[Sparc] Add support for leaf functions in sparc backend.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@182822 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/Sparc/SparcFrameLowering.cpp b/lib/Target/Sparc/SparcFrameLowering.cpp
index afa8411..3832c10 100644
--- a/lib/Target/Sparc/SparcFrameLowering.cpp
+++ b/lib/Target/Sparc/SparcFrameLowering.cpp
@@ -26,7 +26,18 @@
using namespace llvm;
+static cl::opt<bool>
+DisableLeafProc("disable-sparc-leaf-proc",
+ cl::init(true),
+ cl::desc("Disable Sparc leaf procedure optimization."),
+ cl::Hidden);
+
+
void SparcFrameLowering::emitPrologue(MachineFunction &MF) const {
+ SparcMachineFunctionInfo *FuncInfo = MF.getInfo<SparcMachineFunctionInfo>();
+ if (FuncInfo->isLeafProc())
+ return;
+
MachineBasicBlock &MBB = MF.front();
MachineFrameInfo *MFI = MF.getFrameInfo();
const SparcInstrInfo &TII =
@@ -97,6 +108,9 @@
void SparcFrameLowering::emitEpilogue(MachineFunction &MF,
MachineBasicBlock &MBB) const {
+ SparcMachineFunctionInfo *FuncInfo = MF.getInfo<SparcMachineFunctionInfo>();
+ if (FuncInfo->isLeafProc())
+ return;
MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr();
const SparcInstrInfo &TII =
*static_cast<const SparcInstrInfo*>(MF.getTarget().getInstrInfo());
@@ -121,3 +135,65 @@
MFI->hasVarSizedObjects() || MFI->isFrameAddressTaken();
}
+
+static bool verifyLeafProcRegUse(MachineRegisterInfo *MRI)
+{
+
+ for (unsigned reg = SP::I0; reg <= SP::I7; ++reg)
+ if (MRI->isPhysRegUsed(reg))
+ return false;
+
+ for (unsigned reg = SP::L0; reg <= SP::L7; ++reg)
+ if (MRI->isPhysRegUsed(reg))
+ return false;
+
+ return true;
+}
+
+bool SparcFrameLowering::isLeafProc(MachineFunction &MF) const
+{
+
+ MachineRegisterInfo &MRI = MF.getRegInfo();
+ MachineFrameInfo *MFI = MF.getFrameInfo();
+
+ return !(MFI->hasCalls() // has calls
+ || MRI.isPhysRegUsed(SP::L0) // Too many registers needed
+ || MRI.isPhysRegUsed(SP::O6) // %SP is used
+ || hasFP(MF)); // need %FP
+}
+
+void SparcFrameLowering::remapRegsForLeafProc(MachineFunction &MF) const {
+
+ MachineRegisterInfo &MRI = MF.getRegInfo();
+
+ //remap %i[0-7] to %o[0-7]
+ for (unsigned reg = SP::I0; reg <= SP::I7; ++reg) {
+ if (!MRI.isPhysRegUsed(reg))
+ continue;
+ unsigned mapped_reg = (reg - SP::I0 + SP::O0);
+ assert(!MRI.isPhysRegUsed(mapped_reg));
+
+ //Replace I register with O register
+ MRI.replaceRegWith(reg, mapped_reg);
+
+ //mark the reg unused.
+ MRI.setPhysRegUnused(reg);
+ }
+
+ assert(verifyLeafProcRegUse(&MRI));
+#ifdef XDEBUG
+ MF.verify(0, "After LeafProc Remapping");
+#endif
+}
+
+void SparcFrameLowering::processFunctionBeforeCalleeSavedScan
+ (MachineFunction &MF, RegScavenger *RS) const {
+
+ if (!DisableLeafProc && isLeafProc(MF)) {
+ SparcMachineFunctionInfo *MFI = MF.getInfo<SparcMachineFunctionInfo>();
+ MFI->setLeafProc(true);
+
+ remapRegsForLeafProc(MF);
+ }
+
+}