diff options
| author | Michal Terepeta <michal.terepeta@gmail.com> | 2018-03-19 11:58:54 -0400 |
|---|---|---|
| committer | Ben Gamari <ben@smart-cactus.org> | 2018-03-19 12:05:11 -0400 |
| commit | bbcea13af845d41a9d51a932476eb841ba182ea5 (patch) | |
| tree | d846f7d73f60e2bb5865a4bc258b986e63c8f3b7 /compiler/cmm/CmmLayoutStack.hs | |
| parent | 0db0e46c40a3a2af71f23033aa09a142d43b8538 (diff) | |
| download | haskell-bbcea13af845d41a9d51a932476eb841ba182ea5.tar.gz | |
Hoopl: improve postorder calculation
- Fix the naming and comments to indicate that we are calculating
*reverse* postorder (and not the standard postorder).
- Rewrite the calculation to avoid CPS code. I found it fairly
difficult to understand and the new one seems faster (according to
nofib, decreases compiler allocations by 0.2%)
- Remove `LabelsPtr`, which seems unnecessary and could be *really*
confusing. For instance, previously:
`postorder_dfs_from <block with label X>`
and
`postorder_dfs_from <label X>`
would actually mean quite different things (and give different
results).
- Change the `Dataflow` module to always use entry of the graph for
reverse postorder calculation. This should be the only change in
behavior of this commit.
Previously, if the caller provided initial facts for some of the
labels, we would use those labels for our postorder calculation.
However, I don't think that's correct in general - if the initial
facts did not contain the entry of the graph, we would never analyze
the blocks reachable from the entry but unreachable from the labels
provided with the initial facts. It seems that the only analysis that
used this was proc-point analysis, which I think would always include
the entry block (so I don't think there's any bug due to this).
Signed-off-by: Michal Terepeta <michal.terepeta@gmail.com>
Test Plan: ./validate
Reviewers: bgamari, simonmar
Reviewed By: simonmar
Subscribers: rwbarton, thomie, carter
Differential Revision: https://phabricator.haskell.org/D4464
Diffstat (limited to 'compiler/cmm/CmmLayoutStack.hs')
| -rw-r--r-- | compiler/cmm/CmmLayoutStack.hs | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/compiler/cmm/CmmLayoutStack.hs b/compiler/cmm/CmmLayoutStack.hs index 3f1633404c..d2525d1ffd 100644 --- a/compiler/cmm/CmmLayoutStack.hs +++ b/compiler/cmm/CmmLayoutStack.hs @@ -244,7 +244,7 @@ cmmLayoutStack dflags procpoints entry_args -- We need liveness info. Dead assignments are removed later -- by the sinking pass. let liveness = cmmLocalLiveness dflags graph - blocks = postorderDfs graph + blocks = revPostorder graph (final_stackmaps, _final_high_sp, new_blocks) <- mfix $ \ ~(rec_stackmaps, rec_high_sp, _new_blocks) -> |