srem doesn't actually have the same resulting sign as its numerator, you could

also have a zero when numerator = denominator. Reverts parts of r126635 and
r126637.

llvm-svn: 126644

2 files changed, 0 insertions, 22 deletions

diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index 70d51fac3f2..7e208692ac2 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -460,18 +460,6 @@ void llvm::ComputeMaskedBits(Value *V, const APInt &Mask,
         assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?"); 
       }
     }
-    if (Mask.isNegative()) {  // We're looking for the sign bit.
-      APInt Mask2 = APInt::getSignBit(BitWidth);
-      KnownZero2 = 0;
-      KnownOne2 = 0;
-      ComputeMaskedBits(I->getOperand(0), Mask2, KnownZero2, KnownOne2, TD, 
-                        Depth+1);
-      if (KnownOne2[BitWidth-1])
-        KnownOne |= Mask2;
-      if (KnownZero2[BitWidth-1])
-        KnownZero |= Mask2;
-      assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
-    }
     break;
   case Instruction::URem: {
     if (ConstantInt *Rem = dyn_cast<ConstantInt>(I->getOperand(1))) {
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
index 79c5d88c631..fe117c98143 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -1348,16 +1348,6 @@ Instruction *InstCombiner::visitICmpInstWithInstAndIntCst(ICmpInst &ICI,
       }
     }
     break;
-
-  case Instruction::SRem: {
-    bool TrueIfSigned;
-    if (LHSI->hasOneUse() &&
-        isSignBitCheck(ICI.getPredicate(), RHS, TrueIfSigned)) {
-      // srem has the same sign as its dividend so the divisor is irrelevant.
-      return new ICmpInst(ICI.getPredicate(), LHSI->getOperand(0), RHS);
-    }
-    break;
-  }
   }
   
   // Simplify icmp_eq and icmp_ne instructions with integer constant RHS.