#367: Infinite loops can hang Concurrent Haskell
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Reporter: simonpj | Owner: ezyang
Type: bug | Status: new
Priority: lowest | Milestone: _|_
Component: Compiler | Version: 6.4.1
Resolution: None | Keywords: scheduler
allocation
Os: Unknown/Multiple | Architecture: Unknown/Multiple
Failure: Incorrect result at runtime | Difficulty: Unknown
Testcase: | Blockedby:
Blocking: | Related:
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Comment(by ezyang):
Diff botched, here is a formatted one:
{{{
ezyang@javelin:~/Dev/ghc-master$ git show
commit 5a9aee5e1d5a4d140f451aef6c57ab065c428966
Author: Edward Z. Yang <ezy...@mit.edu>
Date: Mon Sep 17 18:28:49 2012 +0200
Better implementation for fixing #367.
Signed-off-by: Edward Z. Yang <ezy...@mit.edu>
diff --git a/compiler/codeGen/StgCmmHeap.hs
b/compiler/codeGen/StgCmmHeap.hs
index fb37391..a70d132 100644
--- a/compiler/codeGen/StgCmmHeap.hs
+++ b/compiler/codeGen/StgCmmHeap.hs
@@ -557,15 +557,22 @@ do_checks checkStack alloc do_gc = do
hp_oflo = CmmMachOp (mo_wordUGt dflags)
[CmmReg hpReg, CmmReg (CmmGlobal HpLim)]
+ -- Yielding if HpLim == 0
+ yielding = CmmMachOp (mo_wordEq dflags)
+ [CmmReg (CmmGlobal HpLim), CmmLit (zeroCLit
dflags)]
+
alloc_n = mkAssign (CmmGlobal HpAlloc) alloc_lit
gc_id <- newLabelC
when checkStack $ do
emit =<< mkCmmIfGoto sp_oflo gc_id
- when (alloc /= 0) $ do
- emitAssign hpReg bump_hp
- emit =<< mkCmmIfThen hp_oflo (alloc_n <*> mkBranch gc_id)
+ if (alloc /= 0)
+ then do
+ emitAssign hpReg bump_hp
+ emit =<< mkCmmIfThen hp_oflo (alloc_n <*> mkBranch gc_id)
+ else do
+ emit =<< mkCmmIfThen yielding (alloc_n <*> mkBranch gc_id)
emitOutOfLine gc_id $
do_gc -- this is expected to jump back somewhere
}}}
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/367#comment:18>
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