llvm-capstone/llvm/lib/CodeGen/MachineCycleAnalysis.cpp
Sameer Sahasrabuddhe 1d0244aed7 Reapply CycleInfo: Introduce cycles as a generalization of loops
Reverts 02940d6d2202. Fixes breakage in the modules build.

LLVM loops cannot represent irreducible structures in the CFG. This
change introduce the concept of cycles as a generalization of loops,
along with a CycleInfo analysis that discovers a nested
hierarchy of such cycles. This is based on Havlak (1997), Nesting of
Reducible and Irreducible Loops.

The cycle analysis is implemented as a generic template and then
instatiated for LLVM IR and Machine IR. The template relies on a new
GenericSSAContext template which must be specialized when used for
each IR.

This review is a restart of an older review request:
https://reviews.llvm.org/D83094

Original implementation by Nicolai Hähnle <nicolai.haehnle@amd.com>,
with recent refactoring by Sameer Sahasrabuddhe <sameer.sahasrabuddhe@amd.com>

Differential Revision: https://reviews.llvm.org/D112696
2021-12-10 14:36:43 +05:30

114 lines
3.5 KiB
C++

//===- MachineCycleAnalysis.cpp - Compute CycleInfo for Machine IR --------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/MachineCycleAnalysis.h"
#include "llvm/ADT/GenericCycleImpl.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineSSAContext.h"
#include "llvm/InitializePasses.h"
using namespace llvm;
template class llvm::GenericCycleInfo<llvm::MachineSSAContext>;
template class llvm::GenericCycle<llvm::MachineSSAContext>;
namespace {
/// Legacy analysis pass which computes a \ref MachineCycleInfo.
class MachineCycleInfoWrapperPass : public MachineFunctionPass {
MachineFunction *F = nullptr;
MachineCycleInfo CI;
public:
static char ID;
MachineCycleInfoWrapperPass();
MachineCycleInfo &getCycleInfo() { return CI; }
const MachineCycleInfo &getCycleInfo() const { return CI; }
bool runOnMachineFunction(MachineFunction &F) override;
void getAnalysisUsage(AnalysisUsage &AU) const override;
void releaseMemory() override;
void print(raw_ostream &OS, const Module *M = nullptr) const override;
// TODO: verify analysis
};
class MachineCycleInfoPrinterPass : public MachineFunctionPass {
public:
static char ID;
MachineCycleInfoPrinterPass();
bool runOnMachineFunction(MachineFunction &F) override;
void getAnalysisUsage(AnalysisUsage &AU) const override;
};
} // namespace
char MachineCycleInfoWrapperPass::ID = 0;
MachineCycleInfoWrapperPass::MachineCycleInfoWrapperPass()
: MachineFunctionPass(ID) {
initializeMachineCycleInfoWrapperPassPass(*PassRegistry::getPassRegistry());
}
INITIALIZE_PASS_BEGIN(MachineCycleInfoWrapperPass, "machine-cycles",
"Machine Cycle Info Analysis", true, true)
INITIALIZE_PASS_END(MachineCycleInfoWrapperPass, "machine-cycles",
"Machine Cycle Info Analysis", true, true)
void MachineCycleInfoWrapperPass::getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesAll();
MachineFunctionPass::getAnalysisUsage(AU);
}
bool MachineCycleInfoWrapperPass::runOnMachineFunction(MachineFunction &Func) {
CI.clear();
F = &Func;
CI.compute(Func);
return false;
}
void MachineCycleInfoWrapperPass::print(raw_ostream &OS, const Module *) const {
OS << "MachineCycleInfo for function: " << F->getName() << "\n";
CI.print(OS);
}
void MachineCycleInfoWrapperPass::releaseMemory() {
CI.clear();
F = nullptr;
}
char MachineCycleInfoPrinterPass::ID = 0;
MachineCycleInfoPrinterPass::MachineCycleInfoPrinterPass()
: MachineFunctionPass(ID) {
initializeMachineCycleInfoPrinterPassPass(*PassRegistry::getPassRegistry());
}
INITIALIZE_PASS_BEGIN(MachineCycleInfoPrinterPass, "print-machine-cycles",
"Print Machine Cycle Info Analysis", true, true)
INITIALIZE_PASS_DEPENDENCY(MachineCycleInfoWrapperPass)
INITIALIZE_PASS_END(MachineCycleInfoPrinterPass, "print-machine-cycles",
"Print Machine Cycle Info Analysis", true, true)
void MachineCycleInfoPrinterPass::getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesAll();
AU.addRequired<MachineCycleInfoWrapperPass>();
MachineFunctionPass::getAnalysisUsage(AU);
}
bool MachineCycleInfoPrinterPass::runOnMachineFunction(MachineFunction &F) {
auto &CI = getAnalysis<MachineCycleInfoWrapperPass>();
CI.print(errs());
return false;
}