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, 83 insertions, 2 deletions

diff --git a/lib/Target/X86/X86FrameLowering.cpp b/lib/Target/X86/X86FrameLowering.cpp
index 2b3d8538af..a05cf5c346 100644
--- a/lib/Target/X86/X86FrameLowering.cpp
+++ b/lib/Target/X86/X86FrameLowering.cpp
@@ -55,8 +55,8 @@ bool X86FrameLowering::hasFP(const MachineFunction &MF) const {
           MMI.callsUnwindInit() || MMI.callsEHReturn());
 }
 
-static unsigned getSUBriOpcode(unsigned isLP64, int64_t Imm) {
-  if (isLP64) {
+static unsigned getSUBriOpcode(unsigned IsLP64, int64_t Imm) {
+  if (IsLP64) {
     if (isInt<8>(Imm))
       return X86::SUB64ri8;
     return X86::SUB64ri32;
@@ -1756,3 +1756,84 @@ void X86FrameLowering::adjustForHiPEPrologue(MachineFunction &MF) const {
   MF.verify();
 #endif
 }
+
+void X86FrameLowering::
+eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
+                              MachineBasicBlock::iterator I) const {
+  const X86InstrInfo &TII = *TM.getInstrInfo();
+  const X86RegisterInfo &RegInfo = *TM.getRegisterInfo();
+  unsigned StackPtr = RegInfo.getStackRegister();
+  bool reseveCallFrame = hasReservedCallFrame(MF);
+  int Opcode = I->getOpcode();
+  bool isDestroy = Opcode == TII.getCallFrameDestroyOpcode();
+  bool IsLP64 = STI.isTarget64BitLP64();
+  DebugLoc DL = I->getDebugLoc();
+  uint64_t Amount = !reseveCallFrame ? I->getOperand(0).getImm() : 0;
+  uint64_t CalleeAmt = isDestroy ? I->getOperand(1).getImm() : 0;
+  I = MBB.erase(I);
+
+  if (!reseveCallFrame) {
+    // If the stack pointer can be changed after prologue, turn the
+    // adjcallstackup instruction into a 'sub ESP, <amt>' and the
+    // adjcallstackdown instruction into 'add ESP, <amt>'
+    // TODO: consider using push / pop instead of sub + store / add
+    if (Amount == 0)
+      return;
+
+    // We need to keep the stack aligned properly.  To do this, we round the
+    // amount of space needed for the outgoing arguments up to the next
+    // alignment boundary.
+    unsigned StackAlign = TM.getFrameLowering()->getStackAlignment();
+    Amount = (Amount + StackAlign - 1) / StackAlign * StackAlign;
+
+    MachineInstr *New = 0;
+    if (Opcode == TII.getCallFrameSetupOpcode()) {
+      New = BuildMI(MF, DL, TII.get(getSUBriOpcode(IsLP64, Amount)),
+                    StackPtr)
+        .addReg(StackPtr)
+        .addImm(Amount);
+    } else {
+      assert(Opcode == TII.getCallFrameDestroyOpcode());
+
+      // Factor out the amount the callee already popped.
+      Amount -= CalleeAmt;
+
+      if (Amount) {
+        unsigned Opc = getADDriOpcode(IsLP64, Amount);
+        New = BuildMI(MF, DL, TII.get(Opc), StackPtr)
+          .addReg(StackPtr).addImm(Amount);
+      }
+    }
+
+    if (New) {
+      // The EFLAGS implicit def is dead.
+      New->getOperand(3).setIsDead();
+
+      // Replace the pseudo instruction with a new instruction.
+      MBB.insert(I, New);
+    }
+
+    return;
+  }
+
+  if (Opcode == TII.getCallFrameDestroyOpcode() && CalleeAmt) {
+    // If we are performing frame pointer elimination and if the callee pops
+    // something off the stack pointer, add it back.  We do this until we have
+    // more advanced stack pointer tracking ability.
+    unsigned Opc = getSUBriOpcode(IsLP64, CalleeAmt);
+    MachineInstr *New = BuildMI(MF, DL, TII.get(Opc), StackPtr)
+      .addReg(StackPtr).addImm(CalleeAmt);
+
+    // The EFLAGS implicit def is dead.
+    New->getOperand(3).setIsDead();
+
+    // We are not tracking the stack pointer adjustment by the callee, so make
+    // sure we restore the stack pointer immediately after the call, there may
+    // be spill code inserted between the CALL and ADJCALLSTACKUP instructions.
+    MachineBasicBlock::iterator B = MBB.begin();
+    while (I != B && !llvm::prior(I)->isCall())
+      --I;
+    MBB.insert(I, New);
+  }
+}
+