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Check TRI->getReservedRegs because other allocators do it. Even though 

it makes no sense for allocation_order iterators to visit reserved regs.
The inline spiller depends on AliasAnalysis.
Manage the Query state to avoid uninitialized or stale results.

llvm-svn: 118800
This commit is contained in:
Andrew Trick 2010-11-11 17:46:29 +00:00
parent 109dfe55d0
commit f11344d770
3 changed files with 57 additions and 37 deletions
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3
llvm/lib/CodeGen/LiveIntervalUnion.h
View File

@ -267,6 +267,9 @@ public:
}
private:
Query(const Query&); // DO NOT IMPLEMENT
void operator=(const Query&); // DO NOT IMPLEMENT
// Private interface for queries
void findIntersection(InterferenceResult &ir) const;
};

14
llvm/lib/CodeGen/RegAllocBase.h
View File

@ -106,6 +106,15 @@ protected:
// A RegAlloc pass should call this before allocatePhysRegs.
void init(const TargetRegisterInfo &tri, VirtRegMap &vrm, LiveIntervals &lis);
// Get an initialized query to check interferences between lvr and preg. Note
// that Query::init must be called at least once for each physical register
// before querying a new live virtual register. This ties queries_ and
// physReg2liu_ together.
LiveIntervalUnion::Query &query(LiveInterval &lvr, unsigned preg) {
queries_[preg].init(&lvr, &physReg2liu_[preg]);
return queries_[preg];
}
// The top-level driver. The output is a VirtRegMap that us updated with
// physical register assignments.
//
@ -135,7 +144,7 @@ protected:
// Helper for spilling all live virtual registers currently unified under preg
// that interfere with the most recently queried lvr. Return true if spilling
// was successful, and append any new spilled/split intervals to splitLVRs.
bool spillInterferences(unsigned preg,
bool spillInterferences(LiveInterval &lvr, unsigned preg,
SmallVectorImpl<LiveInterval*> &splitLVRs);
#ifndef NDEBUG
@ -146,7 +155,8 @@ protected:
private:
void seedLiveVirtRegs(LiveVirtRegQueue &lvrQ);
void spillReg(unsigned reg, SmallVectorImpl<LiveInterval*> &splitLVRs);
void spillReg(LiveInterval &lvr, unsigned reg,
SmallVectorImpl<LiveInterval*> &splitLVRs);
};
} // end namespace llvm

77
llvm/lib/CodeGen/RegAllocBasic.cpp
View File

@ -19,6 +19,7 @@
#include "Spiller.h"
#include "VirtRegMap.h"
#include "VirtRegRewriter.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Function.h"
#include "llvm/PassAnalysisSupport.h"
#include "llvm/CodeGen/CalcSpillWeights.h"
@ -75,6 +76,7 @@ class RABasic : public MachineFunctionPass, public RegAllocBase
MachineFunction *mf_;
const TargetMachine *tm_;
MachineRegisterInfo *mri_;
BitVector reservedRegs_;
// analyses
LiveStacks *ls_;
@ -145,6 +147,8 @@ RABasic::RABasic(): MachineFunctionPass(ID) {
void RABasic::getAnalysisUsage(AnalysisUsage &au) const {
au.setPreservesCFG();
au.addRequired<AliasAnalysis>();
au.addPreserved<AliasAnalysis>();
au.addRequired<LiveIntervals>();
au.addPreserved<SlotIndexes>();
if (StrongPHIElim)
@ -187,8 +191,6 @@ void RegAllocBase::verify() {
for (LiveIntervals::iterator liItr = lis_->begin(), liEnd = lis_->end();
liItr != liEnd; ++liItr) {
unsigned reg = liItr->first;
LiveInterval &li = *liItr->second;
if (li.empty() ) continue;
if (TargetRegisterInfo::isPhysicalRegister(reg)) continue;
if (!vrm_->hasPhys(reg)) continue; // spilled?
unsigned preg = vrm_->getPhys(reg);
@ -271,7 +273,6 @@ void RegAllocBase::seedLiveVirtRegs(LiveVirtRegQueue &lvrQ) {
liItr != liEnd; ++liItr) {
unsigned reg = liItr->first;
LiveInterval &li = *liItr->second;
if (li.empty()) continue;
if (TargetRegisterInfo::isPhysicalRegister(reg)) {
physReg2liu_[reg].unify(li);
}
@ -314,12 +315,10 @@ void RegAllocBase::allocatePhysRegs() {
// register. Return the interfering register.
unsigned RegAllocBase::checkPhysRegInterference(LiveInterval &lvr,
unsigned preg) {
queries_[preg].init(&lvr, &physReg2liu_[preg]);
if (queries_[preg].checkInterference())
if (query(lvr, preg).checkInterference())
return preg;
for (const unsigned *asI = tri_->getAliasSet(preg); *asI; ++asI) {
queries_[*asI].init(&lvr, &physReg2liu_[*asI]);
if (queries_[*asI].checkInterference())
if (query(lvr, *asI).checkInterference())
return *asI;
}
return 0;
@ -334,60 +333,63 @@ struct LessLiveVirtualReg
};
// Spill all interferences currently assigned to this physical register.
void RegAllocBase::spillReg(unsigned reg,
void RegAllocBase::spillReg(LiveInterval& lvr, unsigned reg,
SmallVectorImpl<LiveInterval*> &splitLVRs) {
LiveIntervalUnion::Query &query = queries_[reg];
const SmallVectorImpl<LiveInterval*> &pendingSpills =
query.interferingVRegs();
LiveIntervalUnion::Query &Q = query(lvr, reg);
const SmallVectorImpl<LiveInterval*> &pendingSpills = Q.interferingVRegs();
for (SmallVectorImpl<LiveInterval*>::const_iterator I = pendingSpills.begin(),
E = pendingSpills.end(); I != E; ++I) {
LiveInterval &lvr = **I;
DEBUG(dbgs() <<
"extracting from " << tri_->getName(reg) << " " << lvr << '\n');
LiveInterval &spilledLVR = **I;
DEBUG(dbgs() << "extracting from " <<
tri_->getName(reg) << " " << spilledLVR << '\n');
// Deallocate the interfering vreg by removing it from the union.
// A LiveInterval instance may not be in a union during modification!
physReg2liu_[reg].extract(lvr);
// After extracting segments, the query's results are invalid.
query.clear();
physReg2liu_[reg].extract(spilledLVR);
// Clear the vreg assignment.
vrm_->clearVirt(lvr.reg);
vrm_->clearVirt(spilledLVR.reg);
// Spill the extracted interval.
spiller().spill(&lvr, splitLVRs, pendingSpills);
spiller().spill(&spilledLVR, splitLVRs, pendingSpills);
}
// After extracting segments, the query's results are invalid. But keep the
// contents valid until we're done accessing pendingSpills.
Q.clear();
}
// Spill or split all live virtual registers currently unified under preg that
// interfere with lvr. The newly spilled or split live intervals are returned by
// appending them to splitLVRs.
bool
RegAllocBase::spillInterferences(unsigned preg,
RegAllocBase::spillInterferences(LiveInterval &lvr, unsigned preg,
SmallVectorImpl<LiveInterval*> &splitLVRs) {
// Record each interference and determine if all are spillable before mutating
// either the union or live intervals.
std::vector<LiveInterval*> spilledLVRs;
unsigned numInterferences = queries_[preg].collectInterferingVRegs();
if (queries_[preg].seenUnspillableVReg()) {
// Collect interferences assigned to the requested physical register.
LiveIntervalUnion::Query &QPreg = query(lvr, preg);
unsigned numInterferences = QPreg.collectInterferingVRegs();
if (QPreg.seenUnspillableVReg()) {
return false;
}
// Collect interferences assigned to any alias of the physical register.
for (const unsigned *asI = tri_->getAliasSet(preg); *asI; ++asI) {
numInterferences += queries_[*asI].collectInterferingVRegs();
if (queries_[*asI].seenUnspillableVReg()) {
LiveIntervalUnion::Query &QAlias = query(lvr, *asI);
numInterferences += QAlias.collectInterferingVRegs();
if (QAlias.seenUnspillableVReg()) {
return false;
}
}
DEBUG(dbgs() << "spilling " << tri_->getName(preg) <<
" interferences with " << queries_[preg].lvr() << "\n");
" interferences with " << lvr << "\n");
assert(numInterferences > 0 && "expect interference");
// Spill each interfering vreg allocated to preg or an alias.
spillReg(preg, splitLVRs);
spillReg(lvr, preg, splitLVRs);
for (const unsigned *asI = tri_->getAliasSet(preg); *asI; ++asI)
spillReg(*asI, splitLVRs);
spillReg(lvr, *asI, splitLVRs);
return true;
}
@ -409,7 +411,7 @@ RegAllocBase::spillInterferences(unsigned preg,
unsigned RABasic::selectOrSplit(LiveInterval &lvr,
SmallVectorImpl<LiveInterval*> &splitLVRs) {
// Populate a list of physical register spill candidates.
std::vector<unsigned> pregSpillCands;
SmallVector<unsigned, 8> pregSpillCands;
// Check for an available register in this class.
const TargetRegisterClass *trc = mri_->getRegClass(lvr.reg);
@ -417,6 +419,8 @@ unsigned RABasic::selectOrSplit(LiveInterval &lvr,
trcEnd = trc->allocation_order_end(*mf_);
trcI != trcEnd; ++trcI) {
unsigned preg = *trcI;
if (reservedRegs_.test(preg)) continue;
// Check interference and intialize queries for this lvr as a side effect.
unsigned interfReg = checkPhysRegInterference(lvr, preg);
if (interfReg == 0) {
@ -435,17 +439,17 @@ unsigned RABasic::selectOrSplit(LiveInterval &lvr,
// Try to spill another interfering reg with less spill weight.
//
// FIXME: RAGreedy will sort this list by spill weight.
for (std::vector<unsigned>::iterator pregI = pregSpillCands.begin(),
for (SmallVectorImpl<unsigned>::iterator pregI = pregSpillCands.begin(),
pregE = pregSpillCands.end(); pregI != pregE; ++pregI) {
if (!spillInterferences(*pregI, splitLVRs)) continue;
if (!spillInterferences(lvr, *pregI, splitLVRs)) continue;
unsigned interfReg = checkPhysRegInterference(lvr, *pregI);
if (interfReg != 0) {
const LiveSegment &seg =
*queries_[interfReg].firstInterference().liuSegPos();
dbgs() << "spilling cannot free " << tri_->getName(*pregI) <<
" for " << lvr.reg << " with interference " << seg.liveVirtReg << "\n";
" for " << lvr.reg << " with interference " << *seg.liveVirtReg << "\n";
llvm_unreachable("Interference after spill.");
}
// Tell the caller to allocate to this newly freed physical register.
@ -477,10 +481,13 @@ bool RABasic::runOnMachineFunction(MachineFunction &mf) {
mri_ = &mf.getRegInfo();
DEBUG(rmf_ = &getAnalysis<RenderMachineFunction>());
RegAllocBase::init(*tm_->getRegisterInfo(), getAnalysis<VirtRegMap>(),
const TargetRegisterInfo *TRI = tm_->getRegisterInfo();
RegAllocBase::init(*TRI, getAnalysis<VirtRegMap>(),
getAnalysis<LiveIntervals>());
reservedRegs_ = TRI->getReservedRegs(*mf_);
// We may want to force InlineSpiller for this register allocator. For
// now we're also experimenting with the standard spiller.
//