Prevent instructions using $gp from being placed between a jalr and the instruction that restores the clobbered $gp.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@130847 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/Mips/MipsEmitGPRestore.cpp b/lib/Target/Mips/MipsEmitGPRestore.cpp
new file mode 100644
index 0000000..dd541e5
--- /dev/null
+++ b/lib/Target/Mips/MipsEmitGPRestore.cpp
@@ -0,0 +1,80 @@
+//===-- MipsEmitGPRestore.cpp - Emit GP restore instruction-----------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===-----------------------------------------------------------------------===//
+//
+// This pass emits instructions that restore $gp right
+// after jalr instructions.
+//
+//===-----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "emit-gp-restore"
+
+#include "Mips.h"
+#include "MipsTargetMachine.h"
+#include "MipsMachineFunction.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/Target/TargetInstrInfo.h"
+#include "llvm/ADT/Statistic.h"
+
+using namespace llvm;
+
+namespace {
+ struct Inserter : public MachineFunctionPass {
+
+ TargetMachine &TM;
+ const TargetInstrInfo *TII;
+
+ static char ID;
+ Inserter(TargetMachine &tm)
+ : MachineFunctionPass(ID), TM(tm), TII(tm.getInstrInfo()) { }
+
+ virtual const char *getPassName() const {
+ return "Mips Emit GP Restore";
+ }
+
+ bool runOnMachineBasicBlock(MachineBasicBlock &MBB);
+ bool runOnMachineFunction(MachineFunction &F);
+ };
+ char Inserter::ID = 0;
+} // end of anonymous namespace
+
+bool Inserter::runOnMachineFunction(MachineFunction &F) {
+ if (TM.getRelocationModel() != Reloc::PIC_)
+ return false;
+
+ bool Changed = false;
+ int FI = F.getInfo<MipsFunctionInfo>()->getGPFI();
+
+ for (MachineFunction::iterator MFI = F.begin(), MFE = F.end();
+ MFI != MFE; ++MFI) {
+ MachineBasicBlock& MBB = *MFI;
+ MachineBasicBlock::iterator I = MFI->begin();
+
+ while (I != MFI->end()) {
+ if (I->getOpcode() != Mips::JALR) {
+ ++I;
+ continue;
+ }
+
+ DebugLoc dl = I->getDebugLoc();
+ // emit lw $gp, ($gp save slot on stack) after jalr
+ BuildMI(MBB, ++I, dl, TII->get(Mips::LW), Mips::GP).addImm(0).addFrameIndex(FI);
+ Changed = true;
+ }
+ }
+
+ return Changed;
+}
+
+/// createMipsEmitGPRestorePass - Returns a pass that emits instructions that
+/// restores $gp clobbered by jalr instructions.
+FunctionPass *llvm::createMipsEmitGPRestorePass(MipsTargetMachine &tm) {
+ return new Inserter(tm);
+}
+