[NVPTX] declare no vector registers

Summary:
Without this patch, LoopVectorizer in certain cases (see loop-vectorize.ll)
produces code with complex control flow which hurts later optimizations. Since
NVPTX doesn't have vector registers in LLVM's sense
(NVPTXTTI::getRegisterBitWidth(true) == 32), we for now declare no vector
registers to effectively disable loop vectorization.

Reviewers: jholewinski

Subscribers: jingyue, llvm-commits, jholewinski

Differential Revision: http://reviews.llvm.org/D11089

llvm-svn: 241884

2 files changed, 8 insertions, 0 deletions

diff --git a/llvm/lib/Target/NVPTX/NVPTXTargetTransformInfo.cpp b/llvm/lib/Target/NVPTX/NVPTXTargetTransformInfo.cpp
index 241b145f719..232148d2f8a 100644
--- a/llvm/lib/Target/NVPTX/NVPTXTargetTransformInfo.cpp
+++ b/llvm/lib/Target/NVPTX/NVPTXTargetTransformInfo.cpp
@@ -117,3 +117,9 @@ unsigned NVPTXTTIImpl::getArithmeticInstrCost(
                                          Opd1PropInfo, Opd2PropInfo);
   }
 }
+
+unsigned NVPTXTTIImpl::getNumberOfRegisters(bool Vector) {
+  if (Vector)
+    return 0;
+  return BaseT::getNumberOfRegisters(Vector);
+}
diff --git a/llvm/lib/Target/NVPTX/NVPTXTargetTransformInfo.h b/llvm/lib/Target/NVPTX/NVPTXTargetTransformInfo.h
index c8a855ae8b0..18c9fa985ae 100644
--- a/llvm/lib/Target/NVPTX/NVPTXTargetTransformInfo.h
+++ b/llvm/lib/Target/NVPTX/NVPTXTargetTransformInfo.h
@@ -58,6 +58,8 @@ public:
       TTI::OperandValueKind Opd2Info = TTI::OK_AnyValue,
       TTI::OperandValueProperties Opd1PropInfo = TTI::OP_None,
       TTI::OperandValueProperties Opd2PropInfo = TTI::OP_None);
+
+  unsigned getNumberOfRegisters(bool Vector);
 };
 
 } // end namespace llvm