1 //===- SSEDomainFix.cpp - Use proper int/float domain for SSE ---*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file contains the SSEDomainFix pass.
12 // Some SSE instructions like mov, and, or, xor are available in different
13 // variants for different operand types. These variant instructions are
14 // equivalent, but on Nehalem and newer cpus there is extra latency
15 // transferring data between integer and floating point domains.
17 // This pass changes the variant instructions to minimize domain crossings.
19 //===----------------------------------------------------------------------===//
21 #define DEBUG_TYPE "sse-domain-fix"
22 #include "X86InstrInfo.h"
23 #include "llvm/CodeGen/MachineFunctionPass.h"
24 #include "llvm/CodeGen/MachineRegisterInfo.h"
25 #include "llvm/ADT/DepthFirstIterator.h"
26 #include "llvm/Support/Debug.h"
27 #include "llvm/Support/raw_ostream.h"
32 class SSEDomainFixPass : public MachineFunctionPass {
34 const X86InstrInfo *TII;
37 MachineBasicBlock *MBB;
39 SSEDomainFixPass() : MachineFunctionPass(&ID) {}
41 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
43 MachineFunctionPass::getAnalysisUsage(AU);
46 virtual bool runOnMachineFunction(MachineFunction &MF);
48 virtual const char *getPassName() const {
49 return "SSE execution domain fixup";
53 void enterBasicBlock(MachineBasicBlock *MBB);
57 char SSEDomainFixPass::ID = 0;
59 void SSEDomainFixPass::enterBasicBlock(MachineBasicBlock *mbb) {
61 DEBUG(dbgs() << "Entering MBB " << MBB->getName() << "\n");
64 bool SSEDomainFixPass::runOnMachineFunction(MachineFunction &mf) {
66 TII = static_cast<const X86InstrInfo*>(MF->getTarget().getInstrInfo());
68 // If no XMM registers are used in the function, we can skip it completely.
69 bool XMMIsUsed = false;
70 for (TargetRegisterClass::const_iterator I = X86::VR128RegClass.begin(),
71 E = X86::VR128RegClass.end(); I != E; ++I)
72 if (MF->getRegInfo().isPhysRegUsed(*I)) {
76 if (!XMMIsUsed) return false;
78 MachineBasicBlock *Entry = MF->begin();
79 SmallPtrSet<MachineBasicBlock*, 16> Visited;
80 for (df_ext_iterator<MachineBasicBlock*,
81 SmallPtrSet<MachineBasicBlock*, 16> >
82 DFI = df_ext_begin(Entry, Visited), DFE = df_ext_end(Entry, Visited);
84 enterBasicBlock(*DFI);
85 for (MachineBasicBlock::iterator I = MBB->begin(), E = MBB->end(); I != E;
88 const unsigned *equiv = 0;
89 X86InstrInfo::SSEDomain domain = TII->GetSSEDomain(MI, equiv);
90 DEBUG(dbgs() << "-isd"[domain] << (equiv ? "* " : " ") << *MI);
96 FunctionPass *llvm::createSSEDomainFixPass() {
97 return new SSEDomainFixPass();