X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2FcodeGen%2FStgCmmExpr.hs;h=94afb80f5b16554188cd92f5ac306dfe60ea88f4;hp=462def3d5df8fc88acd707afbd90cee13be61344;hb=a278f3f02d09bc32b0a75d4a04d710090cde250f;hpb=e239aa2329416a2822fcc03c4ed486c7d28739e1 diff --git a/compiler/codeGen/StgCmmExpr.hs b/compiler/codeGen/StgCmmExpr.hs index 462def3..94afb80 100644 --- a/compiler/codeGen/StgCmmExpr.hs +++ b/compiler/codeGen/StgCmmExpr.hs @@ -29,15 +29,17 @@ import StgSyn import MkZipCfgCmm import BlockId -import Cmm() import CmmExpr import CoreSyn import DataCon import ForeignCall import Id import PrimOp +import SMRep import TyCon +import Type import CostCentre ( CostCentreStack, currentCCS ) +import Control.Monad (when) import Maybes import Util import FastString @@ -280,24 +282,65 @@ cgCase (OpApp ) bndr srt AlgAlt [(DataAlt flase, a2] = -} + -- Note [ticket #3132]: we might be looking at a case of a lifted Id + -- that was cast to an unlifted type. The Id will always be bottom, + -- but we don't want the code generator to fall over here. If we + -- just emit an assignment here, the assignment will be + -- type-incorrect Cmm. Hence, we emit the usual enter/return code, + -- (and because bottom must be untagged, it will be entered and the + -- program will crash). + -- The Sequel is a type-correct assignment, albeit bogus. + -- The (dead) continuation loops; it would be better to invoke some kind + -- of panic function here. + -- + -- However, we also want to allow an assignment to be generated + -- in the case when the types are compatible, because this allows + -- some slightly-dodgy but occasionally-useful casts to be used, + -- such as in RtClosureInspect where we cast an HValue to a MutVar# + -- so we can print out the contents of the MutVar#. If we generate + -- code that enters the HValue, then we'll get a runtime panic, because + -- the HValue really is a MutVar#. The types are compatible though, + -- so we can just generate an assignment. +cgCase (StgApp v []) bndr _ alt_type@(PrimAlt _) alts + | isUnLiftedType (idType v) + || reps_compatible + = -- assignment suffices for unlifted types + do { when (not reps_compatible) $ + panic "cgCase: reps do not match, perhaps a dodgy unsafeCoerce?" + ; v_info <- getCgIdInfo v + ; emit (mkAssign (CmmLocal (idToReg (NonVoid bndr))) (idInfoToAmode v_info)) + ; _ <- bindArgsToRegs [NonVoid bndr] + ; cgAlts NoGcInAlts (NonVoid bndr) alt_type alts } + where + reps_compatible = idCgRep v == idCgRep bndr + +cgCase scrut@(StgApp v []) _ _ (PrimAlt _) _ + = -- fail at run-time, not compile-time + do { mb_cc <- maybeSaveCostCentre True + ; withSequel (AssignTo [idToReg (NonVoid v)] False) (cgExpr scrut) + ; restoreCurrentCostCentre mb_cc + ; emit $ mkComment $ mkFastString "should be unreachable code" + ; emit $ withFreshLabel "l" (\l -> mkLabel l <*> mkBranch l)} + cgCase scrut bndr srt alt_type alts - = do { up_hp_usg <- getVirtHp -- Upstream heap usage - ; let ret_bndrs = chooseReturnBndrs bndr alt_type alts - alt_regs = map idToReg ret_bndrs - simple_scrut = isSimpleScrut scrut alt_type - gcInAlts | not simple_scrut = True - | isSingleton alts = False - | up_hp_usg > 0 = False - | otherwise = True - gc_plan = if gcInAlts then GcInAlts alt_regs srt else NoGcInAlts - - ; mb_cc <- maybeSaveCostCentre simple_scrut - ; withSequel (AssignTo alt_regs gcInAlts) (cgExpr scrut) - ; restoreCurrentCostCentre mb_cc + = -- the general case + do { up_hp_usg <- getVirtHp -- Upstream heap usage + ; let ret_bndrs = chooseReturnBndrs bndr alt_type alts + alt_regs = map idToReg ret_bndrs + simple_scrut = isSimpleScrut scrut alt_type + gcInAlts | not simple_scrut = True + | isSingleton alts = False + | up_hp_usg > 0 = False + | otherwise = True + gc_plan = if gcInAlts then GcInAlts alt_regs srt else NoGcInAlts + + ; mb_cc <- maybeSaveCostCentre simple_scrut + ; withSequel (AssignTo alt_regs gcInAlts) (cgExpr scrut) + ; restoreCurrentCostCentre mb_cc -- JD: We need Note: [Better Alt Heap Checks] - ; bindArgsToRegs ret_bndrs - ; cgAlts gc_plan (NonVoid bndr) alt_type alts } + ; _ <- bindArgsToRegs ret_bndrs + ; cgAlts gc_plan (NonVoid bndr) alt_type alts } ----------------- maybeSaveCostCentre :: Bool -> FCode (Maybe LocalReg) @@ -320,8 +363,8 @@ isSimpleScrut _ _ = False isSimpleOp :: StgOp -> Bool -- True iff the op cannot block or allocate isSimpleOp (StgFCallOp (CCall (CCallSpec _ _ safe)) _) = not (playSafe safe) -isSimpleOp (StgFCallOp (DNCall _) _) = False -- Safe! isSimpleOp (StgPrimOp op) = not (primOpOutOfLine op) +isSimpleOp (StgPrimCallOp _) = False ----------------- chooseReturnBndrs :: Id -> AltType -> [StgAlt] -> [NonVoid Id] @@ -407,7 +450,7 @@ cgAltRhss gc_plan bndr alts cg_alt (con, bndrs, _uses, rhs) = getCodeR $ maybeAltHeapCheck gc_plan $ - do { bindConArgs con base_reg bndrs + do { _ <- bindConArgs con base_reg bndrs ; cgExpr rhs ; return con } @@ -464,8 +507,9 @@ cgTailCall fun_id fun_info args = do do { let fun' = CmmLoad fun (cmmExprType fun) ; [ret,call] <- forkAlts [ getCode $ emitReturn [fun], -- Is tagged; no need to untag - getCode $ do emit (mkAssign nodeReg fun) - emitCall NativeCall (entryCode fun') []] -- Not tagged + getCode $ do -- emit (mkAssign nodeReg fun) + emitCall (NativeNodeCall, NativeReturn) + (entryCode fun') [fun]] -- Not tagged ; emit (mkCmmIfThenElse (cmmIsTagged fun) ret call) } SlowCall -> do -- A slow function call via the RTS apply routines @@ -505,8 +549,8 @@ if the assignment to the binder will be dead code (use isDeadBndr). The following example illustrates how badly the code turns out: STG: case <=## [ww_s7Hx y_s7HD] of wild2_sbH8 { - GHC.Bool.False -> // sbH8 dead - GHC.Bool.True -> // sbH8 dead + GHC.Types.False -> // sbH8 dead + GHC.Types.True -> // sbH8 dead }; Cmm: _s7HD::F64 = F64[_sbH7::I64 + 7]; // MidAssign