import MachCodeGen
import PprMach
import RegisterAlloc
-import RegAllocInfo ( jumpDests )
+import RegAllocInfo
import NCGMonad
import PositionIndependentCode
import CmmOpt ( cmmMiniInline, cmmMachOpFold )
import PprCmm ( pprStmt, pprCmms )
import MachOp
-import CLabel ( CLabel, mkSplitMarkerLabel, mkAsmTempLabel )
+import CLabel
#if powerpc_TARGET_ARCH
import CLabel ( mkRtsCodeLabel )
#endif
import List ( groupBy, sortBy )
import CLabel ( pprCLabel )
import ErrUtils ( dumpIfSet_dyn )
-import DynFlags ( DynFlags, DynFlag(..), dopt )
+import DynFlags
import StaticFlags ( opt_Static, opt_PIC )
+import Util
import Config ( cProjectVersion )
import Digraph
genMachCode cmm `thenUs` \ (pre_regalloc, lastMinuteImports) ->
{-# SCC "regAlloc" #-}
mapUs regAlloc pre_regalloc `thenUs` \ with_regs ->
+ {-# SCC "shortcutBranches" #-}
+ shortcutBranches dflags with_regs `bind` \ shorted ->
{-# SCC "sequenceBlocks" #-}
- map sequenceTop with_regs `bind` \ sequenced ->
+ map sequenceTop shorted `bind` \ sequenced ->
{-# SCC "x86fp_kludge" #-}
map x86fp_kludge sequenced `bind` \ final_mach_code ->
{-# SCC "vcat" #-}
sequenceTop :: NatCmmTop -> NatCmmTop
sequenceTop top@(CmmData _ _) = top
sequenceTop (CmmProc info lbl params blocks) =
- CmmProc info lbl params (sequenceBlocks blocks)
+ CmmProc info lbl params (makeFarBranches $ sequenceBlocks blocks)
-- The algorithm is very simple (and stupid): we make a graph out of
-- the blocks where there is an edge from one block to another iff the
| id == id' = (True, (block,id,out) : reverse accum ++ rest)
| otherwise = reorder id (b:accum) rest
+
+-- -----------------------------------------------------------------------------
+-- Making far branches
+
+-- Conditional branches on PowerPC are limited to +-32KB; if our Procs get too
+-- big, we have to work around this limitation.
+
+makeFarBranches :: [NatBasicBlock] -> [NatBasicBlock]
+
+#if powerpc_TARGET_ARCH
+makeFarBranches blocks
+ | last blockAddresses < nearLimit = blocks
+ | otherwise = zipWith handleBlock blockAddresses blocks
+ where
+ blockAddresses = scanl (+) 0 $ map blockLen blocks
+ blockLen (BasicBlock _ instrs) = length instrs
+
+ handleBlock addr (BasicBlock id instrs)
+ = BasicBlock id (zipWith makeFar [addr..] instrs)
+
+ makeFar addr (BCC ALWAYS tgt) = BCC ALWAYS tgt
+ makeFar addr (BCC cond tgt)
+ | abs (addr - targetAddr) >= nearLimit
+ = BCCFAR cond tgt
+ | otherwise
+ = BCC cond tgt
+ where Just targetAddr = lookupUFM blockAddressMap tgt
+ makeFar addr other = other
+
+ nearLimit = 7000 -- 8192 instructions are allowed; let's keep some
+ -- distance, as we have a few pseudo-insns that are
+ -- pretty-printed as multiple instructions,
+ -- and it's just not worth the effort to calculate
+ -- things exactly
+
+ blockAddressMap = listToUFM $ zip (map blockId blocks) blockAddresses
+#else
+makeFarBranches = id
+#endif
+
+-- -----------------------------------------------------------------------------
+-- Shortcut branches
+
+shortcutBranches :: DynFlags -> [NatCmmTop] -> [NatCmmTop]
+shortcutBranches dflags tops
+ | optLevel dflags < 1 = tops -- only with -O or higher
+ | otherwise = map (apply_mapping mapping) tops'
+ where
+ (tops', mappings) = mapAndUnzip build_mapping tops
+ mapping = foldr plusUFM emptyUFM mappings
+
+build_mapping top@(CmmData _ _) = (top, emptyUFM)
+build_mapping (CmmProc info lbl params [])
+ = (CmmProc info lbl params [], emptyUFM)
+build_mapping (CmmProc info lbl params (head:blocks))
+ = (CmmProc info lbl params (head:others), mapping)
+ -- drop the shorted blocks, but don't ever drop the first one,
+ -- because it is pointed to by a global label.
+ where
+ -- find all the blocks that just consist of a jump that can be
+ -- shorted.
+ (shortcut_blocks, others) = partitionWith split blocks
+ split (BasicBlock id [insn]) | Just dest <- canShortcut insn
+ = Left (id,dest)
+ split other = Right other
+
+ -- build a mapping from BlockId to JumpDest for shorting branches
+ mapping = foldl add emptyUFM shortcut_blocks
+ add ufm (id,dest) = addToUFM ufm id dest
+
+apply_mapping ufm (CmmData sec statics)
+ = CmmData sec (map (shortcutStatic (lookupUFM ufm)) statics)
+ -- we need to get the jump tables, so apply the mapping to the entries
+ -- of a CmmData too.
+apply_mapping ufm (CmmProc info lbl params blocks)
+ = CmmProc info lbl params (map short_bb blocks)
+ where
+ short_bb (BasicBlock id insns) = BasicBlock id $! map short_insn insns
+ short_insn i = shortcutJump (lookupUFM ufm) i
+ -- shortcutJump should apply the mapping repeatedly,
+ -- just in case we can short multiple branches.
+
-- -----------------------------------------------------------------------------
-- Instruction selection