#include "llvm/CodeGen/MachineMemOperand.h"
#include "llvm/CodeGen/MachineOperand.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/CodeGen/StackMaps.h"
#include "llvm/CodeGen/TargetRegisterInfo.h"
#include "llvm/CodeGen/TargetSubtargetInfo.h"
return makeArrayRef(TargetFlags);
}
-/// Constants defining how certain sequences should be outlined.
-/// This encompasses how an outlined function should be called, and what kind of
-/// frame should be emitted for that outlined function.
-///
-/// \p MachineOutlinerDefault implies that the function should be called with
-/// a save and restore of LR to the stack.
-///
-/// That is,
-///
-/// I1 Save LR OUTLINED_FUNCTION:
-/// I2 --> BL OUTLINED_FUNCTION I1
-/// I3 Restore LR I2
-/// I3
-/// RET
-///
-/// * Call construction overhead: 3 (save + BL + restore)
-/// * Frame construction overhead: 1 (ret)
-/// * Requires stack fixups? Yes
-///
-/// \p MachineOutlinerTailCall implies that the function is being created from
-/// a sequence of instructions ending in a return.
-///
-/// That is,
-///
-/// I1 OUTLINED_FUNCTION:
-/// I2 --> B OUTLINED_FUNCTION I1
-/// RET I2
-/// RET
-///
-/// * Call construction overhead: 1 (B)
-/// * Frame construction overhead: 0 (Return included in sequence)
-/// * Requires stack fixups? No
-///
-/// \p MachineOutlinerNoLRSave implies that the function should be called using
-/// a BL instruction, but doesn't require LR to be saved and restored. This
-/// happens when LR is known to be dead.
-///
-/// That is,
-///
-/// I1 OUTLINED_FUNCTION:
-/// I2 --> BL OUTLINED_FUNCTION I1
-/// I3 I2
-/// I3
-/// RET
-///
-/// * Call construction overhead: 1 (BL)
-/// * Frame construction overhead: 1 (RET)
-/// * Requires stack fixups? No
-///
+ /// Constants defining how certain sequences should be outlined.
+ /// This encompasses how an outlined function should be called, and what kind of
+ /// frame should be emitted for that outlined function.
+ ///
+ /// \p MachineOutlinerDefault implies that the function should be called with
+ /// a save and restore of LR to the stack.
+ ///
+ /// That is,
+ ///
+ /// I1 Save LR OUTLINED_FUNCTION:
+ /// I2 --> BL OUTLINED_FUNCTION I1
+ /// I3 Restore LR I2
+ /// I3
+ /// RET
+ ///
+ /// * Call construction overhead: 3 (save + BL + restore)
+ /// * Frame construction overhead: 1 (ret)
+ /// * Requires stack fixups? Yes
+ ///
+ /// \p MachineOutlinerTailCall implies that the function is being created from
+ /// a sequence of instructions ending in a return.
+ ///
+ /// That is,
+ ///
+ /// I1 OUTLINED_FUNCTION:
+ /// I2 --> B OUTLINED_FUNCTION I1
+ /// RET I2
+ /// RET
+ ///
+ /// * Call construction overhead: 1 (B)
+ /// * Frame construction overhead: 0 (Return included in sequence)
+ /// * Requires stack fixups? No
+ ///
+ /// \p MachineOutlinerNoLRSave implies that the function should be called using
+ /// a BL instruction, but doesn't require LR to be saved and restored. This
+ /// happens when LR is known to be dead.
+ ///
+ /// That is,
+ ///
+ /// I1 OUTLINED_FUNCTION:
+ /// I2 --> BL OUTLINED_FUNCTION I1
+ /// I3 I2
+ /// I3
+ /// RET
+ ///
+ /// * Call construction overhead: 1 (BL)
+ /// * Frame construction overhead: 1 (RET)
+ /// * Requires stack fixups? No
+ ///
enum MachineOutlinerClass {
MachineOutlinerDefault, /// Emit a save, restore, call, and return.
MachineOutlinerTailCall, /// Only emit a branch.
// Get liveness information from the end of the block to the end of the
// prospective outlined region.
std::for_each(MBB.rbegin(),
- (MachineBasicBlock::reverse_iterator)CallInsertionPt,
- [&LRU](MachineInstr &MI) {LRU.stepBackward(MI);}
- );
+ (MachineBasicBlock::reverse_iterator)CallInsertionPt,
+ [&LRU](MachineInstr &MI) { LRU.stepBackward(MI); });
// If the link register is available at this point, then we can safely outline
// the region without saving/restoring LR. Otherwise, we must emit a save and
NumInstrsToCreateFrame = 1;
}
+ // Check if the range contains a call. These require a save + restore of the
+ // link register.
+ if (std::any_of(RepeatedSequenceLocs[0].first, RepeatedSequenceLocs[0].second,
+ [](const MachineInstr &MI) { return MI.isCall(); }))
+ NumInstrsToCreateFrame += 2; // Save + restore the link register.
+
+ // Handle the last instruction separately. If this is a tail call, then the
+ // last instruction is a call. We don't want to save + restore in this case.
+ // However, it could be possible that the last instruction is a call without
+ // it being valid to tail call this sequence. We should consider this as well.
+ else if (RepeatedSequenceLocs[0].second->isCall() &&
+ FrameID != MachineOutlinerTailCall)
+ NumInstrsToCreateFrame += 2;
+
return MachineOutlinerInfo(NumInstrsForCall, NumInstrsToCreateFrame, CallID,
FrameID);
}
-bool AArch64InstrInfo::isFunctionSafeToOutlineFrom(MachineFunction &MF,
- bool OutlineFromLinkOnceODRs) const {
+bool AArch64InstrInfo::isFunctionSafeToOutlineFrom(
+ MachineFunction &MF, bool OutlineFromLinkOnceODRs) const {
const Function &F = MF.getFunction();
// If F uses a redzone, then don't outline from it because it might mess up
return MachineOutlinerInstrType::Illegal;
}
+ // Outline calls without stack parameters or aggregate parameters.
+ if (MI.isCall()) {
+ const Module *M = MF->getFunction().getParent();
+ assert(M && "No module?");
+
+ // Get the function associated with the call. Look at each operand and find
+ // the one that represents the callee and get its name.
+ Function *Callee = nullptr;
+ for (const MachineOperand &MOP : MI.operands()) {
+ if (MOP.isSymbol()) {
+ Callee = M->getFunction(MOP.getSymbolName());
+ break;
+ }
+
+ else if (MOP.isGlobal()) {
+ Callee = M->getFunction(MOP.getGlobal()->getGlobalIdentifier());
+ break;
+ }
+ }
+
+ // Only handle functions that we have information about.
+ if (!Callee)
+ return MachineOutlinerInstrType::Illegal;
+
+ // We have a function we have information about. Check it if it's something
+ // can safely outline.
+
+ // If the callee is vararg, it passes parameters on the stack. Don't touch
+ // it.
+ // FIXME: Functions like printf are very common and we should be able to
+ // outline them.
+ if (Callee->isVarArg())
+ return MachineOutlinerInstrType::Illegal;
+
+ // Check if any of the arguments are a pointer to a struct. We don't want
+ // to outline these since they might be loaded in two instructions.
+ for (Argument &Arg : Callee->args()) {
+ if (Arg.getType()->isPointerTy() &&
+ Arg.getType()->getPointerElementType()->isAggregateType())
+ return MachineOutlinerInstrType::Illegal;
+ }
+
+ // If the thing we're calling doesn't access memory at all, then we're good
+ // to go.
+ if (Callee->doesNotAccessMemory())
+ return MachineOutlinerInstrType::Legal;
+
+ // It accesses memory. Get the machine function for the callee to see if
+ // it's safe to outline.
+ MachineFunction *CalleeMF = MF->getMMI().getMachineFunction(*Callee);
+
+ // We don't know what's going on with the callee at all. Don't touch it.
+ if (!CalleeMF)
+ return MachineOutlinerInstrType::Illegal;
+
+ // Does it pass anything on the stack? If it does, don't outline it.
+ if (CalleeMF->getInfo<AArch64FunctionInfo>()->getBytesInStackArgArea() != 0)
+ return MachineOutlinerInstrType::Illegal;
+
+ // It doesn't, so it's safe to outline and we're done.
+ return MachineOutlinerInstrType::Legal;
+ }
+
// Don't outline positions.
if (MI.isPosition())
return MachineOutlinerInstrType::Illegal;
if (MI.modifiesRegister(AArch64::SP, &RI) ||
MI.readsRegister(AArch64::SP, &RI)) {
- // Is it a memory operation?
if (MI.mayLoadOrStore()) {
unsigned Base; // Filled with the base regiser of MI.
int64_t Offset; // Filled with the offset of MI.
// Find the minimum/maximum offset for this instruction and check if
// fixing it up would be in range.
int64_t MinOffset, MaxOffset; // Unscaled offsets for the instruction.
- unsigned Scale; // The scale to multiply the offsets by.
- getMemOpInfo(MI.getOpcode(), Scale, DummyWidth, MinOffset,
- MaxOffset);
+ unsigned Scale; // The scale to multiply the offsets by.
+ getMemOpInfo(MI.getOpcode(), Scale, DummyWidth, MinOffset, MaxOffset);
// TODO: We should really test what happens if an instruction overflows.
// This is tricky to test with IR tests, but when the outliner is moved
// to a MIR test, it really ought to be checked.
-
Offset += 16; // Update the offset to what it would be if we outlined.
if (Offset < MinOffset * Scale || Offset > MaxOffset * Scale)
return MachineOutlinerInstrType::Illegal;
MachineBasicBlock &MBB, MachineFunction &MF,
const MachineOutlinerInfo &MInfo) const {
+ bool ContainsCalls = false;
+
+ for (MachineInstr &MI : MBB) {
+ if (MI.isCall()) {
+ ContainsCalls = true;
+ break;
+ }
+ }
+
+ if (ContainsCalls) {
+ // Fix up the instructions in the range, since we're going to modify the
+ // stack.
+ fixupPostOutline(MBB);
+
+ // LR has to be a live in so that we can save it.
+ MBB.addLiveIn(AArch64::LR);
+
+ MachineBasicBlock::iterator It = MBB.begin();
+ MachineBasicBlock::iterator Et = MBB.end();
+
+ if (MInfo.FrameConstructionID == MachineOutlinerTailCall)
+ Et = std::prev(MBB.end());
+
+ // Insert a save before the outlined region
+ MachineInstr *STRXpre = BuildMI(MF, DebugLoc(), get(AArch64::STRXpre))
+ .addReg(AArch64::SP, RegState::Define)
+ .addReg(AArch64::LR)
+ .addReg(AArch64::SP)
+ .addImm(-16);
+ It = MBB.insert(It, STRXpre);
+
+ // Insert a restore before the terminator for the function.
+ MachineInstr *LDRXpost = BuildMI(MF, DebugLoc(), get(AArch64::LDRXpost))
+ .addReg(AArch64::SP, RegState::Define)
+ .addReg(AArch64::LR, RegState::Define)
+ .addReg(AArch64::SP)
+ .addImm(16);
+ Et = MBB.insert(Et, LDRXpost);
+ }
+
// If this is a tail call outlined function, then there's already a return.
if (MInfo.FrameConstructionID == MachineOutlinerTailCall)
return;
It = MBB.insert(It, LDRXpost);
return It;
-}
+}
\ No newline at end of file
projects / llvm / commitdiff