diff options
| -rw-r--r-- | lib/Target/X86/X86RegisterInfo.cpp | 31 |
1 files changed, 16 insertions, 15 deletions
diff --git a/lib/Target/X86/X86RegisterInfo.cpp b/lib/Target/X86/X86RegisterInfo.cpp index 5d56db563b..c733f26a8c 100644 --- a/lib/Target/X86/X86RegisterInfo.cpp +++ b/lib/Target/X86/X86RegisterInfo.cpp @@ -822,13 +822,6 @@ void X86RegisterInfo::emitPrologue(MachineFunction &MF) const { NumBytes = StackSize - X86FI->getCalleeSavedFrameSize(); } - unsigned ReadyLabelId = 0; - if (needsFrameMoves) { - // Mark effective beginning of when frame pointer is ready. - ReadyLabelId = MMI->NextLabelID(); - BuildMI(MBB, MBBI, DL, TII.get(X86::DBG_LABEL)).addImm(ReadyLabelId); - } - // Skip the callee-saved push instructions. while (MBBI != MBB.end() && (MBBI->getOpcode() == X86::PUSH32r || @@ -838,20 +831,20 @@ void X86RegisterInfo::emitPrologue(MachineFunction &MF) const { if (MBBI != MBB.end()) DL = MBBI->getDebugLoc(); - if (NumBytes) { // adjust stack pointer: ESP -= numbytes + if (NumBytes) { // Adjust stack pointer: ESP -= numbytes. if (NumBytes >= 4096 && Subtarget->isTargetCygMing()) { - // Check, whether EAX is livein for this function + // Check, whether EAX is livein for this function. bool isEAXAlive = false; for (MachineRegisterInfo::livein_iterator II = MF.getRegInfo().livein_begin(), EE = MF.getRegInfo().livein_end(); (II != EE) && !isEAXAlive; ++II) { unsigned Reg = II->first; isEAXAlive = (Reg == X86::EAX || Reg == X86::AX || - Reg == X86::AH || Reg == X86::AL); + Reg == X86::AH || Reg == X86::AL); } - // Function prologue calls _alloca to probe the stack when allocating - // more than 4k bytes in one go. Touching the stack at 4K increments is + // Function prologue calls _alloca to probe the stack when allocating more + // than 4k bytes in one go. Touching the stack at 4K increments is // necessary to ensure that the guard pages used by the OS virtual memory // manager are allocated in correct sequence. if (!isEAXAlive) { @@ -863,12 +856,14 @@ void X86RegisterInfo::emitPrologue(MachineFunction &MF) const { // Save EAX BuildMI(MBB, MBBI, DL, TII.get(X86::PUSH32r)) .addReg(X86::EAX, RegState::Kill); + // Allocate NumBytes-4 bytes on stack. We'll also use 4 already // allocated bytes for EAX. - BuildMI(MBB, MBBI, DL, - TII.get(X86::MOV32ri), X86::EAX).addImm(NumBytes-4); + BuildMI(MBB, MBBI, DL, TII.get(X86::MOV32ri), X86::EAX) + .addImm(NumBytes-4); BuildMI(MBB, MBBI, DL, TII.get(X86::CALLpcrel32)) .addExternalSymbol("_alloca"); + // Restore EAX MachineInstr *MI = addRegOffset(BuildMI(MF, DL, TII.get(X86::MOV32rm), X86::EAX), @@ -880,6 +875,7 @@ void X86RegisterInfo::emitPrologue(MachineFunction &MF) const { // merge the two. This can be the case when tail call elimination is // enabled and the callee has more arguments then the caller. NumBytes -= mergeSPUpdates(MBB, MBBI, StackPtr, true); + // If there is an ADD32ri or SUB32ri of ESP immediately after this // instruction, merge the two instructions. mergeSPUpdatesDown(MBB, MBBI, StackPtr, &NumBytes); @@ -889,8 +885,13 @@ void X86RegisterInfo::emitPrologue(MachineFunction &MF) const { } } - if (needsFrameMoves) + if (needsFrameMoves) { + // Mark effective beginning of when frame pointer is ready. + unsigned ReadyLabelId = 0; + ReadyLabelId = MMI->NextLabelID(); + BuildMI(MBB, MBBI, DL, TII.get(X86::DBG_LABEL)).addImm(ReadyLabelId); emitFrameMoves(MF, FrameLabelId, ReadyLabelId); + } } void X86RegisterInfo::emitEpilogue(MachineFunction &MF, |