From: David Greene <greened@obbligato.org>
Date: Mon, 27 Oct 2008 23:24:03 +0000 (+0000)
Subject: Re-apply 55137 with fixes.
X-Git-Url: http://plrg.eecs.uci.edu/git/?a=commitdiff_plain;h=c714f1309049b2fd9e4ab68c8a7b480c63a4be0c;p=oota-llvm.git

Re-apply 55137 with fixes.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@58296 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Analysis/ValueTracking.cpp b/lib/Analysis/ValueTracking.cpp
index 3a04f5eb869..c51a719313f 100644
--- a/lib/Analysis/ValueTracking.cpp
+++ b/lib/Analysis/ValueTracking.cpp
@@ -509,12 +509,15 @@ void llvm::ComputeMaskedBits(Value *V, const APInt &Mask,
           ComputeMaskedBits(R, Mask2, KnownZero2, KnownOne2, TD, Depth+1);
           Mask2 = APInt::getLowBitsSet(BitWidth,
                                        KnownZero2.countTrailingOnes());
-          KnownOne2.clear();
-          KnownZero2.clear();
-          ComputeMaskedBits(L, Mask2, KnownZero2, KnownOne2, TD, Depth+1);
+
+          // We need to take the minimum number of known bits
+          APInt KnownZero3(KnownZero), KnownOne3(KnownOne);
+          ComputeMaskedBits(L, Mask2, KnownZero3, KnownOne3, TD, Depth+1);
+
           KnownZero = Mask &
                       APInt::getLowBitsSet(BitWidth,
-                                           KnownZero2.countTrailingOnes());
+                                           std::min(KnownZero2.countTrailingOnes(),
+                                                    KnownZero3.countTrailingOnes()));
           break;
         }
       }