[GlobalISel] IRTranslator: Return the scalar for <1 x Ty> constant vectors

Summary:
<1 x Ty> is not a legal vector type in LLT, we shouldn’t build G_MERGE_VALUES
instruction for them.

Reviewers: qcolombet, aditya_nandakumar, dsanders, t.p.northover, ab, javed.absar

Reviewed By: qcolombet

Subscribers: dberris, rovka, kristof.beyls, llvm-commits

Differential Revision: https://reviews.llvm.org/D30948

llvm-svn: 297792

1 files changed, 6 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp b/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
index 15bf31cd6d6..3b926a34aaf 100644
--- a/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp
@@ -1068,6 +1068,9 @@ bool IRTranslator::translate(const Constant &C, unsigned Reg) {
   else if (auto CAZ = dyn_cast<ConstantAggregateZero>(&C)) {
     if (!CAZ->getType()->isVectorTy())
       return false;
+    // Return the scalar if it is a <1 x Ty> vector.
+    if (CAZ->getNumElements() == 1)
+      return translate(*CAZ->getElementValue(0u), Reg);
     std::vector<unsigned> Ops;
     for (unsigned i = 0; i < CAZ->getNumElements(); ++i) {
       Constant &Elt = *CAZ->getElementValue(i);
@@ -1075,6 +1078,9 @@ bool IRTranslator::translate(const Constant &C, unsigned Reg) {
     }
     EntryBuilder.buildMerge(Reg, Ops);
   } else if (auto CV = dyn_cast<ConstantDataVector>(&C)) {
+    // Return the scalar if it is a <1 x Ty> vector.
+    if (CV->getNumElements() == 1)
+      return translate(*CV->getElementAsConstant(0), Reg);
     std::vector<unsigned> Ops;
     for (unsigned i = 0; i < CV->getNumElements(); ++i) {
       Constant &Elt = *CV->getElementAsConstant(i);