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x64: Migrate selectif and selectif_spectre_guard to ISLE (#4619)

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https://github.com/bytecodealliance/wasmtime/pull/4619
This commit is contained in:
Trevor Elliott
2022-08-05 09:36:11 -07:00
committed by GitHub
parent 1ce9e8aa5f
commit 0c2a48f682
4 changed files with 26 additions and 231 deletions
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14
cranelift/codegen/src/isa/x64/inst.isle
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@@ -3140,7 +3140,6 @@
(ConsumesFlags.ConsumesFlagsSideEffect
(MInst.JmpTableSeq idx tmp1 tmp2 default_target jt_targets)))))
;;;; Comparisons ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(type IcmpCondResult (enum (Condition (producer ProducesFlags) (cc CC))))
@@ -3157,6 +3156,19 @@
(rule (lower_icmp_bool (IcmpCondResult.Condition producer cc))
(with_flags producer (x64_setcc cc)))
;; Emit a conditional move based on the result of an icmp.
(decl select_icmp (IcmpCondResult Value Value) ValueRegs)
;; Ensure that we put the `x` argument into a register for single-register
;; gpr-typed arguments, as we rely on this for the legalization of heap_addr and
;; loading easily computed constants (like 0) from memory is too expensive.
(rule (select_icmp (IcmpCondResult.Condition producer cc) x @ (value_type (is_gpr_type (is_single_register_type ty))) y)
(with_flags producer (cmove ty cc (put_in_gpr x) y)))
;; Otherwise, fall back on the behavior of `cmove_from_values`.
(rule (select_icmp (IcmpCondResult.Condition producer cc) x @ (value_type ty) y)
(with_flags producer (cmove_from_values ty cc x y)))
(decl emit_cmp (IntCC Value Value) IcmpCondResult)
;; For GPR-held values we only need to emit `CMP + SETCC`. We rely here on