[MachineOutliner] AArch64: Handle instrs that use SP and will never need fixups

This commit does two things. Firstly, it adds a collection of flags which can
be passed along to the target to encode information about the MBB that an
instruction lives in to the outliner.

Second, it adds some of those flags to the AArch64 outliner in order to add
more stack instructions to the list of legal instructions that are handled
by the outliner. The two flags added check if

- There are calls in the MachineBasicBlock containing the instruction
- The link register is available in the entire block

If the link register is available and there are no calls, then a stack
instruction can always be outlined without fixups, regardless of what it is,
since in this case, the outliner will never modify the stack to create a
call or outlined frame.

The motivation for doing this was checking which instructions are most often
missed by the outliner. Instructions like, say

%sp<def> = ADDXri %sp, 32, 0; flags: FrameDestroy

are very common, but cannot be outlined in the case that the outliner might
modify the stack. This commit allows us to outline instructions like this.
  

llvm-svn: 322048

2 files changed, 3 insertions, 3 deletions

diff --git a/llvm/lib/Target/X86/X86InstrInfo.cpp b/llvm/lib/Target/X86/X86InstrInfo.cpp
index 4f6b0b5f26b..b8093641308 100644
--- a/llvm/lib/Target/X86/X86InstrInfo.cpp
+++ b/llvm/lib/Target/X86/X86InstrInfo.cpp
@@ -10937,8 +10937,8 @@ bool X86InstrInfo::isFunctionSafeToOutlineFrom(MachineFunction &MF,
 }
 
 X86GenInstrInfo::MachineOutlinerInstrType
-X86InstrInfo::getOutliningType(MachineInstr &MI) const {
-
+X86InstrInfo::getOutliningType(MachineBasicBlock::iterator &MIT,  unsigned Flags) const {
+  MachineInstr &MI = *MIT;
   // Don't allow debug values to impact outlining type.
   if (MI.isDebugValue() || MI.isIndirectDebugValue())
     return MachineOutlinerInstrType::Invisible;
diff --git a/llvm/lib/Target/X86/X86InstrInfo.h b/llvm/lib/Target/X86/X86InstrInfo.h
index 02a09c340ce..0f76ed76abd 100644
--- a/llvm/lib/Target/X86/X86InstrInfo.h
+++ b/llvm/lib/Target/X86/X86InstrInfo.h
@@ -568,7 +568,7 @@ public:
                                    bool OutlineFromLinkOnceODRs) const override;
 
   llvm::X86GenInstrInfo::MachineOutlinerInstrType
-  getOutliningType(MachineInstr &MI) const override;
+  getOutliningType(MachineBasicBlock::iterator &MIT, unsigned Flags) const override;
 
   void insertOutlinerEpilogue(MachineBasicBlock &MBB, MachineFunction &MF,
                               const MachineOutlinerInfo &MInfo) const override;