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[Utils] Extract CollectDebugInfoForCloning from CloneFunctionInto #114537

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14 changes: 14 additions & 0 deletions llvm/include/llvm/Transforms/Utils/Cloning.h
Original file line number Diff line number Diff line change
Expand Up @@ -207,6 +207,20 @@ void CloneAndPruneFunctionInto(Function *NewFunc, const Function *OldFunc,
const char *NameSuffix = "",
ClonedCodeInfo *CodeInfo = nullptr);

/// Collect debug information such as types, compile units, and other
/// subprograms that are reachable from \p F and can be considered global for
/// the purposes of cloning (and hence not needing to be cloned).
///
/// What debug information should be processed depends on \p Changes: when
/// cloning into the same module we process \p F's subprogram and instructions;
/// when into a cloned module, neither of those.
///
/// Returns DISubprogram of the cloned function when cloning into the same
/// module or nullptr otherwise.
DISubprogram *CollectDebugInfoForCloning(const Function &F,
CloneFunctionChangeType Changes,
DebugInfoFinder &DIFinder);

/// This class captures the data input to the InlineFunction call, and records
/// the auxiliary results produced by it.
class InlineFunctionInfo {
Expand Down
59 changes: 39 additions & 20 deletions llvm/lib/Transforms/Utils/CloneFunction.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,7 @@
#include "llvm/IR/DebugInfo.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/InstIterator.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/LLVMContext.h"
Expand Down Expand Up @@ -136,6 +137,26 @@ void llvm::CloneFunctionAttributesInto(Function *NewFunc,
OldAttrs.getRetAttrs(), NewArgAttrs));
}

DISubprogram *llvm::CollectDebugInfoForCloning(const Function &F,
CloneFunctionChangeType Changes,
DebugInfoFinder &DIFinder) {
DISubprogram *SPClonedWithinModule = nullptr;
if (Changes < CloneFunctionChangeType::DifferentModule) {
SPClonedWithinModule = F.getSubprogram();
}
if (SPClonedWithinModule)
DIFinder.processSubprogram(SPClonedWithinModule);

const Module *M = F.getParent();
if (Changes != CloneFunctionChangeType::ClonedModule && M) {
// Inspect instructions to process e.g. DILexicalBlocks of inlined functions
for (const auto &I : instructions(F))
DIFinder.processInstruction(*M, I);
}

return SPClonedWithinModule;
}

// Clone OldFunc into NewFunc, transforming the old arguments into references to
// VMap values.
void llvm::CloneFunctionInto(Function *NewFunc, const Function *OldFunc,
Expand Down Expand Up @@ -168,44 +189,42 @@ void llvm::CloneFunctionInto(Function *NewFunc, const Function *OldFunc,
// duplicate instructions and then freeze them in the MD map. We also record
// information about dbg.value and dbg.declare to avoid duplicating the
// types.
std::optional<DebugInfoFinder> DIFinder;
DebugInfoFinder DIFinder;

// Track the subprogram attachment that needs to be cloned to fine-tune the
// mapping within the same module.
DISubprogram *SPClonedWithinModule = nullptr;
if (Changes < CloneFunctionChangeType::DifferentModule) {
// Need to find subprograms, types, and compile units.

assert((NewFunc->getParent() == nullptr ||
NewFunc->getParent() == OldFunc->getParent()) &&
"Expected NewFunc to have the same parent, or no parent");

// Need to find subprograms, types, and compile units.
DIFinder.emplace();

SPClonedWithinModule = OldFunc->getSubprogram();
if (SPClonedWithinModule)
DIFinder->processSubprogram(SPClonedWithinModule);
} else {
// Need to find all the compile units.

assert((NewFunc->getParent() == nullptr ||
NewFunc->getParent() != OldFunc->getParent()) &&
"Expected NewFunc to have different parents, or no parent");

if (Changes == CloneFunctionChangeType::DifferentModule) {
assert(NewFunc->getParent() &&
"Need parent of new function to maintain debug info invariants");

// Need to find all the compile units.
DIFinder.emplace();
}
}

DISubprogram *SPClonedWithinModule =
CollectDebugInfoForCloning(*OldFunc, Changes, DIFinder);

// Loop over all of the basic blocks in the function, cloning them as
// appropriate. Note that we save BE this way in order to handle cloning of
// recursive functions into themselves.
for (const BasicBlock &BB : *OldFunc) {

// Create a new basic block and copy instructions into it!
BasicBlock *CBB = CloneBasicBlock(&BB, VMap, NameSuffix, NewFunc, CodeInfo,
DIFinder ? &*DIFinder : nullptr);
// NOTE: don't pass DIFinder because instructions' debug info was processed
// in ProcessSubprogramAttachment. This will be cleaned up further.
BasicBlock *CBB =
CloneBasicBlock(&BB, VMap, NameSuffix, NewFunc, CodeInfo, nullptr);

// Add basic block mapping.
VMap[&BB] = CBB;
Expand All @@ -228,7 +247,7 @@ void llvm::CloneFunctionInto(Function *NewFunc, const Function *OldFunc,
}

if (Changes < CloneFunctionChangeType::DifferentModule &&
DIFinder->subprogram_count() > 0) {
DIFinder.subprogram_count() > 0) {
// Turn on module-level changes, since we need to clone (some of) the
// debug info metadata.
//
Expand All @@ -243,24 +262,24 @@ void llvm::CloneFunctionInto(Function *NewFunc, const Function *OldFunc,

// Avoid cloning types, compile units, and (other) subprograms.
SmallPtrSet<const DISubprogram *, 16> MappedToSelfSPs;
for (DISubprogram *ISP : DIFinder->subprograms()) {
for (DISubprogram *ISP : DIFinder.subprograms()) {
if (ISP != SPClonedWithinModule) {
mapToSelfIfNew(ISP);
MappedToSelfSPs.insert(ISP);
}
}

// If a subprogram isn't going to be cloned skip its lexical blocks as well.
for (DIScope *S : DIFinder->scopes()) {
for (DIScope *S : DIFinder.scopes()) {
auto *LScope = dyn_cast<DILocalScope>(S);
if (LScope && MappedToSelfSPs.count(LScope->getSubprogram()))
mapToSelfIfNew(S);
}

for (DICompileUnit *CU : DIFinder->compile_units())
for (DICompileUnit *CU : DIFinder.compile_units())
mapToSelfIfNew(CU);

for (DIType *Type : DIFinder->types())
for (DIType *Type : DIFinder.types())
mapToSelfIfNew(Type);
} else {
assert(!SPClonedWithinModule &&
Expand Down Expand Up @@ -314,7 +333,7 @@ void llvm::CloneFunctionInto(Function *NewFunc, const Function *OldFunc,
SmallPtrSet<const void *, 8> Visited;
for (auto *Operand : NMD->operands())
Visited.insert(Operand);
for (auto *Unit : DIFinder->compile_units()) {
for (auto *Unit : DIFinder.compile_units()) {
MDNode *MappedUnit =
MapMetadata(Unit, VMap, RF_None, TypeMapper, Materializer);
if (Visited.insert(MappedUnit).second)
Expand Down
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