#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/ADT/DepthFirstIterator.h"
+#include "llvm/Support/Allocator.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
-
using namespace llvm;
-namespace {
-
-/// Allocate objects from a pool, allow objects to be recycled, and provide a
-/// way of deleting everything.
-template<typename T, unsigned PageSize = 64>
-class PoolAllocator {
- std::vector<T*> Pages, Avail;
-public:
- ~PoolAllocator() { Clear(); }
-
- T* Alloc() {
- if (Avail.empty()) {
- T *p = new T[PageSize];
- Pages.push_back(p);
- Avail.reserve(PageSize);
- for (unsigned n = 0; n != PageSize; ++n)
- Avail.push_back(p+n);
- }
- T *p = Avail.back();
- Avail.pop_back();
- return p;
- }
-
- // Allow object to be reallocated. It won't be reconstructed.
- void Recycle(T *p) {
- p->clear();
- Avail.push_back(p);
- }
-
- // Destroy all objects, make sure there are no external pointers to them.
- void Clear() {
- Avail.clear();
- while (!Pages.empty()) {
- delete[] Pages.back();
- Pages.pop_back();
- }
- }
-};
-
-/// A DomainValue is a bit like LiveIntervals' ValNo, but it laso keeps track
+/// A DomainValue is a bit like LiveIntervals' ValNo, but it also keeps track
/// of execution domains.
///
/// An open DomainValue represents a set of instructions that can still switch
/// domain, but if we were forced to pay the penalty of a domain crossing, we
/// keep track of the fact the the register is now available in multiple
/// domains.
+namespace {
struct DomainValue {
// Basic reference counting.
unsigned Refs;
- // Available domains. For an open DomainValue, it is the still possible
- // domains for collapsing. For a collapsed DomainValue it is the domains where
- // the register is available for free.
- unsigned Mask;
+ // Bitmask of available domains. For an open DomainValue, it is the still
+ // possible domains for collapsing. For a collapsed DomainValue it is the
+ // domains where the register is available for free.
+ unsigned AvailableDomains;
// Position of the last defining instruction.
unsigned Dist;
// Twiddleable instructions using or defining these registers.
SmallVector<MachineInstr*, 8> Instrs;
- // Collapsed DomainValue have no instructions to twiddle - it simply keeps
+ // A collapsed DomainValue has no instructions to twiddle - it simply keeps
// track of the domains where the registers are already available.
- bool collapsed() const { return Instrs.empty(); }
+ bool isCollapsed() const { return Instrs.empty(); }
- // Is any domain in mask available?
- bool compat(unsigned mask) const {
- return Mask & mask;
+ // Is domain available?
+ bool hasDomain(unsigned domain) const {
+ return AvailableDomains & (1u << domain);
}
// Mark domain as available.
- void add(unsigned domain) {
- Mask |= 1u << domain;
+ void addDomain(unsigned domain) {
+ AvailableDomains |= 1u << domain;
+ }
+
+ // Restrict to a single domain available.
+ void setSingleDomain(unsigned domain) {
+ AvailableDomains = 1u << domain;
}
- // First domain available in mask.
- unsigned firstDomain() const {
- return CountTrailingZeros_32(Mask);
+ // Return bitmask of domains that are available and in mask.
+ unsigned getCommonDomains(unsigned mask) const {
+ return AvailableDomains & mask;
+ }
+
+ // First domain available.
+ unsigned getFirstDomain() const {
+ return CountTrailingZeros_32(AvailableDomains);
}
DomainValue() { clear(); }
void clear() {
- Refs = Mask = Dist = 0;
+ Refs = AvailableDomains = Dist = 0;
Instrs.clear();
}
};
+}
static const unsigned NumRegs = 16;
+namespace {
class SSEDomainFixPass : public MachineFunctionPass {
static char ID;
- PoolAllocator<DomainValue> Pool;
+ SpecificBumpPtrAllocator<DomainValue> Allocator;
+ SmallVector<DomainValue*,16> Avail;
MachineFunction *MF;
const X86InstrInfo *TII;
unsigned Distance;
public:
- SSEDomainFixPass() : MachineFunctionPass(&ID) {}
+ SSEDomainFixPass() : MachineFunctionPass(ID) {}
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesAll();
// Register mapping.
int RegIndex(unsigned Reg);
+ // DomainValue allocation.
+ DomainValue *Alloc(int domain = -1);
+ void Recycle(DomainValue*);
+
// LiveRegs manipulations.
void SetLiveReg(int rx, DomainValue *DV);
void Kill(int rx);
void visitGenericInstr(MachineInstr*);
void visitSoftInstr(MachineInstr*, unsigned mask);
void visitHardInstr(MachineInstr*, unsigned domain);
-
};
}
/// Translate TRI register number to an index into our smaller tables of
/// interesting registers. Return -1 for boring registers.
int SSEDomainFixPass::RegIndex(unsigned reg) {
- // Registers are sorted lexicographically.
- // We just need them to be consecutive, ordering doesn't matter.
- assert(X86::XMM9 == X86::XMM0+NumRegs-1 && "Unexpected sort");
+ assert(X86::XMM15 == X86::XMM0+NumRegs-1 && "Unexpected sort");
reg -= X86::XMM0;
- return reg < NumRegs ? reg : -1;
+ return reg < NumRegs ? (int) reg : -1;
+}
+
+DomainValue *SSEDomainFixPass::Alloc(int domain) {
+ DomainValue *dv = Avail.empty() ?
+ new(Allocator.Allocate()) DomainValue :
+ Avail.pop_back_val();
+ dv->Dist = Distance;
+ if (domain >= 0)
+ dv->addDomain(domain);
+ return dv;
+}
+
+void SSEDomainFixPass::Recycle(DomainValue *dv) {
+ assert(dv && "Cannot recycle NULL");
+ dv->clear();
+ Avail.push_back(dv);
}
/// Set LiveRegs[rx] = dv, updating reference counts.
void SSEDomainFixPass::SetLiveReg(int rx, DomainValue *dv) {
assert(unsigned(rx) < NumRegs && "Invalid index");
- if (!LiveRegs)
- LiveRegs = (DomainValue**)calloc(sizeof(DomainValue*), NumRegs);
+ if (!LiveRegs) {
+ LiveRegs = new DomainValue*[NumRegs];
+ std::fill(LiveRegs, LiveRegs+NumRegs, (DomainValue*)0);
+ }
if (LiveRegs[rx] == dv)
return;
if (LiveRegs[rx]) {
assert(LiveRegs[rx]->Refs && "Bad refcount");
- if (--LiveRegs[rx]->Refs == 0) Pool.Recycle(LiveRegs[rx]);
+ if (--LiveRegs[rx]->Refs == 0) Recycle(LiveRegs[rx]);
}
LiveRegs[rx] = dv;
if (dv) ++dv->Refs;
// Before killing the last reference to an open DomainValue, collapse it to
// the first available domain.
- if (LiveRegs[rx]->Refs == 1 && !LiveRegs[rx]->collapsed())
- Collapse(LiveRegs[rx], LiveRegs[rx]->firstDomain());
+ if (LiveRegs[rx]->Refs == 1 && !LiveRegs[rx]->isCollapsed())
+ Collapse(LiveRegs[rx], LiveRegs[rx]->getFirstDomain());
else
SetLiveReg(rx, 0);
}
assert(unsigned(rx) < NumRegs && "Invalid index");
DomainValue *dv;
if (LiveRegs && (dv = LiveRegs[rx])) {
- if (dv->collapsed())
- dv->add(domain);
- else
+ if (dv->isCollapsed())
+ dv->addDomain(domain);
+ else if (dv->hasDomain(domain))
Collapse(dv, domain);
+ else {
+ // This is an incompatible open DomainValue. Collapse it to whatever and force
+ // the new value into domain. This costs a domain crossing.
+ Collapse(dv, dv->getFirstDomain());
+ assert(LiveRegs[rx] && "Not live after collapse?");
+ LiveRegs[rx]->addDomain(domain);
+ }
} else {
// Set up basic collapsed DomainValue.
- dv = Pool.Alloc();
- dv->Dist = Distance;
- dv->add(domain);
- SetLiveReg(rx, dv);
+ SetLiveReg(rx, Alloc(domain));
}
}
/// Collapse open DomainValue into given domain. If there are multiple
/// registers using dv, they each get a unique collapsed DomainValue.
void SSEDomainFixPass::Collapse(DomainValue *dv, unsigned domain) {
- assert(dv->compat(1u << domain) && "Cannot collapse");
+ assert(dv->hasDomain(domain) && "Cannot collapse");
// Collapse all the instructions.
- while (!dv->Instrs.empty()) {
- MachineInstr *mi = dv->Instrs.back();
- TII->SetSSEDomain(mi, domain);
- dv->Instrs.pop_back();
- }
- dv->Mask = 1u << domain;
+ while (!dv->Instrs.empty())
+ TII->SetSSEDomain(dv->Instrs.pop_back_val(), domain);
+ dv->setSingleDomain(domain);
// If there are multiple users, give them new, unique DomainValues.
- if (LiveRegs && dv->Refs > 1) {
+ if (LiveRegs && dv->Refs > 1)
for (unsigned rx = 0; rx != NumRegs; ++rx)
- if (LiveRegs[rx] == dv) {
- DomainValue *dv2 = Pool.Alloc();
- dv2->Dist = Distance;
- dv2->add(domain);
- SetLiveReg(rx, dv2);
- }
- }
+ if (LiveRegs[rx] == dv)
+ SetLiveReg(rx, Alloc(domain));
}
/// Merge - All instructions and registers in B are moved to A, and B is
/// released.
bool SSEDomainFixPass::Merge(DomainValue *A, DomainValue *B) {
- assert(!A->collapsed() && "Cannot merge into collapsed");
- assert(!B->collapsed() && "Cannot merge from collapsed");
- if (A == B)
+ assert(!A->isCollapsed() && "Cannot merge into collapsed");
+ assert(!B->isCollapsed() && "Cannot merge from collapsed");
+ if (A == B)
return true;
- if (!A->compat(B->Mask))
+ // Restrict to the domains that A and B have in common.
+ unsigned common = A->getCommonDomains(B->AvailableDomains);
+ if (!common)
return false;
- A->Mask &= B->Mask;
+ A->AvailableDomains = common;
A->Dist = std::max(A->Dist, B->Dist);
A->Instrs.append(B->Instrs.begin(), B->Instrs.end());
for (unsigned rx = 0; rx != NumRegs; ++rx)
void SSEDomainFixPass::enterBasicBlock() {
// Try to coalesce live-out registers from predecessors.
- for (MachineBasicBlock::const_livein_iterator i = MBB->livein_begin(),
+ for (MachineBasicBlock::livein_iterator i = MBB->livein_begin(),
e = MBB->livein_end(); i != e; ++i) {
int rx = RegIndex(*i);
if (rx < 0) continue;
if (fi == LiveOuts.end()) continue;
DomainValue *pdv = fi->second[rx];
if (!pdv) continue;
- if (!LiveRegs || !LiveRegs[rx])
+ if (!LiveRegs || !LiveRegs[rx]) {
SetLiveReg(rx, pdv);
- else {
- // We have a live DomainValue from more than one predecessor.
- if (LiveRegs[rx]->collapsed()) {
- // We are already collapsed, but predecessor is not. Force him.
- if (!pdv->collapsed())
- Collapse(pdv, LiveRegs[rx]->firstDomain());
- } else {
- // Currently open, merge in predecessor.
- if (!pdv->collapsed())
- Merge(LiveRegs[rx], pdv);
- else
- Collapse(LiveRegs[rx], pdv->firstDomain());
- }
+ continue;
+ }
+
+ // We have a live DomainValue from more than one predecessor.
+ if (LiveRegs[rx]->isCollapsed()) {
+ // We are already collapsed, but predecessor is not. Force him.
+ unsigned domain = LiveRegs[rx]->getFirstDomain();
+ if (!pdv->isCollapsed() && pdv->hasDomain(domain))
+ Collapse(pdv, domain);
+ continue;
}
+
+ // Currently open, merge in predecessor.
+ if (!pdv->isCollapsed())
+ Merge(LiveRegs[rx], pdv);
+ else
+ Force(rx, pdv->getFirstDomain());
}
}
}
// A soft instruction can be changed to work in other domains given by mask.
void SSEDomainFixPass::visitSoftInstr(MachineInstr *mi, unsigned mask) {
+ // Bitmask of available domains for this instruction after taking collapsed
+ // operands into account.
+ unsigned available = mask;
+
// Scan the explicit use operands for incoming domains.
- unsigned collmask = mask;
SmallVector<int, 4> used;
if (LiveRegs)
for (unsigned i = mi->getDesc().getNumDefs(),
e = mi->getDesc().getNumOperands(); i != e; ++i) {
- MachineOperand &mo = mi->getOperand(i);
- if (!mo.isReg()) continue;
- int rx = RegIndex(mo.getReg());
- if (rx < 0) continue;
- if (DomainValue *dv = LiveRegs[rx]) {
- // Is it possible to use this collapsed register for free?
- if (dv->collapsed()) {
- if (unsigned m = collmask & dv->Mask)
- collmask = m;
- } else if (dv->compat(collmask))
- used.push_back(rx);
- else
- Kill(rx);
+ MachineOperand &mo = mi->getOperand(i);
+ if (!mo.isReg()) continue;
+ int rx = RegIndex(mo.getReg());
+ if (rx < 0) continue;
+ if (DomainValue *dv = LiveRegs[rx]) {
+ // Bitmask of domains that dv and available have in common.
+ unsigned common = dv->getCommonDomains(available);
+ // Is it possible to use this collapsed register for free?
+ if (dv->isCollapsed()) {
+ // Restrict available domains to the ones in common with the operand.
+ // If there are no common domains, we must pay the cross-domain
+ // penalty for this operand.
+ if (common) available = common;
+ } else if (common)
+ // Open DomainValue is compatible, save it for merging.
+ used.push_back(rx);
+ else
+ // Open DomainValue is not compatible with instruction. It is useless
+ // now.
+ Kill(rx);
+ }
}
- }
// If the collapsed operands force a single domain, propagate the collapse.
- if (isPowerOf2_32(collmask)) {
- unsigned domain = CountTrailingZeros_32(collmask);
+ if (isPowerOf2_32(available)) {
+ unsigned domain = CountTrailingZeros_32(available);
TII->SetSSEDomain(mi, domain);
visitHardInstr(mi, domain);
return;
}
- // Kill off any remaining uses that don't match collmask, and build a list of
- // incoming DomainValue that we want to merge.
+ // Kill off any remaining uses that don't match available, and build a list of
+ // incoming DomainValues that we want to merge.
SmallVector<DomainValue*,4> doms;
for (SmallVector<int, 4>::iterator i=used.begin(), e=used.end(); i!=e; ++i) {
int rx = *i;
DomainValue *dv = LiveRegs[rx];
// This useless DomainValue could have been missed above.
- if (!dv->compat(collmask)) {
+ if (!dv->getCommonDomains(available)) {
Kill(*i);
continue;
}
doms.push_back(dv);
}
- // doms are now sorted in order of appearance. Try to merge them all, giving
- // priority to the latest ones.
+ // doms are now sorted in order of appearance. Try to merge them all, giving
+ // priority to the latest ones.
DomainValue *dv = 0;
while (!doms.empty()) {
- if (!dv)
- dv = doms.back();
- else if (!Merge(dv, doms.back()))
- for (SmallVector<int,4>::iterator i=used.begin(), e=used.end(); i!=e; ++i)
- if (LiveRegs[*i] == doms.back())
- Kill(*i);
- doms.pop_back();
+ if (!dv) {
+ dv = doms.pop_back_val();
+ continue;
+ }
+
+ DomainValue *latest = doms.pop_back_val();
+ if (Merge(dv, latest)) continue;
+
+ // If latest didn't merge, it is useless now. Kill all registers using it.
+ for (SmallVector<int,4>::iterator i=used.begin(), e=used.end(); i != e; ++i)
+ if (LiveRegs[*i] == latest)
+ Kill(*i);
}
// dv is the DomainValue we are going to use for this instruction.
if (!dv)
- dv = Pool.Alloc();
+ dv = Alloc();
dv->Dist = Distance;
- dv->Mask = collmask;
+ dv->AvailableDomains = available;
dv->Instrs.push_back(mi);
// Finally set all defs and non-collapsed uses to dv.
// DomainValues?
for (LiveOutMap::const_iterator i = LiveOuts.begin(), e = LiveOuts.end();
i != e; ++i)
- free(i->second);
+ delete[] i->second;
LiveOuts.clear();
- Pool.Clear();
+ Avail.clear();
+ Allocator.DestroyAll();
return false;
}
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