1 files changed, 124 insertions, 0 deletions
diff --git a/contrib/llvm/lib/Target/SystemZ/SystemZPostRewrite.cpp b/contrib/llvm/lib/Target/SystemZ/SystemZPostRewrite.cpp
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index 000000000000..8e4060eac74c
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+++ b/contrib/llvm/lib/Target/SystemZ/SystemZPostRewrite.cpp
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+//==---- SystemZPostRewrite.cpp - Select pseudos after RegAlloc ---*- C++ -*-=//
+//
+// 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 contains a pass that is run immediately after VirtRegRewriter
+// but before MachineCopyPropagation. The purpose is to lower pseudos to
+// target instructions before any later pass might substitute a register for
+// another.
+//
+//===----------------------------------------------------------------------===//
+
+#include "SystemZ.h"
+#include "SystemZInstrInfo.h"
+#include "SystemZSubtarget.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+using namespace llvm;
+
+#define SYSTEMZ_POSTREWRITE_NAME "SystemZ Post Rewrite pass"
+
+#define DEBUG_TYPE "systemz-postrewrite"
+STATISTIC(MemFoldCopies, "Number of copies inserted before folded mem ops.");
+
+namespace llvm {
+  void initializeSystemZPostRewritePass(PassRegistry&);
+}
+
+namespace {
+
+class SystemZPostRewrite : public MachineFunctionPass {
+public:
+  static char ID;
+  SystemZPostRewrite() : MachineFunctionPass(ID) {
+    initializeSystemZPostRewritePass(*PassRegistry::getPassRegistry());
+  }
+
+  const SystemZInstrInfo *TII;
+
+  bool runOnMachineFunction(MachineFunction &Fn) override;
+
+  StringRef getPassName() const override { return SYSTEMZ_POSTREWRITE_NAME; }
+
+  void getAnalysisUsage(AnalysisUsage &AU) const override {
+    AU.setPreservesAll();
+    MachineFunctionPass::getAnalysisUsage(AU);
+  }
+
+private:
+  bool selectMI(MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI,
+                MachineBasicBlock::iterator &NextMBBI);
+  bool selectMBB(MachineBasicBlock &MBB);
+};
+
+char SystemZPostRewrite::ID = 0;
+
+} // end anonymous namespace
+
+INITIALIZE_PASS(SystemZPostRewrite, "systemz-post-rewrite",
+                SYSTEMZ_POSTREWRITE_NAME, false, false)
+
+/// Returns an instance of the Post Rewrite pass.
+FunctionPass *llvm::createSystemZPostRewritePass(SystemZTargetMachine &TM) {
+  return new SystemZPostRewrite();
+}
+
+/// If MBBI references a pseudo instruction that should be selected here,
+/// do it and return true.  Otherwise return false.
+bool SystemZPostRewrite::selectMI(MachineBasicBlock &MBB,
+                                MachineBasicBlock::iterator MBBI,
+                                MachineBasicBlock::iterator &NextMBBI) {
+  MachineInstr &MI = *MBBI;
+  unsigned Opcode = MI.getOpcode();
+
+  // Note: If this could be done during regalloc in foldMemoryOperandImpl()
+  // while also updating the LiveIntervals, there would be no need for the
+  // MemFoldPseudo to begin with.
+  int TargetMemOpcode = SystemZ::getTargetMemOpcode(Opcode);
+  if (TargetMemOpcode != -1) {
+    MI.setDesc(TII->get(TargetMemOpcode));
+    MI.tieOperands(0, 1);
+    unsigned DstReg = MI.getOperand(0).getReg();
+    MachineOperand &SrcMO = MI.getOperand(1);
+    if (DstReg != SrcMO.getReg()) {
+      BuildMI(MBB, &MI, MI.getDebugLoc(), TII->get(SystemZ::COPY), DstReg)
+        .addReg(SrcMO.getReg());
+      SrcMO.setReg(DstReg);
+      MemFoldCopies++;
+    }
+    return true;
+  }
+
+  return false;
+}
+
+/// Iterate over the instructions in basic block MBB and select any
+/// pseudo instructions.  Return true if anything was modified.
+bool SystemZPostRewrite::selectMBB(MachineBasicBlock &MBB) {
+  bool Modified = false;
+
+  MachineBasicBlock::iterator MBBI = MBB.begin(), E = MBB.end();
+  while (MBBI != E) {
+    MachineBasicBlock::iterator NMBBI = std::next(MBBI);
+    Modified |= selectMI(MBB, MBBI, NMBBI);
+    MBBI = NMBBI;
+  }
+
+  return Modified;
+}
+
+bool SystemZPostRewrite::runOnMachineFunction(MachineFunction &MF) {
+  TII = static_cast<const SystemZInstrInfo *>(MF.getSubtarget().getInstrInfo());
+
+  bool Modified = false;
+  for (auto &MBB : MF)
+    Modified |= selectMBB(MBB);
+
+  return Modified;
+}
+