1. 06 Feb, 2009 1 commit
    • Ian Lynagh's avatar
      When generating C, don't pretend functions are data · 497302c4
      Ian Lynagh authored
      We used to generated things like:
          extern StgWordArray (newCAF) __attribute__((aligned (8)));
          ((void (*)(void *))(W_)&newCAF)((void *)R1.w);
      (which is to say, pretend that newCAF is some data, then cast it to a
      function and call it).
      This goes wrong on at least IA64, where:
          A function pointer on the ia64 does not point to the first byte of
          code. Intsead, it points to a structure that describes the function.
          The first quadword in the structure is the address of the first byte
          of code
      so we end up dereferencing function pointers one time too many, and
      segfaulting.
      497302c4
  2. 29 Dec, 2008 9 commits
  3. 09 Dec, 2008 1 commit
  4. 05 Dec, 2008 1 commit
  5. 28 Nov, 2008 1 commit
  6. 27 Nov, 2008 1 commit
    • Simon Marlow's avatar
      don't emit CmmComments for now · 1f03870f
      Simon Marlow authored
        - if the string contains */, we need to fix it (demonstrated by 
          building Cabal with -fvia-C)
        - the strings can get quite large, so we probably only want to
          inject comments when some debugging option is on.
      1f03870f
  7. 26 Nov, 2008 2 commits
  8. 17 Oct, 2008 1 commit
  9. 16 Oct, 2008 1 commit
    • dias@eecs.harvard.edu's avatar
      Fixed linear regalloc bug, dropped some tracing code · c62b824e
      dias@eecs.harvard.edu authored
      o The linear-scan register allocator sometimes allocated a block
        before allocating one of its predecessors, which could lead
        to inconsistent allocations. Now, we allocate a block only
        if a predecessor has set the "incoming" assignments for the block
        (or if it's the procedure's entry block).
      o Also commented out some tracing code on the new codegen path.
      c62b824e
  10. 14 Oct, 2008 3 commits
    • dias@eecs.harvard.edu's avatar
      Keep update frames live even in functions that never return · 41f7ea2f
      dias@eecs.harvard.edu authored
      An unusual case, but without it:
      (a) we had an assertion failure
      (b) we can overwrite the caller's infotable, which might cause
          the garbage collector to collect live data.
      Better to keep the update frame live at all call sites,
      not just at returns.
      41f7ea2f
    • dias@eecs.harvard.edu's avatar
      Removed space and time inefficiency in procpoint splitting · e13a12b7
      dias@eecs.harvard.edu authored
      I was adding extra jumps to every procpoint, even when the split-off graph
      referred to only some of the procpoints. No effect on correctness,
      but a big effect on space/time efficiency when there are lots of procpoints...
      e13a12b7
    • dias@eecs.harvard.edu's avatar
      Clarify the SRT building process · e367ebeb
      dias@eecs.harvard.edu authored
      Before: building a closure that would build an SRT given the top-level
      SRT. It was somewhat difficult to understand the control flow, and it
      may have had held onto some data structures long after they should be dead.
      Now, I just bundle the info we need about CAFs along with the procedure
      and directly call a new top-level function to build the SRTs later.
      e367ebeb
  11. 13 Oct, 2008 3 commits
    • dias@eecs.harvard.edu's avatar
      93d047a1
    • dias@eecs.harvard.edu's avatar
      forgot a few files · dc6a72b9
      dias@eecs.harvard.edu authored
      dc6a72b9
    • dias@eecs.harvard.edu's avatar
      Big collection of patches for the new codegen branch. · e6243a81
      dias@eecs.harvard.edu authored
      o Fixed bug that emitted the copy-in code for closure entry
        in the wrong place -- at the initialization of the closure.
      o Refactored some of the closure entry code.
      o Added code to check that no LocalRegs are live-in to a procedure
         -- trip up some buggy programs earlier
      o Fixed environment bindings for thunks
         -- we weren't (re)binding the free variables in a thunk
      o Fixed a bug in proc-point splitting that dropped some updates
        to the entry block in a procedure.
      o Fixed improper calls to code that generates CmmLit's for strings
      o New invariant on cg_loc in CgIdInfo: the expression is always tagged
      o Code to load free vars on entry to a thunk was (wrongly) placed before
        the heap check.
      o Some of the StgCmm code was redundantly passing around Id's
        along with CgIdInfo's; no more.
      o Initialize the LocalReg's that point to a closure before allocating and
        initializing the closure itself -- otherwise, we have problems with
        recursive closure bindings
      o BlockEnv and BlockSet types are now abstract.
      o Update frames:
        - push arguments in Old call area
        - keep track of the return sp in the FCode monad
        - keep the return sp in every call, tail call, and return
            (because it might be different at different call sites,
             e.g. tail calls to the gc after a heap check are performed
                  before pushing the update frame)
        - set the sp appropriately on returns and tail calls
      o Reduce call, tail call, and return to a single LastCall node
      o Added slow entry code, using different calling conventions on entry and tail call
      o More fixes to the calling convention code.
        The tricky stuff is all about the closure environment: it must be passed in R1,
        but in non-closures, there is no such argument, so we can't treat all arguments
        the same way: the closure environment is special. Maybe the right step forward
        would be to define a different calling convention for closure arguments.
      o Let-no-escapes need to be emitted out-of-line -- otherwise, we drop code.
      o Respect RTS requirement of word alignment for pointers
        My stack allocation can pack sub-word values into a single word on the stack,
        but it wasn't requiring word-alignment for pointers. It does now,
        by word-aligning both pointer registers and call areas.
      o CmmLint was over-aggresively ruling out non-word-aligned memory references,
        which may be kosher now that we can spill small values into a single word.
      o Wrong label order on a conditional branch when compiling switches.
      o void args weren't dropped in many cases.
        To help prevent this kind of mistake, I defined a NonVoid wrapper,
        which I'm applying only to Id's for now, although there are probably
        other good candidates.
      o A little code refactoring: separate modules for procpoint analysis splitting, 
        stack layout, and building infotables.
      o Stack limit check: insert along with the heap limit check, using a symbolic
        constant (a special CmmLit), then replace it when the stack layout is known.
      o Removed last node: MidAddToContext 
      o Adding block id as a literal: means that the lowering of the calling conventions
        no longer has to produce labels early, which was inhibiting common-block elimination.
        Will also make it easier for the non-procpoint-splitting path.
      o Info tables: don't try to describe the update frame!
      o Over aggressive use of NonVoid!!!!
        Don't drop the non-void args before setting the type of the closure!!!
      o Sanity checking:
        Added a pass to stub dead dead slots on the stack
        (only ~10 lines with the dataflow framework)
      o More sanity checking:
        Check that incoming pointer arguments are non-stubbed.
        Note: these checks are still subject to dead-code removal, but they should
        still be quite helpful.
      o Better sanity checking: why stop at function arguments?
        Instead, in mkAssign, check that _any_ assignment to a pointer type is non-null
        -- the sooner the crash, the easier it is to debug.
        Still need to add the debugging flag to turn these checks on explicitly.
      o Fixed yet another calling convention bug.
        This time, the calls to the GC were wrong. I've added a new convention
        for GC calls and invoked it where appropriate.
        We should really straighten out the calling convention stuff:
          some of the code (and documentation) is spread across the compiler,
          and there's some magical use of the node register that should really
          be handled (not avoided) by calling conventions.
      o Switch bug: the arms in mkCmmLitSwitch weren't returning to a single join point.
      o Environment shadowing problem in Stg->Cmm:
        When a closure f is bound at the top-level, we should not bind f to the
        node register on entry to the closure.
        Why? Because if the body of f contains a let-bound closure g that refers
        to f, we want to make sure that it refers to the static closure for f.
        Normally, this would all be fine, because when we compile a closure,
        we rebind free variables in the environment. But f doesn't look like
        a free variable because it's a static value. So, the binding for f
        remains in the environment when we compile g, inconveniently referring
        to the wrong thing.
        Now, I bind the variable in the local environment only if the closure is not
        bound at the top level. It's still okay to make assumptions about the
        node holding the closure environment; we just won't find the binding
        in the environment, so code that names the closure will now directly
        get the label of the static closure, not the node register holding a
        pointer to the static closure.
      o Don't generate bogus Cmm code containing SRTs during the STG -> Cmm pass!
        The tables made reference to some labels that don't exist when we compute and
        generate the tables in the back end.
      o Safe foreign calls need some special treatment (at least until we have the integrated
        codegen). In particular:
        o they need info tables
        o they are not procpoints -- the successor had better be in the same procedure
        o we cannot (yet) implement the calling conventions early, which means we have
          to carry the calling-conv info all the way to the end
      o We weren't following the old convention when registering a module.
        Now, we use update frames to push any new modules that have to be registered
        and enter the youngest one on the stack.
        We also use the update frame machinery to specify that the return should pop
        the return address off the stack.
      o At each safe foreign call, an infotable must be at the bottom of the stack,
        and the TSO->sp must point to it.
      o More problems with void args in a direct call to a function:
        We were checking the args (minus voids) to check whether the call was saturated,
        which caused problems when the function really wasn't saturated because it
        took an extra void argument.
      o Forgot to distinguish integer != from floating != during Stg->Cmm
      o Updating slotEnv and areaMap to include safe foreign calls
        The dataflow analyses that produce the slotEnv and areaMap give
        results for each basic block, but we also need the results for
        a safe foreign call, which is a middle node.
        After running the dataflow analysis, we have another pass that
        updates the results to includ any safe foreign calls.
      o Added a static flag for the debugging technique that inserts
        instructions to stub dead slots on the stack and crashes when
        a stubbed value is loaded into a pointer-typed LocalReg.
      o C back end expects to see return continuations before their call sites.
        Sorted the flowgraphs appropriately after splitting.
      o PrimOp calling conventions are special -- unlimited registers, no stack
        Yet another calling convention...
      o More void value problems: if the RHS of a case arm is a void-typed variable,
        don't try to return it.
      o When calling some primOp, they may allocate memory; if so, we need to
        do a heap check when we return from the call.
      e6243a81
  12. 14 Aug, 2008 1 commit
    • dias@eecs.harvard.edu's avatar
      Merging in the new codegen branch · 176fa33f
      dias@eecs.harvard.edu authored
      This merge does not turn on the new codegen (which only compiles
      a select few programs at this point),
      but it does introduce some changes to the old code generator.
      
      The high bits:
      1. The Rep Swamp patch is finally here.
         The highlight is that the representation of types at the
         machine level has changed.
         Consequently, this patch contains updates across several back ends.
      2. The new Stg -> Cmm path is here, although it appears to have a
         fair number of bugs lurking.
      3. Many improvements along the CmmCPSZ path, including:
         o stack layout
         o some code for infotables, half of which is right and half wrong
         o proc-point splitting
      176fa33f
  13. 18 Nov, 2008 1 commit
    • Simon Marlow's avatar
      Add optional eager black-holing, with new flag -feager-blackholing · d600bf7a
      Simon Marlow authored
      Eager blackholing can improve parallel performance by reducing the
      chances that two threads perform the same computation.  However, it
      has a cost: one extra memory write per thunk entry.  
      
      To get the best results, any code which may be executed in parallel
      should be compiled with eager blackholing turned on.  But since
      there's a cost for sequential code, we make it optional and turn it on
      for the parallel package only.  It might be a good idea to compile
      applications (or modules) with parallel code in with
      -feager-blackholing.
      
      ToDo: document -feager-blackholing.
      d600bf7a
  14. 14 Sep, 2008 1 commit
  15. 28 Aug, 2008 1 commit
  16. 31 Jul, 2008 5 commits
  17. 25 Jul, 2008 1 commit
  18. 21 Jul, 2008 1 commit
  19. 20 Jul, 2008 3 commits
  20. 11 Jul, 2008 1 commit
  21. 16 Jun, 2008 1 commit
    • Ian Lynagh's avatar
      More commandline flag improvements · 0f5e104c
      Ian Lynagh authored
      * Allow -ffoo flags to be deprecated
      * Mark some -ffoo flags as deprecated
      * Avoid using deprecated flags in error messages, in the build system, etc
      * Add a flag to en/disable the deprecated flag warning
      0f5e104c