Do a scheduling pass ignoring anti-dependencies to identify candidate registers that should be renamed.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85939 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/AggressiveAntiDepBreaker.cpp b/lib/CodeGen/AggressiveAntiDepBreaker.cpp
index 5506a1f..ffb6315 100644
--- a/lib/CodeGen/AggressiveAntiDepBreaker.cpp
+++ b/lib/CodeGen/AggressiveAntiDepBreaker.cpp
@@ -14,7 +14,7 @@
//
//===----------------------------------------------------------------------===//
-#define DEBUG_TYPE "aggressive-antidep"
+#define DEBUG_TYPE "post-RA-sched"
#include "AggressiveAntiDepBreaker.h"
#include "llvm/CodeGen/MachineBasicBlock.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
@@ -31,7 +31,7 @@
static cl::opt<int>
AntiDepTrials("agg-antidep-trials",
cl::desc("Maximum number of anti-dependency breaking passes"),
- cl::init(2), cl::Hidden);
+ cl::init(1), cl::Hidden);
AggressiveAntiDepState::AggressiveAntiDepState(MachineBasicBlock *BB) :
GroupNodes(TargetRegisterInfo::FirstVirtualRegister, 0) {
@@ -265,18 +265,24 @@
}
/// AntiDepPathStep - Return SUnit that SU has an anti-dependence on.
-static void AntiDepPathStep(SUnit *SU, std::vector<SDep*>& Edges) {
- SmallSet<unsigned, 8> Dups;
+static void AntiDepPathStep(SUnit *SU, AntiDepBreaker::AntiDepRegVector& Regs,
+ std::vector<SDep*>& Edges) {
+ AntiDepBreaker::AntiDepRegSet RegSet;
+ for (unsigned i = 0, e = Regs.size(); i < e; ++i)
+ RegSet.insert(Regs[i]);
+
for (SUnit::pred_iterator P = SU->Preds.begin(), PE = SU->Preds.end();
P != PE; ++P) {
if (P->getKind() == SDep::Anti) {
unsigned Reg = P->getReg();
- if (Dups.count(Reg) == 0) {
+ if (RegSet.count(Reg) != 0) {
Edges.push_back(&*P);
- Dups.insert(Reg);
+ RegSet.erase(Reg);
}
}
}
+
+ assert(RegSet.empty() && "Expected all antidep registers to be found");
}
void AggressiveAntiDepBreaker::HandleLastUse(unsigned Reg, unsigned KillIdx,
@@ -593,6 +599,7 @@
///
unsigned AggressiveAntiDepBreaker::BreakAntiDependencies(
std::vector<SUnit>& SUnits,
+ CandidateMap& Candidates,
MachineBasicBlock::iterator& Begin,
MachineBasicBlock::iterator& End,
unsigned InsertPosIndex) {
@@ -601,9 +608,15 @@
std::multimap<unsigned, AggressiveAntiDepState::RegisterReference>&
RegRefs = State->GetRegRefs();
+ // Nothing to do if no candidates.
+ if (Candidates.empty()) {
+ DEBUG(errs() << "\n===== No anti-dependency candidates\n");
+ return 0;
+ }
+
// The code below assumes that there is at least one instruction,
// so just duck out immediately if the block is empty.
- if (SUnits.empty()) return false;
+ if (SUnits.empty()) return 0;
// Manage saved state to enable multiple passes...
if (AntiDepTrials > 1) {
@@ -618,7 +631,8 @@
// ...need a map from MI to SUnit.
std::map<MachineInstr *, SUnit *> MISUnitMap;
- DEBUG(errs() << "Breaking all anti-dependencies\n");
+ DEBUG(errs() << "\n===== Attempting to break " << Candidates.size() <<
+ " anti-dependencies\n");
for (unsigned i = 0, e = SUnits.size(); i != e; ++i) {
SUnit *SU = &SUnits[i];
MISUnitMap.insert(std::pair<MachineInstr *, SUnit *>(SU->getInstr(), SU));
@@ -655,8 +669,10 @@
std::vector<SDep*> Edges;
SUnit *PathSU = MISUnitMap[MI];
- if (PathSU)
- AntiDepPathStep(PathSU, Edges);
+ AntiDepBreaker::CandidateMap::iterator
+ citer = Candidates.find(PathSU);
+ if (citer != Candidates.end())
+ AntiDepPathStep(PathSU, citer->second, Edges);
// Ignore KILL instructions (they form a group in ScanInstruction
// but don't cause any anti-dependence breaking themselves)