SimplifyCFG: Also transform switches that represent a range comparison but are not sorted into sub+icmp.
This transforms another 1000 switches in gcc.c.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@124826 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Utils/SimplifyCFG.cpp b/lib/Transforms/Utils/SimplifyCFG.cpp
index bf753dc..93d8143 100644
--- a/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -2241,14 +2241,25 @@
/// integer range comparison into a sub, an icmp and a branch.
static bool TurnSwitchRangeIntoICmp(SwitchInst *SI) {
assert(SI->getNumCases() > 2 && "Degenerate switch?");
- // We can do this transform if the switch consists of an ascending series
- // and all cases point to the same destination.
- for (unsigned I = 2, E = SI->getNumCases(); I != E; ++I)
- if (SI->getSuccessor(I-1) != SI->getSuccessor(I) ||
- SI->getCaseValue(I-1)->getValue()+1 != SI->getCaseValue(I)->getValue())
- return false;
- Constant *Offset = ConstantExpr::getNeg(SI->getCaseValue(1));
+ // Make sure all cases point to the same destination and gather the values.
+ SmallVector<ConstantInt *, 16> Cases;
+ Cases.push_back(SI->getCaseValue(1));
+ for (unsigned I = 2, E = SI->getNumCases(); I != E; ++I) {
+ if (SI->getSuccessor(I-1) != SI->getSuccessor(I))
+ return false;
+ Cases.push_back(SI->getCaseValue(I));
+ }
+ assert(Cases.size() == SI->getNumCases()-1 && "Not all cases gathered");
+
+ // Sort the case values, then check if they form a range we can transform.
+ array_pod_sort(Cases.begin(), Cases.end(), ConstantIntSortPredicate);
+ for (unsigned I = 1, E = Cases.size(); I != E; ++I) {
+ if (Cases[I-1]->getValue() != Cases[I]->getValue()+1)
+ return false;
+ }
+
+ Constant *Offset = ConstantExpr::getNeg(Cases.back());
Constant *NumCases = ConstantInt::get(Offset->getType(), SI->getNumCases()-1);
Value *Sub = BinaryOperator::CreateAdd(SI->getCondition(), Offset, "off", SI);