factor some code better.

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

diff --git a/lib/Analysis/ValueTracking.cpp b/lib/Analysis/ValueTracking.cpp
index e7e291fb928c0312eedadd47bf2bbc50c4b34866..c51a719313f2a12ae7d000faa27eb86342f10697 100644 (file)
--- a/lib/Analysis/ValueTracking.cpp
+++ b/lib/Analysis/ValueTracking.cpp
@@ -369,15 +369,13 @@ void llvm::ComputeMaskedBits(Value *V, const APInt &Mask,
         ComputeMaskedBits(I->getOperand(0), Mask2, KnownZero2, KnownOne2, TD, 
                           Depth+1);
 
-        // The sign of a remainder is equal to the sign of the first
-        // operand (zero being positive).
+        // If the sign bit of the first operand is zero, the sign bit of
+        // the result is zero. If the first operand has no one bits below
+        // the second operand's single 1 bit, its sign will be zero.
         if (KnownZero2[BitWidth-1] || ((KnownZero2 & LowBits) == LowBits))
           KnownZero2 |= ~LowBits;
-        else if (KnownOne2[BitWidth-1])
-          KnownOne2 |= ~LowBits;
 
         KnownZero |= KnownZero2 & Mask;
-        KnownOne |= KnownOne2 & Mask;
 
         assert((KnownZero & KnownOne) == 0&&"Bits known to be one AND zero?"); 
       }
@@ -511,12 +509,15 @@ void llvm::ComputeMaskedBits(Value *V, const APInt &Mask,
           ComputeMaskedBits(R, Mask2, KnownZero2, KnownOne2, TD, Depth+1);
           Mask2 = APInt::getLowBitsSet(BitWidth,
                                        KnownZero2.countTrailingOnes());
-          KnownOne2.clear();
-          KnownZero2.clear();
-          ComputeMaskedBits(L, Mask2, KnownZero2, KnownOne2, TD, Depth+1);
+
+          // We need to take the minimum number of known bits
+          APInt KnownZero3(KnownZero), KnownOne3(KnownOne);
+          ComputeMaskedBits(L, Mask2, KnownZero3, KnownOne3, TD, Depth+1);
+
           KnownZero = Mask &
                       APInt::getLowBitsSet(BitWidth,
-                                           KnownZero2.countTrailingOnes());
+                                           std::min(KnownZero2.countTrailingOnes(),
+                                                    KnownZero3.countTrailingOnes()));
           break;
         }
       }
@@ -864,7 +865,7 @@ Value *llvm::FindInsertedValue(Value *V, const unsigned *idx_begin,
   else if (Constant *C = dyn_cast<Constant>(V)) {
     if (isa<ConstantArray>(C) || isa<ConstantStruct>(C))
       // Recursively process this constant
-      return FindInsertedValue(C->getOperand(*idx_begin), ++idx_begin, idx_end,
+      return FindInsertedValue(C->getOperand(*idx_begin), idx_begin + 1, idx_end,
                                InsertBefore);
   } else if (InsertValueInst *I = dyn_cast<InsertValueInst>(V)) {
     // Loop the indices for the insertvalue instruction in parallel with the