InstSimplify: Move a transform from InstCombine to InstSimplify

Several combines involving icmp (shl C2, %X) C1 can be simplified
without introducing any new instructions.  Move them to InstSimplify;
while we are at it, make them more powerful.

llvm-svn: 216642

1 files changed, 0 insertions, 10 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
index 4cf836c03b2..32414ba838a 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -1503,16 +1503,10 @@ Instruction *InstCombiner::visitICmpInstWithInstAndIntCst(ICmpInst &ICI,
           unsigned RHSLog2 = RHSV.logBase2();
 
           // (1 << X) >= 2147483648 -> X >= 31 -> X == 31
-          // (1 << X) >  2147483648 -> X >  31 -> false
-          // (1 << X) <= 2147483648 -> X <= 31 -> true
           // (1 << X) <  2147483648 -> X <  31 -> X != 31
           if (RHSLog2 == TypeBits-1) {
             if (Pred == ICmpInst::ICMP_UGE)
               Pred = ICmpInst::ICMP_EQ;
-            else if (Pred == ICmpInst::ICMP_UGT)
-              return ReplaceInstUsesWith(ICI, Builder->getFalse());
-            else if (Pred == ICmpInst::ICMP_ULE)
-              return ReplaceInstUsesWith(ICI, Builder->getTrue());
             else if (Pred == ICmpInst::ICMP_ULT)
               Pred = ICmpInst::ICMP_NE;
           }
@@ -1547,10 +1541,6 @@ Instruction *InstCombiner::visitICmpInstWithInstAndIntCst(ICmpInst &ICI,
           if (RHSVIsPowerOf2)
             return new ICmpInst(
                 Pred, X, ConstantInt::get(RHS->getType(), RHSV.logBase2()));
-
-          return ReplaceInstUsesWith(
-              ICI, Pred == ICmpInst::ICMP_EQ ? Builder->getFalse()
-                                             : Builder->getTrue());
         }
       }
       break;