[llvm-commits] CVS: llvm/lib/Transforms/Scalar/InstructionCombining.cpp

[Chris Lattner]

Changes in directory llvm/lib/Transforms/Scalar:

InstructionCombining.cpp updated: 1.139 -> 1.140

---
Log message:

Fix bug with previous implementation:
-      // ~(c-X) == X-(c-1) == X+(-c+1)
+      // ~(c-X) == X-c-1 == X+(-c-1)

Implement: C - ~X == X + (1+C)


---
Diffs of the changes:  (+11 -4)

Index: llvm/lib/Transforms/Scalar/InstructionCombining.cpp
diff -u llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.139 llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.140
--- llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.139	Tue Nov  4 17:50:51 2003
+++ llvm/lib/Transforms/Scalar/InstructionCombining.cpp	Tue Nov  4 19:06:05 2003
@@ -488,11 +488,18 @@
   if (Value *V = dyn_castNegVal(Op1))
     return BinaryOperator::create(Instruction::Add, Op0, V);
 
-  // Replace (-1 - A) with (~A)...
-  if (ConstantInt *C = dyn_cast<ConstantInt>(Op0))
+  if (ConstantInt *C = dyn_cast<ConstantInt>(Op0)) {
+    // Replace (-1 - A) with (~A)...
     if (C->isAllOnesValue())
       return BinaryOperator::createNot(Op1);
 
+    // C - ~X == X + (1+C)
+    if (BinaryOperator::isNot(Op1))
+      return BinaryOperator::create(Instruction::Add,
+                      BinaryOperator::getNotArgument(cast<BinaryOperator>(Op1)),
+                                    *C + *ConstantInt::get(I.getType(), 1));
+  }
+
   if (BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1))
     if (Op1I->hasOneUse()) {
       // Replace (x - (y - z)) with (x + (z - y)) if the (y - z) subexpression
@@ -1001,10 +1008,10 @@
           return new SetCondInst(SCI->getInverseCondition(),
                                  SCI->getOperand(0), SCI->getOperand(1));
 
-      // ~(c-X) == X-(c-1) == X+(-c+1)
+      // ~(c-X) == X-c-1 == X+(-c-1)
       if (Op0I->getOpcode() == Instruction::Sub && RHS->isAllOnesValue() &&
           isa<Constant>(Op0I->getOperand(0))) {
-        Constant *ConstantRHS = *-*cast<Constant>(Op0I->getOperand(0)) +
+        Constant *ConstantRHS = *-*cast<Constant>(Op0I->getOperand(0)) -
                                 *ConstantInt::get(I.getType(), 1);
         return BinaryOperator::create(Instruction::Add, Op0I->getOperand(1),
                                       ConstantRHS);