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//===- SSEDomainFix.cpp - Use proper int/float domain for SSE ---*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains the SSEDomainFix pass.
//
// Some SSE instructions like mov, and, or, xor are available in different
// variants for different operand types. These variant instructions are
// equivalent, but on Nehalem and newer cpus there is extra latency
// transferring data between integer and floating point domains.
//
// This pass changes the variant instructions to minimize domain crossings.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "sse-domain-fix"
#include "X86InstrInfo.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/ADT/DepthFirstIterator.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
namespace {
class SSEDomainFixPass : public MachineFunctionPass {
static char ID;
const X86InstrInfo *TII;
MachineFunction *MF;
MachineBasicBlock *MBB;
public:
SSEDomainFixPass() : MachineFunctionPass(&ID) {}
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesAll();
MachineFunctionPass::getAnalysisUsage(AU);
}
virtual bool runOnMachineFunction(MachineFunction &MF);
virtual const char *getPassName() const {
return "SSE execution domain fixup";
}
private:
void enterBasicBlock(MachineBasicBlock *MBB);
};
}
char SSEDomainFixPass::ID = 0;
void SSEDomainFixPass::enterBasicBlock(MachineBasicBlock *mbb) {
MBB = mbb;
DEBUG(dbgs() << "Entering MBB " << MBB->getName() << "\n");
}
bool SSEDomainFixPass::runOnMachineFunction(MachineFunction &mf) {
MF = &mf;
TII = static_cast<const X86InstrInfo*>(MF->getTarget().getInstrInfo());
// If no XMM registers are used in the function, we can skip it completely.
bool XMMIsUsed = false;
for (TargetRegisterClass::const_iterator I = X86::VR128RegClass.begin(),
E = X86::VR128RegClass.end(); I != E; ++I)
if (MF->getRegInfo().isPhysRegUsed(*I)) {
XMMIsUsed = true;
break;
}
if (!XMMIsUsed) return false;
MachineBasicBlock *Entry = MF->begin();
SmallPtrSet<MachineBasicBlock*, 16> Visited;
for (df_ext_iterator<MachineBasicBlock*,
SmallPtrSet<MachineBasicBlock*, 16> >
DFI = df_ext_begin(Entry, Visited), DFE = df_ext_end(Entry, Visited);
DFI != DFE; ++DFI) {
enterBasicBlock(*DFI);
for (MachineBasicBlock::iterator I = MBB->begin(), E = MBB->end(); I != E;
++I) {
MachineInstr *MI = I;
const unsigned *equiv = 0;
X86InstrInfo::SSEDomain domain = TII->GetSSEDomain(MI, equiv);
Jakob Stoklund Olesen
committed
DEBUG(dbgs() << "-isd"[domain] << (equiv ? "* " : " ") << *MI);
}
}
return false;
}
FunctionPass *llvm::createSSEDomainFixPass() {
return new SSEDomainFixPass();
}