[PATCH] D12799: [ValueTracking] Teach isKnownNonZero a new trick

Philip Reames via llvm-commits llvm-commits at lists.llvm.org
Mon Sep 21 15:13:55 PDT 2015


reames added inline comments.

================
Comment at: lib/Analysis/ValueTracking.cpp:1841
@@ +1840,3 @@
+      // Are all the bits to be shifted out known zero?
+      if (KnownZero.countTrailingOnes() >= ShiftVal)
+        return isKnownNonZero(X, DL, Depth, Q);
----------------
Shouldn't this be countTrailingZeros?

================
Comment at: test/Analysis/ValueTracking/knownzero-shift.ll:10
@@ +9,3 @@
+  %x = icmp eq i8 %A, 0
+  %y = select i1 %x, i8 6, i8 7    ; ... and should return i8 7.
+  ; CHECK: ret i8 7
----------------
You could just return the i1 directly.  


Repository:
  rL LLVM

http://reviews.llvm.org/D12799





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