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[Sparc] Add support for leaf functions in sparc backend.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@182822 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Venkatraman Govindaraju
2013-05-29 04:46:31 +00:00
parent 0cf4adbcef
commit 5300869256
7 changed files with 180 additions and 28 deletions
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76
lib/Target/Sparc/SparcFrameLowering.cpp
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@ -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 @@ eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
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 @@ bool SparcFrameLowering::hasFP(const MachineFunction &MF) const {
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);
}
}