[llvm-commits] CVS: llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp

[Nate Begeman]

Changes in directory llvm/lib/CodeGen/SelectionDAG:

SelectionDAGISel.cpp updated: 1.236 -> 1.237
---
Log message:

Make emission of jump tables a bit less conservative; they are now required
to be only 31.25% dense, rather than 75% dense.


---
Diffs of the changes:  (+4 -4)

 SelectionDAGISel.cpp |    8 ++++----
 1 files changed, 4 insertions(+), 4 deletions(-)


Index: llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
diff -u llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp:1.236 llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp:1.237
--- llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp:1.236	Sat May  6 04:10:37 2006
+++ llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp	Mon May  8 11:51:36 2006
@@ -880,9 +880,9 @@
   const BasicBlock *LLVMBB = CurMBB->getBasicBlock();
   Reloc::Model Relocs = TLI.getTargetMachine().getRelocationModel();
 
-  // If the switch has more than 5 blocks, and at least 75% dense, then emit a
-  // jump table rather than lowering the switch to a binary tree of conditional
-  // branches.
+  // If the switch has more than 5 blocks, and at least 31.25% dense, and the 
+  // target supports indirect branches, then emit a jump table rather than 
+  // lowering the switch to a binary tree of conditional branches.
   // FIXME: Make this work with PIC code
   if (TLI.isOperationLegal(ISD::BRIND, TLI.getPointerTy()) &&
       (Relocs == Reloc::Static || Relocs == Reloc::DynamicNoPIC) &&
@@ -891,7 +891,7 @@
     uint64_t Last  = cast<ConstantIntegral>(Cases.back().first)->getRawValue();
     double Density = (double)Cases.size() / (double)((Last - First) + 1ULL);
     
-    if (Density >= 0.75) {
+    if (Density >= 0.3125) {
       // Create a new basic block to hold the code for loading the address
       // of the jump table, and jumping to it.  Update successor information;
       // we will either branch to the default case for the switch, or the jump