+ if (needsFrameMoves) {
+ const DataLayout &TD = MF.getDataLayout();
+ const int StackGrowth = -TD.getPointerSize(0);
+ unsigned FramePtr = RegInfo->getFrameRegister(MF);
+ // An example of the prologue:
+ //
+ // .globl __foo
+ // .align 2
+ // __foo:
+ // Ltmp0:
+ // .cfi_startproc
+ // .cfi_personality 155, ___gxx_personality_v0
+ // Leh_func_begin:
+ // .cfi_lsda 16, Lexception33
+ //
+ // stp xa,bx, [sp, -#offset]!
+ // ...
+ // stp x28, x27, [sp, #offset-32]
+ // stp fp, lr, [sp, #offset-16]
+ // add fp, sp, #offset - 16
+ // sub sp, sp, #1360
+ //
+ // The Stack:
+ // +-------------------------------------------+
+ // 10000 | ........ | ........ | ........ | ........ |
+ // 10004 | ........ | ........ | ........ | ........ |
+ // +-------------------------------------------+
+ // 10008 | ........ | ........ | ........ | ........ |
+ // 1000c | ........ | ........ | ........ | ........ |
+ // +===========================================+
+ // 10010 | X28 Register |
+ // 10014 | X28 Register |
+ // +-------------------------------------------+
+ // 10018 | X27 Register |
+ // 1001c | X27 Register |
+ // +===========================================+
+ // 10020 | Frame Pointer |
+ // 10024 | Frame Pointer |
+ // +-------------------------------------------+
+ // 10028 | Link Register |
+ // 1002c | Link Register |
+ // +===========================================+
+ // 10030 | ........ | ........ | ........ | ........ |
+ // 10034 | ........ | ........ | ........ | ........ |
+ // +-------------------------------------------+
+ // 10038 | ........ | ........ | ........ | ........ |
+ // 1003c | ........ | ........ | ........ | ........ |
+ // +-------------------------------------------+
+ //
+ // [sp] = 10030 :: >>initial value<<
+ // sp = 10020 :: stp fp, lr, [sp, #-16]!
+ // fp = sp == 10020 :: mov fp, sp
+ // [sp] == 10020 :: stp x28, x27, [sp, #-16]!
+ // sp == 10010 :: >>final value<<
+ //
+ // The frame pointer (w29) points to address 10020. If we use an offset of
+ // '16' from 'w29', we get the CFI offsets of -8 for w30, -16 for w29, -24
+ // for w27, and -32 for w28:
+ //
+ // Ltmp1:
+ // .cfi_def_cfa w29, 16
+ // Ltmp2:
+ // .cfi_offset w30, -8
+ // Ltmp3:
+ // .cfi_offset w29, -16
+ // Ltmp4:
+ // .cfi_offset w27, -24
+ // Ltmp5:
+ // .cfi_offset w28, -32
+
+ if (HasFP) {
+ // Define the current CFA rule to use the provided FP.
+ unsigned Reg = RegInfo->getDwarfRegNum(FramePtr, true);
+ unsigned CFIIndex = MMI.addFrameInst(
+ MCCFIInstruction::createDefCfa(nullptr, Reg, 2 * StackGrowth));
+ BuildMI(MBB, MBBI, DL, TII->get(TargetOpcode::CFI_INSTRUCTION))
+ .addCFIIndex(CFIIndex)
+ .setMIFlags(MachineInstr::FrameSetup);
+
+ // Record the location of the stored LR
+ unsigned LR = RegInfo->getDwarfRegNum(AArch64::LR, true);
+ CFIIndex = MMI.addFrameInst(
+ MCCFIInstruction::createOffset(nullptr, LR, StackGrowth));
+ BuildMI(MBB, MBBI, DL, TII->get(TargetOpcode::CFI_INSTRUCTION))
+ .addCFIIndex(CFIIndex)
+ .setMIFlags(MachineInstr::FrameSetup);
+
+ // Record the location of the stored FP
+ CFIIndex = MMI.addFrameInst(
+ MCCFIInstruction::createOffset(nullptr, Reg, 2 * StackGrowth));
+ BuildMI(MBB, MBBI, DL, TII->get(TargetOpcode::CFI_INSTRUCTION))
+ .addCFIIndex(CFIIndex)
+ .setMIFlags(MachineInstr::FrameSetup);
+ } else {
+ // Encode the stack size of the leaf function.
+ unsigned CFIIndex = MMI.addFrameInst(
+ MCCFIInstruction::createDefCfaOffset(nullptr, -MFI->getStackSize()));
+ BuildMI(MBB, MBBI, DL, TII->get(TargetOpcode::CFI_INSTRUCTION))
+ .addCFIIndex(CFIIndex)
+ .setMIFlags(MachineInstr::FrameSetup);
+ }
+
+ // Now emit the moves for whatever callee saved regs we have.
+ emitCalleeSavedFrameMoves(MBB, MBBI, FramePtr);