From d323c8f791ac1160813508f1742f845444b6459a Mon Sep 17 00:00:00 2001
From: Alex Richardson <Alexander.Richardson@cl.cam.ac.uk>
Date: Tue, 27 Oct 2020 09:56:19 +0000
Subject: [PATCH] [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.
---
 llvm/lib/Analysis/ValueTracking.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index dc252a2..05eb2fc4 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.
-- 
2.7.4