[Git][ghc/ghc][master] AArch64: Implement takeRegRegMoveInstr

[Marge Bot (@marge-bot)]

Marge Bot pushed to branch master at Glasgow Haskell Compiler / GHC


Commits:
573f9833 by Sven Tennie at 2024-09-08T09:58:21+00:00
AArch64: Implement takeRegRegMoveInstr

This has likely been forgotten.

- - - - -


1 changed file:

- compiler/GHC/CmmToAsm/AArch64/Instr.hs


Changes:

=====================================
compiler/GHC/CmmToAsm/AArch64/Instr.hs
=====================================
@@ -30,6 +30,7 @@ import GHC.Utils.Panic
 import Data.Maybe (fromMaybe)
 
 import GHC.Stack
+import GHC.Platform.Reg.Class
 
 -- | LR and FP (8 byte each) are the prologue of each stack frame
 stackFrameHeaderSize :: Int
@@ -454,10 +455,22 @@ isMetaInstr instr
 mkRegRegMoveInstr :: Reg -> Reg -> Instr
 mkRegRegMoveInstr src dst = ANN (text "Reg->Reg Move: " <> ppr src <> text " -> " <> ppr dst) $ MOV (OpReg W64 dst) (OpReg W64 src)
 
--- | Take the source and destination from this reg -> reg move instruction
--- or Nothing if it's not one
+-- | Take the source and destination registers from a move instruction of same
+-- register class (`RegClass`).
+--
+-- The idea is to identify moves that can be eliminated by the register
+-- allocator: If the source register serves no special purpose, one could
+-- continue using it; saving one move instruction. For this, the register kinds
+-- (classes) must be the same (no conversion involved.)
 takeRegRegMoveInstr :: Instr -> Maybe (Reg,Reg)
---takeRegRegMoveInstr (MOV (OpReg fmt dst) (OpReg fmt' src)) | fmt == fmt' = Just (src, dst)
+takeRegRegMoveInstr (MOV (OpReg _fmt dst) (OpReg _fmt' src))
+  | classOfReg dst == classOfReg src = pure (src, dst)
+  where
+    classOfReg ::Reg -> RegClass
+    classOfReg reg
+      = case reg of
+        RegVirtual vr -> classOfVirtualReg vr
+        RegReal rr -> classOfRealReg rr
 takeRegRegMoveInstr _ = Nothing
 
 -- | Make an unconditional jump instruction.



View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/573f9833a7c56bf8fd8c6731069a7160541e5287

-- 
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/573f9833a7c56bf8fd8c6731069a7160541e5287
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