SelectionDAG: Handle out-of-bounds index in extract vector element
Summary: This patch correctly handles undef case of EXTRACT_VECTOR_ELT node where the element index is constant and not less than vector size.
Test Plan:
CodeGen for X86 test included.
Also one incorrect regression test fixed.
Reviewers: qcolombet, chandlerc, hfinkel
Reviewed By: hfinkel
Subscribers: hfinkel, llvm-commits
Differential Revision: http://reviews.llvm.org/D9250
llvm-svn: 236584
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 3b22e97..d9a8536 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -3408,6 +3408,10 @@
if (N1.getOpcode() == ISD::UNDEF)
return getUNDEF(VT);
+ // EXTRACT_VECTOR_ELT of out-of-bounds element is an UNDEF
+ if (N2C && N2C->getZExtValue() >= N1.getValueType().getVectorNumElements())
+ return getUNDEF(VT);
+
// EXTRACT_VECTOR_ELT of CONCAT_VECTORS is often formed while lowering is
// expanding copies of large vectors from registers.
if (N2C &&