make privateDepth mapping option tunable

Introduce a tunable parameter for the privateDepth option introduced by
the previous commit.  Choose initial depth within the range [0, 6] since
we rarely have deeper loops.

Author: ftynse

tc/autotuner/autotuner-inl.h

@@ -372,6 +372,8 @@ void setupTuningParameters(
   configuration.gridParams.setRange(range, "g");
   configuration.unrollFactor =
       RangeParameter(powers2(FLAGS_tuner_max_unroll_size), "unroll");
+  configuration.privateDepth =
+      RangeParameter({0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10}, "pdepth");
 }
 } // namespace
 

tc/autotuner/parameters.cc

@@ -239,6 +239,7 @@ void TuningConfiguration::applyToParameters(
   unrollCopyShared.apply(f);
   useReadOnlyCache.apply(f);
   matchLibraryCalls.apply(f);
+  privateDepth.apply(f);
 }
 
 bool TuningConfiguration::isValid() const {
@@ -273,6 +274,7 @@ std::vector<ParameterView> TuningConfiguration::collectParameters() {
   params.emplace_back(unrollCopyShared);
   params.emplace_back(useReadOnlyCache);
   params.emplace_back(matchLibraryCalls);
+  params.emplace_back(privateDepth);
 
   return params;
 }
@@ -303,6 +305,7 @@ void TuningConfiguration::fromCudaMappingOptions(
   usePrivateMemory.selectValue(options.proto().use_private_memory());
   unrollCopyShared.selectValue(options.proto().unroll_copy_shared());
   useReadOnlyCache.selectValue(options.proto().use_readonly_cache());
+  privateDepth.selectFromValue(options.proto().private_depth());
 }
 
 void TuningConfiguration::fromCpuMappingOptions(
@@ -331,6 +334,7 @@ void TuningConfiguration::applyToCudaMappingOptions(
   options.usePrivateMemory(usePrivateMemory.value());
   options.unrollCopyShared(unrollCopyShared.value());
   options.useReadOnlyCache(useReadOnlyCache.value());
+  options.privateDepth(privateDepth.value());
 }
 
 void TuningConfiguration::applyToCpuMappingOptions(

tc/autotuner/parameters.h

@@ -190,6 +190,7 @@ class TuningConfiguration {
   BoolParameter unrollCopyShared;
   BoolParameter useReadOnlyCache;
   BoolParameter matchLibraryCalls;
+  RangeParameter privateDepth;
 
  private:
   std::vector<std::function<bool(const TuningConfiguration&)>> validators_;
@@ -227,6 +228,7 @@ class TuningParameterFixer {
   llvm::Optional<bool> unrollCopyShared;
   llvm::Optional<bool> useReadOnlyCache;
   llvm::Optional<bool> matchLibraryCalls;
+  llvm::Optional<uint32_t> privateDepth;
 
   friend class TuningConfiguration;
 };