[PATCH] D55876: [LIR] Add CTTZ support

[Craig Topper via Phabricator via llvm-commits]

craig.topper added inline comments.


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Comment at: lib/Transforms/Scalar/LoopIdiomRecognize.cpp:1624
+  NewCount = Builder.CreateZExtOrTrunc(
+                      IsCntPhiUsedOutsideLoop ? CountPrev : Count,
+                      cast<IntegerType>(CntInst->getType()));
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Can you add a test case for CntPhiUsedOutsideLoop==true with shl?


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Comment at: test/Transforms/LoopIdiom/X86/cttz.ll:27
+  %c = icmp sgt i32 %n, 0
+  %negn = sub nsw i32 0, %n
+  %abs_n = select i1 %c, i32 %n, i32 %negn
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Drop the absolute value. Its not necessary. It was only in the existing tests to make ashr work correctly.


Repository:
  rL LLVM

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D55876/new/

https://reviews.llvm.org/D55876