[llvm] d323c8f - [ValueTracking][NFC] Use Log2(Align) instead of countTrailingZeroes

[Alex Richardson via llvm-commits]

Author: Alex Richardson
Date: 2020-10-27T12:16:45Z
New Revision: d323c8f791ac1160813508f1742f845444b6459a

URL: https://github.com/llvm/llvm-project/commit/d323c8f791ac1160813508f1742f845444b6459a
DIFF: https://github.com/llvm/llvm-project/commit/d323c8f791ac1160813508f1742f845444b6459a.diff

LOG: [ValueTracking][NFC] Use Log2(Align) instead of countTrailingZeroes

The latter can probably be optimized to the same final code, but this might
help -O0 builds.

Added: 
    

Modified: 
    llvm/lib/Analysis/ValueTracking.cpp

Removed: 
    


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diff  --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index dc252a281c4d..05eb2fc48270 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -2003,7 +2003,7 @@ void computeKnownBits(const Value *V, const APInt &DemandedElts,
   // Aligned pointers have trailing zeros - refine Known.Zero set
   if (isa<PointerType>(V->getType())) {
     Align Alignment = V->getPointerAlignment(Q.DL);
-    Known.Zero.setLowBits(countTrailingZeros(Alignment.value()));
+    Known.Zero.setLowBits(Log2(Alignment));
   }
 
   // computeKnownBitsFromAssume strictly refines Known.