[llvm-commits] [llvm] r85522 - in /llvm/trunk/lib/CodeGen: AggressiveAntiDepBreaker.cpp AggressiveAntiDepBreaker.h
David Goodwin
david_goodwin at apple.com
Thu Oct 29 12:17:05 PDT 2009
Author: david_goodwin
Date: Thu Oct 29 14:17:04 2009
New Revision: 85522
URL: http://llvm.org/viewvc/llvm-project?rev=85522&view=rev
Log:
Fix a couple of bugs in aggressive anti-dep breaking.
Modified:
llvm/trunk/lib/CodeGen/AggressiveAntiDepBreaker.cpp
llvm/trunk/lib/CodeGen/AggressiveAntiDepBreaker.h
Modified: llvm/trunk/lib/CodeGen/AggressiveAntiDepBreaker.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AggressiveAntiDepBreaker.cpp?rev=85522&r1=85521&r2=85522&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/AggressiveAntiDepBreaker.cpp (original)
+++ llvm/trunk/lib/CodeGen/AggressiveAntiDepBreaker.cpp Thu Oct 29 14:17:04 2009
@@ -277,29 +277,55 @@
}
}
+void AggressiveAntiDepBreaker::HandleLastUse(unsigned Reg, unsigned KillIdx,
+ const char *tag) {
+ unsigned *KillIndices = State->GetKillIndices();
+ unsigned *DefIndices = State->GetDefIndices();
+ std::multimap<unsigned, AggressiveAntiDepState::RegisterReference>&
+ RegRefs = State->GetRegRefs();
+
+ if (!State->IsLive(Reg)) {
+ KillIndices[Reg] = KillIdx;
+ DefIndices[Reg] = ~0u;
+ RegRefs.erase(Reg);
+ State->LeaveGroup(Reg);
+ DEBUG(errs() << "->g" << State->GetGroup(Reg) << tag);
+ }
+ // Repeat for subregisters.
+ for (const unsigned *Subreg = TRI->getSubRegisters(Reg);
+ *Subreg; ++Subreg) {
+ unsigned SubregReg = *Subreg;
+ if (!State->IsLive(SubregReg)) {
+ KillIndices[SubregReg] = KillIdx;
+ DefIndices[SubregReg] = ~0u;
+ RegRefs.erase(SubregReg);
+ State->LeaveGroup(SubregReg);
+ DEBUG(errs() << " " << TRI->getName(SubregReg) << "->g" <<
+ State->GetGroup(SubregReg) << tag);
+ }
+ }
+}
+
void AggressiveAntiDepBreaker::PrescanInstruction(MachineInstr *MI, unsigned Count,
std::set<unsigned>& PassthruRegs) {
unsigned *DefIndices = State->GetDefIndices();
std::multimap<unsigned, AggressiveAntiDepState::RegisterReference>&
RegRefs = State->GetRegRefs();
- // Scan the register defs for this instruction and update
- // live-ranges, groups and RegRefs.
+ // Handle dead defs by simulating a last-use of the register just
+ // after the def. A dead def can occur because the def is truely
+ // dead, or because only a subregister is live at the def. If we
+ // don't do this the dead def will be incorrectly merged into the
+ // previous def.
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
MachineOperand &MO = MI->getOperand(i);
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;
-
- // Update Def for Reg and subregs.
- DefIndices[Reg] = Count;
- for (const unsigned *Subreg = TRI->getSubRegisters(Reg);
- *Subreg; ++Subreg) {
- unsigned SubregReg = *Subreg;
- DefIndices[SubregReg] = Count;
- }
+
+ DEBUG(errs() << "\tDead Def: " << TRI->getName(Reg));
+ HandleLastUse(Reg, Count + 1, "");
+ DEBUG(errs() << '\n');
}
DEBUG(errs() << "\tDef Groups:");
@@ -311,7 +337,7 @@
DEBUG(errs() << " " << TRI->getName(Reg) << "=g" << State->GetGroup(Reg));
- // If MI's defs have special allocation requirement, don't allow
+ // If MI's defs have a special allocation requirement, don't allow
// any def registers to be changed. Also assume all registers
// defined in a call must not be changed (ABI).
if (MI->getDesc().isCall() || MI->getDesc().hasExtraDefRegAllocReq()) {
@@ -320,7 +346,7 @@
}
// Any aliased that are live at this point are completely or
- // partially defined here, so group those subregisters with Reg.
+ // partially defined here, so group those aliases with Reg.
for (const unsigned *Alias = TRI->getAliasSet(Reg); *Alias; ++Alias) {
unsigned AliasReg = *Alias;
if (State->IsLive(AliasReg)) {
@@ -339,13 +365,30 @@
}
DEBUG(errs() << '\n');
+
+ // Scan the register defs for this instruction and update
+ // live-ranges.
+ for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
+ MachineOperand &MO = MI->getOperand(i);
+ 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;
+
+ // Update def for Reg and subregs.
+ DefIndices[Reg] = Count;
+ for (const unsigned *Subreg = TRI->getSubRegisters(Reg);
+ *Subreg; ++Subreg) {
+ unsigned SubregReg = *Subreg;
+ DefIndices[SubregReg] = Count;
+ }
+ }
}
void AggressiveAntiDepBreaker::ScanInstruction(MachineInstr *MI,
unsigned Count) {
DEBUG(errs() << "\tUse Groups:");
- unsigned *KillIndices = State->GetKillIndices();
- unsigned *DefIndices = State->GetDefIndices();
std::multimap<unsigned, AggressiveAntiDepState::RegisterReference>&
RegRefs = State->GetRegRefs();
@@ -363,26 +406,7 @@
// It wasn't previously live but now it is, this is a kill. Forget
// the previous live-range information and start a new live-range
// for the register.
- if (!State->IsLive(Reg)) {
- KillIndices[Reg] = Count;
- DefIndices[Reg] = ~0u;
- RegRefs.erase(Reg);
- State->LeaveGroup(Reg);
- DEBUG(errs() << "->g" << State->GetGroup(Reg) << "(last-use)");
- }
- // Repeat, for subregisters.
- for (const unsigned *Subreg = TRI->getSubRegisters(Reg);
- *Subreg; ++Subreg) {
- unsigned SubregReg = *Subreg;
- if (!State->IsLive(SubregReg)) {
- KillIndices[SubregReg] = Count;
- DefIndices[SubregReg] = ~0u;
- RegRefs.erase(SubregReg);
- State->LeaveGroup(SubregReg);
- DEBUG(errs() << " " << TRI->getName(SubregReg) << "->g" <<
- State->GetGroup(SubregReg) << "(last-use)");
- }
- }
+ HandleLastUse(Reg, Count, "(last-use)");
// If MI's uses have special allocation requirement, don't allow
// any use registers to be changed. Also assume all registers
@@ -511,6 +535,7 @@
}
// FIXME: for now just handle single register in group case...
+ // FIXME: check only regs that have references...
if (Regs.size() > 1)
return false;
Modified: llvm/trunk/lib/CodeGen/AggressiveAntiDepBreaker.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AggressiveAntiDepBreaker.h?rev=85522&r1=85521&r2=85522&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/AggressiveAntiDepBreaker.h (original)
+++ llvm/trunk/lib/CodeGen/AggressiveAntiDepBreaker.h Thu Oct 29 14:17:04 2009
@@ -159,6 +159,7 @@
/// return that register and all subregisters.
void GetPassthruRegs(MachineInstr *MI, std::set<unsigned>& PassthruRegs);
+ void HandleLastUse(unsigned Reg, unsigned KillIdx, const char *tag);
void PrescanInstruction(MachineInstr *MI, unsigned Count,
std::set<unsigned>& PassthruRegs);
void ScanInstruction(MachineInstr *MI, unsigned Count);
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