From 73ca8340d996123c281417f1206a8d3d7d6bbaba Mon Sep 17 00:00:00 2001
From: Matthew Pickering <matthewtpickering@gmail.com>
Date: Mon, 7 Aug 2023 09:53:19 +0100
Subject: [PATCH] Revert "Aarch ncg: Optimize immediate use for address
calculations"
This reverts commit 8f3b3b78a8cce3bd463ed175ee933c2aabffc631.
See #23793
---
compiler/GHC/CmmToAsm/AArch64/CodeGen.hs | 60 ++++++++++++------------
1 file changed, 31 insertions(+), 29 deletions(-)
diff --git a/compiler/GHC/CmmToAsm/AArch64/CodeGen.hs b/compiler/GHC/CmmToAsm/AArch64/CodeGen.hs
index 0754f1440876..6bb0510ef256 100644
--- a/compiler/GHC/CmmToAsm/AArch64/CodeGen.hs
+++ b/compiler/GHC/CmmToAsm/AArch64/CodeGen.hs
@@ -462,23 +462,6 @@ getBitmaskImm n w
where
truncated = narrowU w n
--- | Load/store immediate.
--- Depends on the width of the store to some extent.
-isOffsetImm :: Int -> Width -> Bool
-isOffsetImm off w
- -- 8 bits + sign for unscaled offsets
- | -256 <= off, off <= 255 = True
- -- Offset using 12-bit positive immediate, scaled by width
- -- LDR/STR: imm12: if reg is 32bit: 0 -- 16380 in multiples of 4
- -- LDR/STR: imm12: if reg is 64bit: 0 -- 32760 in multiples of 8
- -- 16-bit: 0 .. 8188, 8-bit: 0 -- 4095
- | 0 <= off, off < 4096 * byte_width, off `mod` byte_width == 0 = True
- | otherwise = False
- where
- byte_width = widthInBytes w
-
-
-
-- TODO OPT: we might be able give getRegister
-- a hint, what kind of register we want.
@@ -728,11 +711,18 @@ getRegister' config plat expr
-> return (Fixed (cmmTypeFormat (cmmRegType reg))
(getRegisterReg plat reg)
nilOL)
- CmmRegOff reg off ->
- -- If we got here we will load the address into a register either way. So we might as well just expand
- -- and re-use the existing code path to handle "reg + off".
- let !width = cmmRegWidth reg
- in getRegister' config plat (CmmMachOp (MO_Add width) [CmmReg reg, CmmLit (CmmInt (fromIntegral off) width)])
+ CmmRegOff reg off | isNbitEncodeable 12 (fromIntegral off) -> do
+ getRegister' config plat $
+ CmmMachOp (MO_Add width) [CmmReg reg, CmmLit (CmmInt (fromIntegral off) width)]
+ where width = typeWidth (cmmRegType reg)
+
+ CmmRegOff reg off -> do
+ (off_r, _off_format, off_code) <- getSomeReg $ CmmLit (CmmInt (fromIntegral off) width)
+ (reg, _format, code) <- getSomeReg $ CmmReg reg
+ return $ Any (intFormat width) (\dst -> off_code `appOL` code `snocOL` ADD (OpReg width dst) (OpReg width reg) (OpReg width off_r))
+ where width = typeWidth (cmmRegType reg)
+
+
-- for MachOps, see GHC.Cmm.MachOp
-- For CmmMachOp, see GHC.Cmm.Expr
@@ -1271,8 +1261,20 @@ getAmode :: Platform
-- OPTIMIZATION WARNING: Addressing modes.
-- Addressing options:
-getAmode platform w (CmmRegOff reg off)
- | isOffsetImm off w
+-- LDUR/STUR: imm9: -256 - 255
+getAmode platform _ (CmmRegOff reg off) | -256 <= off, off <= 255
+ = return $ Amode (AddrRegImm reg' off') nilOL
+ where reg' = getRegisterReg platform reg
+ off' = ImmInt off
+-- LDR/STR: imm12: if reg is 32bit: 0 -- 16380 in multiples of 4
+getAmode platform W32 (CmmRegOff reg off)
+ | 0 <= off, off <= 16380, off `mod` 4 == 0
+ = return $ Amode (AddrRegImm reg' off') nilOL
+ where reg' = getRegisterReg platform reg
+ off' = ImmInt off
+-- LDR/STR: imm12: if reg is 64bit: 0 -- 32760 in multiples of 8
+getAmode platform W64 (CmmRegOff reg off)
+ | 0 <= off, off <= 32760, off `mod` 8 == 0
= return $ Amode (AddrRegImm reg' off') nilOL
where reg' = getRegisterReg platform reg
off' = ImmInt off
@@ -1281,15 +1283,15 @@ getAmode platform w (CmmRegOff reg off)
-- CmmStore (CmmMachOp (MO_Add w) [CmmLoad expr, CmmLit (CmmInt n w')]) (expr2)
-- E.g. a CmmStoreOff really. This can be translated to `str $expr2, [$expr, #n ]
-- for `n` in range.
-getAmode _platform w (CmmMachOp (MO_Add _w) [expr, CmmLit (CmmInt off _w')])
- | isOffsetImm (fromIntegral off) w
+getAmode _platform _ (CmmMachOp (MO_Add _w) [expr, CmmLit (CmmInt off _w')])
+ | -256 <= off, off <= 255
= do (reg, _format, code) <- getSomeReg expr
return $ Amode (AddrRegImm reg (ImmInteger off)) code
-getAmode _platform w (CmmMachOp (MO_Sub _w) [expr, CmmLit (CmmInt off _w')])
- | isOffsetImm (fromIntegral $ -off) w
+getAmode _platform _ (CmmMachOp (MO_Sub _w) [expr, CmmLit (CmmInt off _w')])
+ | -256 <= -off, -off <= 255
= do (reg, _format, code) <- getSomeReg expr
- return $ Amode (AddrRegImm reg (ImmInteger $ -off)) code
+ return $ Amode (AddrRegImm reg (ImmInteger (-off))) code
-- Generic case
getAmode _platform _ expr
--
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