diff options
Diffstat (limited to 'llvm/lib')
| -rw-r--r-- | llvm/lib/Target/X86/X86FrameLowering.cpp | 20 |
1 files changed, 16 insertions, 4 deletions
diff --git a/llvm/lib/Target/X86/X86FrameLowering.cpp b/llvm/lib/Target/X86/X86FrameLowering.cpp index 182af84f7ca..27b762af69f 100644 --- a/llvm/lib/Target/X86/X86FrameLowering.cpp +++ b/llvm/lib/Target/X86/X86FrameLowering.cpp @@ -1306,6 +1306,10 @@ GetScratchRegister(bool Is64Bit, const MachineFunction &MF) { } } +// The stack limit in the TCB is set to this many bytes above the actual stack +// limit. +static const uint64_t kSplitStackAvailable = 256; + void X86FrameLowering::adjustForSegmentedStacks(MachineFunction &MF) const { MachineBasicBlock &prologueMBB = MF.front(); @@ -1360,16 +1364,24 @@ X86FrameLowering::adjustForSegmentedStacks(MachineFunction &MF) const { TlsReg = X86::FS; TlsOffset = 0x70; - BuildMI(checkMBB, DL, TII.get(X86::LEA64r), ScratchReg).addReg(X86::RSP) - .addImm(0).addReg(0).addImm(-StackSize).addReg(0); + if (StackSize < kSplitStackAvailable) + ScratchReg = X86::RSP; + else + BuildMI(checkMBB, DL, TII.get(X86::LEA64r), ScratchReg).addReg(X86::RSP) + .addImm(0).addReg(0).addImm(-StackSize).addReg(0); + BuildMI(checkMBB, DL, TII.get(X86::CMP64rm)).addReg(ScratchReg) .addReg(0).addImm(0).addReg(0).addImm(TlsOffset).addReg(TlsReg); } else { TlsReg = X86::GS; TlsOffset = 0x30; - BuildMI(checkMBB, DL, TII.get(X86::LEA32r), ScratchReg).addReg(X86::ESP) - .addImm(0).addReg(0).addImm(-StackSize).addReg(0); + if (StackSize < kSplitStackAvailable) + ScratchReg = X86::ESP; + else + BuildMI(checkMBB, DL, TII.get(X86::LEA32r), ScratchReg).addReg(X86::ESP) + .addImm(0).addReg(0).addImm(-StackSize).addReg(0); + BuildMI(checkMBB, DL, TII.get(X86::CMP32rm)).addReg(ScratchReg) .addReg(0).addImm(0).addReg(0).addImm(TlsOffset).addReg(TlsReg); } |
