#include "llvm/Target/TargetData.h"
#include "llvm/Support/GetElementPtrTypeIterator.h"
#include "llvm/Support/MathExtras.h"
-#include "llvm/ADT/SmallPtrSet.h"
using namespace llvm;
//===----------------------------------------------------------------------===//
void llvm::RecursivelyDeleteTriviallyDeadInstructions(Value *V,
SmallVectorImpl<Instruction*> *DeadInst) {
Instruction *I = dyn_cast<Instruction>(V);
- if (!I || !I->use_empty()) return;
+ if (!I || !I->use_empty() || !isInstructionTriviallyDead(I))
+ return;
- SmallPtrSet<Instruction*, 16> Insts;
- Insts.insert(I);
+ SmallVector<Instruction*, 16> DeadInsts;
+ DeadInsts.push_back(I);
- while (!Insts.empty()) {
- I = *Insts.begin();
- Insts.erase(I);
+ while (!DeadInsts.empty()) {
+ I = DeadInsts.back();
+ DeadInsts.pop_back();
- // Okay, if the instruction is dead, delete it.
- if (!isInstructionTriviallyDead(I))
- continue;
-
- for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
- if (Instruction *U = dyn_cast<Instruction>(I->getOperand(i)))
- Insts.insert(U);
- I->eraseFromParent();
-
+ // If the client wanted to know, tell it about deleted instructions.
if (DeadInst)
DeadInst->push_back(I);
+
+ // Null out all of the instruction's operands to see if any operand becomes
+ // dead as we go.
+ for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) {
+ Value *OpV = I->getOperand(i);
+ I->setOperand(i, 0);
+
+ if (!OpV->use_empty()) continue;
+
+ // If the operand is an instruction that became dead as we nulled out the
+ // operand, and if it is 'trivially' dead, delete it in a future loop
+ // iteration.
+ if (Instruction *OpI = dyn_cast<Instruction>(OpV))
+ if (isInstructionTriviallyDead(OpI))
+ DeadInsts.push_back(OpI);
+ }
+
+ I->eraseFromParent();
}
}