-module CmmLive (
- CmmLive,
- BlockEntryLiveness,
- cmmLiveness,
- cmmFormalsToLiveLocals,
- ) where
+{-# LANGUAGE GADTs #-}
+{-# OPTIONS_GHC -fno-warn-warnings-deprecations #-}
-#include "HsVersions.h"
+module CmmLive
+ ( CmmLive
+ , cmmLiveness
+ , liveLattice
+ , noLiveOnEntry, xferLive
+ )
+where
import BlockId
import Cmm
-import Dataflow
+import CmmExpr
+import Control.Monad
+import OptimizationFuel
+import PprCmmExpr ()
+import Compiler.Hoopl
import Maybes
-import Panic
+import Outputable
import UniqSet
-----------------------------------------------------------------------------
-----------------------------------------------------------------------------
-- | The variables live on entry to a block
-type CmmLive = UniqSet LocalReg
+type CmmLive = RegSet
+
+-- | The dataflow lattice
+liveLattice :: DataflowLattice CmmLive
+liveLattice = DataflowLattice "live LocalReg's" emptyRegSet add
+ where add _ (OldFact old) (NewFact new) = case unionUniqSets old new of
+ join -> (changeIf $ sizeUniqSet join > sizeUniqSet old, join)
-- | A mapping from block labels to the variables live on entry
type BlockEntryLiveness = BlockEnv CmmLive
--- | A mapping from block labels to the blocks that target it
-type BlockSources = BlockEnv (UniqSet BlockId)
-
--- | A mapping from block labels to the statements in the block
-type BlockStmts = BlockEnv [CmmStmt]
-
------------------------------------------------------------------------------
--- | Calculated liveness info for a list of 'CmmBasicBlock'
------------------------------------------------------------------------------
-cmmLiveness :: [CmmBasicBlock] -> BlockEntryLiveness
-cmmLiveness blocks =
- fixedpoint (cmmBlockDependants sources)
- (cmmBlockUpdate blocks')
- (map blockId blocks)
- (mkBlockEnv [(blockId b, emptyUniqSet) | b <- blocks])
- where
- sources :: BlockSources
- sources = cmmBlockSources blocks
-
- blocks' :: BlockStmts
- blocks' = mkBlockEnv $ map block_name blocks
-
- block_name :: CmmBasicBlock -> (BlockId, [CmmStmt])
- block_name b = (blockId b, blockStmts b)
-
-{-
--- For debugging, annotate each block with a comment indicating
--- the calculated live variables
-cmmLivenessComment ::
- BlockEnv (UniqSet LocalReg) -> CmmBasicBlock -> CmmBasicBlock
-cmmLivenessComment live (BasicBlock ident stmts) =
- BasicBlock ident stmts' where
- stmts' = (CmmComment $ mkFastString $ showSDoc $ ppr $ live'):stmts
- live' = map CmmLocal $ uniqSetToList $ lookupWithDefaultUFM live emptyUniqSet ident
--}
-
-
------------------------------------------------------------------------------
--- | Calculates a table of where one can lookup the blocks that might
--- need updating after a given block is updated in the liveness analysis
------------------------------------------------------------------------------
-cmmBlockSources :: [CmmBasicBlock] -> BlockSources
-cmmBlockSources blocks = foldr aux emptyBlockEnv blocks
- where
- aux :: CmmBasicBlock
- -> BlockSources
- -> BlockSources
- aux block sourcesUFM =
- foldUniqSet (add_source_edges $ blockId block)
- sourcesUFM
- (branch_targets $ blockStmts block)
-
- add_source_edges :: BlockId -> BlockId
- -> BlockSources
- -> BlockSources
- add_source_edges source target ufm =
- addToBEnv_Acc (flip addOneToUniqSet) unitUniqSet ufm target source
-
- branch_targets :: [CmmStmt] -> UniqSet BlockId
- branch_targets stmts =
- mkUniqSet $ concatMap target stmts where
- target (CmmBranch ident) = [ident]
- target (CmmCondBranch _ ident) = [ident]
- target (CmmSwitch _ blocks) = mapMaybe id blocks
- target _ = []
-
------------------------------------------------------------------------------
--- | Given the table calculated by 'cmmBlockSources', list all blocks
--- that depend on the result of a particular block.
---
--- Used by the call to 'fixedpoint'.
------------------------------------------------------------------------------
-cmmBlockDependants :: BlockSources -> BlockId -> [BlockId]
-cmmBlockDependants sources ident =
- uniqSetToList $ lookupWithDefaultBEnv sources emptyUniqSet ident
-
------------------------------------------------------------------------------
--- | Given the table of type 'BlockStmts' and a block that was updated,
--- calculate an updated BlockEntryLiveness
-----------------------------------------------------------------------------
-cmmBlockUpdate ::
- BlockStmts
- -> BlockId
- -> Maybe BlockId
- -> BlockEntryLiveness
- -> Maybe BlockEntryLiveness
-cmmBlockUpdate blocks node _ state =
- if (sizeUniqSet old_live) == (sizeUniqSet new_live)
- then Nothing
- else Just $ extendBlockEnv state node new_live
- where
- new_live, old_live :: CmmLive
- new_live = cmmStmtListLive state block_stmts
- old_live = lookupWithDefaultBEnv state missing_live node
-
- block_stmts :: [CmmStmt]
- block_stmts = lookupWithDefaultBEnv blocks missing_block node
-
- missing_live = panic "unknown block id during liveness analysis"
- missing_block = panic "unknown block id during liveness analysis"
-
+-- | Calculated liveness info for a CmmGraph
-----------------------------------------------------------------------------
--- Section:
------------------------------------------------------------------------------
------------------------------------------------------------------------------
--- CmmBlockLive, cmmStmtListLive and helpers
------------------------------------------------------------------------------
-
--- Calculate the live registers for a local block (list of statements)
-
-cmmStmtListLive :: BlockEntryLiveness -> [CmmStmt] -> CmmLive
-cmmStmtListLive other_live stmts =
- foldr ((.) . (cmmStmtLive other_live)) id stmts emptyUniqSet
-
------------------------------------------------------------------------------
--- This code is written in the style of a state monad,
--- but since Control.Monad.State is not in the core
--- we can't use it in GHC, so we'll fake one here.
--- We don't need a return value so well leave it out.
--- Thus 'bind' reduces to function composition.
-
-type CmmLivenessTransformer = CmmLive -> CmmLive
-
--- Helpers for the "Monad"
-addLive, addKilled :: CmmLive -> CmmLivenessTransformer
-addLive new_live live = live `unionUniqSets` new_live
-addKilled new_killed live = live `minusUniqSet` new_killed
-
---------------------------------
--- Liveness of a CmmStmt
---------------------------------
-cmmFormalsToLiveLocals :: HintedCmmFormals -> [LocalReg]
-cmmFormalsToLiveLocals formals = map hintlessCmm formals
-
-cmmStmtLive :: BlockEntryLiveness -> CmmStmt -> CmmLivenessTransformer
-cmmStmtLive _ (CmmNop) = id
-cmmStmtLive _ (CmmComment _) = id
-cmmStmtLive _ (CmmAssign reg expr) =
- cmmExprLive expr . reg_liveness where
- reg_liveness =
- case reg of
- (CmmLocal reg') -> addKilled $ unitUniqSet reg'
- (CmmGlobal _) -> id
-cmmStmtLive _ (CmmStore expr1 expr2) =
- cmmExprLive expr2 . cmmExprLive expr1
-cmmStmtLive _ (CmmCall target results arguments _ _) =
- target_liveness .
- foldr ((.) . cmmExprLive) id (map hintlessCmm arguments) .
- addKilled (mkUniqSet $ cmmFormalsToLiveLocals results) where
- target_liveness =
- case target of
- (CmmCallee target _) -> cmmExprLive target
- (CmmPrim _) -> id
-cmmStmtLive other_live (CmmBranch target) =
- addLive (lookupWithDefaultBEnv other_live emptyUniqSet target)
-cmmStmtLive other_live (CmmCondBranch expr target) =
- cmmExprLive expr .
- addLive (lookupWithDefaultBEnv other_live emptyUniqSet target)
-cmmStmtLive other_live (CmmSwitch expr targets) =
- cmmExprLive expr .
- (foldr ((.) . (addLive .
- lookupWithDefaultBEnv other_live emptyUniqSet))
- id
- (mapCatMaybes id targets))
-cmmStmtLive _ (CmmJump expr params) =
- const (cmmExprLive expr $ foldr ((.) . cmmExprLive) id (map hintlessCmm params) $ emptyUniqSet)
-cmmStmtLive _ (CmmReturn params) =
- const (foldr ((.) . cmmExprLive) id (map hintlessCmm params) $ emptyUniqSet)
-
---------------------------------
--- Liveness of a CmmExpr
---------------------------------
-cmmExprLive :: CmmExpr -> CmmLivenessTransformer
-cmmExprLive expr = addLive (mkUniqSet $ expr_liveness expr) where
- expr_liveness :: CmmExpr -> [LocalReg]
- expr_liveness (CmmLit _) = []
- expr_liveness (CmmLoad expr _) = expr_liveness expr
- expr_liveness (CmmReg reg) = reg_liveness reg
- expr_liveness (CmmMachOp _ exprs) = concatMap expr_liveness exprs
- expr_liveness (CmmRegOff reg _) = reg_liveness reg
- expr_liveness (CmmStackSlot _ _) = panic "cmmExprLive CmmStackSlot"
- reg_liveness :: CmmReg -> [LocalReg]
- reg_liveness (CmmLocal reg) = [reg]
- reg_liveness (CmmGlobal _) = []
+cmmLiveness :: CmmGraph -> FuelUniqSM BlockEntryLiveness
+cmmLiveness graph =
+ liftM check $ liftM snd $ dataflowPassBwd graph [] $ analBwd liveLattice xferLive
+ where entry = g_entry graph
+ check facts = noLiveOnEntry entry (expectJust "check" $ mapLookup entry facts) facts
+
+gen_kill :: (DefinerOfLocalRegs a, UserOfLocalRegs a) => a -> CmmLive -> CmmLive
+gen_kill a = gen a . kill a
+
+-- | On entry to the procedure, there had better not be any LocalReg's live-in.
+noLiveOnEntry :: BlockId -> CmmLive -> a -> a
+noLiveOnEntry bid in_fact x =
+ if isEmptyUniqSet in_fact then x
+ else pprPanic "LocalReg's live-in to graph" (ppr bid <+> ppr in_fact)
+
+-- | The transfer equations use the traditional 'gen' and 'kill'
+-- notations, which should be familiar from the dragon book.
+gen :: UserOfLocalRegs a => a -> RegSet -> RegSet
+gen a live = foldRegsUsed extendRegSet live a
+kill :: DefinerOfLocalRegs a => a -> RegSet -> RegSet
+kill a live = foldRegsDefd delOneFromUniqSet live a
+
+xferLive :: BwdTransfer CmmNode CmmLive
+xferLive = mkBTransfer3 fst mid lst
+ where fst _ f = f
+ mid :: CmmNode O O -> CmmLive -> CmmLive
+ mid n f = gen_kill n $ case n of CmmUnsafeForeignCall {} -> emptyRegSet
+ _ -> f
+ lst :: CmmNode O C -> FactBase CmmLive -> CmmLive
+ lst n f = gen_kill n $ case n of CmmCall {} -> emptyRegSet
+ CmmForeignCall {} -> emptyRegSet
+ _ -> joinOutFacts liveLattice n f
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