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106 lines
3.3 KiB
C++
106 lines
3.3 KiB
C++
//===-- X86VZeroUpper.cpp - AVX vzeroupper instruction inserter -----------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file defines the pass which inserts x86 AVX vzeroupper instructions
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// before calls to SSE encoded functions. This avoids transition latency
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// penalty when tranfering control between AVX encoded instructions and old
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// SSE encoding mode.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "x86-codegen"
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#include "X86.h"
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#include "X86InstrInfo.h"
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#include "llvm/ADT/Statistic.h"
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#include "llvm/CodeGen/MachineFunctionPass.h"
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#include "llvm/CodeGen/MachineInstrBuilder.h"
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#include "llvm/CodeGen/Passes.h"
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#include "llvm/GlobalValue.h"
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#include "llvm/Target/TargetInstrInfo.h"
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using namespace llvm;
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STATISTIC(NumVZU, "Number of vzeroupper instructions inserted");
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namespace {
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struct VZeroUpperInserter : public MachineFunctionPass {
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static char ID;
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VZeroUpperInserter() : MachineFunctionPass(ID) {}
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virtual bool runOnMachineFunction(MachineFunction &MF);
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bool processBasicBlock(MachineFunction &MF, MachineBasicBlock &MBB);
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virtual const char *getPassName() const { return "X86 vzeroupper inserter";}
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private:
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const TargetInstrInfo *TII; // Machine instruction info.
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MachineBasicBlock *MBB; // Current basic block
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};
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char VZeroUpperInserter::ID = 0;
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}
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FunctionPass *llvm::createX86IssueVZeroUpperPass() {
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return new VZeroUpperInserter();
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}
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/// runOnMachineFunction - Loop over all of the basic blocks, inserting
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/// vzero upper instructions before function calls.
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bool VZeroUpperInserter::runOnMachineFunction(MachineFunction &MF) {
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TII = MF.getTarget().getInstrInfo();
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bool Changed = false;
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// Process any unreachable blocks in arbitrary order now.
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for (MachineFunction::iterator BB = MF.begin(), E = MF.end(); BB != E; ++BB)
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Changed |= processBasicBlock(MF, *BB);
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return Changed;
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}
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static bool isCallToModuleFn(const MachineInstr *MI) {
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assert(MI->getDesc().isCall() && "Isn't a call instruction");
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for (int i = 0, e = MI->getNumOperands(); i != e; ++i) {
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const MachineOperand &MO = MI->getOperand(i);
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if (!MO.isGlobal())
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continue;
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const GlobalValue *GV = MO.getGlobal();
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GlobalValue::LinkageTypes LT = GV->getLinkage();
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if (GV->isInternalLinkage(LT) || GV->isPrivateLinkage(LT) ||
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(GV->isExternalLinkage(LT) && !GV->isDeclaration()))
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return true;
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return false;
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}
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return false;
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}
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/// processBasicBlock - Loop over all of the instructions in the basic block,
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/// inserting vzero upper instructions before function calls.
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bool VZeroUpperInserter::processBasicBlock(MachineFunction &MF,
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MachineBasicBlock &BB) {
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bool Changed = false;
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MBB = &BB;
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for (MachineBasicBlock::iterator I = BB.begin(); I != BB.end(); ++I) {
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MachineInstr *MI = I;
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DebugLoc dl = I->getDebugLoc();
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// Insert a vzeroupper instruction before each control transfer
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// to functions outside this module
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if (MI->getDesc().isCall() && !isCallToModuleFn(MI)) {
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BuildMI(*MBB, I, dl, TII->get(X86::VZEROUPPER));
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++NumVZU;
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}
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}
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return Changed;
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}
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