[PATCH] D95508: [X86] Fix tile config register spill issue for AMX

[Xiang Zhang via Phabricator via llvm-commits]

xiangzhangllvm added inline comments.


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Comment at: llvm/lib/Target/X86/X86PreTileConfig.cpp:242
+    MachineBasicBlock::iterator MII = MI ? MI->getIterator() : MBB->begin();
+    for (auto E = MBB->end(); MII != E; ++MII) {
+      if (isAMXInstruction(MII)) {
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pengfei wrote:
> Since you iterate all MI twice, the total complex is 2 * N(BB) * M(MI), which is worse than D56136 (N * M + N).
we see O(N) == O(2N) in program.


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Comment at: llvm/lib/Target/X86/X86PreTileConfig.cpp:260
     }
+    AMXBBVisited[MBB] = ReachAMX;
+    return ReachAMX;
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pengfei wrote:
> If it is also succsor of itself, it will drop into infinite loop.
good catch! it should move ahead.




CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D95508/new/

https://reviews.llvm.org/D95508