[llvm-commits] [llvm] r120471 - /llvm/trunk/lib/Transforms/Scalar/DeadStoreElimination.cpp
Chris Lattner
sabre at nondot.org
Tue Nov 30 13:58:15 PST 2010
Author: lattner
Date: Tue Nov 30 15:58:14 2010
New Revision: 120471
URL: http://llvm.org/viewvc/llvm-project?rev=120471&view=rev
Log:
Make DeleteDeadInstruction be a static function, move some code around.
Modified:
llvm/trunk/lib/Transforms/Scalar/DeadStoreElimination.cpp
Modified: llvm/trunk/lib/Transforms/Scalar/DeadStoreElimination.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/DeadStoreElimination.cpp?rev=120471&r1=120470&r2=120471&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/DeadStoreElimination.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/DeadStoreElimination.cpp Tue Nov 30 15:58:14 2010
@@ -66,8 +66,6 @@
bool handleEndBlock(BasicBlock &BB);
void RemoveAccessedObjects(const AliasAnalysis::Location &LoadedLoc,
SmallPtrSet<Value*, 16> &DeadStackObjects);
- void DeleteDeadInstruction(Instruction *I,
- SmallPtrSet<Value*, 16> *deadPointers = 0);
// getAnalysisUsage - We require post dominance frontiers (aka Control
@@ -93,6 +91,53 @@
FunctionPass *llvm::createDeadStoreEliminationPass() { return new DSE(); }
+//===----------------------------------------------------------------------===//
+// Helper functions
+//===----------------------------------------------------------------------===//
+
+/// DeleteDeadInstruction - Delete this instruction. Before we do, go through
+/// and zero out all the operands of this instruction. If any of them become
+/// dead, delete them and the computation tree that feeds them.
+///
+/// If ValueSet is non-null, remove any deleted instructions from it as well.
+///
+static void DeleteDeadInstruction(Instruction *I,
+ MemoryDependenceAnalysis &MD,
+ SmallPtrSet<Value*, 16> *ValueSet = 0) {
+ SmallVector<Instruction*, 32> NowDeadInsts;
+
+ NowDeadInsts.push_back(I);
+ --NumFastOther;
+
+ // Before we touch this instruction, remove it from memdep!
+ do {
+ Instruction *DeadInst = NowDeadInsts.pop_back_val();
+ ++NumFastOther;
+
+ // This instruction is dead, zap it, in stages. Start by removing it from
+ // MemDep, which needs to know the operands and needs it to be in the
+ // function.
+ MD.removeInstruction(DeadInst);
+
+ for (unsigned op = 0, e = DeadInst->getNumOperands(); op != e; ++op) {
+ Value *Op = DeadInst->getOperand(op);
+ DeadInst->setOperand(op, 0);
+
+ // If this operand just became dead, add it to the NowDeadInsts list.
+ if (!Op->use_empty()) continue;
+
+ if (Instruction *OpI = dyn_cast<Instruction>(Op))
+ if (isInstructionTriviallyDead(OpI))
+ NowDeadInsts.push_back(OpI);
+ }
+
+ DeadInst->eraseFromParent();
+
+ if (ValueSet) ValueSet->erase(DeadInst);
+ } while (!NowDeadInsts.empty());
+}
+
+
/// hasMemoryWrite - Does this instruction write some memory? This only returns
/// true for things that we can analyze with other helpers below.
static bool hasMemoryWrite(Instruction *I) {
@@ -177,21 +222,18 @@
}
}
-/// getPointerOperand - Return the pointer that is being written to.
-static Value *getPointerOperand(Instruction *I) {
- assert(hasMemoryWrite(I));
+/// getStoredPointerOperand - Return the pointer that is being written to.
+static Value *getStoredPointerOperand(Instruction *I) {
if (StoreInst *SI = dyn_cast<StoreInst>(I))
return SI->getPointerOperand();
if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(I))
- return MI->getArgOperand(0);
+ return MI->getDest();
IntrinsicInst *II = cast<IntrinsicInst>(I);
switch (II->getIntrinsicID()) {
default: assert(false && "Unexpected intrinsic!");
case Intrinsic::init_trampoline:
return II->getArgOperand(0);
- case Intrinsic::lifetime_end:
- return II->getArgOperand(1);
}
}
@@ -243,6 +285,11 @@
return true;
}
+
+//===----------------------------------------------------------------------===//
+// DSE Pass
+//===----------------------------------------------------------------------===//
+
bool DSE::runOnBasicBlock(BasicBlock &BB) {
bool MadeChange = false;
@@ -280,7 +327,7 @@
// in case we need it.
WeakVH NextInst(BBI);
- DeleteDeadInstruction(SI);
+ DeleteDeadInstruction(SI, *MD);
if (NextInst == 0) // Next instruction deleted.
BBI = BB.begin();
@@ -318,7 +365,7 @@
// store to 'Loc' then we can remove it.
if (isRemovable(DepWrite) && isCompleteOverwrite(Loc, DepLoc, *AA)) {
// Delete the store and now-dead instructions that feed it.
- DeleteDeadInstruction(DepWrite);
+ DeleteDeadInstruction(DepWrite, *MD);
++NumFastStores;
MadeChange = true;
@@ -367,7 +414,8 @@
if (!hasMemoryWrite(Dependency) || !isRemovable(Dependency))
return false;
- Value *DepPointer = getPointerOperand(Dependency)->getUnderlyingObject();
+ Value *DepPointer =
+ getStoredPointerOperand(Dependency)->getUnderlyingObject();
// Check for aliasing.
if (AA->alias(F->getArgOperand(0), 1, DepPointer, 1) !=
@@ -375,7 +423,7 @@
return false;
// DCE instructions only used to calculate that store
- DeleteDeadInstruction(Dependency);
+ DeleteDeadInstruction(Dependency, *MD);
++NumFastStores;
// Inst's old Dependency is now deleted. Compute the next dependency,
@@ -422,14 +470,13 @@
// If we find a store, check to see if it points into a dead stack value.
if (hasMemoryWrite(BBI) && isRemovable(BBI)) {
// See through pointer-to-pointer bitcasts
- Value *Pointer = getPointerOperand(BBI)->getUnderlyingObject();
+ Value *Pointer = getStoredPointerOperand(BBI)->getUnderlyingObject();
- // Alloca'd pointers or byval arguments (which are functionally like
- // alloca's) are valid candidates for removal.
+ // Stores to stack values are valid candidates for removal.
if (DeadStackObjects.count(Pointer)) {
// DCE instructions only used to calculate that store.
Instruction *Dead = BBI++;
- DeleteDeadInstruction(Dead, &DeadStackObjects);
+ DeleteDeadInstruction(Dead, *MD, &DeadStackObjects);
++NumFastStores;
MadeChange = true;
continue;
@@ -439,7 +486,7 @@
// Remove any dead non-memory-mutating instructions.
if (isInstructionTriviallyDead(BBI)) {
Instruction *Inst = BBI++;
- DeleteDeadInstruction(Inst, &DeadStackObjects);
+ DeleteDeadInstruction(Inst, *MD, &DeadStackObjects);
++NumFastOther;
MadeChange = true;
continue;
@@ -553,45 +600,3 @@
DeadStackObjects.erase(*I);
}
-/// DeleteDeadInstruction - Delete this instruction. Before we do, go through
-/// and zero out all the operands of this instruction. If any of them become
-/// dead, delete them and the computation tree that feeds them.
-///
-/// If ValueSet is non-null, remove any deleted instructions from it as well.
-///
-void DSE::DeleteDeadInstruction(Instruction *I,
- SmallPtrSet<Value*, 16> *ValueSet) {
- SmallVector<Instruction*, 32> NowDeadInsts;
-
- NowDeadInsts.push_back(I);
- --NumFastOther;
-
- // Before we touch this instruction, remove it from memdep!
- do {
- Instruction *DeadInst = NowDeadInsts.pop_back_val();
-
- ++NumFastOther;
-
- // This instruction is dead, zap it, in stages. Start by removing it from
- // MemDep, which needs to know the operands and needs it to be in the
- // function.
- MD->removeInstruction(DeadInst);
-
- for (unsigned op = 0, e = DeadInst->getNumOperands(); op != e; ++op) {
- Value *Op = DeadInst->getOperand(op);
- DeadInst->setOperand(op, 0);
-
- // If this operand just became dead, add it to the NowDeadInsts list.
- if (!Op->use_empty()) continue;
-
- if (Instruction *OpI = dyn_cast<Instruction>(Op))
- if (isInstructionTriviallyDead(OpI))
- NowDeadInsts.push_back(OpI);
- }
-
- DeadInst->eraseFromParent();
-
- if (ValueSet) ValueSet->erase(DeadInst);
- } while (!NowDeadInsts.empty());
-}
-
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