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

[Chris Lattner]

Changes in directory llvm/lib/Transforms/Scalar:

InstructionCombining.cpp updated: 1.384 -> 1.385
---
Log message:

Make MaskedValueIsZero a bit more aggressive


---
Diffs of the changes:  (+9 -3)

 InstructionCombining.cpp |   12 +++++++++---
 1 files changed, 9 insertions(+), 3 deletions(-)


Index: llvm/lib/Transforms/Scalar/InstructionCombining.cpp
diff -u llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.384 llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.385
--- llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.384	Sun Oct  9 01:36:35 2005
+++ llvm/lib/Transforms/Scalar/InstructionCombining.cpp	Sun Oct  9 17:08:50 2005
@@ -404,11 +404,17 @@
     switch (I->getOpcode()) {
     case Instruction::And:
       // (X & C1) & C2 == 0   iff   C1 & C2 == 0.
-      if (ConstantIntegral *CI = dyn_cast<ConstantIntegral>(I->getOperand(1)))
-        if (ConstantExpr::getAnd(CI, Mask)->isNullValue())
+      if (ConstantIntegral *CI = dyn_cast<ConstantIntegral>(I->getOperand(1))) {
+        ConstantIntegral *C1C2 = 
+          cast<ConstantIntegral>(ConstantExpr::getAnd(CI, Mask));
+        if (MaskedValueIsZero(I->getOperand(0), C1C2))
           return true;
-      break;
+      }
+      // If either the LHS or the RHS are MaskedValueIsZero, the result is zero.
+      return MaskedValueIsZero(I->getOperand(1), Mask) ||
+             MaskedValueIsZero(I->getOperand(0), Mask);
     case Instruction::Or:
+    case Instruction::Xor:
       // If the LHS and the RHS are MaskedValueIsZero, the result is also zero.
       return MaskedValueIsZero(I->getOperand(1), Mask) &&
              MaskedValueIsZero(I->getOperand(0), Mask);