diff options
| author | Nico Rieck <nico.rieck@gmail.com> | 2013-07-08 11:20:11 +0000 |
|---|---|---|
| committer | Nico Rieck <nico.rieck@gmail.com> | 2013-07-08 11:20:11 +0000 |
| commit | 4010110ccf21be0517034b6ccf9493628afaad77 (patch) | |
| tree | bbdd2808b85b35c53dd4f6aede1f7bedae5d2c6a /lib/Target/X86/X86FrameLowering.cpp | |
| parent | 63e7778b53a1c8c190d5c67a9e8871c2acb00b26 (diff) | |
Reuse %rax after calling __chkstk on win64
Reapply this as I reverted the wrong commit.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185807 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/Target/X86/X86FrameLowering.cpp')
| -rw-r--r-- | lib/Target/X86/X86FrameLowering.cpp | 13 |
1 files changed, 8 insertions, 5 deletions
diff --git a/lib/Target/X86/X86FrameLowering.cpp b/lib/Target/X86/X86FrameLowering.cpp index 9d66bfd88a8..5db431b60a4 100644 --- a/lib/Target/X86/X86FrameLowering.cpp +++ b/lib/Target/X86/X86FrameLowering.cpp @@ -914,11 +914,14 @@ void X86FrameLowering::emitPrologue(MachineFunction &MF) const { .addReg(X86::EFLAGS, RegState::Define | RegState::Implicit) .setMIFlag(MachineInstr::FrameSetup); - // MSVC x64's __chkstk needs to adjust %rsp. - // FIXME: %rax preserves the offset and should be available. - if (isSPUpdateNeeded) - emitSPUpdate(MBB, MBBI, StackPtr, -(int64_t)NumBytes, Is64Bit, IsLP64, - UseLEA, TII, *RegInfo); + // MSVC x64's __chkstk does not adjust %rsp itself. + // It also does not clobber %rax so we can reuse it when adjusting %rsp. + if (isSPUpdateNeeded) { + BuildMI(MBB, MBBI, DL, TII.get(X86::SUB64rr), StackPtr) + .addReg(StackPtr) + .addReg(X86::RAX) + .setMIFlag(MachineInstr::FrameSetup); + } if (isEAXAlive) { // Restore EAX |