Back out r160101 and instead implement a dag combine to recover from instcombine transformation.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160387 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 0e5ecd5..013e8be 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -2716,6 +2716,34 @@
}
}
+ if (N0.getOpcode() == ISD::ADD && N1.getOpcode() == ISD::SRL &&
+ VT.getSizeInBits() <= 64) {
+ if (ConstantSDNode *ADDI = dyn_cast<ConstantSDNode>(N0.getOperand(1))) {
+ APInt ADDC = ADDI->getAPIntValue();
+ if (!TLI.isLegalAddImmediate(ADDC.getSExtValue())) {
+ // Look for (and (add x, c1), (lshr y, c2)). If C1 wasn't a legal
+ // immediate for an add, but it is legal if its top c2 bits are set,
+ // transform the ADD so the immediate doesn't need to be materialized
+ // in a register.
+ if (ConstantSDNode *SRLI = dyn_cast<ConstantSDNode>(N1.getOperand(1))) {
+ APInt Mask = APInt::getHighBitsSet(VT.getSizeInBits(),
+ SRLI->getZExtValue());
+ if (DAG.MaskedValueIsZero(N0.getOperand(1), Mask)) {
+ ADDC |= Mask;
+ if (TLI.isLegalAddImmediate(ADDC.getSExtValue())) {
+ SDValue NewAdd =
+ DAG.getNode(ISD::ADD, N0.getDebugLoc(), VT,
+ N0.getOperand(0), DAG.getConstant(ADDC, VT));
+ CombineTo(N0.getNode(), NewAdd);
+ return SDValue(N, 0); // Return N so it doesn't get rechecked!
+ }
+ }
+ }
+ }
+ }
+ }
+
+
return SDValue();
}