[llvm] r363992 - [CodeGen] Refactor check of suitability for a jump table (NFC)

[Evandro Menezes via llvm-commits]

Author: evandro
Date: Thu Jun 20 15:03:54 2019
New Revision: 363992

URL: http://llvm.org/viewvc/llvm-project?rev=363992&view=rev
Log:
[CodeGen] Refactor check of suitability for a jump table (NFC)

Modified:
    llvm/trunk/include/llvm/CodeGen/TargetLowering.h

Modified: llvm/trunk/include/llvm/CodeGen/TargetLowering.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/CodeGen/TargetLowering.h?rev=363992&r1=363991&r2=363992&view=diff
==============================================================================
--- llvm/trunk/include/llvm/CodeGen/TargetLowering.h (original)
+++ llvm/trunk/include/llvm/CodeGen/TargetLowering.h Thu Jun 20 15:03:54 2019
@@ -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;
     }