Refactor the code that checks that all operands of a node are UNDEFs.
Add a micro-optimization to getNode of CONCAT_VECTORS when both operands are undefs.
Can't find a testcase for this because VECTOR_SHUFFLE already handles undef operands, but Duncan suggested that we add this.
Together with Michael Kuperstein <michael.m.kuperstein@intel.com>
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160229 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index a8dce21..3947648 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -219,6 +219,22 @@
return true;
}
+/// allOperandsUndef - Return true if the node has at least one operand
+/// and all operands of the specified node are ISD::UNDEF.
+bool ISD::allOperandsUndef(const SDNode *N) {
+ // Return false if the node has no operands.
+ // This is "logically inconsistent" with the definition of "all" but
+ // is probably the desired behavior.
+ if (N->getNumOperands() == 0)
+ return false;
+
+ for (unsigned i = 0, e = N->getNumOperands(); i != e ; ++i)
+ if (N->getOperand(i).getOpcode() != ISD::UNDEF)
+ return false;
+
+ return true;
+}
+
/// getSetCCSwappedOperands - Return the operation corresponding to (Y op X)
/// when given the operation for (X op Y).
ISD::CondCode ISD::getSetCCSwappedOperands(ISD::CondCode Operation) {
@@ -2674,6 +2690,11 @@
if (N1 == N2) return N1;
break;
case ISD::CONCAT_VECTORS:
+ // Concat of UNDEFs is UNDEF.
+ if (N1.getOpcode() == ISD::UNDEF &&
+ N2.getOpcode() == ISD::UNDEF)
+ return getUNDEF(VT);
+
// A CONCAT_VECTOR with all operands BUILD_VECTOR can be simplified to
// one big BUILD_VECTOR.
if (N1.getOpcode() == ISD::BUILD_VECTOR &&