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f88e4c8e91
Since `MachineInstr` is required to have a trivial destructor, it cannot remove itself from `LeakDetection`. Remove the calls. As it happens, this requirement is because `MachineFunction` allocates all `MachineInstr`s in a custom allocator; when the `MachineFunction` is destroyed they're dropped of the edge. There's no benefit to detecting leaks. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@224061 91177308-0d34-0410-b5e6-96231b3b80d8
1205 lines
42 KiB
C++
1205 lines
42 KiB
C++
//===-- llvm/CodeGen/MachineBasicBlock.cpp ----------------------*- C++ -*-===//
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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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// Collect the sequence of machine instructions for a basic block.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/CodeGen/MachineBasicBlock.h"
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#include "llvm/ADT/SmallPtrSet.h"
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#include "llvm/ADT/SmallString.h"
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#include "llvm/CodeGen/LiveIntervalAnalysis.h"
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#include "llvm/CodeGen/LiveVariables.h"
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#include "llvm/CodeGen/MachineDominators.h"
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#include "llvm/CodeGen/MachineFunction.h"
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#include "llvm/CodeGen/MachineInstrBuilder.h"
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#include "llvm/CodeGen/MachineLoopInfo.h"
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#include "llvm/CodeGen/MachineRegisterInfo.h"
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#include "llvm/CodeGen/SlotIndexes.h"
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#include "llvm/IR/BasicBlock.h"
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#include "llvm/IR/DataLayout.h"
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#include "llvm/IR/LeakDetector.h"
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#include "llvm/MC/MCAsmInfo.h"
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#include "llvm/MC/MCContext.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/raw_ostream.h"
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#include "llvm/Target/TargetInstrInfo.h"
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#include "llvm/Target/TargetMachine.h"
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#include "llvm/Target/TargetRegisterInfo.h"
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#include "llvm/Target/TargetSubtargetInfo.h"
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#include <algorithm>
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using namespace llvm;
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#define DEBUG_TYPE "codegen"
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MachineBasicBlock::MachineBasicBlock(MachineFunction &mf, const BasicBlock *bb)
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: BB(bb), Number(-1), xParent(&mf), Alignment(0), IsLandingPad(false),
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AddressTaken(false), CachedMCSymbol(nullptr) {
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Insts.Parent = this;
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}
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MachineBasicBlock::~MachineBasicBlock() {
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LeakDetector::removeGarbageObject(this);
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}
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/// getSymbol - Return the MCSymbol for this basic block.
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///
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MCSymbol *MachineBasicBlock::getSymbol() const {
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if (!CachedMCSymbol) {
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const MachineFunction *MF = getParent();
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MCContext &Ctx = MF->getContext();
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const char *Prefix = Ctx.getAsmInfo()->getPrivateLabelPrefix();
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CachedMCSymbol = Ctx.GetOrCreateSymbol(Twine(Prefix) + "BB" +
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Twine(MF->getFunctionNumber()) +
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"_" + Twine(getNumber()));
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}
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return CachedMCSymbol;
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}
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raw_ostream &llvm::operator<<(raw_ostream &OS, const MachineBasicBlock &MBB) {
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MBB.print(OS);
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return OS;
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}
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/// addNodeToList (MBB) - When an MBB is added to an MF, we need to update the
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/// parent pointer of the MBB, the MBB numbering, and any instructions in the
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/// MBB to be on the right operand list for registers.
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///
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/// MBBs start out as #-1. When a MBB is added to a MachineFunction, it
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/// gets the next available unique MBB number. If it is removed from a
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/// MachineFunction, it goes back to being #-1.
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void ilist_traits<MachineBasicBlock>::addNodeToList(MachineBasicBlock *N) {
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MachineFunction &MF = *N->getParent();
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N->Number = MF.addToMBBNumbering(N);
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// Make sure the instructions have their operands in the reginfo lists.
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MachineRegisterInfo &RegInfo = MF.getRegInfo();
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for (MachineBasicBlock::instr_iterator
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I = N->instr_begin(), E = N->instr_end(); I != E; ++I)
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I->AddRegOperandsToUseLists(RegInfo);
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LeakDetector::removeGarbageObject(N);
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}
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void ilist_traits<MachineBasicBlock>::removeNodeFromList(MachineBasicBlock *N) {
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N->getParent()->removeFromMBBNumbering(N->Number);
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N->Number = -1;
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LeakDetector::addGarbageObject(N);
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}
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/// addNodeToList (MI) - When we add an instruction to a basic block
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/// list, we update its parent pointer and add its operands from reg use/def
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/// lists if appropriate.
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void ilist_traits<MachineInstr>::addNodeToList(MachineInstr *N) {
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assert(!N->getParent() && "machine instruction already in a basic block");
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N->setParent(Parent);
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// Add the instruction's register operands to their corresponding
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// use/def lists.
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MachineFunction *MF = Parent->getParent();
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N->AddRegOperandsToUseLists(MF->getRegInfo());
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}
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/// removeNodeFromList (MI) - When we remove an instruction from a basic block
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/// list, we update its parent pointer and remove its operands from reg use/def
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/// lists if appropriate.
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void ilist_traits<MachineInstr>::removeNodeFromList(MachineInstr *N) {
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assert(N->getParent() && "machine instruction not in a basic block");
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// Remove from the use/def lists.
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if (MachineFunction *MF = N->getParent()->getParent())
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N->RemoveRegOperandsFromUseLists(MF->getRegInfo());
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N->setParent(nullptr);
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}
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/// transferNodesFromList (MI) - When moving a range of instructions from one
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/// MBB list to another, we need to update the parent pointers and the use/def
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/// lists.
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void ilist_traits<MachineInstr>::
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transferNodesFromList(ilist_traits<MachineInstr> &fromList,
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ilist_iterator<MachineInstr> first,
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ilist_iterator<MachineInstr> last) {
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assert(Parent->getParent() == fromList.Parent->getParent() &&
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"MachineInstr parent mismatch!");
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// Splice within the same MBB -> no change.
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if (Parent == fromList.Parent) return;
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// If splicing between two blocks within the same function, just update the
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// parent pointers.
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for (; first != last; ++first)
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first->setParent(Parent);
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}
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void ilist_traits<MachineInstr>::deleteNode(MachineInstr* MI) {
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assert(!MI->getParent() && "MI is still in a block!");
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Parent->getParent()->DeleteMachineInstr(MI);
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}
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MachineBasicBlock::iterator MachineBasicBlock::getFirstNonPHI() {
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instr_iterator I = instr_begin(), E = instr_end();
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while (I != E && I->isPHI())
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++I;
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assert((I == E || !I->isInsideBundle()) &&
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"First non-phi MI cannot be inside a bundle!");
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return I;
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}
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MachineBasicBlock::iterator
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MachineBasicBlock::SkipPHIsAndLabels(MachineBasicBlock::iterator I) {
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iterator E = end();
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while (I != E && (I->isPHI() || I->isPosition() || I->isDebugValue()))
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++I;
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// FIXME: This needs to change if we wish to bundle labels / dbg_values
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// inside the bundle.
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assert((I == E || !I->isInsideBundle()) &&
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"First non-phi / non-label instruction is inside a bundle!");
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return I;
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}
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MachineBasicBlock::iterator MachineBasicBlock::getFirstTerminator() {
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iterator B = begin(), E = end(), I = E;
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while (I != B && ((--I)->isTerminator() || I->isDebugValue()))
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; /*noop */
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while (I != E && !I->isTerminator())
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++I;
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return I;
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}
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MachineBasicBlock::const_iterator
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MachineBasicBlock::getFirstTerminator() const {
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const_iterator B = begin(), E = end(), I = E;
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while (I != B && ((--I)->isTerminator() || I->isDebugValue()))
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; /*noop */
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while (I != E && !I->isTerminator())
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++I;
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return I;
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}
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MachineBasicBlock::instr_iterator MachineBasicBlock::getFirstInstrTerminator() {
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instr_iterator B = instr_begin(), E = instr_end(), I = E;
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while (I != B && ((--I)->isTerminator() || I->isDebugValue()))
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; /*noop */
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while (I != E && !I->isTerminator())
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++I;
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return I;
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}
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MachineBasicBlock::iterator MachineBasicBlock::getLastNonDebugInstr() {
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// Skip over end-of-block dbg_value instructions.
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instr_iterator B = instr_begin(), I = instr_end();
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while (I != B) {
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--I;
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// Return instruction that starts a bundle.
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if (I->isDebugValue() || I->isInsideBundle())
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continue;
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return I;
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}
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// The block is all debug values.
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return end();
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}
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MachineBasicBlock::const_iterator
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MachineBasicBlock::getLastNonDebugInstr() const {
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// Skip over end-of-block dbg_value instructions.
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const_instr_iterator B = instr_begin(), I = instr_end();
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while (I != B) {
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--I;
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// Return instruction that starts a bundle.
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if (I->isDebugValue() || I->isInsideBundle())
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continue;
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return I;
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}
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// The block is all debug values.
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return end();
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}
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const MachineBasicBlock *MachineBasicBlock::getLandingPadSuccessor() const {
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// A block with a landing pad successor only has one other successor.
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if (succ_size() > 2)
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return nullptr;
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for (const_succ_iterator I = succ_begin(), E = succ_end(); I != E; ++I)
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if ((*I)->isLandingPad())
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return *I;
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return nullptr;
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}
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#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
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void MachineBasicBlock::dump() const {
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print(dbgs());
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}
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#endif
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StringRef MachineBasicBlock::getName() const {
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if (const BasicBlock *LBB = getBasicBlock())
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return LBB->getName();
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else
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return "(null)";
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}
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/// Return a hopefully unique identifier for this block.
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std::string MachineBasicBlock::getFullName() const {
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std::string Name;
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if (getParent())
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Name = (getParent()->getName() + ":").str();
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if (getBasicBlock())
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Name += getBasicBlock()->getName();
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else
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Name += (Twine("BB") + Twine(getNumber())).str();
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return Name;
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}
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void MachineBasicBlock::print(raw_ostream &OS, SlotIndexes *Indexes) const {
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const MachineFunction *MF = getParent();
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if (!MF) {
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OS << "Can't print out MachineBasicBlock because parent MachineFunction"
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<< " is null\n";
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return;
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}
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if (Indexes)
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OS << Indexes->getMBBStartIdx(this) << '\t';
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OS << "BB#" << getNumber() << ": ";
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const char *Comma = "";
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if (const BasicBlock *LBB = getBasicBlock()) {
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OS << Comma << "derived from LLVM BB ";
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LBB->printAsOperand(OS, /*PrintType=*/false);
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Comma = ", ";
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}
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if (isLandingPad()) { OS << Comma << "EH LANDING PAD"; Comma = ", "; }
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if (hasAddressTaken()) { OS << Comma << "ADDRESS TAKEN"; Comma = ", "; }
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if (Alignment)
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OS << Comma << "Align " << Alignment << " (" << (1u << Alignment)
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<< " bytes)";
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OS << '\n';
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const TargetRegisterInfo *TRI = MF->getSubtarget().getRegisterInfo();
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if (!livein_empty()) {
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if (Indexes) OS << '\t';
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OS << " Live Ins:";
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for (livein_iterator I = livein_begin(),E = livein_end(); I != E; ++I)
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OS << ' ' << PrintReg(*I, TRI);
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OS << '\n';
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}
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// Print the preds of this block according to the CFG.
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if (!pred_empty()) {
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if (Indexes) OS << '\t';
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OS << " Predecessors according to CFG:";
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for (const_pred_iterator PI = pred_begin(), E = pred_end(); PI != E; ++PI)
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OS << " BB#" << (*PI)->getNumber();
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OS << '\n';
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}
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for (const_instr_iterator I = instr_begin(); I != instr_end(); ++I) {
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if (Indexes) {
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if (Indexes->hasIndex(I))
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OS << Indexes->getInstructionIndex(I);
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OS << '\t';
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}
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OS << '\t';
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if (I->isInsideBundle())
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OS << " * ";
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I->print(OS, &getParent()->getTarget());
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}
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// Print the successors of this block according to the CFG.
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if (!succ_empty()) {
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if (Indexes) OS << '\t';
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OS << " Successors according to CFG:";
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for (const_succ_iterator SI = succ_begin(), E = succ_end(); SI != E; ++SI) {
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OS << " BB#" << (*SI)->getNumber();
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if (!Weights.empty())
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OS << '(' << *getWeightIterator(SI) << ')';
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}
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OS << '\n';
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}
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}
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void MachineBasicBlock::printAsOperand(raw_ostream &OS, bool /*PrintType*/) const {
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OS << "BB#" << getNumber();
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}
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void MachineBasicBlock::removeLiveIn(unsigned Reg) {
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std::vector<unsigned>::iterator I =
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std::find(LiveIns.begin(), LiveIns.end(), Reg);
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if (I != LiveIns.end())
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LiveIns.erase(I);
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}
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bool MachineBasicBlock::isLiveIn(unsigned Reg) const {
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livein_iterator I = std::find(livein_begin(), livein_end(), Reg);
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return I != livein_end();
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}
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unsigned
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MachineBasicBlock::addLiveIn(unsigned PhysReg, const TargetRegisterClass *RC) {
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assert(getParent() && "MBB must be inserted in function");
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assert(TargetRegisterInfo::isPhysicalRegister(PhysReg) && "Expected physreg");
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assert(RC && "Register class is required");
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assert((isLandingPad() || this == &getParent()->front()) &&
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"Only the entry block and landing pads can have physreg live ins");
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bool LiveIn = isLiveIn(PhysReg);
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iterator I = SkipPHIsAndLabels(begin()), E = end();
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MachineRegisterInfo &MRI = getParent()->getRegInfo();
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const TargetInstrInfo &TII = *getParent()->getSubtarget().getInstrInfo();
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// Look for an existing copy.
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if (LiveIn)
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for (;I != E && I->isCopy(); ++I)
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if (I->getOperand(1).getReg() == PhysReg) {
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unsigned VirtReg = I->getOperand(0).getReg();
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if (!MRI.constrainRegClass(VirtReg, RC))
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llvm_unreachable("Incompatible live-in register class.");
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return VirtReg;
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}
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// No luck, create a virtual register.
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unsigned VirtReg = MRI.createVirtualRegister(RC);
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BuildMI(*this, I, DebugLoc(), TII.get(TargetOpcode::COPY), VirtReg)
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.addReg(PhysReg, RegState::Kill);
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if (!LiveIn)
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addLiveIn(PhysReg);
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return VirtReg;
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}
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void MachineBasicBlock::moveBefore(MachineBasicBlock *NewAfter) {
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getParent()->splice(NewAfter, this);
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}
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void MachineBasicBlock::moveAfter(MachineBasicBlock *NewBefore) {
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MachineFunction::iterator BBI = NewBefore;
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getParent()->splice(++BBI, this);
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}
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void MachineBasicBlock::updateTerminator() {
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const TargetInstrInfo *TII = getParent()->getSubtarget().getInstrInfo();
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// A block with no successors has no concerns with fall-through edges.
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if (this->succ_empty()) return;
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MachineBasicBlock *TBB = nullptr, *FBB = nullptr;
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SmallVector<MachineOperand, 4> Cond;
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DebugLoc dl; // FIXME: this is nowhere
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bool B = TII->AnalyzeBranch(*this, TBB, FBB, Cond);
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(void) B;
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assert(!B && "UpdateTerminators requires analyzable predecessors!");
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if (Cond.empty()) {
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if (TBB) {
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// The block has an unconditional branch. If its successor is now
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// its layout successor, delete the branch.
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if (isLayoutSuccessor(TBB))
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TII->RemoveBranch(*this);
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} else {
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// The block has an unconditional fallthrough. If its successor is not
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// its layout successor, insert a branch. First we have to locate the
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// only non-landing-pad successor, as that is the fallthrough block.
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for (succ_iterator SI = succ_begin(), SE = succ_end(); SI != SE; ++SI) {
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if ((*SI)->isLandingPad())
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continue;
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assert(!TBB && "Found more than one non-landing-pad successor!");
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TBB = *SI;
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}
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// If there is no non-landing-pad successor, the block has no
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// fall-through edges to be concerned with.
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if (!TBB)
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return;
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// Finally update the unconditional successor to be reached via a branch
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// if it would not be reached by fallthrough.
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if (!isLayoutSuccessor(TBB))
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TII->InsertBranch(*this, TBB, nullptr, Cond, dl);
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}
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} else {
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if (FBB) {
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// The block has a non-fallthrough conditional branch. If one of its
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// successors is its layout successor, rewrite it to a fallthrough
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// conditional branch.
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if (isLayoutSuccessor(TBB)) {
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if (TII->ReverseBranchCondition(Cond))
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return;
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TII->RemoveBranch(*this);
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TII->InsertBranch(*this, FBB, nullptr, Cond, dl);
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} else if (isLayoutSuccessor(FBB)) {
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TII->RemoveBranch(*this);
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TII->InsertBranch(*this, TBB, nullptr, Cond, dl);
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}
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} else {
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// Walk through the successors and find the successor which is not
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// a landing pad and is not the conditional branch destination (in TBB)
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// as the fallthrough successor.
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MachineBasicBlock *FallthroughBB = nullptr;
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for (succ_iterator SI = succ_begin(), SE = succ_end(); SI != SE; ++SI) {
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if ((*SI)->isLandingPad() || *SI == TBB)
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continue;
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assert(!FallthroughBB && "Found more than one fallthrough successor.");
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FallthroughBB = *SI;
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}
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if (!FallthroughBB && canFallThrough()) {
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// We fallthrough to the same basic block as the conditional jump
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// targets. Remove the conditional jump, leaving unconditional
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// fallthrough.
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// FIXME: This does not seem like a reasonable pattern to support, but it
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// has been seen in the wild coming out of degenerate ARM test cases.
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TII->RemoveBranch(*this);
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// Finally update the unconditional successor to be reached via a branch
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// if it would not be reached by fallthrough.
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if (!isLayoutSuccessor(TBB))
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TII->InsertBranch(*this, TBB, nullptr, Cond, dl);
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return;
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}
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// The block has a fallthrough conditional branch.
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if (isLayoutSuccessor(TBB)) {
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if (TII->ReverseBranchCondition(Cond)) {
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// We can't reverse the condition, add an unconditional branch.
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Cond.clear();
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TII->InsertBranch(*this, FallthroughBB, nullptr, Cond, dl);
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return;
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}
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TII->RemoveBranch(*this);
|
|
TII->InsertBranch(*this, FallthroughBB, nullptr, Cond, dl);
|
|
} else if (!isLayoutSuccessor(FallthroughBB)) {
|
|
TII->RemoveBranch(*this);
|
|
TII->InsertBranch(*this, TBB, FallthroughBB, Cond, dl);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
void MachineBasicBlock::addSuccessor(MachineBasicBlock *succ, uint32_t weight) {
|
|
|
|
// If we see non-zero value for the first time it means we actually use Weight
|
|
// list, so we fill all Weights with 0's.
|
|
if (weight != 0 && Weights.empty())
|
|
Weights.resize(Successors.size());
|
|
|
|
if (weight != 0 || !Weights.empty())
|
|
Weights.push_back(weight);
|
|
|
|
Successors.push_back(succ);
|
|
succ->addPredecessor(this);
|
|
}
|
|
|
|
void MachineBasicBlock::removeSuccessor(MachineBasicBlock *succ) {
|
|
succ->removePredecessor(this);
|
|
succ_iterator I = std::find(Successors.begin(), Successors.end(), succ);
|
|
assert(I != Successors.end() && "Not a current successor!");
|
|
|
|
// If Weight list is empty it means we don't use it (disabled optimization).
|
|
if (!Weights.empty()) {
|
|
weight_iterator WI = getWeightIterator(I);
|
|
Weights.erase(WI);
|
|
}
|
|
|
|
Successors.erase(I);
|
|
}
|
|
|
|
MachineBasicBlock::succ_iterator
|
|
MachineBasicBlock::removeSuccessor(succ_iterator I) {
|
|
assert(I != Successors.end() && "Not a current successor!");
|
|
|
|
// If Weight list is empty it means we don't use it (disabled optimization).
|
|
if (!Weights.empty()) {
|
|
weight_iterator WI = getWeightIterator(I);
|
|
Weights.erase(WI);
|
|
}
|
|
|
|
(*I)->removePredecessor(this);
|
|
return Successors.erase(I);
|
|
}
|
|
|
|
void MachineBasicBlock::replaceSuccessor(MachineBasicBlock *Old,
|
|
MachineBasicBlock *New) {
|
|
if (Old == New)
|
|
return;
|
|
|
|
succ_iterator E = succ_end();
|
|
succ_iterator NewI = E;
|
|
succ_iterator OldI = E;
|
|
for (succ_iterator I = succ_begin(); I != E; ++I) {
|
|
if (*I == Old) {
|
|
OldI = I;
|
|
if (NewI != E)
|
|
break;
|
|
}
|
|
if (*I == New) {
|
|
NewI = I;
|
|
if (OldI != E)
|
|
break;
|
|
}
|
|
}
|
|
assert(OldI != E && "Old is not a successor of this block");
|
|
Old->removePredecessor(this);
|
|
|
|
// If New isn't already a successor, let it take Old's place.
|
|
if (NewI == E) {
|
|
New->addPredecessor(this);
|
|
*OldI = New;
|
|
return;
|
|
}
|
|
|
|
// New is already a successor.
|
|
// Update its weight instead of adding a duplicate edge.
|
|
if (!Weights.empty()) {
|
|
weight_iterator OldWI = getWeightIterator(OldI);
|
|
*getWeightIterator(NewI) += *OldWI;
|
|
Weights.erase(OldWI);
|
|
}
|
|
Successors.erase(OldI);
|
|
}
|
|
|
|
void MachineBasicBlock::addPredecessor(MachineBasicBlock *pred) {
|
|
Predecessors.push_back(pred);
|
|
}
|
|
|
|
void MachineBasicBlock::removePredecessor(MachineBasicBlock *pred) {
|
|
pred_iterator I = std::find(Predecessors.begin(), Predecessors.end(), pred);
|
|
assert(I != Predecessors.end() && "Pred is not a predecessor of this block!");
|
|
Predecessors.erase(I);
|
|
}
|
|
|
|
void MachineBasicBlock::transferSuccessors(MachineBasicBlock *fromMBB) {
|
|
if (this == fromMBB)
|
|
return;
|
|
|
|
while (!fromMBB->succ_empty()) {
|
|
MachineBasicBlock *Succ = *fromMBB->succ_begin();
|
|
uint32_t Weight = 0;
|
|
|
|
// If Weight list is empty it means we don't use it (disabled optimization).
|
|
if (!fromMBB->Weights.empty())
|
|
Weight = *fromMBB->Weights.begin();
|
|
|
|
addSuccessor(Succ, Weight);
|
|
fromMBB->removeSuccessor(Succ);
|
|
}
|
|
}
|
|
|
|
void
|
|
MachineBasicBlock::transferSuccessorsAndUpdatePHIs(MachineBasicBlock *fromMBB) {
|
|
if (this == fromMBB)
|
|
return;
|
|
|
|
while (!fromMBB->succ_empty()) {
|
|
MachineBasicBlock *Succ = *fromMBB->succ_begin();
|
|
uint32_t Weight = 0;
|
|
if (!fromMBB->Weights.empty())
|
|
Weight = *fromMBB->Weights.begin();
|
|
addSuccessor(Succ, Weight);
|
|
fromMBB->removeSuccessor(Succ);
|
|
|
|
// Fix up any PHI nodes in the successor.
|
|
for (MachineBasicBlock::instr_iterator MI = Succ->instr_begin(),
|
|
ME = Succ->instr_end(); MI != ME && MI->isPHI(); ++MI)
|
|
for (unsigned i = 2, e = MI->getNumOperands()+1; i != e; i += 2) {
|
|
MachineOperand &MO = MI->getOperand(i);
|
|
if (MO.getMBB() == fromMBB)
|
|
MO.setMBB(this);
|
|
}
|
|
}
|
|
}
|
|
|
|
bool MachineBasicBlock::isPredecessor(const MachineBasicBlock *MBB) const {
|
|
return std::find(pred_begin(), pred_end(), MBB) != pred_end();
|
|
}
|
|
|
|
bool MachineBasicBlock::isSuccessor(const MachineBasicBlock *MBB) const {
|
|
return std::find(succ_begin(), succ_end(), MBB) != succ_end();
|
|
}
|
|
|
|
bool MachineBasicBlock::isLayoutSuccessor(const MachineBasicBlock *MBB) const {
|
|
MachineFunction::const_iterator I(this);
|
|
return std::next(I) == MachineFunction::const_iterator(MBB);
|
|
}
|
|
|
|
bool MachineBasicBlock::canFallThrough() {
|
|
MachineFunction::iterator Fallthrough = this;
|
|
++Fallthrough;
|
|
// If FallthroughBlock is off the end of the function, it can't fall through.
|
|
if (Fallthrough == getParent()->end())
|
|
return false;
|
|
|
|
// If FallthroughBlock isn't a successor, no fallthrough is possible.
|
|
if (!isSuccessor(Fallthrough))
|
|
return false;
|
|
|
|
// Analyze the branches, if any, at the end of the block.
|
|
MachineBasicBlock *TBB = nullptr, *FBB = nullptr;
|
|
SmallVector<MachineOperand, 4> Cond;
|
|
const TargetInstrInfo *TII = getParent()->getSubtarget().getInstrInfo();
|
|
if (TII->AnalyzeBranch(*this, TBB, FBB, Cond)) {
|
|
// If we couldn't analyze the branch, examine the last instruction.
|
|
// If the block doesn't end in a known control barrier, assume fallthrough
|
|
// is possible. The isPredicated check is needed because this code can be
|
|
// called during IfConversion, where an instruction which is normally a
|
|
// Barrier is predicated and thus no longer an actual control barrier.
|
|
return empty() || !back().isBarrier() || TII->isPredicated(&back());
|
|
}
|
|
|
|
// If there is no branch, control always falls through.
|
|
if (!TBB) return true;
|
|
|
|
// If there is some explicit branch to the fallthrough block, it can obviously
|
|
// reach, even though the branch should get folded to fall through implicitly.
|
|
if (MachineFunction::iterator(TBB) == Fallthrough ||
|
|
MachineFunction::iterator(FBB) == Fallthrough)
|
|
return true;
|
|
|
|
// If it's an unconditional branch to some block not the fall through, it
|
|
// doesn't fall through.
|
|
if (Cond.empty()) return false;
|
|
|
|
// Otherwise, if it is conditional and has no explicit false block, it falls
|
|
// through.
|
|
return FBB == nullptr;
|
|
}
|
|
|
|
MachineBasicBlock *
|
|
MachineBasicBlock::SplitCriticalEdge(MachineBasicBlock *Succ, Pass *P) {
|
|
// Splitting the critical edge to a landing pad block is non-trivial. Don't do
|
|
// it in this generic function.
|
|
if (Succ->isLandingPad())
|
|
return nullptr;
|
|
|
|
MachineFunction *MF = getParent();
|
|
DebugLoc dl; // FIXME: this is nowhere
|
|
|
|
// Performance might be harmed on HW that implements branching using exec mask
|
|
// where both sides of the branches are always executed.
|
|
if (MF->getTarget().requiresStructuredCFG())
|
|
return nullptr;
|
|
|
|
// We may need to update this's terminator, but we can't do that if
|
|
// AnalyzeBranch fails. If this uses a jump table, we won't touch it.
|
|
const TargetInstrInfo *TII = MF->getSubtarget().getInstrInfo();
|
|
MachineBasicBlock *TBB = nullptr, *FBB = nullptr;
|
|
SmallVector<MachineOperand, 4> Cond;
|
|
if (TII->AnalyzeBranch(*this, TBB, FBB, Cond))
|
|
return nullptr;
|
|
|
|
// Avoid bugpoint weirdness: A block may end with a conditional branch but
|
|
// jumps to the same MBB is either case. We have duplicate CFG edges in that
|
|
// case that we can't handle. Since this never happens in properly optimized
|
|
// code, just skip those edges.
|
|
if (TBB && TBB == FBB) {
|
|
DEBUG(dbgs() << "Won't split critical edge after degenerate BB#"
|
|
<< getNumber() << '\n');
|
|
return nullptr;
|
|
}
|
|
|
|
MachineBasicBlock *NMBB = MF->CreateMachineBasicBlock();
|
|
MF->insert(std::next(MachineFunction::iterator(this)), NMBB);
|
|
DEBUG(dbgs() << "Splitting critical edge:"
|
|
" BB#" << getNumber()
|
|
<< " -- BB#" << NMBB->getNumber()
|
|
<< " -- BB#" << Succ->getNumber() << '\n');
|
|
|
|
LiveIntervals *LIS = P->getAnalysisIfAvailable<LiveIntervals>();
|
|
SlotIndexes *Indexes = P->getAnalysisIfAvailable<SlotIndexes>();
|
|
if (LIS)
|
|
LIS->insertMBBInMaps(NMBB);
|
|
else if (Indexes)
|
|
Indexes->insertMBBInMaps(NMBB);
|
|
|
|
// On some targets like Mips, branches may kill virtual registers. Make sure
|
|
// that LiveVariables is properly updated after updateTerminator replaces the
|
|
// terminators.
|
|
LiveVariables *LV = P->getAnalysisIfAvailable<LiveVariables>();
|
|
|
|
// Collect a list of virtual registers killed by the terminators.
|
|
SmallVector<unsigned, 4> KilledRegs;
|
|
if (LV)
|
|
for (instr_iterator I = getFirstInstrTerminator(), E = instr_end();
|
|
I != E; ++I) {
|
|
MachineInstr *MI = I;
|
|
for (MachineInstr::mop_iterator OI = MI->operands_begin(),
|
|
OE = MI->operands_end(); OI != OE; ++OI) {
|
|
if (!OI->isReg() || OI->getReg() == 0 ||
|
|
!OI->isUse() || !OI->isKill() || OI->isUndef())
|
|
continue;
|
|
unsigned Reg = OI->getReg();
|
|
if (TargetRegisterInfo::isPhysicalRegister(Reg) ||
|
|
LV->getVarInfo(Reg).removeKill(MI)) {
|
|
KilledRegs.push_back(Reg);
|
|
DEBUG(dbgs() << "Removing terminator kill: " << *MI);
|
|
OI->setIsKill(false);
|
|
}
|
|
}
|
|
}
|
|
|
|
SmallVector<unsigned, 4> UsedRegs;
|
|
if (LIS) {
|
|
for (instr_iterator I = getFirstInstrTerminator(), E = instr_end();
|
|
I != E; ++I) {
|
|
MachineInstr *MI = I;
|
|
|
|
for (MachineInstr::mop_iterator OI = MI->operands_begin(),
|
|
OE = MI->operands_end(); OI != OE; ++OI) {
|
|
if (!OI->isReg() || OI->getReg() == 0)
|
|
continue;
|
|
|
|
unsigned Reg = OI->getReg();
|
|
if (std::find(UsedRegs.begin(), UsedRegs.end(), Reg) == UsedRegs.end())
|
|
UsedRegs.push_back(Reg);
|
|
}
|
|
}
|
|
}
|
|
|
|
ReplaceUsesOfBlockWith(Succ, NMBB);
|
|
|
|
// If updateTerminator() removes instructions, we need to remove them from
|
|
// SlotIndexes.
|
|
SmallVector<MachineInstr*, 4> Terminators;
|
|
if (Indexes) {
|
|
for (instr_iterator I = getFirstInstrTerminator(), E = instr_end();
|
|
I != E; ++I)
|
|
Terminators.push_back(I);
|
|
}
|
|
|
|
updateTerminator();
|
|
|
|
if (Indexes) {
|
|
SmallVector<MachineInstr*, 4> NewTerminators;
|
|
for (instr_iterator I = getFirstInstrTerminator(), E = instr_end();
|
|
I != E; ++I)
|
|
NewTerminators.push_back(I);
|
|
|
|
for (SmallVectorImpl<MachineInstr*>::iterator I = Terminators.begin(),
|
|
E = Terminators.end(); I != E; ++I) {
|
|
if (std::find(NewTerminators.begin(), NewTerminators.end(), *I) ==
|
|
NewTerminators.end())
|
|
Indexes->removeMachineInstrFromMaps(*I);
|
|
}
|
|
}
|
|
|
|
// Insert unconditional "jump Succ" instruction in NMBB if necessary.
|
|
NMBB->addSuccessor(Succ);
|
|
if (!NMBB->isLayoutSuccessor(Succ)) {
|
|
Cond.clear();
|
|
MF->getSubtarget().getInstrInfo()->InsertBranch(*NMBB, Succ, nullptr, Cond,
|
|
dl);
|
|
|
|
if (Indexes) {
|
|
for (instr_iterator I = NMBB->instr_begin(), E = NMBB->instr_end();
|
|
I != E; ++I) {
|
|
// Some instructions may have been moved to NMBB by updateTerminator(),
|
|
// so we first remove any instruction that already has an index.
|
|
if (Indexes->hasIndex(I))
|
|
Indexes->removeMachineInstrFromMaps(I);
|
|
Indexes->insertMachineInstrInMaps(I);
|
|
}
|
|
}
|
|
}
|
|
|
|
// Fix PHI nodes in Succ so they refer to NMBB instead of this
|
|
for (MachineBasicBlock::instr_iterator
|
|
i = Succ->instr_begin(),e = Succ->instr_end();
|
|
i != e && i->isPHI(); ++i)
|
|
for (unsigned ni = 1, ne = i->getNumOperands(); ni != ne; ni += 2)
|
|
if (i->getOperand(ni+1).getMBB() == this)
|
|
i->getOperand(ni+1).setMBB(NMBB);
|
|
|
|
// Inherit live-ins from the successor
|
|
for (MachineBasicBlock::livein_iterator I = Succ->livein_begin(),
|
|
E = Succ->livein_end(); I != E; ++I)
|
|
NMBB->addLiveIn(*I);
|
|
|
|
// Update LiveVariables.
|
|
const TargetRegisterInfo *TRI = MF->getSubtarget().getRegisterInfo();
|
|
if (LV) {
|
|
// Restore kills of virtual registers that were killed by the terminators.
|
|
while (!KilledRegs.empty()) {
|
|
unsigned Reg = KilledRegs.pop_back_val();
|
|
for (instr_iterator I = instr_end(), E = instr_begin(); I != E;) {
|
|
if (!(--I)->addRegisterKilled(Reg, TRI, /* addIfNotFound= */ false))
|
|
continue;
|
|
if (TargetRegisterInfo::isVirtualRegister(Reg))
|
|
LV->getVarInfo(Reg).Kills.push_back(I);
|
|
DEBUG(dbgs() << "Restored terminator kill: " << *I);
|
|
break;
|
|
}
|
|
}
|
|
// Update relevant live-through information.
|
|
LV->addNewBlock(NMBB, this, Succ);
|
|
}
|
|
|
|
if (LIS) {
|
|
// After splitting the edge and updating SlotIndexes, live intervals may be
|
|
// in one of two situations, depending on whether this block was the last in
|
|
// the function. If the original block was the last in the function, all live
|
|
// intervals will end prior to the beginning of the new split block. If the
|
|
// original block was not at the end of the function, all live intervals will
|
|
// extend to the end of the new split block.
|
|
|
|
bool isLastMBB =
|
|
std::next(MachineFunction::iterator(NMBB)) == getParent()->end();
|
|
|
|
SlotIndex StartIndex = Indexes->getMBBEndIdx(this);
|
|
SlotIndex PrevIndex = StartIndex.getPrevSlot();
|
|
SlotIndex EndIndex = Indexes->getMBBEndIdx(NMBB);
|
|
|
|
// Find the registers used from NMBB in PHIs in Succ.
|
|
SmallSet<unsigned, 8> PHISrcRegs;
|
|
for (MachineBasicBlock::instr_iterator
|
|
I = Succ->instr_begin(), E = Succ->instr_end();
|
|
I != E && I->isPHI(); ++I) {
|
|
for (unsigned ni = 1, ne = I->getNumOperands(); ni != ne; ni += 2) {
|
|
if (I->getOperand(ni+1).getMBB() == NMBB) {
|
|
MachineOperand &MO = I->getOperand(ni);
|
|
unsigned Reg = MO.getReg();
|
|
PHISrcRegs.insert(Reg);
|
|
if (MO.isUndef())
|
|
continue;
|
|
|
|
LiveInterval &LI = LIS->getInterval(Reg);
|
|
VNInfo *VNI = LI.getVNInfoAt(PrevIndex);
|
|
assert(VNI && "PHI sources should be live out of their predecessors.");
|
|
LI.addSegment(LiveInterval::Segment(StartIndex, EndIndex, VNI));
|
|
}
|
|
}
|
|
}
|
|
|
|
MachineRegisterInfo *MRI = &getParent()->getRegInfo();
|
|
for (unsigned i = 0, e = MRI->getNumVirtRegs(); i != e; ++i) {
|
|
unsigned Reg = TargetRegisterInfo::index2VirtReg(i);
|
|
if (PHISrcRegs.count(Reg) || !LIS->hasInterval(Reg))
|
|
continue;
|
|
|
|
LiveInterval &LI = LIS->getInterval(Reg);
|
|
if (!LI.liveAt(PrevIndex))
|
|
continue;
|
|
|
|
bool isLiveOut = LI.liveAt(LIS->getMBBStartIdx(Succ));
|
|
if (isLiveOut && isLastMBB) {
|
|
VNInfo *VNI = LI.getVNInfoAt(PrevIndex);
|
|
assert(VNI && "LiveInterval should have VNInfo where it is live.");
|
|
LI.addSegment(LiveInterval::Segment(StartIndex, EndIndex, VNI));
|
|
} else if (!isLiveOut && !isLastMBB) {
|
|
LI.removeSegment(StartIndex, EndIndex);
|
|
}
|
|
}
|
|
|
|
// Update all intervals for registers whose uses may have been modified by
|
|
// updateTerminator().
|
|
LIS->repairIntervalsInRange(this, getFirstTerminator(), end(), UsedRegs);
|
|
}
|
|
|
|
if (MachineDominatorTree *MDT =
|
|
P->getAnalysisIfAvailable<MachineDominatorTree>())
|
|
MDT->recordSplitCriticalEdge(this, Succ, NMBB);
|
|
|
|
if (MachineLoopInfo *MLI = P->getAnalysisIfAvailable<MachineLoopInfo>())
|
|
if (MachineLoop *TIL = MLI->getLoopFor(this)) {
|
|
// If one or the other blocks were not in a loop, the new block is not
|
|
// either, and thus LI doesn't need to be updated.
|
|
if (MachineLoop *DestLoop = MLI->getLoopFor(Succ)) {
|
|
if (TIL == DestLoop) {
|
|
// Both in the same loop, the NMBB joins loop.
|
|
DestLoop->addBasicBlockToLoop(NMBB, MLI->getBase());
|
|
} else if (TIL->contains(DestLoop)) {
|
|
// Edge from an outer loop to an inner loop. Add to the outer loop.
|
|
TIL->addBasicBlockToLoop(NMBB, MLI->getBase());
|
|
} else if (DestLoop->contains(TIL)) {
|
|
// Edge from an inner loop to an outer loop. Add to the outer loop.
|
|
DestLoop->addBasicBlockToLoop(NMBB, MLI->getBase());
|
|
} else {
|
|
// Edge from two loops with no containment relation. Because these
|
|
// are natural loops, we know that the destination block must be the
|
|
// header of its loop (adding a branch into a loop elsewhere would
|
|
// create an irreducible loop).
|
|
assert(DestLoop->getHeader() == Succ &&
|
|
"Should not create irreducible loops!");
|
|
if (MachineLoop *P = DestLoop->getParentLoop())
|
|
P->addBasicBlockToLoop(NMBB, MLI->getBase());
|
|
}
|
|
}
|
|
}
|
|
|
|
return NMBB;
|
|
}
|
|
|
|
/// Prepare MI to be removed from its bundle. This fixes bundle flags on MI's
|
|
/// neighboring instructions so the bundle won't be broken by removing MI.
|
|
static void unbundleSingleMI(MachineInstr *MI) {
|
|
// Removing the first instruction in a bundle.
|
|
if (MI->isBundledWithSucc() && !MI->isBundledWithPred())
|
|
MI->unbundleFromSucc();
|
|
// Removing the last instruction in a bundle.
|
|
if (MI->isBundledWithPred() && !MI->isBundledWithSucc())
|
|
MI->unbundleFromPred();
|
|
// If MI is not bundled, or if it is internal to a bundle, the neighbor flags
|
|
// are already fine.
|
|
}
|
|
|
|
MachineBasicBlock::instr_iterator
|
|
MachineBasicBlock::erase(MachineBasicBlock::instr_iterator I) {
|
|
unbundleSingleMI(I);
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|
return Insts.erase(I);
|
|
}
|
|
|
|
MachineInstr *MachineBasicBlock::remove_instr(MachineInstr *MI) {
|
|
unbundleSingleMI(MI);
|
|
MI->clearFlag(MachineInstr::BundledPred);
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|
MI->clearFlag(MachineInstr::BundledSucc);
|
|
return Insts.remove(MI);
|
|
}
|
|
|
|
MachineBasicBlock::instr_iterator
|
|
MachineBasicBlock::insert(instr_iterator I, MachineInstr *MI) {
|
|
assert(!MI->isBundledWithPred() && !MI->isBundledWithSucc() &&
|
|
"Cannot insert instruction with bundle flags");
|
|
// Set the bundle flags when inserting inside a bundle.
|
|
if (I != instr_end() && I->isBundledWithPred()) {
|
|
MI->setFlag(MachineInstr::BundledPred);
|
|
MI->setFlag(MachineInstr::BundledSucc);
|
|
}
|
|
return Insts.insert(I, MI);
|
|
}
|
|
|
|
/// removeFromParent - This method unlinks 'this' from the containing function,
|
|
/// and returns it, but does not delete it.
|
|
MachineBasicBlock *MachineBasicBlock::removeFromParent() {
|
|
assert(getParent() && "Not embedded in a function!");
|
|
getParent()->remove(this);
|
|
return this;
|
|
}
|
|
|
|
|
|
/// eraseFromParent - This method unlinks 'this' from the containing function,
|
|
/// and deletes it.
|
|
void MachineBasicBlock::eraseFromParent() {
|
|
assert(getParent() && "Not embedded in a function!");
|
|
getParent()->erase(this);
|
|
}
|
|
|
|
|
|
/// ReplaceUsesOfBlockWith - Given a machine basic block that branched to
|
|
/// 'Old', change the code and CFG so that it branches to 'New' instead.
|
|
void MachineBasicBlock::ReplaceUsesOfBlockWith(MachineBasicBlock *Old,
|
|
MachineBasicBlock *New) {
|
|
assert(Old != New && "Cannot replace self with self!");
|
|
|
|
MachineBasicBlock::instr_iterator I = instr_end();
|
|
while (I != instr_begin()) {
|
|
--I;
|
|
if (!I->isTerminator()) break;
|
|
|
|
// Scan the operands of this machine instruction, replacing any uses of Old
|
|
// with New.
|
|
for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
|
|
if (I->getOperand(i).isMBB() &&
|
|
I->getOperand(i).getMBB() == Old)
|
|
I->getOperand(i).setMBB(New);
|
|
}
|
|
|
|
// Update the successor information.
|
|
replaceSuccessor(Old, New);
|
|
}
|
|
|
|
/// CorrectExtraCFGEdges - Various pieces of code can cause excess edges in the
|
|
/// CFG to be inserted. If we have proven that MBB can only branch to DestA and
|
|
/// DestB, remove any other MBB successors from the CFG. DestA and DestB can be
|
|
/// null.
|
|
///
|
|
/// Besides DestA and DestB, retain other edges leading to LandingPads
|
|
/// (currently there can be only one; we don't check or require that here).
|
|
/// Note it is possible that DestA and/or DestB are LandingPads.
|
|
bool MachineBasicBlock::CorrectExtraCFGEdges(MachineBasicBlock *DestA,
|
|
MachineBasicBlock *DestB,
|
|
bool isCond) {
|
|
// The values of DestA and DestB frequently come from a call to the
|
|
// 'TargetInstrInfo::AnalyzeBranch' method. We take our meaning of the initial
|
|
// values from there.
|
|
//
|
|
// 1. If both DestA and DestB are null, then the block ends with no branches
|
|
// (it falls through to its successor).
|
|
// 2. If DestA is set, DestB is null, and isCond is false, then the block ends
|
|
// with only an unconditional branch.
|
|
// 3. If DestA is set, DestB is null, and isCond is true, then the block ends
|
|
// with a conditional branch that falls through to a successor (DestB).
|
|
// 4. If DestA and DestB is set and isCond is true, then the block ends with a
|
|
// conditional branch followed by an unconditional branch. DestA is the
|
|
// 'true' destination and DestB is the 'false' destination.
|
|
|
|
bool Changed = false;
|
|
|
|
MachineFunction::iterator FallThru =
|
|
std::next(MachineFunction::iterator(this));
|
|
|
|
if (!DestA && !DestB) {
|
|
// Block falls through to successor.
|
|
DestA = FallThru;
|
|
DestB = FallThru;
|
|
} else if (DestA && !DestB) {
|
|
if (isCond)
|
|
// Block ends in conditional jump that falls through to successor.
|
|
DestB = FallThru;
|
|
} else {
|
|
assert(DestA && DestB && isCond &&
|
|
"CFG in a bad state. Cannot correct CFG edges");
|
|
}
|
|
|
|
// Remove superfluous edges. I.e., those which aren't destinations of this
|
|
// basic block, duplicate edges, or landing pads.
|
|
SmallPtrSet<const MachineBasicBlock*, 8> SeenMBBs;
|
|
MachineBasicBlock::succ_iterator SI = succ_begin();
|
|
while (SI != succ_end()) {
|
|
const MachineBasicBlock *MBB = *SI;
|
|
if (!SeenMBBs.insert(MBB).second ||
|
|
(MBB != DestA && MBB != DestB && !MBB->isLandingPad())) {
|
|
// This is a superfluous edge, remove it.
|
|
SI = removeSuccessor(SI);
|
|
Changed = true;
|
|
} else {
|
|
++SI;
|
|
}
|
|
}
|
|
|
|
return Changed;
|
|
}
|
|
|
|
/// findDebugLoc - find the next valid DebugLoc starting at MBBI, skipping
|
|
/// any DBG_VALUE instructions. Return UnknownLoc if there is none.
|
|
DebugLoc
|
|
MachineBasicBlock::findDebugLoc(instr_iterator MBBI) {
|
|
DebugLoc DL;
|
|
instr_iterator E = instr_end();
|
|
if (MBBI == E)
|
|
return DL;
|
|
|
|
// Skip debug declarations, we don't want a DebugLoc from them.
|
|
while (MBBI != E && MBBI->isDebugValue())
|
|
MBBI++;
|
|
if (MBBI != E)
|
|
DL = MBBI->getDebugLoc();
|
|
return DL;
|
|
}
|
|
|
|
/// getSuccWeight - Return weight of the edge from this block to MBB.
|
|
///
|
|
uint32_t MachineBasicBlock::getSuccWeight(const_succ_iterator Succ) const {
|
|
if (Weights.empty())
|
|
return 0;
|
|
|
|
return *getWeightIterator(Succ);
|
|
}
|
|
|
|
/// Set successor weight of a given iterator.
|
|
void MachineBasicBlock::setSuccWeight(succ_iterator I, uint32_t weight) {
|
|
if (Weights.empty())
|
|
return;
|
|
*getWeightIterator(I) = weight;
|
|
}
|
|
|
|
/// getWeightIterator - Return wight iterator corresonding to the I successor
|
|
/// iterator
|
|
MachineBasicBlock::weight_iterator MachineBasicBlock::
|
|
getWeightIterator(MachineBasicBlock::succ_iterator I) {
|
|
assert(Weights.size() == Successors.size() && "Async weight list!");
|
|
size_t index = std::distance(Successors.begin(), I);
|
|
assert(index < Weights.size() && "Not a current successor!");
|
|
return Weights.begin() + index;
|
|
}
|
|
|
|
/// getWeightIterator - Return wight iterator corresonding to the I successor
|
|
/// iterator
|
|
MachineBasicBlock::const_weight_iterator MachineBasicBlock::
|
|
getWeightIterator(MachineBasicBlock::const_succ_iterator I) const {
|
|
assert(Weights.size() == Successors.size() && "Async weight list!");
|
|
const size_t index = std::distance(Successors.begin(), I);
|
|
assert(index < Weights.size() && "Not a current successor!");
|
|
return Weights.begin() + index;
|
|
}
|
|
|
|
/// Return whether (physical) register "Reg" has been <def>ined and not <kill>ed
|
|
/// as of just before "MI".
|
|
///
|
|
/// Search is localised to a neighborhood of
|
|
/// Neighborhood instructions before (searching for defs or kills) and N
|
|
/// instructions after (searching just for defs) MI.
|
|
MachineBasicBlock::LivenessQueryResult
|
|
MachineBasicBlock::computeRegisterLiveness(const TargetRegisterInfo *TRI,
|
|
unsigned Reg, MachineInstr *MI,
|
|
unsigned Neighborhood) {
|
|
unsigned N = Neighborhood;
|
|
MachineBasicBlock *MBB = MI->getParent();
|
|
|
|
// Start by searching backwards from MI, looking for kills, reads or defs.
|
|
|
|
MachineBasicBlock::iterator I(MI);
|
|
// If this is the first insn in the block, don't search backwards.
|
|
if (I != MBB->begin()) {
|
|
do {
|
|
--I;
|
|
|
|
MachineOperandIteratorBase::PhysRegInfo Analysis =
|
|
MIOperands(I).analyzePhysReg(Reg, TRI);
|
|
|
|
if (Analysis.Defines)
|
|
// Outputs happen after inputs so they take precedence if both are
|
|
// present.
|
|
return Analysis.DefinesDead ? LQR_Dead : LQR_Live;
|
|
|
|
if (Analysis.Kills || Analysis.Clobbers)
|
|
// Register killed, so isn't live.
|
|
return LQR_Dead;
|
|
|
|
else if (Analysis.ReadsOverlap)
|
|
// Defined or read without a previous kill - live.
|
|
return Analysis.Reads ? LQR_Live : LQR_OverlappingLive;
|
|
|
|
} while (I != MBB->begin() && --N > 0);
|
|
}
|
|
|
|
// Did we get to the start of the block?
|
|
if (I == MBB->begin()) {
|
|
// If so, the register's state is definitely defined by the live-in state.
|
|
for (MCRegAliasIterator RAI(Reg, TRI, /*IncludeSelf=*/true);
|
|
RAI.isValid(); ++RAI) {
|
|
if (MBB->isLiveIn(*RAI))
|
|
return (*RAI == Reg) ? LQR_Live : LQR_OverlappingLive;
|
|
}
|
|
|
|
return LQR_Dead;
|
|
}
|
|
|
|
N = Neighborhood;
|
|
|
|
// Try searching forwards from MI, looking for reads or defs.
|
|
I = MachineBasicBlock::iterator(MI);
|
|
// If this is the last insn in the block, don't search forwards.
|
|
if (I != MBB->end()) {
|
|
for (++I; I != MBB->end() && N > 0; ++I, --N) {
|
|
MachineOperandIteratorBase::PhysRegInfo Analysis =
|
|
MIOperands(I).analyzePhysReg(Reg, TRI);
|
|
|
|
if (Analysis.ReadsOverlap)
|
|
// Used, therefore must have been live.
|
|
return (Analysis.Reads) ?
|
|
LQR_Live : LQR_OverlappingLive;
|
|
|
|
else if (Analysis.Clobbers || Analysis.Defines)
|
|
// Defined (but not read) therefore cannot have been live.
|
|
return LQR_Dead;
|
|
}
|
|
}
|
|
|
|
// At this point we have no idea of the liveness of the register.
|
|
return LQR_Unknown;
|
|
}
|