//===----------------------------------------------------------------------===//
#include "llvm/Transforms/Scalar.h"
-#include "llvm/Transforms/Utils/UnifyFunctionExitNodes.h"
-#include "llvm/Constants.h"
-#include "llvm/Function.h"
-#include "llvm/Instructions.h"
-#include "llvm/LLVMContext.h"
-#include "llvm/Pass.h"
#include "llvm/ADT/STLExtras.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/LLVMContext.h"
+#include "llvm/Pass.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
+#include "llvm/Transforms/Utils/UnifyFunctionExitNodes.h"
#include <algorithm>
using namespace llvm;
+#define DEBUG_TYPE "lower-switch"
+
namespace {
/// LowerSwitch Pass - Replace all SwitchInst instructions with chained branch
/// instructions.
initializeLowerSwitchPass(*PassRegistry::getPassRegistry());
}
- virtual bool runOnFunction(Function &F);
-
- virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ bool runOnFunction(Function &F) override;
+
+ void getAnalysisUsage(AnalysisUsage &AU) const override {
// This is a cluster of orthogonal Transforms
AU.addPreserved<UnifyFunctionExitNodes>();
AU.addPreserved("mem2reg");
Constant* High;
BasicBlock* BB;
- CaseRange(Constant *low = 0, Constant *high = 0, BasicBlock *bb = 0) :
+ CaseRange(Constant *low = nullptr, Constant *high = nullptr,
+ BasicBlock *bb = nullptr) :
Low(low), High(high), BB(bb) { }
};
BasicBlock* OrigBlock, BasicBlock* Default);
unsigned Clusterify(CaseVector& Cases, SwitchInst *SI);
};
+
+ /// The comparison function for sorting the switch case values in the vector.
+ /// WARNING: Case ranges should be disjoint!
+ struct CaseCmp {
+ bool operator () (const LowerSwitch::CaseRange& C1,
+ const LowerSwitch::CaseRange& C2) {
+
+ const ConstantInt* CI1 = cast<const ConstantInt>(C1.Low);
+ const ConstantInt* CI2 = cast<const ConstantInt>(C2.High);
+ return CI1->getValue().slt(CI2->getValue());
+ }
+ };
}
char LowerSwitch::ID = 0;
Function::iterator FI = OrigBlock;
F->getBasicBlockList().insert(++FI, NewNode);
- ICmpInst* Comp = new ICmpInst(ICmpInst::ICMP_ULT,
+ ICmpInst* Comp = new ICmpInst(ICmpInst::ICMP_SLT,
Val, Pivot.Low, "Pivot");
NewNode->getInstList().push_back(Comp);
BranchInst::Create(LBranch, RBranch, Comp, NewNode);
F->getBasicBlockList().insert(++FI, NewLeaf);
// Emit comparison
- ICmpInst* Comp = NULL;
+ ICmpInst* Comp = nullptr;
if (Leaf.Low == Leaf.High) {
// Make the seteq instruction...
Comp = new ICmpInst(*NewLeaf, ICmpInst::ICMP_EQ, Val,
// Clusterify - Transform simple list of Cases into list of CaseRange's
unsigned LowerSwitch::Clusterify(CaseVector& Cases, SwitchInst *SI) {
-
- IntegersSubsetToBB TheClusterifier;
+ unsigned numCmps = 0;
// Start with "simple" cases
- for (SwitchInst::CaseIt i = SI->case_begin(), e = SI->case_end();
- i != e; ++i) {
- BasicBlock *SuccBB = i.getCaseSuccessor();
- IntegersSubset CaseRanges = i.getCaseValueEx();
- TheClusterifier.add(CaseRanges, SuccBB);
- }
+ for (SwitchInst::CaseIt i = SI->case_begin(), e = SI->case_end(); i != e; ++i)
+ Cases.push_back(CaseRange(i.getCaseValue(), i.getCaseValue(),
+ i.getCaseSuccessor()));
- TheClusterifier.optimize();
-
- size_t numCmps = 0;
- for (IntegersSubsetToBB::RangeIterator i = TheClusterifier.begin(),
- e = TheClusterifier.end(); i != e; ++i, ++numCmps) {
- const IntegersSubsetToBB::RangeTy &R = i->first;
- BasicBlock *S = i->second;
-
- // FIXME: Currently work with ConstantInt based numbers.
- // Changing it to APInt based is a pretty heavy for this commit.
- Cases.push_back(CaseRange(R.getLow().toConstantInt(),
- R.getHigh().toConstantInt(), S));
- if (R.isSingleNumber())
+ std::sort(Cases.begin(), Cases.end(), CaseCmp());
+
+ // Merge case into clusters
+ if (Cases.size()>=2)
+ for (CaseItr I = Cases.begin(), J = std::next(Cases.begin());
+ J != Cases.end();) {
+ int64_t nextValue = cast<ConstantInt>(J->Low)->getSExtValue();
+ int64_t currentValue = cast<ConstantInt>(I->High)->getSExtValue();
+ BasicBlock* nextBB = J->BB;
+ BasicBlock* currentBB = I->BB;
+
+ // If the two neighboring cases go to the same destination, merge them
+ // into a single case.
+ if ((nextValue-currentValue==1) && (currentBB == nextBB)) {
+ I->High = J->High;
+ J = Cases.erase(J);
+ } else {
+ I = J++;
+ }
+ }
+
+ for (CaseItr I=Cases.begin(), E=Cases.end(); I!=E; ++I, ++numCmps) {
+ if (I->Low != I->High)
// A range counts double, since it requires two compares.
++numCmps;
}
- return numCmps;
+ return numCmps;
}
// processSwitchInst - Replace the specified switch instruction with a sequence