mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-08-23 17:29:19 +00:00
must be called in the pass's constructor. This function uses static dependency declarations to recursively initialize the pass's dependencies. Clients that only create passes through the createFooPass() APIs will require no changes. Clients that want to use the CommandLine options for passes will need to manually call the appropriate initialization functions in PassInitialization.h before parsing commandline arguments. I have tested this with all standard configurations of clang and llvm-gcc on Darwin. It is possible that there are problems with the static dependencies that will only be visible with non-standard options. If you encounter any crash in pass registration/creation, please send the testcase to me directly. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@116820 91177308-0d34-0410-b5e6-96231b3b80d8
191 lines
6.2 KiB
C++
191 lines
6.2 KiB
C++
//===-- OptimizePHIs.cpp - Optimize machine instruction PHIs --------------===//
|
|
//
|
|
// The LLVM Compiler Infrastructure
|
|
//
|
|
// This file is distributed under the University of Illinois Open Source
|
|
// License. See LICENSE.TXT for details.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// This pass optimizes machine instruction PHIs to take advantage of
|
|
// opportunities created during DAG legalization.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#define DEBUG_TYPE "phi-opt"
|
|
#include "llvm/CodeGen/Passes.h"
|
|
#include "llvm/CodeGen/MachineFunctionPass.h"
|
|
#include "llvm/CodeGen/MachineInstr.h"
|
|
#include "llvm/CodeGen/MachineRegisterInfo.h"
|
|
#include "llvm/Target/TargetInstrInfo.h"
|
|
#include "llvm/Function.h"
|
|
#include "llvm/ADT/SmallPtrSet.h"
|
|
#include "llvm/ADT/Statistic.h"
|
|
using namespace llvm;
|
|
|
|
STATISTIC(NumPHICycles, "Number of PHI cycles replaced");
|
|
STATISTIC(NumDeadPHICycles, "Number of dead PHI cycles");
|
|
|
|
namespace {
|
|
class OptimizePHIs : public MachineFunctionPass {
|
|
MachineRegisterInfo *MRI;
|
|
const TargetInstrInfo *TII;
|
|
|
|
public:
|
|
static char ID; // Pass identification
|
|
OptimizePHIs() : MachineFunctionPass(ID) {
|
|
initializeOptimizePHIsPass(*PassRegistry::getPassRegistry());
|
|
}
|
|
|
|
virtual bool runOnMachineFunction(MachineFunction &MF);
|
|
|
|
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
|
|
AU.setPreservesCFG();
|
|
MachineFunctionPass::getAnalysisUsage(AU);
|
|
}
|
|
|
|
private:
|
|
typedef SmallPtrSet<MachineInstr*, 16> InstrSet;
|
|
typedef SmallPtrSetIterator<MachineInstr*> InstrSetIterator;
|
|
|
|
bool IsSingleValuePHICycle(MachineInstr *MI, unsigned &SingleValReg,
|
|
InstrSet &PHIsInCycle);
|
|
bool IsDeadPHICycle(MachineInstr *MI, InstrSet &PHIsInCycle);
|
|
bool OptimizeBB(MachineBasicBlock &MBB);
|
|
};
|
|
}
|
|
|
|
char OptimizePHIs::ID = 0;
|
|
INITIALIZE_PASS(OptimizePHIs, "opt-phis",
|
|
"Optimize machine instruction PHIs", false, false)
|
|
|
|
FunctionPass *llvm::createOptimizePHIsPass() { return new OptimizePHIs(); }
|
|
|
|
bool OptimizePHIs::runOnMachineFunction(MachineFunction &Fn) {
|
|
MRI = &Fn.getRegInfo();
|
|
TII = Fn.getTarget().getInstrInfo();
|
|
|
|
// Find dead PHI cycles and PHI cycles that can be replaced by a single
|
|
// value. InstCombine does these optimizations, but DAG legalization may
|
|
// introduce new opportunities, e.g., when i64 values are split up for
|
|
// 32-bit targets.
|
|
bool Changed = false;
|
|
for (MachineFunction::iterator I = Fn.begin(), E = Fn.end(); I != E; ++I)
|
|
Changed |= OptimizeBB(*I);
|
|
|
|
return Changed;
|
|
}
|
|
|
|
/// IsSingleValuePHICycle - Check if MI is a PHI where all the source operands
|
|
/// are copies of SingleValReg, possibly via copies through other PHIs. If
|
|
/// SingleValReg is zero on entry, it is set to the register with the single
|
|
/// non-copy value. PHIsInCycle is a set used to keep track of the PHIs that
|
|
/// have been scanned.
|
|
bool OptimizePHIs::IsSingleValuePHICycle(MachineInstr *MI,
|
|
unsigned &SingleValReg,
|
|
InstrSet &PHIsInCycle) {
|
|
assert(MI->isPHI() && "IsSingleValuePHICycle expects a PHI instruction");
|
|
unsigned DstReg = MI->getOperand(0).getReg();
|
|
|
|
// See if we already saw this register.
|
|
if (!PHIsInCycle.insert(MI))
|
|
return true;
|
|
|
|
// Don't scan crazily complex things.
|
|
if (PHIsInCycle.size() == 16)
|
|
return false;
|
|
|
|
// Scan the PHI operands.
|
|
for (unsigned i = 1; i != MI->getNumOperands(); i += 2) {
|
|
unsigned SrcReg = MI->getOperand(i).getReg();
|
|
if (SrcReg == DstReg)
|
|
continue;
|
|
MachineInstr *SrcMI = MRI->getVRegDef(SrcReg);
|
|
|
|
// Skip over register-to-register moves.
|
|
if (SrcMI && SrcMI->isCopy() &&
|
|
!SrcMI->getOperand(0).getSubReg() &&
|
|
!SrcMI->getOperand(1).getSubReg() &&
|
|
TargetRegisterInfo::isVirtualRegister(SrcMI->getOperand(1).getReg()))
|
|
SrcMI = MRI->getVRegDef(SrcMI->getOperand(1).getReg());
|
|
if (!SrcMI)
|
|
return false;
|
|
|
|
if (SrcMI->isPHI()) {
|
|
if (!IsSingleValuePHICycle(SrcMI, SingleValReg, PHIsInCycle))
|
|
return false;
|
|
} else {
|
|
// Fail if there is more than one non-phi/non-move register.
|
|
if (SingleValReg != 0)
|
|
return false;
|
|
SingleValReg = SrcReg;
|
|
}
|
|
}
|
|
return true;
|
|
}
|
|
|
|
/// IsDeadPHICycle - Check if the register defined by a PHI is only used by
|
|
/// other PHIs in a cycle.
|
|
bool OptimizePHIs::IsDeadPHICycle(MachineInstr *MI, InstrSet &PHIsInCycle) {
|
|
assert(MI->isPHI() && "IsDeadPHICycle expects a PHI instruction");
|
|
unsigned DstReg = MI->getOperand(0).getReg();
|
|
assert(TargetRegisterInfo::isVirtualRegister(DstReg) &&
|
|
"PHI destination is not a virtual register");
|
|
|
|
// See if we already saw this register.
|
|
if (!PHIsInCycle.insert(MI))
|
|
return true;
|
|
|
|
// Don't scan crazily complex things.
|
|
if (PHIsInCycle.size() == 16)
|
|
return false;
|
|
|
|
for (MachineRegisterInfo::use_iterator I = MRI->use_begin(DstReg),
|
|
E = MRI->use_end(); I != E; ++I) {
|
|
MachineInstr *UseMI = &*I;
|
|
if (!UseMI->isPHI() || !IsDeadPHICycle(UseMI, PHIsInCycle))
|
|
return false;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
/// OptimizeBB - Remove dead PHI cycles and PHI cycles that can be replaced by
|
|
/// a single value.
|
|
bool OptimizePHIs::OptimizeBB(MachineBasicBlock &MBB) {
|
|
bool Changed = false;
|
|
for (MachineBasicBlock::iterator
|
|
MII = MBB.begin(), E = MBB.end(); MII != E; ) {
|
|
MachineInstr *MI = &*MII++;
|
|
if (!MI->isPHI())
|
|
break;
|
|
|
|
// Check for single-value PHI cycles.
|
|
unsigned SingleValReg = 0;
|
|
InstrSet PHIsInCycle;
|
|
if (IsSingleValuePHICycle(MI, SingleValReg, PHIsInCycle) &&
|
|
SingleValReg != 0) {
|
|
MRI->replaceRegWith(MI->getOperand(0).getReg(), SingleValReg);
|
|
MI->eraseFromParent();
|
|
++NumPHICycles;
|
|
Changed = true;
|
|
continue;
|
|
}
|
|
|
|
// Check for dead PHI cycles.
|
|
PHIsInCycle.clear();
|
|
if (IsDeadPHICycle(MI, PHIsInCycle)) {
|
|
for (InstrSetIterator PI = PHIsInCycle.begin(), PE = PHIsInCycle.end();
|
|
PI != PE; ++PI) {
|
|
MachineInstr *PhiMI = *PI;
|
|
if (&*MII == PhiMI)
|
|
++MII;
|
|
PhiMI->eraseFromParent();
|
|
}
|
|
++NumDeadPHICycles;
|
|
Changed = true;
|
|
}
|
|
}
|
|
return Changed;
|
|
}
|