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[CGData][MachineOutliner] Global Outlining #90074

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Sep 10, 2024
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6 changes: 6 additions & 0 deletions llvm/include/llvm/ADT/StableHashing.h
Original file line number Diff line number Diff line change
Expand Up @@ -53,6 +53,12 @@ inline stable_hash stable_hash_combine(stable_hash A, stable_hash B,
// Removes suffixes introduced by LLVM from the name to enhance stability and
// maintain closeness to the original name across different builds.
inline StringRef get_stable_name(StringRef Name) {
// Return the part after ".content." that represents contents.
auto [P0, S0] = Name.rsplit(".content.");
if (!S0.empty())
return S0;

// Ignore these suffixes.
auto [P1, S1] = Name.rsplit(".llvm.");
auto [P2, S2] = P1.rsplit(".__uniq.");
return P2;
Expand Down
40 changes: 38 additions & 2 deletions llvm/include/llvm/CodeGen/MachineOutliner.h
Original file line number Diff line number Diff line change
Expand Up @@ -18,6 +18,7 @@
#include "llvm/CodeGen/LiveRegUnits.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/MachineStableHash.h"
#include <initializer_list>

namespace llvm {
Expand Down Expand Up @@ -234,11 +235,11 @@ struct OutlinedFunction {
unsigned FrameConstructionID = 0;

/// Return the number of candidates for this \p OutlinedFunction.
unsigned getOccurrenceCount() const { return Candidates.size(); }
virtual unsigned getOccurrenceCount() const { return Candidates.size(); }

/// Return the number of bytes it would take to outline this
/// function.
unsigned getOutliningCost() const {
virtual unsigned getOutliningCost() const {
unsigned CallOverhead = 0;
for (const Candidate &C : Candidates)
CallOverhead += C.getCallOverhead();
Expand Down Expand Up @@ -272,7 +273,42 @@ struct OutlinedFunction {
}

OutlinedFunction() = delete;
virtual ~OutlinedFunction() = default;
};

/// The information necessary to create an outlined function that is matched
/// globally.
struct GlobalOutlinedFunction : public OutlinedFunction {
explicit GlobalOutlinedFunction(std::unique_ptr<OutlinedFunction> OF,
unsigned GlobalOccurrenceCount)
: OutlinedFunction(*OF), GlobalOccurrenceCount(GlobalOccurrenceCount) {}

unsigned GlobalOccurrenceCount;

/// Return the number of times that appear globally.
/// Global outlining candidate is uniquely created per each match, but this
/// might be erased out when it's overlapped with the previous outlining
/// instance.
unsigned getOccurrenceCount() const override {
assert(Candidates.size() <= 1);
return Candidates.empty() ? 0 : GlobalOccurrenceCount;
}

/// Return the outlining cost using the global occurrence count
/// with the same cost as the first (unique) candidate.
unsigned getOutliningCost() const override {
assert(Candidates.size() <= 1);
unsigned CallOverhead =
Candidates.empty()
? 0
: Candidates[0].getCallOverhead() * getOccurrenceCount();
return CallOverhead + SequenceSize + FrameOverhead;
}

GlobalOutlinedFunction() = delete;
~GlobalOutlinedFunction() = default;
};

} // namespace outliner
} // namespace llvm

Expand Down
26 changes: 25 additions & 1 deletion llvm/lib/CGData/CodeGenData.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,13 @@
using namespace llvm;
using namespace cgdata;

cl::opt<bool>
CodeGenDataGenerate("codegen-data-generate", cl::init(false), cl::Hidden,
cl::desc("Emit CodeGen Data into custom sections"));
cl::opt<std::string>
CodeGenDataUsePath("codegen-data-use-path", cl::init(""), cl::Hidden,
cl::desc("File path to where .cgdata file is read"));

static std::string getCGDataErrString(cgdata_error Err,
const std::string &ErrMsg = "") {
std::string Msg;
Expand Down Expand Up @@ -132,7 +139,24 @@ CodeGenData &CodeGenData::getInstance() {
std::call_once(CodeGenData::OnceFlag, []() {
Instance = std::unique_ptr<CodeGenData>(new CodeGenData());

// TODO: Initialize writer or reader mode for the client optimization.
if (CodeGenDataGenerate)
Instance->EmitCGData = true;
else if (!CodeGenDataUsePath.empty()) {
// Initialize the global CGData if the input file name is given.
// We do not error-out when failing to parse the input file.
// Instead, just emit an warning message and fall back as if no CGData
// were available.
auto FS = vfs::getRealFileSystem();
auto ReaderOrErr = CodeGenDataReader::create(CodeGenDataUsePath, *FS);
if (Error E = ReaderOrErr.takeError()) {
warn(std::move(E), CodeGenDataUsePath);
return;
}
// Publish each CGData based on the data type in the header.
auto Reader = ReaderOrErr->get();
if (Reader->hasOutlinedHashTree())
Instance->publishOutlinedHashTree(Reader->releaseOutlinedHashTree());
}
});
return *(Instance.get());
}
Expand Down
1 change: 1 addition & 0 deletions llvm/lib/CodeGen/CMakeLists.txt
Original file line number Diff line number Diff line change
Expand Up @@ -267,6 +267,7 @@ add_llvm_component_library(LLVMCodeGen
Analysis
BitReader
BitWriter
CGData
CodeGenTypes
Core
MC
Expand Down
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