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Fix a couple of problems with maintaining liveness information for antidep breaking. 

llvm-svn: 89404
This commit is contained in:
David Goodwin 2009-11-19 23:12:37 +00:00
parent b73918c42d
commit dd1c6198d4
2 changed files with 50 additions and 18 deletions
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64
llvm/lib/CodeGen/AggressiveAntiDepBreaker.cpp
View File

@ -33,6 +33,16 @@ AntiDepTrials("agg-antidep-trials",
cl::desc("Maximum number of anti-dependency breaking passes"),
cl::init(1), cl::Hidden);
// If DebugDiv > 0 then only break antidep with (ID % DebugDiv) == DebugMod
static cl::opt<int>
DebugDiv("agg-antidep-debugdiv",
cl::desc("Debug control for aggressive anti-dep breaker"),
cl::init(0), cl::Hidden);
static cl::opt<int>
DebugMod("agg-antidep-debugmod",
cl::desc("Debug control for aggressive anti-dep breaker"),
cl::init(0), cl::Hidden);
AggressiveAntiDepState::AggressiveAntiDepState(MachineBasicBlock *BB) :
GroupNodes(TargetRegisterInfo::FirstVirtualRegister, 0) {
// Initialize all registers to be in their own group. Initially we
@ -332,7 +342,8 @@ static SUnit *CriticalPathStep(SUnit *SU) {
}
void AggressiveAntiDepBreaker::HandleLastUse(unsigned Reg, unsigned KillIdx,
const char *tag) {
const char *tag, const char *header,
const char *footer) {
unsigned *KillIndices = State->GetKillIndices();
unsigned *DefIndices = State->GetDefIndices();
std::multimap<unsigned, AggressiveAntiDepState::RegisterReference>&
@ -343,6 +354,8 @@ void AggressiveAntiDepBreaker::HandleLastUse(unsigned Reg, unsigned KillIdx,
DefIndices[Reg] = ~0u;
RegRefs.erase(Reg);
State->LeaveGroup(Reg);
DEBUG(if (header != NULL) {
errs() << header << TRI->getName(Reg); header = NULL; });
DEBUG(errs() << "->g" << State->GetGroup(Reg) << tag);
}
// Repeat for subregisters.
@ -354,10 +367,14 @@ void AggressiveAntiDepBreaker::HandleLastUse(unsigned Reg, unsigned KillIdx,
DefIndices[SubregReg] = ~0u;
RegRefs.erase(SubregReg);
State->LeaveGroup(SubregReg);
DEBUG(if (header != NULL) {
errs() << header << TRI->getName(Reg); header = NULL; });
DEBUG(errs() << " " << TRI->getName(SubregReg) << "->g" <<
State->GetGroup(SubregReg) << tag);
}
}
DEBUG(if ((header == NULL) && (footer != NULL)) errs() << footer);
}
void AggressiveAntiDepBreaker::PrescanInstruction(MachineInstr *MI, unsigned Count,
@ -377,9 +394,7 @@ void AggressiveAntiDepBreaker::PrescanInstruction(MachineInstr *MI, unsigned Cou
unsigned Reg = MO.getReg();
if (Reg == 0) continue;
DEBUG(errs() << "\tDead Def: " << TRI->getName(Reg));
HandleLastUse(Reg, Count + 1, "");
DEBUG(errs() << '\n');
HandleLastUse(Reg, Count + 1, "", "\tDead Def: ", "\n");
}
DEBUG(errs() << "\tDef Groups:");
@ -427,15 +442,17 @@ void AggressiveAntiDepBreaker::PrescanInstruction(MachineInstr *MI, unsigned Cou
if (!MO.isReg() || !MO.isDef()) continue;
unsigned Reg = MO.getReg();
if (Reg == 0) continue;
// Ignore passthru registers for liveness...
if (PassthruRegs.count(Reg) != 0) continue;
// Ignore KILLs and passthru registers for liveness...
if ((MI->getOpcode() == TargetInstrInfo::KILL) ||
(PassthruRegs.count(Reg) != 0))
continue;
// Update def for Reg and subregs.
// Update def for Reg and aliases.
DefIndices[Reg] = Count;
for (const unsigned *Subreg = TRI->getSubRegisters(Reg);
*Subreg; ++Subreg) {
unsigned SubregReg = *Subreg;
DefIndices[SubregReg] = Count;
for (const unsigned *Alias = TRI->getAliasSet(Reg);
*Alias; ++Alias) {
unsigned AliasReg = *Alias;
DefIndices[AliasReg] = Count;
}
}
}
@ -610,6 +627,18 @@ bool AggressiveAntiDepBreaker::FindSuitableFreeRegisters(
return false;
}
#ifndef NDEBUG
// If DebugDiv > 0 then only rename (renamecnt % DebugDiv) == DebugMod
if (DebugDiv > 0) {
static int renamecnt = 0;
if (renamecnt++ % DebugDiv != DebugMod)
return false;
errs() << "*** Performing rename " << TRI->getName(SuperReg) <<
" for debug ***\n";
}
#endif
if (RenameOrder.count(SuperRC) == 0)
RenameOrder.insert(RenameOrderType::value_type(SuperRC, RE));
@ -629,17 +658,18 @@ bool AggressiveAntiDepBreaker::FindSuitableFreeRegisters(
// If Reg is dead and Reg's most recent def is not before
// SuperRegs's kill, it's safe to replace SuperReg with Reg. We
// must also check all subregisters of Reg.
// must also check all aliases of Reg. because we can't define a
// register when any sub or super is already live.
if (State->IsLive(Reg) || (KillIndices[SuperReg] > DefIndices[Reg])) {
DEBUG(errs() << "(live)");
continue;
} else {
bool found = false;
for (const unsigned *Subreg = TRI->getSubRegisters(Reg);
*Subreg; ++Subreg) {
unsigned SubregReg = *Subreg;
if (State->IsLive(SubregReg) || (KillIndices[SuperReg] > DefIndices[SubregReg])) {
DEBUG(errs() << "(subreg " << TRI->getName(SubregReg) << " live)");
for (const unsigned *Alias = TRI->getAliasSet(Reg);
*Alias; ++Alias) {
unsigned AliasReg = *Alias;
if (State->IsLive(AliasReg) || (KillIndices[SuperReg] > DefIndices[AliasReg])) {
DEBUG(errs() << "(alias " << TRI->getName(AliasReg) << " live)");
found = true;
break;
}

4
llvm/lib/CodeGen/AggressiveAntiDepBreaker.h
View File

@ -175,7 +175,9 @@ namespace llvm {
/// return that register and all subregisters.
void GetPassthruRegs(MachineInstr *MI, std::set<unsigned>& PassthruRegs);
void HandleLastUse(unsigned Reg, unsigned KillIdx, const char *tag);
void HandleLastUse(unsigned Reg, unsigned KillIdx, const char *tag,
const char *header =NULL, const char *footer =NULL);
void PrescanInstruction(MachineInstr *MI, unsigned Count,
std::set<unsigned>& PassthruRegs);
void ScanInstruction(MachineInstr *MI, unsigned Count);