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Make emission of jump tables a bit less conservative; they are now required

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to be only 31.25% dense, rather than 75% dense.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@28165 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nate Begeman 2006-05-08 16:51:36 +00:00
parent 403be7eafc
commit 17c275ff2c
1 changed files with 4 additions and 4 deletions
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8
lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
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@ -880,9 +880,9 @@ void SelectionDAGLowering::visitSwitch(SwitchInst &I) {
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 @@ void SelectionDAGLowering::visitSwitch(SwitchInst &I) {
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