#include "llvm/Target/TargetLowering.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/PromoteMemToReg.h"
-#include "llvm/Transforms/Utils/SSAUpdater.h"
using namespace llvm;
STATISTIC(NumLandingPadsSplit, "Number of landing pads split");
STATISTIC(NumExceptionValuesMoved, "Number of eh.exception calls moved");
STATISTIC(NumStackTempsIntroduced, "Number of stack temporaries introduced");
-static void PromoteAlloca(AllocaInst *AI);
-
namespace {
class DwarfEHPrepare : public FunctionPass {
const TargetMachine *TM;
// Dominator info is used when turning stack temporaries into registers.
DominatorTree *DT;
+ DominanceFrontier *DF;
// The function we are running on.
Function *F;
/// PromoteStoreInst - Perform Mem2Reg on a StoreInst.
bool PromoteStoreInst(StoreInst *SI) {
+ if (!SI || !DT || !DF) return false;
+
AllocaInst *AI = dyn_cast<AllocaInst>(SI->getOperand(1));
if (!AI || !isAllocaPromotable(AI)) return false;
- PromoteAlloca(AI);
+ // Turn the alloca into a register.
+ std::vector<AllocaInst*> Allocas(1, AI);
+ PromoteMemToReg(Allocas, *DT, *DF);
return true;
}
/// PromoteEHPtrStore - Promote the storing of an EH pointer into a
/// register. This should get rid of the store and subsequent loads.
bool PromoteEHPtrStore(IntrinsicInst *II) {
- if (!CompileFast) return false;
+ if (!DT || !DF) return false;
bool Changed = false;
StoreInst *SI;
if (SI) break;
}
- if (SI && !PromoteStoreInst(SI))
+ if (!PromoteStoreInst(SI))
break;
Changed = true;
virtual bool runOnFunction(Function &Fn);
+ // getAnalysisUsage - We need dominance frontiers for memory promotion.
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ if (!CompileFast)
+ AU.addRequired<DominatorTree>();
AU.addPreserved<DominatorTree>();
+ if (!CompileFast)
+ AU.addRequired<DominanceFrontier>();
+ AU.addPreserved<DominanceFrontier>();
}
const char *getPassName() const {
return new DwarfEHPrepare(tm, fast);
}
-/// PromoteAlloca - This promotes an alloca to registers when we know that it
-/// only has non-volatile loads and stores to it.
-static void PromoteAlloca(AllocaInst *AI) {
- assert(isAllocaPromotable(AI));
-
- // First step: bucket up uses of the pointers by the block they occur in.
- // This is important because we have to handle multiple defs/uses in a block
- // ourselves: SSAUpdater is purely for cross-block references.
- // FIXME: Want a TinyVector<Instruction*> since there is usually 0/1 element.
- DenseMap<BasicBlock*, std::vector<Instruction*> > UsesByBlock;
- for (Value::use_iterator UI = AI->use_begin(), E = AI->use_end();
- UI != E; ++UI) {
- Instruction *User = cast<Instruction>(*UI);
- UsesByBlock[User->getParent()].push_back(User);
- }
-
- SSAUpdater SSA;
-
- // It wants to know some value of the same type as what we'll be inserting.
- Value *SomeValue;
- if (isa<LoadInst>(*AI->use_begin()))
- SomeValue = *AI->use_begin();
- else
- SomeValue = cast<StoreInst>(*AI->use_begin())->getOperand(0);
- SSA.Initialize(SomeValue);
-
- // Okay, now we can iterate over all the blocks in the loop with uses,
- // processing them. Keep track of which loads are loading a live-in value.
- SmallVector<LoadInst*, 32> LiveInLoads;
-
- for (Value::use_iterator UI = AI->use_begin(), E = AI->use_end();
- UI != E; ++UI) {
- Instruction *User = cast<Instruction>(*UI);
- std::vector<Instruction*> &BlockUses = UsesByBlock[User->getParent()];
-
- // If this block has already been processed, ignore this repeat use.
- if (BlockUses.empty()) continue;
-
- // Okay, this is the first use in the block. If this block just has a
- // single user in it, we can rewrite it trivially.
- if (BlockUses.size() == 1) {
- // If it is a store, it is a trivial def of the value in the block.
- if (isa<StoreInst>(User)) {
- SSA.AddAvailableValue(User->getParent(),
- cast<StoreInst>(User)->getOperand(0));
- } else {
- // Otherwise it is a load, queue it to rewrite as a live-in load.
- LiveInLoads.push_back(cast<LoadInst>(User));
- }
- BlockUses.clear();
- continue;
- }
-
- // Otherwise, check to see if this block is all loads. If so, we can queue
- // them all as live in loads.
- bool HasStore = false;
- for (unsigned i = 0, e = BlockUses.size(); i != e; ++i) {
- if (isa<StoreInst>(BlockUses[i])) {
- HasStore = true;
- break;
- }
- }
-
- if (!HasStore) {
- for (unsigned i = 0, e = BlockUses.size(); i != e; ++i)
- LiveInLoads.push_back(cast<LoadInst>(BlockUses[i]));
- BlockUses.clear();
- continue;
- }
-
- // Otherwise, we have mixed loads and stores (or just a bunch of stores).
- // Since SSAUpdater is purely for cross-block values, we need to determine
- // the order of these instructions in the block. If the first use in the
- // block is a load, then it uses the live in value. The last store defines
- // the live out value. We handle this by doing a linear scan of the block.
- BasicBlock *BB = User->getParent();
- Value *StoredValue = 0;
- for (BasicBlock::iterator II = BB->begin(), E = BB->end(); II != E; ++II) {
- if (LoadInst *L = dyn_cast<LoadInst>(II)) {
- // If this is a load to an unrelated pointer, ignore it.
- if (L->getOperand(0) != AI) continue;
-
- // If we haven't seen a store yet, this is a live in use, otherwise
- // use the stored value.
- if (StoredValue)
- L->replaceAllUsesWith(StoredValue);
- else
- LiveInLoads.push_back(L);
- continue;
- }
-
- if (StoreInst *S = dyn_cast<StoreInst>(II)) {
- // If this is a store to an unrelated pointer, ignore it.
- if (S->getOperand(1) != AI) continue;
-
- // Remember that this is the active value in the block.
- StoredValue = S->getOperand(0);
- }
- }
-
- // The last stored value that happened is the live-out for the block.
- assert(StoredValue && "Already checked that there is a store in block");
- SSA.AddAvailableValue(BB, StoredValue);
- BlockUses.clear();
- }
-
- // Okay, now we rewrite all loads that use live-in values in the loop,
- // inserting PHI nodes as necessary.
- for (unsigned i = 0, e = LiveInLoads.size(); i != e; ++i) {
- LoadInst *ALoad = LiveInLoads[i];
- ALoad->replaceAllUsesWith(SSA.GetValueInMiddleOfBlock(ALoad->getParent()));
- }
-
- // Now that everything is rewritten, delete the old instructions from the body
- // of the loop. They should all be dead now.
- for (Value::use_iterator UI = AI->use_begin(), E = AI->use_end();
- UI != E; ++UI)
- cast<Instruction>(*UI)->eraseFromParent();
-}
-
-
-
/// HasCatchAllInSelector - Return true if the intrinsic instruction has a
/// catch-all.
bool DwarfEHPrepare::HasCatchAllInSelector(IntrinsicInst *II) {
// Add a fallthrough from NewBB to the original landing pad.
BranchInst::Create(LPad, NewBB);
- // Now update DominatorTree analysis information if it is around.
+ // Now update DominatorTree and DominanceFrontier analysis information.
if (DT)
DT->splitBlock(NewBB);
+ if (DF)
+ DF->splitBlock(NewBB);
// Remember the newly constructed landing pad. The original landing pad
// LPad is no longer a landing pad now that all unwind edges have been
/// PromoteStackTemporaries - Turn any stack temporaries we introduced into
/// registers if possible.
bool DwarfEHPrepare::PromoteStackTemporaries() {
- // Turn the exception temporary into registers and phi nodes if possible.
- if (ExceptionValueVar && isAllocaPromotable(ExceptionValueVar)) {
- PromoteAlloca(ExceptionValueVar);
+ if (ExceptionValueVar && DT && DF && isAllocaPromotable(ExceptionValueVar)) {
+ // Turn the exception temporary into registers and phi nodes if possible.
+ std::vector<AllocaInst*> Allocas(1, ExceptionValueVar);
+ PromoteMemToReg(Allocas, *DT, *DF);
return true;
}
return false;
// Initialize internal state.
DT = getAnalysisIfAvailable<DominatorTree>();
+ DF = getAnalysisIfAvailable<DominanceFrontier>();
ExceptionValueVar = 0;
F = &Fn;
// Initialize any stack temporaries we introduced.
Changed |= FinishStackTemporaries();
- // Turn any stack temporaries into registers.
+ // Turn any stack temporaries into registers if possible.
if (!CompileFast)
Changed |= PromoteStackTemporaries();
projects / oota-llvm.git / commitdiff