The main goal here is to reduce fragmentation, which turns out to be the case of #743. While I was here I found some opportunities to improve performance too. The code is rather more complex, but it also contains a long comment describing the strategy, so please take a look at that for the details.
People keep complaining, with some justification, that runST $ foo doesn't work. So I've finally caved in. The difficulty with the above is that we need to decide how to instantiate ($)'s type arguments based on the first argument (runST), and then use that info to check the second argumnent. There is a left-to-right flow of information. It's not hard to implement this, and it's clearly useful. The main change is in TcExpr.tcArgs, with some knock-on effects elsewhere. I was finally provoked into this by Trac #981, which turned out, after some head-scratching, to be another instance of the same problem. (There was some bug-fixing too; a type like ((?x::Int) => ...) is a polytype even though it has no leading for-alls, but the new TcUnify code was not treating it right.) Test for this is tc222
Work around the PowerPC architecture's +-32KB limitation for conditional branches by conditionally skipping an unconditional branch instead (unconditional branches have a +-32MB range). This requires an extra pass over the basic blocks for each CmmTop after block sequencing, to determine which branches are "far". Fixes ticket #709, "Fixup too large" error with -fasm on PowerPC
conc021 is an example of a program that broke. It doesn't handle them particularly well still, but it doesn't crash at least.
Specifically, this disables the special support in the RTS for looking up the datacon name corresponding to an address. Correspondingly, the debugging commads in GHCi will not be available, and neither will the '-fdebugging' flag
The :print, :sprint and :force commands for GHCi. This set of commands allows inspection of heap structures of the bindings in the interactive environment. This is useful to observe lazyness and specially to inspect things with undespecified polymorphic types, as happens often in breakpoints.
This patch adds dynamic breakpoints to GHCi There is a new ':breakpoint' command to manage breakpoints. GHCi simply uses the breakpoint api functions in ghc-api to install itself as a client. The mechanism used by GHCi to keep track of enabled breakpoints is a simple table. When a breakpoint is hit, a new interactive session is launched and the bindings in the breakpoint are injected. Some commands are disabled in this sub session
…ated functions I found this convenient while I was extending ghci with the debugger. I wanted to put all the debugger stuff in a separate module, but I would need a huge hs-boot file to break the circular dependencies. This option seemed better
Used in the desugaring of the breakpoint primitive
The dynamic linker has been modified so that it won't panic if one of the breakpointJump functions fails to resolve. Now, if the dynamic linker fails to find a HValue for a Name, before looking for a static symbol it will ask to Breakpoints.lookupBogusBreakpointVal :: Name -> Maybe HValue which returns an identity function for the Jump names or Nothing else. A TH function might contain a call to a breakpoint function. So if it is compiled to bytecodes, the breakpoints will be desugared to 'jumps'. Whenever this code is spliced, the linker will fail to find the jumpfunctions unless there is a default.
Instrumentation gets activated by the '-fdebugging' dynflag. All the instrumentation occurrs in the desugarer; it consists of inserting 'breakpoint' combinators at a number of places in the AST, namely: - Binding sites - Do-notation statements These 'breakpoint' combinators will later be further desugared (at DsExpr) into ___Jump functions. For more info about this and all the ghci.debugger see the page at the GHC wiki: http://hackage.haskell.org/trac/ghc/wiki/GhciDebugger
The entry point is: setBreakpointHandler :: Session -> BkptHandler Module -> IO ()
RtClosureInspect includes a bunch of stuff for playing with closures: - the datatype Closure is the low level representation type - the datatype Term is the high level representation type - cvObtainTerm is the main entry point, providing the Term representation of an arbitrary closure
This patch extends the RTS linker and the dynamic linker so that it is possible to find out the datacon of a closure in heap at runtime: - The RTS linker now carries a hashtable 'Address->Symbol' for data constructors - The Persistent Linker State in the dynamic linker is extended in a similar way. Finally, these two sources of information are consulted by: > Linker.recoverDataCon :: a -> TcM Name
- infoPtr# :: a -> Addr# - closurePayload# :: a -> (# Array b, ByteArr# #) These prim ops provide the magic behind the ':print' command