[KnownBits] Add bit counting methods to KnownBits struct and use them where possible

This patch adds min/max population count, leading/trailing zero/one bit counting methods.

The min methods return answers based on bits that are known without considering unknown bits. The max methods give answers taking into account the largest count that unknown bits could give.

Differential Revision: https://reviews.llvm.org/D32931

llvm-svn: 302925

3 files changed, 7 insertions, 7 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
index 6989d67f006..face7abcc95 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -1384,10 +1384,10 @@ static Instruction *foldCttzCtlz(IntrinsicInst &II, InstCombiner &IC) {
 
   // Create a mask for bits above (ctlz) or below (cttz) the first known one.
   bool IsTZ = II.getIntrinsicID() == Intrinsic::cttz;
-  unsigned PossibleZeros = IsTZ ? Known.One.countTrailingZeros()
-                                : Known.One.countLeadingZeros();
-  unsigned DefiniteZeros = IsTZ ? Known.Zero.countTrailingOnes()
-                                : Known.Zero.countLeadingOnes();
+  unsigned PossibleZeros = IsTZ ? Known.countMaxTrailingZeros()
+                                : Known.countMaxLeadingZeros();
+  unsigned DefiniteZeros = IsTZ ? Known.countMinTrailingZeros()
+                                : Known.countMinLeadingZeros();
 
   // If all bits above (ctlz) or below (cttz) the first known one are known
   // zero, this value is constant.
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
index 05b01774cd5..4028a92771a 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineSimplifyDemanded.cpp
@@ -611,7 +611,7 @@ Value *InstCombiner::SimplifyDemandedUseBits(Value *V, APInt DemandedMask,
         SimplifyDemandedBits(I, 1, AllOnes, Known2, Depth + 1))
       return I;
 
-    unsigned Leaders = Known2.Zero.countLeadingOnes();
+    unsigned Leaders = Known2.countMinLeadingZeros();
     Known.Zero = APInt::getHighBitsSet(BitWidth, Leaders) & DemandedMask;
     break;
   }
diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
index 1792cb585f8..04e81f4bd15 100644
--- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -2264,8 +2264,8 @@ Instruction *InstCombiner::visitSwitchInst(SwitchInst &SI) {
   unsigned BitWidth = cast<IntegerType>(Cond->getType())->getBitWidth();
   KnownBits Known(BitWidth);
   computeKnownBits(Cond, Known, 0, &SI);
-  unsigned LeadingKnownZeros = Known.Zero.countLeadingOnes();
-  unsigned LeadingKnownOnes = Known.One.countLeadingOnes();
+  unsigned LeadingKnownZeros = Known.countMinLeadingZeros();
+  unsigned LeadingKnownOnes = Known.countMinLeadingOnes();
 
   // Compute the number of leading bits we can ignore.
   // TODO: A better way to determine this would use ComputeNumSignBits().