[PATCH] D99205: Add jump-threading optimization for deterministic finite automata

[Justin Kreiner via Phabricator via llvm-commits]

jkreiner marked 4 inline comments as done.
jkreiner added a comment.

I removed the unnecessary conditions, and used the llvm::DenseMap instead.



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Comment at: llvm/lib/CodeGen/DFAJumpThreading.cpp:740
+    unsigned NumInsts = Metrics.NumInsts;
+    unsigned DuplicationCost = NumInsts / CondBranches;
+
----------------
Here is the cost calculation we implemented. It could be more accurate by accounting for instructions and blocks that get simplified, but for now it at least prevents code explosion. 


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Comment at: llvm/lib/CodeGen/DFAJumpThreading.cpp:453
+    // Vector select instructions are not supported.
+    if (!SI->getCondition()->getType()->isIntegerTy(1)) {
+      return false;
----------------
efriedma wrote:
> Don't think you can end up with a vector select here; you've already constrained the result to be an integer.
Yes, I agree the vector select check was unnecessary here.


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  https://reviews.llvm.org/D99205/new/

https://reviews.llvm.org/D99205