Move the eliminateCallFramePseudoInstr method from TargetRegisterInfo

to TargetFrameLowering, where it belongs. Incidentally, this allows us
to delete some duplicated (and slightly different!) code in TRI.

There are potentially other layering problems that can be cleaned up
as a result, or in a similar manner.

The refactoring was OK'd by Anton Korobeynikov on llvmdev.

Note: this touches the target interfaces, so out-of-tree targets may
be affected.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@175788 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 40 insertions, 0 deletions

diff --git a/lib/Target/AArch64/AArch64FrameLowering.cpp b/lib/Target/AArch64/AArch64FrameLowering.cpp
index 24d1576e5a..cca6d12e16 100644
--- a/lib/Target/AArch64/AArch64FrameLowering.cpp
+++ b/lib/Target/AArch64/AArch64FrameLowering.cpp
@@ -644,3 +644,43 @@ AArch64FrameLowering::hasReservedCallFrame(const MachineFunction &MF) const {
   // variable-sized objects that prevent reservation of a call frame.
   return !(hasFP(MF) && MFI->hasVarSizedObjects());
 }
+
+void
+AArch64FrameLowering::eliminateCallFramePseudoInstr(
+                                MachineFunction &MF,
+                                MachineBasicBlock &MBB,
+                                MachineBasicBlock::iterator MI) const {
+  const AArch64InstrInfo &TII =
+    *static_cast<const AArch64InstrInfo *>(MF.getTarget().getInstrInfo());
+  DebugLoc dl = MI->getDebugLoc();
+  int Opcode = MI->getOpcode();
+  bool IsDestroy = Opcode == TII.getCallFrameDestroyOpcode();
+  uint64_t CalleePopAmount = IsDestroy ? MI->getOperand(1).getImm() : 0;
+
+  if (!hasReservedCallFrame(MF)) {
+    unsigned Align = getStackAlignment();
+
+    int64_t Amount = MI->getOperand(0).getImm();
+    Amount = RoundUpToAlignment(Amount, Align);
+    if (!IsDestroy) Amount = -Amount;
+
+    // N.b. if CalleePopAmount is valid but zero (i.e. callee would pop, but it
+    // doesn't have to pop anything), then the first operand will be zero too so
+    // this adjustment is a no-op.
+    if (CalleePopAmount == 0) {
+      // FIXME: in-function stack adjustment for calls is limited to 12-bits
+      // because there's no guaranteed temporary register available. Mostly call
+      // frames will be allocated at the start of a function so this is OK, but
+      // it is a limitation that needs dealing with.
+      assert(Amount > -0xfff && Amount < 0xfff && "call frame too large");
+      emitSPUpdate(MBB, MI, dl, TII, AArch64::NoRegister, Amount);
+    }
+  } else if (CalleePopAmount != 0) {
+    // If the calling convention demands that the callee pops arguments from the
+    // stack, we want to add it back if we have a reserved call frame.
+    assert(CalleePopAmount < 0xfff && "call frame too large");
+    emitSPUpdate(MBB, MI, dl, TII, AArch64::NoRegister, -CalleePopAmount);
+  }
+
+  MBB.erase(MI);
+}