Minor cleanup related to my latest scheduler changes.

[oota-llvm.git] / lib / Transforms / InstCombine / InstCombineSelect.cpp

diff --git a/lib/Transforms/InstCombine/InstCombineSelect.cpp b/lib/Transforms/InstCombine/InstCombineSelect.cpp
index 6f0da3eb64a918c553e4a81a6a1f5b8dc7917990..c15378bc742d0776dfa05134149f78c97cc769fc 100644 (file)
--- a/lib/Transforms/InstCombine/InstCombineSelect.cpp
+++ b/lib/Transforms/InstCombine/InstCombineSelect.cpp
@@ -195,7 +195,10 @@ static bool isSelect01(Constant *C1, Constant *C2) {
   ConstantInt *C2I = dyn_cast<ConstantInt>(C2);
   if (!C2I)
     return false;
-  return (C1I->isZero() || C1I->isOne()) && (C2I->isZero() || C2I->isOne());
+  if (!C1I->isZero() && !C2I->isZero()) // One side must be zero.
+    return false;
+  return C1I->isOne() || C1I->isAllOnesValue() ||
+         C2I->isOne() || C2I->isAllOnesValue();
 }
 
 /// FoldSelectIntoOp - Try fold the select into one of the operands to
@@ -219,7 +222,7 @@ Instruction *InstCombiner::FoldSelectIntoOp(SelectInst &SI, Value *TrueVal,
           Constant *C = GetSelectFoldableConstant(TVI);
           Value *OOp = TVI->getOperand(2-OpToFold);
           // Avoid creating select between 2 constants unless it's selecting
-          // between 0 and 1.
+          // between 0, 1 and -1.
           if (!isa<Constant>(OOp) || isSelect01(C, cast<Constant>(OOp))) {
             Instruction *NewSel = SelectInst::Create(SI.getCondition(), OOp, C);
             InsertNewInstBefore(NewSel, SI);
@@ -248,7 +251,7 @@ Instruction *InstCombiner::FoldSelectIntoOp(SelectInst &SI, Value *TrueVal,
           Constant *C = GetSelectFoldableConstant(FVI);
           Value *OOp = FVI->getOperand(2-OpToFold);
           // Avoid creating select between 2 constants unless it's selecting
-          // between 0 and 1.
+          // between 0, 1 and -1.
           if (!isa<Constant>(OOp) || isSelect01(C, cast<Constant>(OOp))) {
             Instruction *NewSel = SelectInst::Create(SI.getCondition(), C, OOp);
             InsertNewInstBefore(NewSel, SI);
@@ -457,10 +460,6 @@ static Value *foldSelectICmpAnd(const SelectInst &SI, ConstantInt *TrueVal,
   if (!IC || !IC->isEquality())
     return 0;
 
-  // One of the select arms must be zero.
-  if (!TrueVal->isZero() && !FalseVal->isZero())
-    return 0;
-
   if (ConstantInt *C = dyn_cast<ConstantInt>(IC->getOperand(1)))
     if (!C->isZero())
       return 0;
@@ -471,6 +470,24 @@ static Value *foldSelectICmpAnd(const SelectInst &SI, ConstantInt *TrueVal,
       !match(LHS, m_And(m_Value(), m_ConstantInt(AndRHS))))
     return 0;
 
+  // If both select arms are non-zero see if we have a select of the form
+  // 'x ? 2^n + C : C'. Then we can offset both arms by C, use the logic
+  // for 'x ? 2^n : 0' and fix the thing up at the end.
+  ConstantInt *Offset = 0;
+  if (!TrueVal->isZero() && !FalseVal->isZero()) {
+    if ((TrueVal->getValue() - FalseVal->getValue()).isPowerOf2())
+      Offset = FalseVal;
+    else if ((FalseVal->getValue() - TrueVal->getValue()).isPowerOf2())
+      Offset = TrueVal;
+    else
+      return 0;
+
+    // Adjust TrueVal and FalseVal to the offset.
+    TrueVal = ConstantInt::get(Builder->getContext(),
+                               TrueVal->getValue() - Offset->getValue());
+    FalseVal = ConstantInt::get(Builder->getContext(),
+                                FalseVal->getValue() - Offset->getValue());
+  }
 
   // Make sure the mask in the 'and' and one of the select arms is a power of 2.
   if (!AndRHS->getValue().isPowerOf2() ||
@@ -496,6 +513,10 @@ static Value *foldSelectICmpAnd(const SelectInst &SI, ConstantInt *TrueVal,
   ShouldNotVal ^= IC->getPredicate() == ICmpInst::ICMP_NE;
   if (ShouldNotVal)
     V = Builder->CreateXor(V, ValC);
+
+  // Apply an offset if needed.
+  if (Offset)
+    V = Builder->CreateAdd(V, Offset);
   return V;
 }