1 files changed, 88 insertions, 0 deletions
diff --git a/llvm/lib/CodeGen/LiveStacks.cpp b/llvm/lib/CodeGen/LiveStacks.cpp
new file mode 100644
index 000000000000..8df84ebf4f06
--- /dev/null
+++ b/llvm/lib/CodeGen/LiveStacks.cpp
@@ -0,0 +1,88 @@
+//===-- LiveStacks.cpp - Live Stack Slot Analysis -------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the live stack slot analysis pass. It is analogous to
+// live interval analysis except it's analyzing liveness of stack slots rather
+// than registers.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/CodeGen/LiveStacks.h"
+#include "llvm/CodeGen/LiveIntervals.h"
+#include "llvm/CodeGen/Passes.h"
+#include "llvm/CodeGen/TargetRegisterInfo.h"
+#include "llvm/CodeGen/TargetSubtargetInfo.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
+using namespace llvm;
+
+#define DEBUG_TYPE "livestacks"
+
+char LiveStacks::ID = 0;
+INITIALIZE_PASS_BEGIN(LiveStacks, DEBUG_TYPE,
+                "Live Stack Slot Analysis", false, false)
+INITIALIZE_PASS_DEPENDENCY(SlotIndexes)
+INITIALIZE_PASS_END(LiveStacks, DEBUG_TYPE,
+                "Live Stack Slot Analysis", false, false)
+
+char &llvm::LiveStacksID = LiveStacks::ID;
+
+void LiveStacks::getAnalysisUsage(AnalysisUsage &AU) const {
+  AU.setPreservesAll();
+  AU.addPreserved<SlotIndexes>();
+  AU.addRequiredTransitive<SlotIndexes>();
+  MachineFunctionPass::getAnalysisUsage(AU);
+}
+
+void LiveStacks::releaseMemory() {
+  // Release VNInfo memory regions, VNInfo objects don't need to be dtor'd.
+  VNInfoAllocator.Reset();
+  S2IMap.clear();
+  S2RCMap.clear();
+}
+
+bool LiveStacks::runOnMachineFunction(MachineFunction &MF) {
+  TRI = MF.getSubtarget().getRegisterInfo();
+  // FIXME: No analysis is being done right now. We are relying on the
+  // register allocators to provide the information.
+  return false;
+}
+
+LiveInterval &
+LiveStacks::getOrCreateInterval(int Slot, const TargetRegisterClass *RC) {
+  assert(Slot >= 0 && "Spill slot indice must be >= 0");
+  SS2IntervalMap::iterator I = S2IMap.find(Slot);
+  if (I == S2IMap.end()) {
+    I = S2IMap
+            .emplace(
+                std::piecewise_construct, std::forward_as_tuple(Slot),
+                std::forward_as_tuple(Register::index2StackSlot(Slot), 0.0F))
+            .first;
+    S2RCMap.insert(std::make_pair(Slot, RC));
+  } else {
+    // Use the largest common subclass register class.
+    const TargetRegisterClass *OldRC = S2RCMap[Slot];
+    S2RCMap[Slot] = TRI->getCommonSubClass(OldRC, RC);
+  }
+  return I->second;
+}
+
+/// print - Implement the dump method.
+void LiveStacks::print(raw_ostream &OS, const Module*) const {
+
+  OS << "********** INTERVALS **********\n";
+  for (const_iterator I = begin(), E = end(); I != E; ++I) {
+    I->second.print(OS);
+    int Slot = I->first;
+    const TargetRegisterClass *RC = getIntervalRegClass(Slot);
+    if (RC)
+      OS << " [" << TRI->getRegClassName(RC) << "]\n";
+    else
+      OS << " [Unknown]\n";
+  }
+}