void X86FrameLowering::BuildStackAlignAND(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MBBI,
- DebugLoc DL,
+ DebugLoc DL, unsigned Reg,
uint64_t MaxAlign) const {
uint64_t Val = -MaxAlign;
- MachineInstr *MI =
- BuildMI(MBB, MBBI, DL, TII.get(getANDriOpcode(Uses64BitFramePtr, Val)),
- StackPtr)
- .addReg(StackPtr)
- .addImm(Val)
- .setMIFlag(MachineInstr::FrameSetup);
+ unsigned AndOp = getANDriOpcode(Uses64BitFramePtr, Val);
+ MachineInstr *MI = BuildMI(MBB, MBBI, DL, TII.get(AndOp), Reg)
+ .addReg(Reg)
+ .addImm(Val)
+ .setMIFlag(MachineInstr::FrameSetup);
// The EFLAGS implicit def is dead.
MI->getOperand(3).setIsDead();
// Don't do this for Win64, it needs to realign the stack after the prologue.
if (!IsWin64Prologue && !IsFunclet && TRI->needsStackRealignment(MF)) {
assert(HasFP && "There should be a frame pointer if stack is realigned.");
- BuildStackAlignAND(MBB, MBBI, DL, MaxAlign);
+ BuildStackAlignAND(MBB, MBBI, DL, StackPtr, MaxAlign);
}
// If there is an SUB32ri of ESP immediately before this instruction, merge
.setMIFlag(MachineInstr::FrameSetup);
int SEHFrameOffset = 0;
+ unsigned SPOrEstablisher = IsFunclet ? Establisher : StackPtr;
if (IsWin64Prologue && HasFP) {
// Set RBP to a small fixed offset from RSP. In the funclet case, we base
// this calculation on the incoming establisher, which holds the value of
// RSP from the parent frame at the end of the prologue.
- unsigned SPOrEstablisher = IsFunclet ? Establisher : StackPtr;
SEHFrameOffset = calculateSetFPREG(ParentFrameNumBytes);
if (SEHFrameOffset)
addRegOffset(BuildMI(MBB, MBBI, DL, TII.get(X86::LEA64r), FramePtr),
// Win64 requires aligning the stack after the prologue.
if (IsWin64Prologue && TRI->needsStackRealignment(MF)) {
assert(HasFP && "There should be a frame pointer if stack is realigned.");
- BuildStackAlignAND(MBB, MBBI, DL, MaxAlign);
+ BuildStackAlignAND(MBB, MBBI, DL, SPOrEstablisher, MaxAlign);
}
+ // We already dealt with stack realignment and funclets above.
+ if (IsFunclet && STI.is32Bit())
+ return;
+
// If we need a base pointer, set it up here. It's whatever the value
// of the stack pointer is at this point. Any variable size objects
// will be allocated after this, so we can still use the base pointer
// Update the base pointer with the current stack pointer.
unsigned Opc = Uses64BitFramePtr ? X86::MOV64rr : X86::MOV32rr;
BuildMI(MBB, MBBI, DL, TII.get(Opc), BasePtr)
- .addReg(StackPtr)
+ .addReg(SPOrEstablisher)
.setMIFlag(MachineInstr::FrameSetup);
if (X86FI->getRestoreBasePointer()) {
// Stash value of base pointer. Saving RSP instead of EBP shortens
unsigned Opm = Uses64BitFramePtr ? X86::MOV64mr : X86::MOV32mr;
addRegOffset(BuildMI(MBB, MBBI, DL, TII.get(Opm)),
FramePtr, true, X86FI->getRestoreBasePointerOffset())
- .addReg(StackPtr)
+ .addReg(SPOrEstablisher)
.setMIFlag(MachineInstr::FrameSetup);
}
- if (X86FI->getHasSEHFramePtrSave()) {
+ if (X86FI->getHasSEHFramePtrSave() && !IsFunclet) {
// Stash the value of the frame pointer relative to the base pointer for
// Win32 EH. This supports Win32 EH, which does the inverse of the above:
// it recovers the frame pointer from the base pointer rather than the
const uint64_t StackSize = MFI->getStackSize();
{
#ifndef NDEBUG
- // Note: LLVM arranges the stack as:
- // Args > Saved RetPC (<--FP) > CSRs > dynamic alignment (<--BP)
- // > "Stack Slots" (<--SP)
- // We can always address StackSlots from RSP. We can usually (unless
- // needsStackRealignment) address CSRs from RSP, but sometimes need to
- // address them from RBP. FixedObjects can be placed anywhere in the stack
- // frame depending on their specific requirements (i.e. we can actually
- // refer to arguments to the function which are stored in the *callers*
- // frame). As a result, THE RESULT OF THIS CALL IS MEANINGLESS FOR CSRs
- // AND FixedObjects IFF needsStackRealignment or hasVarSizedObject.
-
- assert(!TRI->hasBasePointer(MF) && "we don't handle this case");
-
- // We don't handle tail calls, and shouldn't be seeing them
- // either.
+ // LLVM arranges the stack as follows:
+ // ...
+ // ARG2
+ // ARG1
+ // RETADDR
+ // PUSH RBP <-- RBP points here
+ // PUSH CSRs
+ // ~~~~~~~ <-- optional stack realignment dynamic adjustment
+ // ...
+ // STACK OBJECTS
+ // ... <-- RSP after prologue points here
+ //
+ // if (hasVarSizedObjects()):
+ // ... <-- "base pointer" (ESI/RBX) points here
+ // DYNAMIC ALLOCAS
+ // ... <-- RSP points here
+ //
+ // Case 1: In the simple case of no stack realignment and no dynamic
+ // allocas, both "fixed" stack objects (arguments and CSRs) are addressable
+ // with fixed offsets from RSP.
+ //
+ // Case 2: In the case of stack realignment with no dynamic allocas, fixed
+ // stack objects are addressed with RBP and regular stack objects with RSP.
+ //
+ // Case 3: In the case of dynamic allocas and stack realignment, RSP is used
+ // to address stack arguments for outgoing calls and nothing else. The "base
+ // pointer" points to local variables, and RBP points to fixed objects.
+ //
+ // In cases 2 and 3, we can only answer for non-fixed stack objects, and the
+ // answer we give is relative to the SP after the prologue, and not the
+ // SP in the middle of the function.
+
+ assert((!TRI->needsStackRealignment(MF) || !MFI->isFixedObjectIndex(FI)) &&
+ "offset from fixed object to SP is not static");
+
+ // We don't handle tail calls, and shouldn't be seeing them either.
int TailCallReturnAddrDelta =
MF.getInfo<X86MachineFunctionInfo>()->getTCReturnAddrDelta();
assert(!(TailCallReturnAddrDelta < 0) && "we don't handle this case!");
projects / oota-llvm.git / blobdiff