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Fix a bug Joe found in DI: when exploding a copyaddr that is

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loading from our current allocation, we'd sometimes add loads
corresponding to the "assign" to the use list for this memory
object.

No testcase as this will be tested by Joe's forthcoming patch
to produce more copyaddrs from silgen.


Swift SVN r10559
This commit is contained in:
Chris Lattner
2013-11-19 19:52:05 +00:00
parent 3a1d504cff
commit 614ab66d6b
1 changed files with 22 additions and 5 deletions
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27
lib/SILPasses/DefiniteInitialization.cpp
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@@ -244,6 +244,19 @@ static unsigned getNumSubElements(SILType T, SILModule &M) {
return 1;
}
/// getAccessPathRoot - Given an address, dive through any tuple/struct element
/// addresses to get the underlying value.
static SILValue getAccessPathRoot(SILValue Pointer) {
while (1) {
if (auto *TEAI = dyn_cast<TupleElementAddrInst>(Pointer))
Pointer = TEAI->getOperand();
else if (auto SEAI = dyn_cast<StructElementAddrInst>(Pointer))
Pointer = SEAI->getOperand();
else
return Pointer;
}
}
/// Compute the access path indicated by the specified pointer (which is derived
/// from the root by a series of tuple/struct element addresses) and return
/// the first subelement addressed by the address. For example, given:
@@ -1367,8 +1380,9 @@ bool ElementPromotion::promoteLoad(SILInstruction *Inst) {
SILType LoadTy = Inst->getOperand(0).getType().getObjectType();
// If this is a load from a struct field that we want to promote, compute the
// access path down to the field so we can determine precise def/use behavior.
// If this is a load/copy_addr from a struct field that we want to promote,
// compute the access path down to the field so we can determine precise
// def/use behavior.
unsigned FirstElt = ComputeAccessPath(Inst->getOperand(0), TheMemory);
unsigned NumLoadSubElements =
getNumSubElements(LoadTy, TheMemory->getModule());
@@ -1503,7 +1517,6 @@ void ElementPromotion::explodeCopyAddr(CopyAddrInst *CAI) {
SmallVector<SILInstruction*, 4> NewInsts;
SILBuilder B(CAI, &NewInsts);
// Use type lowering to lower the copyaddr into a load sequence + store
// sequence appropriate for the type.
SILValue StoredValue = TL.emitLoadOfCopy(B, CAI->getLoc(), CAI->getSrc(),
@@ -1568,8 +1581,12 @@ void ElementPromotion::explodeCopyAddr(CopyAddrInst *CAI) {
case ValueKind::LoadInst:
// If it is a load from the memory object (as oppose to a load from
// something else), track it as an access.
if (LoadUse.isValid()) {
// something else), track it as an access. We need to explictly check to
// see if the load accesses "TheMemory" because it could either be a load
// for the copy_addr source, or it could be a load corresponding to the
// "assign" operation on the destination of the copyaddr.
if (LoadUse.isValid() &&
getAccessPathRoot(NewInst->getOperand(0)).getDef() == TheMemory) {
LoadUse.Inst = NewInst;
Uses.push_back(LoadUse);
}