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[mips] Add support for dynamic stack realignment.

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Summary:
With this change we are able to realign the stack dynamically, whenever it
contains objects with alignment requirements that are larger than the
alignment specified from the given ABI.

We have to use the $fp register as the frame pointer when we perform
dynamic stack realignment. In complex stack frames, with variably-sized
objects, we reserve additionally the callee-saved register $s7 as the
base pointer in order to reference locals.

Reviewers: dsanders

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D8633

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@238829 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Vasileios Kalintiris
2015-06-02 13:14:46 +00:00
parent 9751e35f20
commit 330e5f16d1
10 changed files with 443 additions and 11 deletions
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34
lib/Target/Mips/MipsSEFrameLowering.cpp
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@@ -382,6 +382,11 @@ void MipsSEFrameLowering::emitPrologue(MachineFunction &MF,
unsigned FP = ABI.GetFramePtr();
unsigned ZERO = ABI.GetNullPtr();
unsigned ADDu = ABI.GetPtrAdduOp();
unsigned ADDiu = ABI.GetPtrAddiuOp();
unsigned AND = ABI.IsN64() ? Mips::AND64 : Mips::AND;
const TargetRegisterClass *RC = ABI.ArePtrs64bit() ?
&Mips::GPR64RegClass : &Mips::GPR32RegClass;
// First, compute final stack size.
uint64_t StackSize = MFI->getStackSize();
@@ -464,15 +469,12 @@ void MipsSEFrameLowering::emitPrologue(MachineFunction &MF,
}
if (MipsFI->callsEhReturn()) {
const TargetRegisterClass *PtrRC =
ABI.ArePtrs64bit() ? &Mips::GPR64RegClass : &Mips::GPR32RegClass;
// Insert instructions that spill eh data registers.
for (int I = 0; I < 4; ++I) {
if (!MBB.isLiveIn(ABI.GetEhDataReg(I)))
MBB.addLiveIn(ABI.GetEhDataReg(I));
TII.storeRegToStackSlot(MBB, MBBI, ABI.GetEhDataReg(I), false,
MipsFI->getEhDataRegFI(I), PtrRC, &RegInfo);
MipsFI->getEhDataRegFI(I), RC, &RegInfo);
}
// Emit .cfi_offset directives for eh data registers.
@@ -497,6 +499,26 @@ void MipsSEFrameLowering::emitPrologue(MachineFunction &MF,
nullptr, MRI->getDwarfRegNum(FP, true)));
BuildMI(MBB, MBBI, dl, TII.get(TargetOpcode::CFI_INSTRUCTION))
.addCFIIndex(CFIIndex);
if (RegInfo.needsStackRealignment(MF)) {
// addiu $Reg, $zero, -MaxAlignment
// andi $sp, $sp, $Reg
unsigned VR = MF.getRegInfo().createVirtualRegister(RC);
assert(isInt<16>(MFI->getMaxAlignment()) &&
"Function's alignment size requirement is not supported.");
int MaxAlign = - (signed) MFI->getMaxAlignment();
BuildMI(MBB, MBBI, dl, TII.get(ADDiu), VR).addReg(ZERO) .addImm(MaxAlign);
BuildMI(MBB, MBBI, dl, TII.get(AND), SP).addReg(SP).addReg(VR);
if (hasBP(MF)) {
// move $s7, $sp
unsigned BP = STI.isABI_N64() ? Mips::S7_64 : Mips::S7;
BuildMI(MBB, MBBI, dl, TII.get(ADDu), BP)
.addReg(SP)
.addReg(ZERO);
}
}
}
}
@@ -606,10 +628,14 @@ processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
MipsFunctionInfo *MipsFI = MF.getInfo<MipsFunctionInfo>();
MipsABIInfo ABI = STI.getABI();
unsigned FP = ABI.GetFramePtr();
unsigned BP = ABI.IsN64() ? Mips::S7_64 : Mips::S7;
// Mark $fp as used if function has dedicated frame pointer.
if (hasFP(MF))
MRI.setPhysRegUsed(FP);
// Mark $s7 as used if function has dedicated base pointer.
if (hasBP(MF))
MRI.setPhysRegUsed(BP);
// Create spill slots for eh data registers if function calls eh_return.
if (MipsFI->callsEhReturn())