1 files changed, 22 insertions, 0 deletions
diff --git a/llvm/lib/CodeGen/TargetLoweringBase.cpp b/llvm/lib/CodeGen/TargetLoweringBase.cpp
index 9b23012f47e..cb95d47e598 100644
--- a/llvm/lib/CodeGen/TargetLoweringBase.cpp
+++ b/llvm/lib/CodeGen/TargetLoweringBase.cpp
@@ -1456,6 +1456,28 @@ unsigned TargetLoweringBase::getVectorTypeBreakdown(LLVMContext &Context, EVT VT
   return NumVectorRegs;
 }
 
+bool TargetLoweringBase::isSuitableForJumpTable(const SwitchInst *SI,
+                                                uint64_t NumCases,
+                                                uint64_t Range,
+                                                ProfileSummaryInfo *PSI,
+                                                BlockFrequencyInfo *BFI) const {
+  // FIXME: This function check the maximum table size and density, but the
+  // minimum size is not checked. It would be nice if the minimum size is
+  // also combined within this function. Currently, the minimum size check is
+  // performed in findJumpTable() in SelectionDAGBuiler and
+  // getEstimatedNumberOfCaseClusters() in BasicTTIImpl.
+  const bool OptForSize =
+      SI->getParent()->getParent()->hasOptSize() ||
+      llvm::shouldOptimizeForSize(SI->getParent(), PSI, BFI);
+  const unsigned MinDensity = getMinimumJumpTableDensity(OptForSize);
+  const unsigned MaxJumpTableSize = getMaximumJumpTableSize();
+
+  // Check whether the number of cases is small enough and
+  // the range is dense enough for a jump table.
+  return (OptForSize || Range <= MaxJumpTableSize) &&
+         (NumCases * 100 >= Range * MinDensity);
+}
+
 /// Get the EVTs and ArgFlags collections that represent the legalized return
 /// type of the given function.  This does not require a DAG or a return value,
 /// and is suitable for use before any DAGs for the function are constructed.