<div dir="ltr"><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Fri, Nov 6, 2020 at 6:41 PM Simon Pilgrim via llvm-commits <<a href="mailto:llvm-commits@lists.llvm.org">llvm-commits@lists.llvm.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><br>
Author: Simon Pilgrim<br>
Date: 2020-11-06T17:27:13Z<br>
New Revision: 20f87d82ed31fff7f11b893d0fef5111295a6cce<br>
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URL: <a href="https://github.com/llvm/llvm-project/commit/20f87d82ed31fff7f11b893d0fef5111295a6cce" rel="noreferrer" target="_blank">https://github.com/llvm/llvm-project/commit/20f87d82ed31fff7f11b893d0fef5111295a6cce</a><br>
DIFF: <a href="https://github.com/llvm/llvm-project/commit/20f87d82ed31fff7f11b893d0fef5111295a6cce.diff" rel="noreferrer" target="_blank">https://github.com/llvm/llvm-project/commit/20f87d82ed31fff7f11b893d0fef5111295a6cce.diff</a><br>
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LOG: [InstCombine] computeKnownBitsMul - use KnownBits::isNonZero() helper.<br>
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Avoid an expensive isKnownNonZero() call - this is a small cleanup before moving the extra NSW functionality from computeKnownBitsMul into KnownBits::computeForMul.<br>
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Added: <br>
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Modified: <br>
    llvm/include/llvm/Support/KnownBits.h<br>
    llvm/lib/Analysis/ValueTracking.cpp<br>
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Removed: <br>
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################################################################################<br>
diff  --git a/llvm/include/llvm/Support/KnownBits.h b/llvm/include/llvm/Support/KnownBits.h<br>
index de1c0cdf9177..40470b6e0f7b 100644<br>
--- a/llvm/include/llvm/Support/KnownBits.h<br>
+++ b/llvm/include/llvm/Support/KnownBits.h<br>
@@ -97,6 +97,9 @@ struct KnownBits {<br>
   /// Returns true if this value is known to be non-negative.<br>
   bool isNonNegative() const { return Zero.isSignBitSet(); }<br>
<br>
+  /// Returns true if this value is known to be non-zero.<br>
+  bool isNonZero() const { return One.countPopulation() != 0; }<br>
+<br></blockquote><div><br></div><div>Can't you write this as just "One != 0"?</div><div><br></div><div>Nikita<br></div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
   /// Returns true if this value is known to be positive.<br>
   bool isStrictlyPositive() const { return Zero.isSignBitSet() && !One.isNullValue(); }<br>
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diff  --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp<br>
index 44cf4f80b59d..db591ce67709 100644<br>
--- a/llvm/lib/Analysis/ValueTracking.cpp<br>
+++ b/llvm/lib/Analysis/ValueTracking.cpp<br>
@@ -436,10 +436,10 @@ static void computeKnownBitsMul(const Value *Op0, const Value *Op1, bool NSW,<br>
       // The product of a negative number and a non-negative number is either<br>
       // negative or zero.<br>
       if (!isKnownNonNegative)<br>
-        isKnownNegative = (isKnownNegativeOp1 && isKnownNonNegativeOp0 &&<br>
-                           isKnownNonZero(Op0, Depth, Q)) ||<br>
-                          (isKnownNegativeOp0 && isKnownNonNegativeOp1 &&<br>
-                           isKnownNonZero(Op1, Depth, Q));<br>
+        isKnownNegative =<br>
+            (isKnownNegativeOp1 && isKnownNonNegativeOp0 &&<br>
+             Known2.isNonZero()) ||<br>
+            (isKnownNegativeOp0 && isKnownNonNegativeOp1 && Known.isNonZero());<br>
     }<br>
   }<br>
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