diff options
| author | Simon Marlow <marlowsd@gmail.com> | 2012-08-02 10:36:58 +0100 |
|---|---|---|
| committer | Simon Marlow <marlowsd@gmail.com> | 2012-08-02 11:57:30 +0100 |
| commit | 3ae875c45d7d228514547be639d30042d6bf1d26 (patch) | |
| tree | 4deaa81fa89245df5dea203c3fad3e8640e5d40e /compiler/cmm/CmmSink.hs | |
| parent | 95686360bb8898e77b2998d3aec11a4e2c31c4ad (diff) | |
| download | haskell-3ae875c45d7d228514547be639d30042d6bf1d26.tar.gz | |
Eliminate "r = r" assignments.
Previously these were caught by removeDeadAssignments, but we aren't
doing that now.
Diffstat (limited to 'compiler/cmm/CmmSink.hs')
| -rw-r--r-- | compiler/cmm/CmmSink.hs | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/compiler/cmm/CmmSink.hs b/compiler/cmm/CmmSink.hs index 02195c91e1..80c6eed349 100644 --- a/compiler/cmm/CmmSink.hs +++ b/compiler/cmm/CmmSink.hs @@ -205,7 +205,12 @@ walk nodes assigs = go nodes emptyBlock assigs -- to get all the dead code, but it catches the common case of -- superfluous reloads from the stack that the stack allocator -- leaves behind. + -- + -- Also we catch "r = r" here. You might think it would fall + -- out of inlining, but the inliner will see that r is live + -- after the instruction and choose not to inline r in the rhs. discard = case node of + CmmAssign r (CmmReg r') | r == r' -> True CmmAssign (CmmLocal r) _ -> not (r `Set.member` live) _otherwise -> False |