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[PartialInliner] Inline vararg functions that forward varargs.

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Summary:
This patch extends the partial inliner to support inlining parts of
vararg functions, if the vararg handling is done in the outlined part.

It adds a `ForwardVarArgsTo` argument to InlineFunction. If it is
non-null, all varargs passed to the inlined function will be added to
all calls to `ForwardVarArgsTo`.

The partial inliner takes care to only pass `ForwardVarArgsTo` if the
varargs handing is done in the outlined function. It checks that vastart
is not part of the function to be inlined.

`test/Transforms/CodeExtractor/PartialInlineNoInline.ll` (already part
of the repo) checks we do not do partial inlining if vastart is used in
a basic block that will be inlined.

Reviewers: davide, davidxl, grosser

Reviewed By: davide, davidxl, grosser

Subscribers: gyiu, grosser, eraman, llvm-commits

Differential Revision: https://reviews.llvm.org/D39607

llvm-svn: 318028
This commit is contained in:
Florian Hahn
2017-11-13 10:35:52 +00:00
parent 070a7ff1ad
commit 0e9dec672d
6 changed files with 176 additions and 29 deletions
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57
llvm/lib/Transforms/Utils/CodeExtractor.cpp
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@@ -78,7 +78,8 @@ AggregateArgsOpt("aggregate-extracted-args", cl::Hidden,
cl::desc("Aggregate arguments to code-extracted functions"));
/// \brief Test whether a block is valid for extraction.
bool CodeExtractor::isBlockValidForExtraction(const BasicBlock &BB) {
bool CodeExtractor::isBlockValidForExtraction(const BasicBlock &BB,
bool AllowVarArgs) {
// Landing pads must be in the function where they were inserted for cleanup.
if (BB.isEHPad())
return false;
@@ -110,14 +111,19 @@ bool CodeExtractor::isBlockValidForExtraction(const BasicBlock &BB) {
}
}
// Don't hoist code containing allocas, invokes, or vastarts.
// Don't hoist code containing allocas or invokes. If explicitly requested,
// allow vastart.
for (BasicBlock::const_iterator I = BB.begin(), E = BB.end(); I != E; ++I) {
if (isa<AllocaInst>(I) || isa<InvokeInst>(I))
return false;
if (const CallInst *CI = dyn_cast<CallInst>(I))
if (const Function *F = CI->getCalledFunction())
if (F->getIntrinsicID() == Intrinsic::vastart)
return false;
if (F->getIntrinsicID() == Intrinsic::vastart) {
if (AllowVarArgs)
continue;
else
return false;
}
}
return true;
@@ -125,7 +131,8 @@ bool CodeExtractor::isBlockValidForExtraction(const BasicBlock &BB) {
/// \brief Build a set of blocks to extract if the input blocks are viable.
static SetVector<BasicBlock *>
buildExtractionBlockSet(ArrayRef<BasicBlock *> BBs, DominatorTree *DT) {
buildExtractionBlockSet(ArrayRef<BasicBlock *> BBs, DominatorTree *DT,
bool AllowVarArgs) {
assert(!BBs.empty() && "The set of blocks to extract must be non-empty");
SetVector<BasicBlock *> Result;
@@ -138,7 +145,7 @@ buildExtractionBlockSet(ArrayRef<BasicBlock *> BBs, DominatorTree *DT) {
if (!Result.insert(BB))
llvm_unreachable("Repeated basic blocks in extraction input");
if (!CodeExtractor::isBlockValidForExtraction(*BB)) {
if (!CodeExtractor::isBlockValidForExtraction(*BB, AllowVarArgs)) {
Result.clear();
return Result;
}
@@ -160,15 +167,17 @@ buildExtractionBlockSet(ArrayRef<BasicBlock *> BBs, DominatorTree *DT) {
CodeExtractor::CodeExtractor(ArrayRef<BasicBlock *> BBs, DominatorTree *DT,
bool AggregateArgs, BlockFrequencyInfo *BFI,
BranchProbabilityInfo *BPI)
BranchProbabilityInfo *BPI, bool AllowVarArgs)
: DT(DT), AggregateArgs(AggregateArgs || AggregateArgsOpt), BFI(BFI),
BPI(BPI), Blocks(buildExtractionBlockSet(BBs, DT)) {}
BPI(BPI), AllowVarArgs(AllowVarArgs),
Blocks(buildExtractionBlockSet(BBs, DT, AllowVarArgs)) {}
CodeExtractor::CodeExtractor(DominatorTree &DT, Loop &L, bool AggregateArgs,
BlockFrequencyInfo *BFI,
BranchProbabilityInfo *BPI)
: DT(&DT), AggregateArgs(AggregateArgs || AggregateArgsOpt), BFI(BFI),
BPI(BPI), Blocks(buildExtractionBlockSet(L.getBlocks(), &DT)) {}
BPI(BPI), Blocks(buildExtractionBlockSet(L.getBlocks(), &DT,
/* AllowVarArgs */ false)) {}
/// definedInRegion - Return true if the specified value is defined in the
/// extracted region.
@@ -594,7 +603,8 @@ Function *CodeExtractor::constructFunction(const ValueSet &inputs,
paramTy.push_back(PointerType::getUnqual(StructTy));
}
FunctionType *funcType =
FunctionType::get(RetTy, paramTy, false);
FunctionType::get(RetTy, paramTy,
AllowVarArgs && oldFunction->isVarArg());
// Create the new function
Function *newFunction = Function::Create(funcType,
@@ -957,12 +967,31 @@ Function *CodeExtractor::extractCodeRegion() {
if (!isEligible())
return nullptr;
ValueSet inputs, outputs, SinkingCands, HoistingCands;
BasicBlock *CommonExit = nullptr;
// Assumption: this is a single-entry code region, and the header is the first
// block in the region.
BasicBlock *header = *Blocks.begin();
Function *oldFunction = header->getParent();
// For functions with varargs, check that varargs handling is only done in the
// outlined function, i.e vastart and vaend are only used in outlined blocks.
if (AllowVarArgs && oldFunction->getFunctionType()->isVarArg()) {
auto containsVarArgIntrinsic = [](Instruction &I) {
if (const CallInst *CI = dyn_cast<CallInst>(&I))
if (const Function *F = CI->getCalledFunction())
return F->getIntrinsicID() == Intrinsic::vastart ||
F->getIntrinsicID() == Intrinsic::vaend;
return false;
};
for (auto &BB : *oldFunction) {
if (Blocks.count(&BB))
continue;
if (llvm::any_of(BB, containsVarArgIntrinsic))
return nullptr;
}
}
ValueSet inputs, outputs, SinkingCands, HoistingCands;
BasicBlock *CommonExit = nullptr;
// Calculate the entry frequency of the new function before we change the root
// block.
@@ -984,8 +1013,6 @@ Function *CodeExtractor::extractCodeRegion() {
// that the return is not in the region.
splitReturnBlocks();
Function *oldFunction = header->getParent();
// This takes place of the original loop
BasicBlock *codeReplacer = BasicBlock::Create(header->getContext(),
"codeRepl", oldFunction,