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[flang] Restructured TBAA trees in AddAliasTags pass. #136725

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merged 2 commits into from
Apr 29, 2025
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[flang] Restructured TBAA trees in AddAliasTags pass. #136725

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75b83fb
[flang] Restructured TBAA trees in AddAliasTags pass.
vzakhari Apr 21, 2025
0699f18
Added common/equivalence test.
vzakhari Apr 23, 2025
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6 changes: 6 additions & 0 deletions flang/include/flang/Optimizer/Analysis/AliasAnalysis.h
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Original file line number Diff line number Diff line change
Expand Up @@ -155,6 +155,12 @@ struct AliasAnalysis {
/// Return true, if Target or Pointer attribute is set.
bool isTargetOrPointer() const;

/// Return true, if Target attribute is set.
bool isTarget() const;

/// Return true, if Pointer attribute is set.
bool isPointer() const;

bool isDummyArgument() const;
bool isData() const;
bool isBoxData() const;
Expand Down
35 changes: 34 additions & 1 deletion flang/include/flang/Optimizer/Analysis/TBAAForest.h
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Expand Up @@ -40,6 +40,12 @@ struct TBAATree {

mlir::LLVM::TBAATagAttr getTag(llvm::StringRef uniqueId) const;

/// Create a TBAA tag pointing to the root of this subtree,
/// i.e. all the children tags will alias with this tag.
mlir::LLVM::TBAATagAttr getTag() const;

mlir::LLVM::TBAATypeDescriptorAttr getRoot() const { return parent; }

private:
SubtreeState(mlir::MLIRContext *ctx, std::string name,
mlir::LLVM::TBAANodeAttr grandParent)
Expand All @@ -51,17 +57,44 @@ struct TBAATree {
const std::string parentId;
mlir::MLIRContext *const context;
mlir::LLVM::TBAATypeDescriptorAttr parent;
llvm::DenseMap<llvm::StringRef, mlir::LLVM::TBAATagAttr> tagDedup;
};

/// A subtree for POINTER/TARGET variables data.
/// Any POINTER variable must use a tag that points
/// to the root of this subtree.
/// A TARGET dummy argument must also point to this root.
SubtreeState targetDataTree;
/// A subtree for global variables data (e.g. user module variables).
SubtreeState globalDataTree;
/// A subtree for variables allocated via fir.alloca or fir.allocmem.
SubtreeState allocatedDataTree;
/// A subtree for subprogram's dummy arguments.
/// It only contains children for the dummy arguments
/// that are not POINTER/TARGET. They all do not conflict
/// with each other and with any other data access, except
/// with unknown data accesses (FIR alias analysis uses
/// SourceKind::Indirect for sources of such accesses).
SubtreeState dummyArgDataTree;
/// A subtree for global variables descriptors.
SubtreeState directDataTree;
mlir::LLVM::TBAATypeDescriptorAttr anyAccessDesc;
mlir::LLVM::TBAATypeDescriptorAttr boxMemberTypeDesc;
mlir::LLVM::TBAATypeDescriptorAttr anyDataTypeDesc;

// Structure of the created tree:
// Function root
// |
// "any access"
// |
// |- "descriptor member"
// |- "any data access"
// |
// |- "dummy arg data"
// |- "target data"
// |
// |- "allocated data"
// |- "direct data"
// |- "global data"
static TBAATree buildTree(mlir::StringAttr functionName);

private:
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8 changes: 8 additions & 0 deletions flang/lib/Optimizer/Analysis/AliasAnalysis.cpp
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Expand Up @@ -110,6 +110,14 @@ bool AliasAnalysis::Source::isTargetOrPointer() const {
attributes.test(Attribute::Target);
}

bool AliasAnalysis::Source::isTarget() const {
return attributes.test(Attribute::Target);
}

bool AliasAnalysis::Source::isPointer() const {
return attributes.test(Attribute::Pointer);
}

bool AliasAnalysis::Source::isDummyArgument() const {
if (auto v = origin.u.dyn_cast<mlir::Value>()) {
return fir::isDummyArgument(v);
Expand Down
17 changes: 11 additions & 6 deletions flang/lib/Optimizer/Analysis/TBAAForest.cpp
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Expand Up @@ -11,9 +11,6 @@

mlir::LLVM::TBAATagAttr
fir::TBAATree::SubtreeState::getTag(llvm::StringRef uniqueName) const {
// mlir::LLVM::TBAATagAttr &tag = tagDedup[uniqueName];
// if (tag)
// return tag;
std::string id = (parentId + "/" + uniqueName).str();
mlir::LLVM::TBAATypeDescriptorAttr type =
mlir::LLVM::TBAATypeDescriptorAttr::get(
Expand All @@ -22,6 +19,10 @@ fir::TBAATree::SubtreeState::getTag(llvm::StringRef uniqueName) const {
// return tag;
}

mlir::LLVM::TBAATagAttr fir::TBAATree::SubtreeState::getTag() const {
return mlir::LLVM::TBAATagAttr::get(parent, parent, 0);
}

fir::TBAATree fir::TBAATree::buildTree(mlir::StringAttr func) {
llvm::StringRef funcName = func.getValue();
std::string rootId = ("Flang function root " + funcName).str();
Expand Down Expand Up @@ -53,9 +54,13 @@ fir::TBAATree fir::TBAATree::buildTree(mlir::StringAttr func) {
fir::TBAATree::TBAATree(mlir::LLVM::TBAATypeDescriptorAttr anyAccess,
mlir::LLVM::TBAATypeDescriptorAttr dataRoot,
mlir::LLVM::TBAATypeDescriptorAttr boxMemberTypeDesc)
: globalDataTree(dataRoot.getContext(), "global data", dataRoot),
allocatedDataTree(dataRoot.getContext(), "allocated data", dataRoot),
: targetDataTree(dataRoot.getContext(), "target data", dataRoot),
globalDataTree(dataRoot.getContext(), "global data",
targetDataTree.getRoot()),
allocatedDataTree(dataRoot.getContext(), "allocated data",
targetDataTree.getRoot()),
dummyArgDataTree(dataRoot.getContext(), "dummy arg data", dataRoot),
directDataTree(dataRoot.getContext(), "direct data", dataRoot),
directDataTree(dataRoot.getContext(), "direct data",
targetDataTree.getRoot()),
anyAccessDesc(anyAccess), boxMemberTypeDesc(boxMemberTypeDesc),
anyDataTypeDesc(dataRoot) {}
51 changes: 35 additions & 16 deletions flang/lib/Optimizer/Transforms/AddAliasTags.cpp
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Expand Up @@ -198,12 +198,6 @@ void AddAliasTagsPass::runOnAliasInterface(fir::FirAliasTagOpInterface op,
LLVM_DEBUG(llvm::dbgs() << "Analysing " << op << "\n");

const fir::AliasAnalysis::Source &source = state.getSource(memref);
if (source.isTargetOrPointer()) {
LLVM_DEBUG(llvm::dbgs().indent(2) << "Skipping TARGET/POINTER\n");
// These will get an "any data access" tag in TBAABuilder (CodeGen): causing
// them to "MayAlias" with all non-box accesses
return;
}

// Process the scopes, if not processed yet.
state.processFunctionScopes(func);
Expand All @@ -228,37 +222,48 @@ void AddAliasTagsPass::runOnAliasInterface(fir::FirAliasTagOpInterface op,
LLVM_DEBUG(llvm::dbgs().indent(2)
<< "Found reference to dummy argument at " << *op << "\n");
std::string name = getFuncArgName(llvm::cast<mlir::Value>(source.origin.u));
if (!name.empty())
// If it is a TARGET or POINTER, then we do not care about the name,
// because the tag points to the root of the subtree currently.
if (source.isTargetOrPointer()) {
tag = state.getFuncTreeWithScope(func, scopeOp).targetDataTree.getTag();
} else if (!name.empty()) {
tag = state.getFuncTreeWithScope(func, scopeOp)
.dummyArgDataTree.getTag(name);
else
} else {
LLVM_DEBUG(llvm::dbgs().indent(2)
<< "WARN: couldn't find a name for dummy argument " << *op
<< "\n");
tag = state.getFuncTreeWithScope(func, scopeOp).dummyArgDataTree.getTag();
}

// TBAA for global variables
// TBAA for global variables without descriptors
} else if (enableGlobals &&
source.kind == fir::AliasAnalysis::SourceKind::Global &&
!source.isBoxData()) {
mlir::SymbolRefAttr glbl = llvm::cast<mlir::SymbolRefAttr>(source.origin.u);
const char *name = glbl.getRootReference().data();
LLVM_DEBUG(llvm::dbgs().indent(2) << "Found reference to global " << name
<< " at " << *op << "\n");
tag = state.getFuncTreeWithScope(func, scopeOp).globalDataTree.getTag(name);
if (source.isPointer())
tag = state.getFuncTreeWithScope(func, scopeOp).targetDataTree.getTag();
else
tag =
state.getFuncTreeWithScope(func, scopeOp).globalDataTree.getTag(name);

// TBAA for SourceKind::Direct
// TBAA for global variables with descriptors
} else if (enableDirect &&
source.kind == fir::AliasAnalysis::SourceKind::Global &&
source.isBoxData()) {
if (auto glbl = llvm::dyn_cast<mlir::SymbolRefAttr>(source.origin.u)) {
const char *name = glbl.getRootReference().data();
LLVM_DEBUG(llvm::dbgs().indent(2) << "Found reference to direct " << name
<< " at " << *op << "\n");
tag =
state.getFuncTreeWithScope(func, scopeOp).directDataTree.getTag(name);
if (source.isPointer())
tag = state.getFuncTreeWithScope(func, scopeOp).targetDataTree.getTag();
else
tag = state.getFuncTreeWithScope(func, scopeOp)
.directDataTree.getTag(name);
} else {
// SourceKind::Direct is likely to be extended to cases which are not a
// SymbolRefAttr in the future
LLVM_DEBUG(llvm::dbgs().indent(2) << "Can't get name for direct "
<< source << " at " << *op << "\n");
}
Expand All @@ -269,11 +274,23 @@ void AddAliasTagsPass::runOnAliasInterface(fir::FirAliasTagOpInterface op,
std::optional<llvm::StringRef> name;
mlir::Operation *sourceOp =
llvm::cast<mlir::Value>(source.origin.u).getDefiningOp();
bool unknownAllocOp = false;
if (auto alloc = mlir::dyn_cast_or_null<fir::AllocaOp>(sourceOp))
name = alloc.getUniqName();
else if (auto alloc = mlir::dyn_cast_or_null<fir::AllocMemOp>(sourceOp))
name = alloc.getUniqName();
if (name) {
else
unknownAllocOp = true;

if (unknownAllocOp) {
LLVM_DEBUG(llvm::dbgs().indent(2)
<< "WARN: unknown defining op for SourceKind::Allocate " << *op
<< "\n");
} else if (source.isPointer()) {
LLVM_DEBUG(llvm::dbgs().indent(2)
<< "Found reference to allocation at " << *op << "\n");
tag = state.getFuncTreeWithScope(func, scopeOp).targetDataTree.getTag();
} else if (name) {
LLVM_DEBUG(llvm::dbgs().indent(2) << "Found reference to allocation "
<< name << " at " << *op << "\n");
tag = state.getFuncTreeWithScope(func, scopeOp)
Expand All @@ -282,6 +299,8 @@ void AddAliasTagsPass::runOnAliasInterface(fir::FirAliasTagOpInterface op,
LLVM_DEBUG(llvm::dbgs().indent(2)
<< "WARN: couldn't find a name for allocation " << *op
<< "\n");
tag =
state.getFuncTreeWithScope(func, scopeOp).allocatedDataTree.getTag();
}
} else {
if (source.kind != fir::AliasAnalysis::SourceKind::Argument &&
Expand Down
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