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[mlgo][regalloc] Fix register masking 

If AllocationOrder has less than 32 elements, we were treating the extra
positions as if they were valid. This was detected by a subsequent
assert. The fix also tightens the asserts.
This commit is contained in:
Mircea Trofin 2022-01-30 14:56:38 -08:00
parent dc3b9365b6
commit a8a7bf922c
1 changed files with 4 additions and 3 deletions
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7
llvm/lib/CodeGen/MLRegallocEvictAdvisor.cpp
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@ -615,16 +615,15 @@ MCRegister MLEvictAdvisor::tryFindEvictionCandidate(
for (auto I = Order.begin(), E = Order.getOrderLimitEnd(OrderLimit); I != E; for (auto I = Order.begin(), E = Order.getOrderLimitEnd(OrderLimit); I != E;
++I, ++Pos) { ++I, ++Pos) {
MCRegister PhysReg = *I; MCRegister PhysReg = *I;
Regs[Pos] = std::make_pair(PhysReg, true); assert(!Regs[Pos].second);
assert(PhysReg); assert(PhysReg);
if (!canAllocatePhysReg(CostPerUseLimit, PhysReg)) { if (!canAllocatePhysReg(CostPerUseLimit, PhysReg)) {
Regs[Pos].second = false;
continue; continue;
} }
if (loadInterferenceFeatures(VirtReg, PhysReg, I.isHint(), FixedRegisters, if (loadInterferenceFeatures(VirtReg, PhysReg, I.isHint(), FixedRegisters,
Largest, Pos)) { Largest, Pos)) {
++Available; ++Available;
Regs[Pos].second = true; Regs[Pos] = std::make_pair(PhysReg, true);
} }
} }
if (Available == 0) { if (Available == 0) {
@ -632,6 +631,7 @@ MCRegister MLEvictAdvisor::tryFindEvictionCandidate(
assert(!MustFindEviction); assert(!MustFindEviction);
return MCRegister::NoRegister; return MCRegister::NoRegister;
} }
const size_t ValidPosLimit = Pos;
// If we must find eviction, the candidate should be masked out of the // If we must find eviction, the candidate should be masked out of the
// decision making process. // decision making process.
Regs[CandidateVirtRegPos].second = !MustFindEviction; Regs[CandidateVirtRegPos].second = !MustFindEviction;
@ -665,6 +665,7 @@ MCRegister MLEvictAdvisor::tryFindEvictionCandidate(
assert(!MustFindEviction); assert(!MustFindEviction);
return MCRegister::NoRegister; return MCRegister::NoRegister;
} }
assert(CandidatePos < ValidPosLimit);
return Regs[CandidatePos].first; return Regs[CandidatePos].first;
} }