Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

JIT: Disallow implicit byref args and return buffers from aliasing #104616

Merged
merged 1 commit into from
Jul 10, 2024
Merged

JIT: Disallow implicit byref args and return buffers from aliasing #104616

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
14 changes: 7 additions & 7 deletions src/coreclr/jit/gentree.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -17974,11 +17974,14 @@ GenTreeLclVarCommon* GenTree::IsImplicitByrefParameterValuePreMorph(Compiler* co
// compiler - compiler instance
// addr - [out] tree representing the address computation on top of the implicit byref.
// Will be the same as the return value if the whole implicit byref is used, for example.
// offset - [out] Offset that "addr" is adding on top of the returned local.
//
// Return Value:
// Node for the local, or nullptr.
//
GenTreeLclVar* GenTree::IsImplicitByrefParameterValuePostMorph(Compiler* compiler, GenTree** addr)
GenTreeLclVar* GenTree::IsImplicitByrefParameterValuePostMorph(Compiler* compiler,
GenTree** addr,
target_ssize_t* offset)
{
#if FEATURE_IMPLICIT_BYREFS && !defined(TARGET_LOONGARCH64) // TODO-LOONGARCH64-CQ: enable this.

Expand All @@ -17987,13 +17990,10 @@ GenTreeLclVar* GenTree::IsImplicitByrefParameterValuePostMorph(Compiler* compile
return nullptr;
}

*addr = AsIndir()->Addr();
GenTree* innerAddr = *addr;
*addr = AsIndir()->Addr();

while (innerAddr->OperIs(GT_ADD) && innerAddr->gtGetOp2()->IsCnsIntOrI())
{
innerAddr = innerAddr->gtGetOp1();
}
GenTree* innerAddr = *addr;
compiler->gtPeelOffsets(&innerAddr, offset);

if (innerAddr->OperIs(GT_LCL_VAR))
{
Expand Down
2 changes: 1 addition & 1 deletion src/coreclr/jit/gentree.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1972,7 +1972,7 @@ struct GenTree
unsigned* pSize = nullptr);

GenTreeLclVarCommon* IsImplicitByrefParameterValuePreMorph(Compiler* compiler);
GenTreeLclVar* IsImplicitByrefParameterValuePostMorph(Compiler* compiler, GenTree** addr);
GenTreeLclVar* IsImplicitByrefParameterValuePostMorph(Compiler* compiler, GenTree** addr, target_ssize_t* offset);

unsigned IsLclVarUpdateTree(GenTree** otherTree, genTreeOps* updateOper);

Expand Down
29 changes: 27 additions & 2 deletions src/coreclr/jit/morph.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -3157,13 +3157,15 @@ void Compiler::fgMakeOutgoingStructArgCopy(GenTreeCall* call, CallArg* arg)
if (opts.OptimizationEnabled() && arg->AbiInfo.PassedByRef)
{
GenTree* implicitByRefLclAddr;
target_ssize_t implicitByRefLclOffs;
GenTreeLclVarCommon* implicitByRefLcl =
argx->IsImplicitByrefParameterValuePostMorph(this, &implicitByRefLclAddr);
argx->IsImplicitByrefParameterValuePostMorph(this, &implicitByRefLclAddr, &implicitByRefLclOffs);

GenTreeLclVarCommon* lcl = implicitByRefLcl;
if ((lcl == nullptr) && argx->OperIsLocal())
{
lcl = argx->AsLclVarCommon();
lcl = argx->AsLclVarCommon();
implicitByRefLclOffs = lcl->GetLclOffs();
}

if (lcl != nullptr)
Expand Down Expand Up @@ -3191,6 +3193,28 @@ void Compiler::fgMakeOutgoingStructArgCopy(GenTreeCall* call, CallArg* arg)
!varDsc->lvPromoted && !varDsc->lvIsStructField && ((lcl->gtFlags & GTF_VAR_DEATH) != 0);
}

// Disallow the argument from potentially aliasing the return
// buffer.
if (omitCopy)
{
GenTreeLclVarCommon* retBuffer = gtCallGetDefinedRetBufLclAddr(call);
if ((retBuffer != nullptr) && (retBuffer->GetLclNum() == varNum))
{
unsigned retBufferSize = typGetObjLayout(call->gtRetClsHnd)->GetSize();
target_ssize_t retBufferStart = retBuffer->GetLclOffs();
target_ssize_t retBufferEnd = retBufferStart + static_cast<target_ssize_t>(retBufferSize);

unsigned argSize = arg->GetSignatureType() == TYP_STRUCT
? typGetObjLayout(arg->GetSignatureClassHandle())->GetSize()
: genTypeSize(arg->GetSignatureType());
target_ssize_t implByrefStart = implicitByRefLclOffs;
target_ssize_t implByrefEnd = implByrefStart + static_cast<target_ssize_t>(argSize);

bool disjoint = (retBufferEnd <= implByrefStart) || (implByrefEnd <= retBufferStart);
omitCopy = disjoint;
}
}

if (omitCopy)
{
if (implicitByRefLcl != nullptr)
Expand Down Expand Up @@ -3218,6 +3242,7 @@ void Compiler::fgMakeOutgoingStructArgCopy(GenTreeCall* call, CallArg* arg)
#endif

JITDUMP("making an outgoing copy for struct arg\n");
assert(!call->IsTailCall() || !arg->AbiInfo.PassedByRef);

CORINFO_CLASS_HANDLE copyBlkClass = arg->GetSignatureClassHandle();
unsigned tmp = 0;
Expand Down
Loading