Hide two different AlignMode enums in anonymous namespaces. This bug is reported...

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

diff --git a/lib/Analysis/InstructionSimplify.cpp b/lib/Analysis/InstructionSimplify.cpp
index 31263bb7de89226f05e062a29a442bf0dac0a064..459fc92bce1a856a2d621b6aedc24c76c18c2d1a 100644 (file)
--- a/lib/Analysis/InstructionSimplify.cpp
+++ b/lib/Analysis/InstructionSimplify.cpp
@@ -676,6 +676,18 @@ static Value *SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
   if (Op0 == Op1)
     return Constant::getNullValue(Op0->getType());
 
+  // X - (0 - Y) -> X if the second sub is NUW.
+  // If Y != 0, 0 - Y is a poison value.
+  // If Y == 0, 0 - Y simplifies to 0.
+  if (BinaryOperator::isNeg(Op1)) {
+    if (const auto *BO = dyn_cast<BinaryOperator>(Op1)) {
+      assert(BO->getOpcode() == Instruction::Sub &&
+             "Expected a subtraction operator!");
+      if (BO->hasNoUnsignedWrap())
+        return Op0;
+    }
+  }
+
   // (X + Y) - Z -> X + (Y - Z) or Y + (X - Z) if everything simplifies.
   // For example, (X + Y) - Y -> X; (Y + X) - Y -> X
   Value *X = nullptr, *Y = nullptr, *Z = Op1;
@@ -1346,6 +1358,11 @@ static Value *SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact,
       cast<OverflowingBinaryOperator>(Op0)->hasNoSignedWrap())
     return X;
 
+  // Arithmetic shifting an all-sign-bit value is a no-op.
+  unsigned NumSignBits = ComputeNumSignBits(Op0, Q.DL);
+  if (NumSignBits == Op0->getType()->getScalarSizeInBits())
+    return Op0;
+
   return nullptr;
 }
 
@@ -1948,17 +1965,33 @@ static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
       if (!CI2->isZero())
         Upper = NegOne.udiv(CI2->getValue()) + 1;
     } else if (match(LHS, m_SDiv(m_ConstantInt(CI2), m_Value()))) {
-      // 'sdiv CI2, x' produces [-|CI2|, |CI2|].
-      Upper = CI2->getValue().abs() + 1;
-      Lower = (-Upper) + 1;
+      if (CI2->isMinSignedValue()) {
+        // 'sdiv INT_MIN, x' produces [INT_MIN, INT_MIN / -2].
+        Lower = CI2->getValue();
+        Upper = Lower.lshr(1) + 1;
+      } else {
+        // 'sdiv CI2, x' produces [-|CI2|, |CI2|].
+        Upper = CI2->getValue().abs() + 1;
+        Lower = (-Upper) + 1;
+      }
     } else if (match(LHS, m_SDiv(m_Value(), m_ConstantInt(CI2)))) {
-      // 'sdiv x, CI2' produces [INT_MIN / CI2, INT_MAX / CI2].
       APInt IntMin = APInt::getSignedMinValue(Width);
       APInt IntMax = APInt::getSignedMaxValue(Width);
-      APInt Val = CI2->getValue().abs();
-      if (!Val.isMinValue()) {
+      APInt Val = CI2->getValue();
+      if (Val.isAllOnesValue()) {
+        // 'sdiv x, -1' produces [INT_MIN + 1, INT_MAX]
+        //    where CI2 != -1 and CI2 != 0 and CI2 != 1
+        Lower = IntMin + 1;
+        Upper = IntMax + 1;
+      } else if (Val.countLeadingZeros() < Width - 1) {
+        // 'sdiv x, CI2' produces [INT_MIN / CI2, INT_MAX / CI2]
+        //    where CI2 != -1 and CI2 != 0 and CI2 != 1
         Lower = IntMin.sdiv(Val);
-        Upper = IntMax.sdiv(Val) + 1;
+        Upper = IntMax.sdiv(Val);
+        if (Lower.sgt(Upper))
+          std::swap(Lower, Upper);
+        Upper = Upper + 1;
+        assert(Upper != Lower && "Upper part of range has wrapped!");
       }
     } else if (match(LHS, m_LShr(m_Value(), m_ConstantInt(CI2)))) {
       // 'lshr x, CI2' produces [0, UINT_MAX >> CI2].