[llvm] r242049 - Enable partial and runtime loop unrolling for NVPTX.

[Mark Heffernan]

Author: meheff
Date: Mon Jul 13 13:33:21 2015
New Revision: 242049

URL: http://llvm.org/viewvc/llvm-project?rev=242049&view=rev
Log:
Enable partial and runtime loop unrolling for NVPTX.

Enable partial and runtime loop unrolling for NVPTX backend via
TTI::UnrollingPreferences with a small threshold. This partially unrolls
small loops which are often unrolled by the PTX to SASS compiler
and unrolling earlier can be beneficial.


Modified:
    llvm/trunk/lib/Target/NVPTX/NVPTXTargetTransformInfo.cpp
    llvm/trunk/lib/Target/NVPTX/NVPTXTargetTransformInfo.h

Modified: llvm/trunk/lib/Target/NVPTX/NVPTXTargetTransformInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/NVPTX/NVPTXTargetTransformInfo.cpp?rev=242049&r1=242048&r2=242049&view=diff
==============================================================================
--- llvm/trunk/lib/Target/NVPTX/NVPTXTargetTransformInfo.cpp (original)
+++ llvm/trunk/lib/Target/NVPTX/NVPTXTargetTransformInfo.cpp Mon Jul 13 13:33:21 2015
@@ -117,3 +117,15 @@ unsigned NVPTXTTIImpl::getArithmeticInst
                                          Opd1PropInfo, Opd2PropInfo);
   }
 }
+
+void NVPTXTTIImpl::getUnrollingPreferences(Loop *L,
+                                           TTI::UnrollingPreferences &UP) {
+  BaseT::getUnrollingPreferences(L, UP);
+
+  // Enable partial unrolling and runtime unrolling, but reduce the
+  // threshold.  This partially unrolls small loops which are often
+  // unrolled by the PTX to SASS compiler and unrolling earlier can be
+  // beneficial.
+  UP.Partial = UP.Runtime = true;
+  UP.PartialThreshold = UP.Threshold / 4;
+}

Modified: llvm/trunk/lib/Target/NVPTX/NVPTXTargetTransformInfo.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/NVPTX/NVPTXTargetTransformInfo.h?rev=242049&r1=242048&r2=242049&view=diff
==============================================================================
--- llvm/trunk/lib/Target/NVPTX/NVPTXTargetTransformInfo.h (original)
+++ llvm/trunk/lib/Target/NVPTX/NVPTXTargetTransformInfo.h Mon Jul 13 13:33:21 2015
@@ -58,6 +58,8 @@ public:
       TTI::OperandValueKind Opd2Info = TTI::OK_AnyValue,
       TTI::OperandValueProperties Opd1PropInfo = TTI::OP_None,
       TTI::OperandValueProperties Opd2PropInfo = TTI::OP_None);
+
+  void getUnrollingPreferences(Loop *L, TTI::UnrollingPreferences &UP);
 };
 
 } // end namespace llvm