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

[Chris Lattner]

Changes in directory llvm/lib/Transforms/Scalar:

InstructionCombining.cpp updated: 1.718 -> 1.719
---
Log message:

simplify (x+c)^signbit as (x+c+signbit), pointed out by PR1288: http://llvm.org/PR1288 .  This implements
test/Transforms/InstCombine/xor.ll:test28


---
Diffs of the changes:  (+7 -1)

 InstructionCombining.cpp |    8 +++++++-
 1 files changed, 7 insertions(+), 1 deletion(-)


Index: llvm/lib/Transforms/Scalar/InstructionCombining.cpp
diff -u llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.718 llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.719
--- llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.718	Sun Apr  1 15:57:36 2007
+++ llvm/lib/Transforms/Scalar/InstructionCombining.cpp	Mon Apr  2 00:36:22 2007
@@ -4005,7 +4005,7 @@
           return BinaryOperator::createOr(Op0NotVal, NotY);
         }
       }
-
+          
       if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
         if (Op0I->getOpcode() == Instruction::Add) {
           // ~(X-c) --> (-c-1)-X
@@ -4015,6 +4015,12 @@
                            ConstantExpr::getSub(NegOp0CI,
                                              ConstantInt::get(I.getType(), 1)),
                                           Op0I->getOperand(0));
+          } else if (RHS->getValue().isMinSignedValue()) {
+            // (X + C) ^ signbit -> (X + C + signbit)
+            Constant *C = ConstantInt::get(RHS->getValue() + Op0CI->getValue());
+            return BinaryOperator::createAdd(Op0I->getOperand(0), C);
+                                             
+                                                              
           }
         } else if (Op0I->getOpcode() == Instruction::Or) {
           // (X|C1)^C2 -> X^(C1|C2) iff X&~C1 == 0