[ValueTracking] Replace all uses of ComputeSignBit with computeKnownBits.

This patch finishes off the conversion of ComputeSignBit to computeKnownBits.

Differential Revision: https://reviews.llvm.org/D33166

llvm-svn: 303035

1 files changed, 2 insertions, 3 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
index 4939859470f..001a4bcf16f 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
@@ -1188,9 +1188,8 @@ Instruction *InstCombiner::visitSExt(SExtInst &CI) {
 
   // If we know that the value being extended is positive, we can use a zext
   // instead.
-  bool KnownZero, KnownOne;
-  ComputeSignBit(Src, KnownZero, KnownOne, 0, &CI);
-  if (KnownZero) {
+  KnownBits Known = computeKnownBits(Src, 0, &CI);
+  if (Known.isNonNegative()) {
     Value *ZExt = Builder->CreateZExt(Src, DestTy);
     return replaceInstUsesWith(CI, ZExt);
   }