type ArgumentFormat a b = [(a, ParamLocation b)]
--- Stack parameters are returned as word offsets.
assignArguments :: (a -> CmmType) -> [a] -> ArgumentFormat a WordOff
+-- Stack parameters are returned as word offsets.
assignArguments _ _ = panic "assignArguments only used in dead codegen" -- assignments
-- | JD: For the new stack story, I want arguments passed on the stack to manifest as
-- Also, I want byte offsets, not word offsets.
assignArgumentsPos :: (Outputable a) => Convention -> (a -> CmmType) -> [a] ->
ArgumentFormat a ByteOff
+-- Given a list of arguments, and a function that tells their types,
+-- return a list showing where each argument is passed
assignArgumentsPos conv arg_ty reps = assignments
where -- The calling conventions (CgCallConv.hs) are complicated, to say the least
regs = case (reps, conv) of
-- functions to pass the arguments in an overflow area and to pass them in spill slots.
copyInOflow :: Convention -> Area -> CmmFormals -> (Int, CmmAGraph)
copyInSlot :: Convention -> CmmFormals -> [CmmNode O O]
-copyOutOflow :: Convention -> Transfer -> Area -> CmmActuals -> UpdFrameOffset ->
- (Int, CmmAGraph)
copyOutSlot :: Convention -> [LocalReg] -> [CmmNode O O]
copyInOflow conv area formals = (offset, catAGraphs $ map mkMiddle nodes)
-- Factoring out the common parts of the copyout functions yielded something
-- more complicated:
+copyOutOflow :: Convention -> Transfer -> Area -> CmmActuals -> UpdFrameOffset ->
+ (Int, CmmAGraph)
+-- Generate code to move the actual parameters into the locations
+-- required by the calling convention. This includes a store for the return address.
+--
-- The argument layout function ignores the pointer to the info table, so we slot that
-- in here. When copying-out to a young area, we set the info table for return
-- and adjust the offsets of the other parameters.
-- If this is a call instruction, we adjust the offsets of the other parameters.
-copyOutOflow conv transfer area@(CallArea a) actuals updfr_off =
- foldr co (init_offset, emptyAGraph) args'
- where co (v, RegisterParam r) (n, ms) = (n, mkAssign (CmmGlobal r) v <*> ms)
- co (v, StackParam off) (n, ms) =
- (max n off, mkStore (CmmStackSlot area off) v <*> ms)
- (setRA, init_offset) =
- case a of Young id -> id `seq` -- set RA if making a call
- if transfer == Call then
- ([(CmmLit (CmmBlock id), StackParam init_offset)],
- widthInBytes wordWidth)
- else ([], 0)
- Old -> ([], updfr_off)
- args = assignArgumentsPos conv cmmExprType actuals
- args' = foldl adjust setRA args
- where adjust rst (v, StackParam off) = (v, StackParam (off + init_offset)) : rst
- adjust rst x@(_, RegisterParam _) = x : rst
+copyOutOflow conv transfer area@(CallArea a) actuals updfr_off
+ = foldr co (init_offset, emptyAGraph) args'
+ where
+ co (v, RegisterParam r) (n, ms) = (n, mkAssign (CmmGlobal r) v <*> ms)
+ co (v, StackParam off) (n, ms) = (max n off, mkStore (CmmStackSlot area off) v <*> ms)
+
+ (setRA, init_offset) =
+ case a of Young id -> id `seq` -- Generate a store instruction for
+ -- the return address if making a call
+ if transfer == Call then
+ ([(CmmLit (CmmBlock id), StackParam init_offset)],
+ widthInBytes wordWidth)
+ else ([], 0)
+ Old -> ([], updfr_off)
+
+ args :: [(CmmExpr, ParamLocation ByteOff)] -- The argument and where to put it
+ args = assignArgumentsPos conv cmmExprType actuals
+
+ args' = foldl adjust setRA args
+ where adjust rst (v, StackParam off) = (v, StackParam (off + init_offset)) : rst
+ adjust rst x@(_, RegisterParam _) = x : rst
+
copyOutOflow _ _ (RegSlot _) _ _ = panic "cannot copy arguments into a register slot"
-- Args passed only in registers and stack slots; no overflow space.
+More notes (June 11)\r
+~~~~~~~~~~~~~~~~~~~~\r
+* Kill dead code assignArguments, argumentsSize in CmmCallConv.\r
+ Bake in ByteOff to ParamLocation and ArgumentFormat\r
+ CmmActuals -> [CmmActual] similary CmmFormals\r
+\r
+* Possible refactoring: Nuke AGraph in favour of \r
+ mkIfThenElse :: Expr -> Graph -> Graph -> FCode Graph\r
+ or even\r
+ mkIfThenElse :: HasUniques m => Expr -> Graph -> Graph -> m Graph\r
+ (Remmber that the .cmm file parser must use this function)\r
+\r
+ or parameterise FCode over its envt; the CgState part seem useful for both\r
+\r
+* Move top and tail calls to runCmmContFlowOpts from HscMain to CmmCps.cpsTop\r
+ (and rename the latter!)\r
+\r
+* "Remove redundant reloads" in CmmSpillReload should be redundant; since\r
+ insertLateReloads is now gone, every reload is reloading a live variable.\r
+ Test and nuke.\r
+\r
+* Sink and inline S(RegSlot(x)) = e in precisely the same way that we\r
+ sink and inline x = e\r
+\r
+* Stack layout is very like register assignment: find non-conflicting assigments.\r
+ In particular we can use colouring or linear scan (etc).\r
+\r
+ We'd fine-grain interference (on a word by word basis) to get maximum overlap.\r
+ But that may make very big interference graphs. So linear scan might be\r
+ more attactive.\r
+\r
+ NB: linear scan does on-the-fly live range splitting.\r
+\r
+* When stubbing dead slots be careful not to write into an area that\r
+ overlaps with an area that's in use. So stubbing needs to *follow* \r
+ stack layout.\r
+\r
+\r
More notes (May 11)\r
~~~~~~~~~~~~~~~~~~~\r
In CmmNode, consider spliting CmmCall into two: call and jump\r