Merging r258690:

[oota-llvm.git] / lib / Analysis / DemandedBits.cpp

diff --git a/lib/Analysis/DemandedBits.cpp b/lib/Analysis/DemandedBits.cpp
index 775cbac4c53ed4089761e92b042b8a9c4ee463fa..143d0b79f188e5f59372ddd1a2231acf1cfa0747 100644 (file)
--- a/lib/Analysis/DemandedBits.cpp
+++ b/lib/Analysis/DemandedBits.cpp
@@ -25,6 +25,7 @@
 #include "llvm/ADT/DepthFirstIterator.h"
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/StringExtras.h"
 #include "llvm/Analysis/AssumptionCache.h"
 #include "llvm/Analysis/ValueTracking.h"
 #include "llvm/IR/BasicBlock.h"
@@ -131,6 +132,7 @@ void DemandedBits::determineLiveOperandBits(
     break;
   case Instruction::Add:
   case Instruction::Sub:
+  case Instruction::Mul:
     // Find the highest live output bit. We don't need any more input
     // bits than that (adds, and thus subtracts, ripple only to the
     // left).
@@ -240,6 +242,13 @@ void DemandedBits::determineLiveOperandBits(
     if (OperandNo != 0)
       AB = AOut;
     break;
+  case Instruction::ICmp:
+    // Count the number of leading zeroes in each operand.
+    ComputeKnownBits(BitWidth, UserI->getOperand(0), UserI->getOperand(1));
+    auto NumLeadingZeroes = std::min(KnownZero.countLeadingOnes(),
+                                     KnownZero2.countLeadingOnes());
+    AB = ~APInt::getHighBitsSet(BitWidth, NumLeadingZeroes);
+    break;
   }
 }
 
@@ -368,6 +377,16 @@ bool DemandedBits::isInstructionDead(Instruction *I) {
     !isAlwaysLive(I);
 }
 
+void DemandedBits::print(raw_ostream &OS, const Module *M) const {
+  // This is gross. But the alternative is making all the state mutable
+  // just because of this one debugging method.
+  const_cast<DemandedBits*>(this)->performAnalysis();
+  for (auto &KV : AliveBits) {
+    OS << "DemandedBits: 0x" << utohexstr(KV.second.getLimitedValue()) << " for "
+       << *KV.first << "\n";
+  }
+}
+
 FunctionPass *llvm::createDemandedBitsPass() {
   return new DemandedBits();
 }