From e70401045009bda43683a0e758f4afe25751d247 Mon Sep 17 00:00:00 2001 From: Reid Kleckner Date: Mon, 4 Aug 2014 21:05:27 +0000 Subject: Fix failure to invoke exception handler on Win64 When the last instruction prior to a function epilogue is a call, we need to emit a nop so that the return address is not in the epilogue IP range. This is consistent with MSVC's behavior, and may be a workaround for a bug in the Win64 unwinder. Differential Revision: http://reviews.llvm.org/D4751 Patch by Vadim Chugunov! llvm-svn: 214775 --- llvm/lib/Target/X86/X86FrameLowering.cpp | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) (limited to 'llvm/lib/Target/X86/X86FrameLowering.cpp') diff --git a/llvm/lib/Target/X86/X86FrameLowering.cpp b/llvm/lib/Target/X86/X86FrameLowering.cpp index 8c029a8c22d..b1aa35048c9 100644 --- a/llvm/lib/Target/X86/X86FrameLowering.cpp +++ b/llvm/lib/Target/X86/X86FrameLowering.cpp @@ -849,6 +849,11 @@ void X86FrameLowering::emitEpilogue(MachineFunction &MF, unsigned FramePtr = RegInfo->getFrameRegister(MF); unsigned StackPtr = RegInfo->getStackRegister(); + bool IsWinEH = + MF.getTarget().getMCAsmInfo()->getExceptionHandlingType() == + ExceptionHandling::WinEH; + bool NeedsWinEH = IsWinEH && MF.getFunction()->needsUnwindTableEntry(); + switch (RetOpcode) { default: llvm_unreachable("Can only insert epilog into returning blocks"); @@ -933,17 +938,29 @@ void X86FrameLowering::emitEpilogue(MachineFunction &MF, unsigned Opc = getLEArOpcode(IsLP64); addRegOffset(BuildMI(MBB, MBBI, DL, TII.get(Opc), StackPtr), FramePtr, false, -CSSize); + --MBBI; } else { unsigned Opc = (Is64Bit ? X86::MOV64rr : X86::MOV32rr); BuildMI(MBB, MBBI, DL, TII.get(Opc), StackPtr) .addReg(FramePtr); + --MBBI; } } else if (NumBytes) { // Adjust stack pointer back: ESP += numbytes. emitSPUpdate(MBB, MBBI, StackPtr, NumBytes, Is64Bit, IsLP64, UseLEA, TII, *RegInfo); + --MBBI; } + // Windows unwinder will not invoke function's exception handler if IP is + // either in prologue or in epilogue. This behavior causes a problem when a + // call immediately precedes an epilogue, because the return address points + // into the epilogue. To cope with that, we insert an epilogue marker here, + // then replace it with a 'nop' if it ends up immediately after a CALL in the + // final emitted code. + if (NeedsWinEH) + BuildMI(MBB, MBBI, DL, TII.get(X86::SEH_Epilogue)); + // We're returning from function via eh_return. if (RetOpcode == X86::EH_RETURN || RetOpcode == X86::EH_RETURN64) { MBBI = MBB.getLastNonDebugInstr(); -- cgit v1.2.3