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Implement SimplifyCFG/2003-08-17-FoldSwitch.ll:test5

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@8093 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2003-08-23 23:18:19 +00:00
parent 2231d5892b
commit 7d6c24cdbf
1 changed files with 13 additions and 0 deletions
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13
lib/Transforms/Utils/Local.cpp
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@ -80,6 +80,9 @@ bool ConstantFoldTerminator(BasicBlock *BB) {
// single branch instruction! // single branch instruction!
ConstantInt *CI = dyn_cast<ConstantInt>(SI->getCondition()); ConstantInt *CI = dyn_cast<ConstantInt>(SI->getCondition());
BasicBlock *TheOnlyDest = SI->getSuccessor(0); // The default dest BasicBlock *TheOnlyDest = SI->getSuccessor(0); // The default dest
BasicBlock *DefaultDest = TheOnlyDest;
assert(TheOnlyDest == SI->getDefaultDest() &&
"Default destination is not successor #0?");
// Figure out which case it goes to... // Figure out which case it goes to...
for (unsigned i = 1, e = SI->getNumSuccessors(); i != e; ++i) { for (unsigned i = 1, e = SI->getNumSuccessors(); i != e; ++i) {
@ -89,6 +92,16 @@ bool ConstantFoldTerminator(BasicBlock *BB) {
break; break;
} }
// Check to see if this branch is going to the same place as the default
// dest. If so, eliminate it as an explicit compare.
if (SI->getSuccessor(i) == DefaultDest) {
// Remove this entry...
DefaultDest->removePredecessor(SI->getParent());
SI->removeCase(i);
--i; --e; // Don't skip an entry...
continue;
}
// Otherwise, check to see if the switch only branches to one destination. // Otherwise, check to see if the switch only branches to one destination.
// We do this by reseting "TheOnlyDest" to null when we find two non-equal // We do this by reseting "TheOnlyDest" to null when we find two non-equal
// destinations. // destinations.