#include "llvm/Support/raw_ostream.h"
using namespace llvm;
-//===----------------------------------------------------------------------===//
-// Local analysis.
-//
-
-/// isSafeToLoadUnconditionally - Return true if we know that executing a load
-/// from this value cannot trap. If it is not obviously safe to load from the
-/// specified pointer, we do a quick local scan of the basic block containing
-/// ScanFrom, to determine if the address is already accessed.
-bool llvm::isSafeToLoadUnconditionally(Value *V, Instruction *ScanFrom) {
- // If it is an alloca it is always safe to load from.
- if (isa<AllocaInst>(V)) return true;
-
- // If it is a global variable it is mostly safe to load from.
- if (const GlobalValue *GV = dyn_cast<GlobalVariable>(V))
- // Don't try to evaluate aliases. External weak GV can be null.
- return !isa<GlobalAlias>(GV) && !GV->hasExternalWeakLinkage();
-
- // Otherwise, be a little bit agressive by scanning the local block where we
- // want to check to see if the pointer is already being loaded or stored
- // from/to. If so, the previous load or store would have already trapped,
- // so there is no harm doing an extra load (also, CSE will later eliminate
- // the load entirely).
- BasicBlock::iterator BBI = ScanFrom, E = ScanFrom->getParent()->begin();
-
- while (BBI != E) {
- --BBI;
-
- // If we see a free or a call which may write to memory (i.e. which might do
- // a free) the pointer could be marked invalid.
- if (isa<CallInst>(BBI) && BBI->mayWriteToMemory() &&
- !isa<DbgInfoIntrinsic>(BBI))
- return false;
-
- if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) {
- if (LI->getOperand(0) == V) return true;
- } else if (StoreInst *SI = dyn_cast<StoreInst>(BBI)) {
- if (SI->getOperand(1) == V) return true;
- }
- }
- return false;
-}
-
-
//===----------------------------------------------------------------------===//
// Local constant propagation.
//
if (!PHIs.insert(cast<PHINode>(JP))) {
// Break the cycle and delete the PHI and its operands.
JP->replaceAllUsesWith(UndefValue::get(JP->getType()));
- Changed |= RecursivelyDeleteTriviallyDeadInstructions(JP);
+ (void)RecursivelyDeleteTriviallyDeadInstructions(JP);
+ Changed = true;
break;
}
return Changed;
}
+/// SimplifyInstructionsInBlock - Scan the specified basic block and try to
+/// simplify any instructions in it and recursively delete dead instructions.
+///
+/// This returns true if it changed the code, note that it can delete
+/// instructions in other blocks as well in this block.
+bool llvm::SimplifyInstructionsInBlock(BasicBlock *BB, const TargetData *TD) {
+ bool MadeChange = false;
+ for (BasicBlock::iterator BI = BB->begin(), E = BB->end(); BI != E; ) {
+ Instruction *Inst = BI++;
+
+ if (Value *V = SimplifyInstruction(Inst, TD)) {
+ WeakVH BIHandle(BI);
+ ReplaceAndSimplifyAllUses(Inst, V, TD);
+ MadeChange = true;
+ if (BIHandle != BI)
+ BI = BB->begin();
+ continue;
+ }
+
+ MadeChange |= RecursivelyDeleteTriviallyDeadInstructions(Inst);
+ }
+ return MadeChange;
+}
+
//===----------------------------------------------------------------------===//
// Control Flow Graph Restructuring.
//
// value into all of its uses.
assert(PNV != PN && "hasConstantValue broken");
+ Value *OldPhiIt = PhiIt;
ReplaceAndSimplifyAllUses(PN, PNV, TD);
// If recursive simplification ended up deleting the next PHI node we would
// iterate to, then our iterator is invalid, restart scanning from the top
// of the block.
- if (PhiIt == 0) PhiIt = &BB->front();
+ if (PhiIt != OldPhiIt) PhiIt = &BB->front();
}
}
// Splice all the instructions from PredBB to DestBB.
PredBB->getTerminator()->eraseFromParent();
DestBB->getInstList().splice(DestBB->begin(), PredBB->getInstList());
+
+ // Zap anything that took the address of DestBB. Not doing this will give the
+ // address an invalid value.
+ if (DestBB->hasAddressTaken()) {
+ BlockAddress *BA = BlockAddress::get(DestBB);
+ Constant *Replacement =
+ ConstantInt::get(llvm::Type::getInt32Ty(BA->getContext()), 1);
+ BA->replaceAllUsesWith(ConstantExpr::getIntToPtr(Replacement,
+ BA->getType()));
+ BA->destroyConstant();
+ }
// Anything that branched to PredBB now branches to DestBB.
PredBB->replaceAllUsesWith(DestBB);
// Use that list to make another list of common predecessors of BB and Succ
BlockSet CommonPreds;
for (pred_iterator PI = pred_begin(Succ), PE = pred_end(Succ);
- PI != PE; ++PI)
- if (BBPreds.count(*PI))
- CommonPreds.insert(*PI);
+ PI != PE; ++PI) {
+ BasicBlock *P = *PI;
+ if (BBPreds.count(P))
+ CommonPreds.insert(P);
+ }
// Shortcut, if there are no common predecessors, merging is always safe
if (CommonPreds.empty())
return true;
}
-
-
-/// OnlyUsedByDbgIntrinsics - Return true if the instruction I is only used
-/// by DbgIntrinsics. If DbgInUses is specified then the vector is filled
-/// with the DbgInfoIntrinsic that use the instruction I.
-bool llvm::OnlyUsedByDbgInfoIntrinsics(Instruction *I,
- SmallVectorImpl<DbgInfoIntrinsic *> *DbgInUses) {
- if (DbgInUses)
- DbgInUses->clear();
-
- for (Value::use_iterator UI = I->use_begin(), UE = I->use_end(); UI != UE;
- ++UI) {
- if (DbgInfoIntrinsic *DI = dyn_cast<DbgInfoIntrinsic>(*UI)) {
- if (DbgInUses)
- DbgInUses->push_back(DI);
- } else {
- if (DbgInUses)
- DbgInUses->clear();
- return false;
- }
- }
- return true;
-}
-
/// EliminateDuplicatePHINodes - Check for and eliminate duplicate PHI
/// nodes in this block. This doesn't try to be clever about PHI nodes
/// which differ only in the order of the incoming values, but instcombine
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