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cranelift: Remove redundant branch and select instructions (#5097)

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As discussed in the 2022/10/19 meeting, this PR removes many of the branch and select instructions that used iflags, in favor if using brz/brnz and select in their place. Additionally, it reworks selectif_spectre_guard to take an i8 input instead of an iflags input.

For reference, the removed instructions are: br_icmp, brif, brff, trueif, trueff, and selectif.
This commit is contained in:
Trevor Elliott
2022-10-24 16:14:35 -07:00
committed by GitHub
parent 30589170b4
commit ec12415b1f
40 changed files with 579 additions and 2527 deletions
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23
cranelift/codegen/src/isa/riscv64/inst.isle
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@@ -1915,24 +1915,29 @@
(rule
(lower_branch (brz v @ (value_type ty) _ _) targets)
(lower_brz_or_nz (IntCC.Equal) (normalize_value ty v) targets ty))
(rule 1
(lower_branch (brz (icmp cc a @ (value_type ty) b) _ _) targets)
(lower_br_icmp (intcc_inverse cc) a b targets ty))
(rule 1
(lower_branch (brz (fcmp cc a @ (value_type ty) b) _ _) targets)
(lower_br_fcmp (floatcc_inverse cc) a b targets ty))
;;;;
(rule
(lower_branch (brnz v @ (value_type ty) _ _) targets)
(lower_brz_or_nz (IntCC.NotEqual) (normalize_value ty v) targets ty))
;;;
(rule
(lower_branch (br_icmp cc a @ (value_type ty) b _ _) targets)
(rule 1
(lower_branch (brnz (icmp cc a @ (value_type ty) b) _ _) targets)
(lower_br_icmp cc a b targets ty))
(rule
(lower_branch (brif cc (ifcmp a @ (value_type ty) b) _ _) targets)
(lower_br_icmp cc a b targets ty))
(rule
(lower_branch (brff cc (ffcmp a @ (value_type ty) b) _ _) targets)
(rule 1
(lower_branch (brnz (fcmp cc a @ (value_type ty) b) _ _) targets)
(lower_br_fcmp cc a b targets ty))
;;;
(decl lower_br_table (Reg VecMachLabel) InstOutput)
(extern constructor lower_br_table lower_br_table)