[PATCH] D71007: [ARM][LowOverheadLoops] Remove dead loop update instructions

[Sam Parker via Phabricator via llvm-commits]

samparker added inline comments.


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Comment at: llvm/lib/CodeGen/ReachingDefAnalysis.cpp:282
+
+  while (It-- != MI->getParent()->front()) {
+    for (auto &MO : It->operands())
----------------
How about using reverse iterators? Probably would have saved you from the the off-by-one?


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Comment at: llvm/lib/Target/ARM/ARMLowOverheadLoops.cpp:695
+  // And also analyse the uses before this Def in this loop block.
+  while ((Use = RDA->getInstWithUseBefore(Pos, ElemCount))) {
+    // Ignore the VCTP instruction, this is allowed to use the elem count
----------------
Looks like it would be better to modify the RDA method to provide all the uses. Then we'll have similar functionality to getReachingLocalUses.


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  https://reviews.llvm.org/D71007/new/

https://reviews.llvm.org/D71007