From: Evandro Menezes <e.menezes@samsung.com>
Date: Thu, 20 Jun 2019 22:03:54 +0000 (+0000)
Subject: [CodeGen] Refactor check of suitability for a jump table (NFC)
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=9bd1044f0ca3a83dcf6c0d9e10a7b4c05cdba2eb;p=llvm

[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 b22d2a0aa71..b8672509df5 100644
--- 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;
     }