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| author | Sanne Wouda <sanne.wouda@arm.com> | 2017-02-03 11:15:53 +0000 |
|---|---|---|
| committer | Sanne Wouda <sanne.wouda@arm.com> | 2017-02-03 11:15:53 +0000 |
| commit | a9941857579f17057994a270dba17fee6b9fd281 (patch) | |
| tree | 3f341d0b562dff4521313aa1b179ca54916e53a4 /llvm/lib/Target/ARM/Thumb1FrameLowering.cpp | |
| parent | 57b63d6ade0f370b47c422ea62c0bdce5467f3c7 (diff) | |
| download | bcm5719-llvm-a9941857579f17057994a270dba17fee6b9fd281.tar.gz bcm5719-llvm-a9941857579f17057994a270dba17fee6b9fd281.zip | |
[ARM] Change TCReturn to tBL if tailcall optimization fails.
Summary:
The tail call optimisation is performed before register allocation, so
at that point we don't know if LR is being spilt or not. If LR was spilt
to the stack, then we cannot do a tail call optimisation. That would
involve popping back into LR which is not possible in Thumb1 code.
Reviewers: rengolin, jmolloy, rovka, olista01
Reviewed By: olista01
Subscribers: llvm-commits, aemerson
Differential Revision: https://reviews.llvm.org/D29020
llvm-svn: 294000
Diffstat (limited to 'llvm/lib/Target/ARM/Thumb1FrameLowering.cpp')
| -rw-r--r-- | llvm/lib/Target/ARM/Thumb1FrameLowering.cpp | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/llvm/lib/Target/ARM/Thumb1FrameLowering.cpp b/llvm/lib/Target/ARM/Thumb1FrameLowering.cpp index a2e60299c88..fc083b98395 100644 --- a/llvm/lib/Target/ARM/Thumb1FrameLowering.cpp +++ b/llvm/lib/Target/ARM/Thumb1FrameLowering.cpp @@ -888,6 +888,16 @@ restoreCalleeSavedRegisters(MachineBasicBlock &MBB, // ARMv4T requires BX, see emitEpilogue if (!STI.hasV5TOps()) continue; + // Tailcall optimization failed; change TCRETURN to a tBL + if (MI->getOpcode() == ARM::TCRETURNdi || + MI->getOpcode() == ARM::TCRETURNri) { + unsigned Opcode = MI->getOpcode() == ARM::TCRETURNdi + ? ARM::tBL : ARM::tBLXr; + MachineInstrBuilder BL = BuildMI(MF, DL, TII.get(Opcode)); + BL.add(predOps(ARMCC::AL)); + BL.add(MI->getOperand(0)); + MBB.insert(MI, &*BL); + } Reg = ARM::PC; (*MIB).setDesc(TII.get(ARM::tPOP_RET)); if (MI != MBB.end()) |
