#include "X86Subtarget.h"
#include "X86TargetMachine.h"
#include "llvm/ADT/SmallSet.h"
+#include "llvm/Analysis/LibCallSemantics.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
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();
uint64_t MaxAlign = calculateMaxStackAlign(MF); // Desired stack alignment.
uint64_t StackSize = MFI->getStackSize(); // Number of bytes to allocate.
bool IsFunclet = MBB.isEHFuncletEntry();
+ bool IsClrFunclet =
+ IsFunclet &&
+ classifyEHPersonality(Fn->getPersonalityFn()) == EHPersonality::CoreCLR;
bool HasFP = hasFP(MF);
bool IsWin64CC = STI.isCallingConvWin64(Fn->getCallingConv());
bool IsWin64Prologue = MF.getTarget().getMCAsmInfo()->usesWindowsCFI();
? getX86SubSuperRegister(FramePtr, MVT::i64, false)
: FramePtr;
unsigned BasePtr = TRI->getBaseRegister();
+
+ // Debug location must be unknown since the first debug location is used
+ // to determine the end of the prologue.
DebugLoc DL;
// Add RETADDR move area to callee saved frame size.
uint64_t NumBytes = 0;
int stackGrowth = -SlotSize;
- unsigned RDX = Uses64BitFramePtr ? X86::RDX : X86::EDX;
- if (IsWin64Prologue && IsFunclet) {
- // Immediately spill RDX into the home slot. The runtime cares about this.
+ // Find the funclet establisher parameter
+ unsigned Establisher = X86::NoRegister;
+ if (IsClrFunclet)
+ Establisher = Uses64BitFramePtr ? X86::RCX : X86::ECX;
+ else if (IsFunclet)
+ Establisher = Uses64BitFramePtr ? X86::RDX : X86::EDX;
+
+ if (IsWin64Prologue && IsFunclet & !IsClrFunclet) {
+ // Immediately spill establisher into the home slot.
+ // The runtime cares about this.
// MOV64mr %rdx, 16(%rsp)
unsigned MOVmr = Uses64BitFramePtr ? X86::MOV64mr : X86::MOV32mr;
addRegOffset(BuildMI(MBB, MBBI, DL, TII.get(MOVmr)), StackPtr, true, 16)
- .addReg(RDX)
+ .addReg(Establisher)
.setMIFlag(MachineInstr::FrameSetup);
+ MBB.addLiveIn(Establisher);
}
if (HasFP) {
}
}
- // Mark the FramePtr as live-in in every block.
- for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I)
- I->addLiveIn(MachineFramePtr);
+ // Mark the FramePtr as live-in in every block. Don't do this again for
+ // funclet prologues.
+ if (!IsFunclet) {
+ for (MachineBasicBlock &EveryMBB : MF)
+ EveryMBB.addLiveIn(MachineFramePtr);
+ }
} else {
assert(!IsFunclet && "funclets without FPs not yet implemented");
NumBytes = StackSize - X86FI->getCalleeSavedFrameSize();
// 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 RDX, which holds the value of RSP from
- // the parent frame at the end of the prologue.
- unsigned SPOrRDX = !IsFunclet ? StackPtr : RDX;
+ // this calculation on the incoming establisher, which holds the value of
+ // RSP from the parent frame at the end of the prologue.
SEHFrameOffset = calculateSetFPREG(ParentFrameNumBytes);
if (SEHFrameOffset)
addRegOffset(BuildMI(MBB, MBBI, DL, TII.get(X86::LEA64r), FramePtr),
- SPOrRDX, false, SEHFrameOffset);
+ SPOrEstablisher, false, SEHFrameOffset);
else
BuildMI(MBB, MBBI, DL, TII.get(X86::MOV64rr), FramePtr)
- .addReg(SPOrRDX);
+ .addReg(SPOrEstablisher);
// If this is not a funclet, emit the CFI describing our frame pointer.
if (NeedsWinCFI && !IsFunclet)
// 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
bool NeedsWinCFI =
IsWin64Prologue && MF.getFunction()->needsUnwindTableEntry();
bool IsFunclet = isFuncletReturnInstr(MBBI);
- MachineBasicBlock *RestoreMBB = nullptr;
+ MachineBasicBlock *TargetMBB = nullptr;
// Get the number of bytes to allocate from the FrameInfo.
uint64_t StackSize = MFI->getStackSize();
uint64_t NumBytes = 0;
if (MBBI->getOpcode() == X86::CATCHRET) {
+ // SEH shouldn't use catchret.
+ assert(!isAsynchronousEHPersonality(
+ classifyEHPersonality(MF.getFunction()->getPersonalityFn())) &&
+ "SEH should not use CATCHRET");
+
NumBytes = getWinEHFuncletFrameSize(MF);
assert(hasFP(MF) && "EH funclets without FP not yet implemented");
- MachineBasicBlock *TargetMBB = MBBI->getOperand(0).getMBB();
-
- // If this is SEH, this isn't really a funclet return.
- bool IsSEH = isAsynchronousEHPersonality(
- classifyEHPersonality(MF.getFunction()->getPersonalityFn()));
- if (IsSEH) {
- if (STI.is32Bit())
- restoreWin32EHStackPointers(MBB, MBBI, DL, /*RestoreSP=*/true);
- BuildMI(MBB, MBBI, DL, TII.get(X86::JMP_4)).addMBB(TargetMBB);
- MBBI->eraseFromParent();
- return;
- }
-
- // For 32-bit, create a new block for the restore code.
- RestoreMBB = TargetMBB;
- if (STI.is32Bit()) {
- RestoreMBB = MF.CreateMachineBasicBlock(MBB.getBasicBlock());
- MF.insert(TargetMBB->getIterator(), RestoreMBB);
- MBB.removeSuccessor(TargetMBB);
- MBB.addSuccessor(RestoreMBB);
- RestoreMBB->addSuccessor(TargetMBB);
- MBBI->getOperand(0).setMBB(RestoreMBB);
- }
+ TargetMBB = MBBI->getOperand(0).getMBB();
// Pop EBP.
BuildMI(MBB, MBBI, DL, TII.get(Is64Bit ? X86::POP64r : X86::POP32r),
MachineFramePtr)
.setMIFlag(MachineInstr::FrameDestroy);
-
- // Insert frame restoration code in a new block.
- if (STI.is32Bit()) {
- auto RestoreMBBI = RestoreMBB->begin();
- restoreWin32EHStackPointers(*RestoreMBB, RestoreMBBI, DL,
- /*RestoreSP=*/true);
- BuildMI(*RestoreMBB, RestoreMBBI, DL, TII.get(X86::JMP_4))
- .addMBB(TargetMBB);
- }
} else if (MBBI->getOpcode() == X86::CLEANUPRET) {
NumBytes = getWinEHFuncletFrameSize(MF);
assert(hasFP(MF) && "EH funclets without FP not yet implemented");
}
MachineBasicBlock::iterator FirstCSPop = MBBI;
- if (RestoreMBB) {
+ if (TargetMBB) {
// Fill EAX/RAX with the address of the target block.
unsigned ReturnReg = STI.is64Bit() ? X86::RAX : X86::EAX;
if (STI.is64Bit()) {
- // LEA64r RestoreMBB(%rip), %rax
+ // LEA64r TargetMBB(%rip), %rax
BuildMI(MBB, FirstCSPop, DL, TII.get(X86::LEA64r), ReturnReg)
.addReg(X86::RIP)
.addImm(0)
.addReg(0)
- .addMBB(RestoreMBB)
+ .addMBB(TargetMBB)
.addReg(0);
} else {
- // MOV32ri $RestoreMBB, %eax
- BuildMI(MBB, FirstCSPop, DL, TII.get(X86::MOV32ri))
- .addReg(ReturnReg)
- .addMBB(RestoreMBB);
+ // MOV32ri $TargetMBB, %eax
+ BuildMI(MBB, FirstCSPop, DL, TII.get(X86::MOV32ri), ReturnReg)
+ .addMBB(TargetMBB);
}
- // Record that we've taken the address of RestoreMBB and no longer just
+ // Record that we've taken the address of TargetMBB and no longer just
// reference it in a terminator.
- RestoreMBB->setHasAddressTaken();
+ TargetMBB->setHasAddressTaken();
}
if (MBBI != MBB.end())
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!");
bool X86FrameLowering::canUseAsEpilogue(const MachineBasicBlock &MBB) const {
assert(MBB.getParent() && "Block is not attached to a function!");
+ // Win64 has strict requirements in terms of epilogue and we are
+ // not taking a chance at messing with them.
+ // I.e., unless this block is already an exit block, we can't use
+ // it as an epilogue.
+ if (MBB.getParent()->getSubtarget<X86Subtarget>().isTargetWin64() &&
+ !MBB.succ_empty() && !MBB.isReturnBlock())
+ return false;
+
if (canUseLEAForSPInEpilogue(*MBB.getParent()))
return true;
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