[CodeGen] Refactor check of suitability for a jump table (NFC)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@363992 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/CodeGen/TargetLowering.h b/include/llvm/CodeGen/TargetLowering.h
index b22d2a0aa71d73e42861ceff551fbc93ae538f00..b8672509df5323fe8e23bd045e11ea8d89013d76 100644 (file)
--- a/include/llvm/CodeGen/TargetLowering.h
+++ b/include/llvm/CodeGen/TargetLowering.h
@@ -972,20 +972,20 @@ public:
 
   /// Return true if lowering to a jump table is suitable for a set of case
   /// clusters which may contain \p NumCases cases, \p Range range of values.
-  /// 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.
   virtual bool isSuitableForJumpTable(const SwitchInst *SI, uint64_t NumCases,
                                       uint64_t Range) 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();
     const unsigned MinDensity = getMinimumJumpTableDensity(OptForSize);
-    const unsigned MaxJumpTableSize =
-        OptForSize ? UINT_MAX : getMaximumJumpTableSize();
-
-    // Check whether a range of clusters is dense enough for a jump table.
-    if (Range <= MaxJumpTableSize &&
+    const unsigned MaxJumpTableSize = getMaximumJumpTableSize();
+    
+    // Check whether the number of cases is small enough and
+    // the range is dense enough for a jump table.
+    if ((OptForSize || Range <= MaxJumpTableSize) &&
         (NumCases * 100 >= Range * MinDensity)) {
       return true;
     }