[ValueTracking] Make isImpliedCondition return an Optional<bool>. NFC.

Phabricator Revision: http://reviews.llvm.org/D19277

llvm-svn: 266904
diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
index ca3ab10..1e8a1dd 100644
--- a/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/llvm/lib/Analysis/InstructionSimplify.cpp
@@ -2135,8 +2135,7 @@
       // X >=u 1 -> X
       if (match(RHS, m_One()))
         return LHS;
-      bool ImpliedTrue;
-      if (isImpliedCondition(RHS, LHS, ImpliedTrue, Q.DL) && ImpliedTrue)
+      if (isImpliedCondition(RHS, LHS, Q.DL).getValueOr(false))
         return getTrue(ITy);
       break;
     }
@@ -2148,8 +2147,7 @@
       ///  0  |  1  |  1 (0 >= -1)  |  1
       ///  1  |  0  |  0 (-1 >= 0)  |  0
       ///  1  |  1  |  1 (-1 >= -1) |  1
-      bool ImpliedTrue;
-      if (isImpliedCondition(LHS, RHS, ImpliedTrue, Q.DL) && ImpliedTrue)
+      if (isImpliedCondition(LHS, RHS, Q.DL).getValueOr(false))
         return getTrue(ITy);
       break;
     }
@@ -2164,8 +2162,7 @@
         return LHS;
       break;
     case ICmpInst::ICMP_ULE: {
-      bool ImpliedTrue;
-      if (isImpliedCondition(LHS, RHS, ImpliedTrue, Q.DL) && ImpliedTrue)
+      if (isImpliedCondition(LHS, RHS, Q.DL).getValueOr(false))
         return getTrue(ITy);
       break;
     }