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When removing a store to an alloca that has only one

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use, check also for the case where it has two uses,
the other being a llvm.dbg.declare.  This is needed so
debug info doesn't affect codegen.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@65970 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dale Johannesen
2009-03-03 21:26:39 +00:00
parent 44e3dd1672
commit 4945c65784
3 changed files with 157 additions and 12 deletions
Download Patch File Download Diff File Expand all files Collapse all files

58
lib/Transforms/Scalar/InstructionCombining.cpp
View File

@@ -250,6 +250,8 @@ namespace {
Instruction *transformZExtICmp(ICmpInst *ICI, Instruction &CI,
bool DoXform = true);
bool WillNotOverflowSignedAdd(Value *LHS, Value *RHS);
DbgDeclareInst *hasOneUsePlusDeclare(Value *V);
public:
// InsertNewInstBefore - insert an instruction New before instruction Old
@@ -11403,6 +11405,23 @@ static bool equivalentAddressValues(Value *A, Value *B) {
return false;
}
// If this instruction has two uses, one of which is a llvm.dbg.declare,
// return the llvm.dbg.declare.
DbgDeclareInst *InstCombiner::hasOneUsePlusDeclare(Value *V) {
if (!V->hasNUses(2))
return 0;
for (Value::use_iterator UI = V->use_begin(), E = V->use_end();
UI != E; ++UI) {
if (DbgDeclareInst *DI = dyn_cast<DbgDeclareInst>(UI))
return DI;
if (isa<BitCastInst>(UI) && UI->hasOneUse()) {
if (DbgDeclareInst *DI = dyn_cast<DbgDeclareInst>(UI->use_begin()))
return DI;
}
}
return 0;
}
Instruction *InstCombiner::visitStoreInst(StoreInst &SI) {
Value *Val = SI.getOperand(0);
Value *Ptr = SI.getOperand(1);
@@ -11415,20 +11434,39 @@ Instruction *InstCombiner::visitStoreInst(StoreInst &SI) {
// If the RHS is an alloca with a single use, zapify the store, making the
// alloca dead.
if (Ptr->hasOneUse() && !SI.isVolatile()) {
if (isa<AllocaInst>(Ptr)) {
EraseInstFromFunction(SI);
++NumCombined;
return 0;
}
if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Ptr))
if (isa<AllocaInst>(GEP->getOperand(0)) &&
GEP->getOperand(0)->hasOneUse()) {
// If the RHS is an alloca with a two uses, the other one being a
// llvm.dbg.declare, zapify the store and the declare, making the
// alloca dead. We must do this to prevent declare's from affecting
// codegen.
if (!SI.isVolatile()) {
if (Ptr->hasOneUse()) {
if (isa<AllocaInst>(Ptr)) {
EraseInstFromFunction(SI);
++NumCombined;
return 0;
}
if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Ptr)) {
if (isa<AllocaInst>(GEP->getOperand(0))) {
if (GEP->getOperand(0)->hasOneUse()) {
EraseInstFromFunction(SI);
++NumCombined;
return 0;
}
if (DbgDeclareInst *DI = hasOneUsePlusDeclare(GEP->getOperand(0))) {
EraseInstFromFunction(*DI);
EraseInstFromFunction(SI);
++NumCombined;
return 0;
}
}
}
}
if (DbgDeclareInst *DI = hasOneUsePlusDeclare(Ptr)) {
EraseInstFromFunction(*DI);
EraseInstFromFunction(SI);
++NumCombined;
return 0;
}
}
// Attempt to improve the alignment.

3
lib/Transforms/Utils/BasicBlockUtils.cpp
View File

@@ -540,8 +540,7 @@ void llvm::CopyPrecedingStopPoint(Instruction *I,
if (I != I->getParent()->begin()) {
BasicBlock::iterator BBI = I; --BBI;
if (DbgStopPointInst *DSPI = dyn_cast<DbgStopPointInst>(BBI)) {
DbgStopPointInst *newDSPI =
reinterpret_cast<DbgStopPointInst*>(DSPI->clone());
CallInst *newDSPI = DSPI->clone();
newDSPI->insertBefore(InsertPos);
}
}