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| author | Jakob Stoklund Olesen <stoklund@2pi.dk> | 2011-09-16 00:03:35 +0000 |
|---|---|---|
| committer | Jakob Stoklund Olesen <stoklund@2pi.dk> | 2011-09-16 00:03:35 +0000 |
| commit | ebac0c1747d20e48f359d76dd454444107080d83 (patch) | |
| tree | 970f4b0170b4c1320e6dc9ad42aa8e93ddb0697b /lib/CodeGen/LiveDebugVariables.cpp | |
| parent | 69cf1cac3f62e60a50ff0aa9808ea4d317e273ef (diff) | |
Spill mode: Hoist back-copies locally.
The leaveIntvAfter() function normally inserts a back-copy after the
requested instruction, making the back-copy kill the live range.
In spill mode, try to insert the back-copy before the last use instead.
That means the last use becomes the kill instead of the back-copy. This
lowers the register pressure because the last use can now redefine the
same register it was reading.
This will also improve compile time: The back-copy isn't a kill, so
hoisting it in hoistCopiesForSize() won't force a recomputation of the
source live range. Similarly, if the back-copy isn't hoisted by the
splitter, the spiller will not attempt hoisting it locally.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@139883 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/CodeGen/LiveDebugVariables.cpp')
0 files changed, 0 insertions, 0 deletions