Implement sub.ll:test17, -X/C -> X/-C

llvm-svn: 16863
2004-10-09 02:50:40 +00:00 · 2004-10-09 02:50:40 +00:00 · 4ad08352b4
parent cdc19d6a0e
commit 4ad08352b4
1 changed files with 5 additions and 0 deletions
--- a/llvm/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/Scalar/InstructionCombining.cpp
@ -946,6 +946,11 @@ Instruction *InstCombiner::visitDiv(BinaryOperator &I) {
          return new ShiftInst(Instruction::Shr, I.getOperand(0),
                               ConstantUInt::get(Type::UByteTy, C));

+    // -X/C -> X/-C
+    if (RHS->getType()->isSigned())
+      if (Value *LHSNeg = dyn_castNegVal(I.getOperand(0)))
+        return BinaryOperator::createDiv(LHSNeg, ConstantExpr::getNeg(RHS));
+
    if (isa<PHINode>(I.getOperand(0)) && !RHS->isNullValue())
      if (Instruction *NV = FoldOpIntoPhi(I))
        return NV;