1 files changed, 142 insertions, 0 deletions
diff --git a/lib/CodeGen/RegUsageInfoCollector.cpp b/lib/CodeGen/RegUsageInfoCollector.cpp
new file mode 100644
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+++ b/lib/CodeGen/RegUsageInfoCollector.cpp
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+//===-- RegUsageInfoCollector.cpp - Register Usage Information Collector --===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+///
+/// This pass is required to take advantage of the interprocedural register
+/// allocation infrastructure.
+///
+/// This pass is simple MachineFunction pass which collects register usage
+/// details by iterating through each physical registers and checking
+/// MRI::isPhysRegUsed() then creates a RegMask based on this details.
+/// The pass then stores this RegMask in PhysicalRegisterUsageInfo.cpp
+///
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ADT/Statistic.h"
+#include "llvm/CodeGen/MachineBasicBlock.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineInstr.h"
+#include "llvm/CodeGen/MachineOperand.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/CodeGen/Passes.h"
+#include "llvm/CodeGen/RegisterUsageInfo.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/Target/TargetFrameLowering.h"
+
+using namespace llvm;
+
+#define DEBUG_TYPE "ip-regalloc"
+
+STATISTIC(NumCSROpt,
+          "Number of functions optimized for callee saved registers");
+
+namespace llvm {
+void initializeRegUsageInfoCollectorPass(PassRegistry &);
+}
+
+namespace {
+class RegUsageInfoCollector : public MachineFunctionPass {
+public:
+  RegUsageInfoCollector() : MachineFunctionPass(ID) {
+    PassRegistry &Registry = *PassRegistry::getPassRegistry();
+    initializeRegUsageInfoCollectorPass(Registry);
+  }
+
+  const char *getPassName() const override {
+    return "Register Usage Information Collector Pass";
+  }
+
+  void getAnalysisUsage(AnalysisUsage &AU) const override;
+
+  bool runOnMachineFunction(MachineFunction &MF) override;
+
+  static char ID;
+
+private:
+  void markRegClobbered(const TargetRegisterInfo *TRI, uint32_t *RegMask,
+                        unsigned PReg);
+};
+} // end of anonymous namespace
+
+char RegUsageInfoCollector::ID = 0;
+
+INITIALIZE_PASS_BEGIN(RegUsageInfoCollector, "RegUsageInfoCollector",
+                      "Register Usage Information Collector", false, false)
+INITIALIZE_PASS_DEPENDENCY(PhysicalRegisterUsageInfo)
+INITIALIZE_PASS_END(RegUsageInfoCollector, "RegUsageInfoCollector",
+                    "Register Usage Information Collector", false, false)
+
+FunctionPass *llvm::createRegUsageInfoCollector() {
+  return new RegUsageInfoCollector();
+}
+
+void RegUsageInfoCollector::markRegClobbered(const TargetRegisterInfo *TRI,
+                                             uint32_t *RegMask, unsigned PReg) {
+  // If PReg is clobbered then all of its alias are also clobbered.
+  for (MCRegAliasIterator AI(PReg, TRI, true); AI.isValid(); ++AI)
+    RegMask[*AI / 32] &= ~(1u << *AI % 32);
+}
+
+void RegUsageInfoCollector::getAnalysisUsage(AnalysisUsage &AU) const {
+  AU.addRequired<PhysicalRegisterUsageInfo>();
+  AU.setPreservesAll();
+  MachineFunctionPass::getAnalysisUsage(AU);
+}
+
+bool RegUsageInfoCollector::runOnMachineFunction(MachineFunction &MF) {
+  MachineRegisterInfo *MRI = &MF.getRegInfo();
+  const TargetRegisterInfo *TRI = MF.getSubtarget().getRegisterInfo();
+  const TargetMachine &TM = MF.getTarget();
+
+  DEBUG(dbgs() << " -------------------- " << getPassName()
+               << " -------------------- \n");
+  DEBUG(dbgs() << "Function Name : " << MF.getName() << "\n");
+
+  std::vector<uint32_t> RegMask;
+
+  // Compute the size of the bit vector to represent all the registers.
+  // The bit vector is broken into 32-bit chunks, thus takes the ceil of
+  // the number of registers divided by 32 for the size.
+  unsigned RegMaskSize = (TRI->getNumRegs() + 31) / 32;
+  RegMask.resize(RegMaskSize, 0xFFFFFFFF);
+
+  const Function *F = MF.getFunction();
+
+  PhysicalRegisterUsageInfo *PRUI = &getAnalysis<PhysicalRegisterUsageInfo>();
+
+  PRUI->setTargetMachine(&TM);
+
+  DEBUG(dbgs() << "Clobbered Registers: ");
+
+  for (unsigned PReg = 1, PRegE = TRI->getNumRegs(); PReg < PRegE; ++PReg)
+    if (MRI->isPhysRegModified(PReg, true))
+      markRegClobbered(TRI, &RegMask[0], PReg);
+
+  if (!TargetFrameLowering::isSafeForNoCSROpt(F)) {
+    const uint32_t *CallPreservedMask =
+        TRI->getCallPreservedMask(MF, F->getCallingConv());
+    // Set callee saved register as preserved.
+    for (unsigned i = 0; i < RegMaskSize; ++i)
+      RegMask[i] = RegMask[i] | CallPreservedMask[i];
+  } else {
+    ++NumCSROpt;
+    DEBUG(dbgs() << MF.getName()
+                 << " function optimized for not having CSR.\n");
+  }
+
+  for (unsigned PReg = 1, PRegE = TRI->getNumRegs(); PReg < PRegE; ++PReg)
+    if (MachineOperand::clobbersPhysReg(&(RegMask[0]), PReg))
+      DEBUG(dbgs() << TRI->getName(PReg) << " ");
+
+  DEBUG(dbgs() << " \n----------------------------------------\n");
+
+  PRUI->storeUpdateRegUsageInfo(F, std::move(RegMask));
+
+  return false;
+}