(extern extractor sum_extend_fits_in_32_bits sum_extend_fits_in_32_bits (in in out))
(decl pure sum_extend_fits_in_32_bits (Type Imm64 Offset32) u32)
(extern constructor sum_extend_fits_in_32_bits sum_extend_fits_in_32_bits)
;; To generate an address for a memory access, we can pattern-match various CLIF
;; sub-trees to x64's complex addressing modes (`Amode`). In pseudo-code:
@@ -828,14 +828,18 @@
;; extractor to check that the offset and constant value (`c`, the in
;; parameter), when summed will fit into x64's 32-bit displacement, returned as
;; `sum` (the out parameter). The syntax for this could be improved (TODO).
(rule (to_amode flags (iadd (iconst c) base) _offset @ (sum_extend_fits_in_32_bits <$I64 <c sum))
(rule (to_amode flags (iadd (iconst c) base) offset)
(if-let sum (sum_extend_fits_in_32_bits $I64 c offset))
(amode_imm_reg_flags sum (put_in_gpr base) flags))
(rule (to_amode flags (iadd base (iconst c)) _offset @ (sum_extend_fits_in_32_bits <$I64 <c sum))
(rule (to_amode flags (iadd base (iconst c)) offset)
(if-let sum (sum_extend_fits_in_32_bits $I64 c offset))
(amode_imm_reg_flags sum (put_in_gpr base) flags))
;; ...matches (uextend(iconst c) ...); see notes above.
(rule (to_amode flags (iadd (has_type ty (uextend (iconst c))) base) _offset @ (sum_extend_fits_in_32_bits <ty <c sum))
(rule (to_amode flags (iadd (has_type ty (uextend (iconst c))) base) offset)
(if-let sum (sum_extend_fits_in_32_bits $I64 c offset))
(amode_imm_reg_flags sum (put_in_gpr base) flags))
(rule (to_amode flags (iadd base (has_type ty (uextend (iconst c)))) _offset @ (sum_extend_fits_in_32_bits <ty <c sum))
(rule (to_amode flags (iadd base (has_type ty (uextend (iconst c)))) offset)
(if-let sum (sum_extend_fits_in_32_bits $I64 c offset))
(amode_imm_reg_flags sum (put_in_gpr base) flags))
;; ...else only matches (iadd(a b))
(rule (to_amode flags (iadd base index) offset)