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| author | Michael D. Adams <adamsmd@cs.indiana.edu> | 2007-07-15 16:20:03 +0000 |
|---|---|---|
| committer | Michael D. Adams <adamsmd@cs.indiana.edu> | 2007-07-15 16:20:03 +0000 |
| commit | ca9c90e51724d8efdebfd97128b21c5bc0eed555 (patch) | |
| tree | 1998b162af478acdad6b50a9e8bd935998576170 /compiler | |
| parent | a9eda06434ea9fb4764c2a587ccd53df09f7c470 (diff) | |
| download | haskell-ca9c90e51724d8efdebfd97128b21c5bc0eed555.tar.gz | |
Keep the CPS pass from creating proc points due to unreachable parents.
The parser/flattener will generate an extra block after an if/else
statement even if both branches exit the function. So it is possible
for the input to the CPS pass to have dead/unreachable blocks.
If a dead block goes to a live block then the live block would
have more parents than the dead block and prior to this patch
the live block would then be identified as a proc point.
This is fixed by adding a check to see if the parent
has at least one owner.
Diffstat (limited to 'compiler')
| -rw-r--r-- | compiler/cmm/CmmProcPoint.hs | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/compiler/cmm/CmmProcPoint.hs b/compiler/cmm/CmmProcPoint.hs index fe64608022..df408c666f 100644 --- a/compiler/cmm/CmmProcPoint.hs +++ b/compiler/cmm/CmmProcPoint.hs @@ -79,8 +79,12 @@ calculateNewProcPoints owners block = where parent_owners = lookupWithDefaultUFM owners emptyUniqSet parent_id child_owners = lookupWithDefaultUFM owners emptyUniqSet child_id - needs_proc_point = not $ isEmptyUniqSet $ - child_owners `minusUniqSet` parent_owners + needs_proc_point = + -- only if parent isn't dead + (not $ isEmptyUniqSet parent_owners) && + -- and only if child has more owners than parent + (not $ isEmptyUniqSet $ + child_owners `minusUniqSet` parent_owners) calculateOwnership :: BlockEnv BrokenBlock -> UniqSet BlockId |