[PATCH] D92385: [ARM] Add a pass that re-arranges blocks when there is a backwards WLS branch
Sam Parker via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Wed Dec 2 05:21:14 PST 2020
samparker added inline comments.
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Comment at: llvm/lib/Target/ARM/ARMLowOverheadLoopBlockPlacement.cpp:49
+ continue;
+ moveBasicBlock(Target, &BB);
+ Changed = true;
----------------
I think moving a block with invalidate your BBUtils info, but I'm hoping adjustBBOffsetsAfter can be used instead of recomputing everthing. We should also have a test which exercises multiple block rearrangements.
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Comment at: llvm/lib/Target/ARM/ARMLowOverheadLoopBlockPlacement.cpp:61
+
+bool ARMLowOverheadLoopBlockPlacement::canMoveBasicBlock(
+ MachineBasicBlock *BB, MachineBasicBlock *To) {
----------------
Looks like you're duplicating work here:
- iterating through BB twice to find t2WhileLoopStart
- extra call to blockIsBefore?
================
Comment at: llvm/lib/Target/ARM/ARMLowOverheadLoopBlockPlacement.cpp:88
+ if (BBPrevious && BBPrevious->isSuccessor(BB))
+ fixFallthrough(BBPrevious, BB);
+ // Fix fall through from the destination BB to the one that used to follow
----------------
Keep the code together and have fixFallThrough as a lambda?
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D92385/new/
https://reviews.llvm.org/D92385
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