isSplatMask() bug: first element can be an undef.
llvm-svn: 27847
diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index f1da4cf..15027c2 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -1753,17 +1753,29 @@
// This is a splat operation if each element of the permute is the same, and
// if the value doesn't reference the second vector.
- SDOperand Elt = N->getOperand(0);
- assert(isa<ConstantSDNode>(Elt) && "Invalid VECTOR_SHUFFLE mask!");
- for (unsigned i = 1, e = N->getNumOperands(); i != e; ++i) {
+ unsigned NumElems = N->getNumOperands();
+ SDOperand ElementBase;
+ unsigned i = 0;
+ for (; i != NumElems; ++i) {
+ SDOperand Elt = N->getOperand(i);
+ if (ConstantSDNode *EltV = dyn_cast<ConstantSDNode>(Elt)) {
+ ElementBase = Elt;
+ break;
+ }
+ }
+
+ if (!ElementBase.Val)
+ return false;
+
+ for (; i != NumElems; ++i) {
SDOperand Arg = N->getOperand(i);
if (Arg.getOpcode() == ISD::UNDEF) continue;
assert(isa<ConstantSDNode>(Arg) && "Invalid VECTOR_SHUFFLE mask!");
- if (Arg != Elt) return false;
+ if (Arg != ElementBase) return false;
}
// Make sure it is a splat of the first vector operand.
- return cast<ConstantSDNode>(Elt)->getValue() < N->getNumOperands();
+ return cast<ConstantSDNode>(ElementBase)->getValue() < NumElems;
}
/// isSplatMask - Return true if the specified VECTOR_SHUFFLE operand specifies
@@ -1771,7 +1783,7 @@
bool X86::isSplatMask(SDNode *N) {
assert(N->getOpcode() == ISD::BUILD_VECTOR);
- // We can only splat 64-bit, and 32-bit quantities.
+ // We can only splat 64-bit, and 32-bit quantities with a single instruction.
if (N->getNumOperands() != 4 && N->getNumOperands() != 2)
return false;
return ::isSplatMask(N);