Add call frame setup instruction elimination and lowerid for bunch of call-related stuff.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@70728 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 70 insertions, 3 deletions

diff --git a/lib/Target/MSP430/MSP430RegisterInfo.cpp b/lib/Target/MSP430/MSP430RegisterInfo.cpp
index 292dd28129..c7efa5e351 100644
--- a/lib/Target/MSP430/MSP430RegisterInfo.cpp
+++ b/lib/Target/MSP430/MSP430RegisterInfo.cpp
@@ -15,8 +15,10 @@
 
 #include "MSP430.h"
 #include "MSP430RegisterInfo.h"
+#include "MSP430TargetMachine.h"
 #include "llvm/CodeGen/MachineFrameInfo.h"
 #include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
 #include "llvm/Target/TargetMachine.h"
 #include "llvm/Target/TargetOptions.h"
 #include "llvm/ADT/BitVector.h"
@@ -24,9 +26,12 @@
 using namespace llvm;
 
 // FIXME: Provide proper call frame setup / destroy opcodes.
-MSP430RegisterInfo::MSP430RegisterInfo(const TargetInstrInfo &tii)
-  : MSP430GenRegisterInfo(MSP430::NOP, MSP430::NOP),
-    TII(tii) {}
+MSP430RegisterInfo::MSP430RegisterInfo(MSP430TargetMachine &tm,
+                                       const TargetInstrInfo &tii)
+  : MSP430GenRegisterInfo(MSP430::ADJCALLSTACKDOWN, MSP430::ADJCALLSTACKUP),
+    TM(tm), TII(tii) {
+  StackAlign = TM.getFrameInfo()->getStackAlignment();
+}
 
 const unsigned*
 MSP430RegisterInfo::getCalleeSavedRegs(const MachineFunction *MF) const {
@@ -73,6 +78,68 @@ bool MSP430RegisterInfo::hasFP(const MachineFunction &MF) const {
   return NoFramePointerElim || MF.getFrameInfo()->hasVarSizedObjects();
 }
 
+bool MSP430RegisterInfo::hasReservedCallFrame(MachineFunction &MF) const {
+  return !MF.getFrameInfo()->hasVarSizedObjects();
+}
+
+void MSP430RegisterInfo::
+eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
+                              MachineBasicBlock::iterator I) const {
+  if (!hasReservedCallFrame(MF)) {
+    // If the stack pointer can be changed after prologue, turn the
+    // adjcallstackup instruction into a 'sub SPW, <amt>' and the
+    // adjcallstackdown instruction into 'add SPW, <amt>'
+    // TODO: consider using push / pop instead of sub + store / add
+    MachineInstr *Old = I;
+    uint64_t Amount = Old->getOperand(0).getImm();
+    if (Amount != 0) {
+      // 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.
+      Amount = (Amount+StackAlign-1)/StackAlign*StackAlign;
+
+      MachineInstr *New = 0;
+      if (Old->getOpcode() == getCallFrameSetupOpcode()) {
+        New = BuildMI(MF, Old->getDebugLoc(),
+                      TII.get(MSP430::SUB16ri), MSP430::SPW)
+          .addReg(MSP430::SPW).addImm(Amount);
+      } else {
+        assert(Old->getOpcode() == getCallFrameDestroyOpcode());
+        // factor out the amount the callee already popped.
+        uint64_t CalleeAmt = Old->getOperand(1).getImm();
+        Amount -= CalleeAmt;
+        if (Amount)
+          New = BuildMI(MF, Old->getDebugLoc(),
+                        TII.get(MSP430::ADD16ri), MSP430::SPW)
+            .addReg(MSP430::SPW).addImm(Amount);
+      }
+
+      if (New) {
+        // The SRW implicit def is dead.
+        New->getOperand(3).setIsDead();
+
+        // Replace the pseudo instruction with a new instruction...
+        MBB.insert(I, New);
+      }
+    }
+  } else if (I->getOpcode() == getCallFrameDestroyOpcode()) {
+    // If we are performing frame pointer elimination and if the callee pops
+    // something off the stack pointer, add it back.
+    if (uint64_t CalleeAmt = I->getOperand(1).getImm()) {
+      MachineInstr *Old = I;
+      MachineInstr *New =
+        BuildMI(MF, Old->getDebugLoc(), TII.get(MSP430::SUB16ri),
+                MSP430::SPW).addReg(MSP430::SPW).addImm(CalleeAmt);
+      // The SRW implicit def is dead.
+      New->getOperand(3).setIsDead();
+
+      MBB.insert(I, New);
+    }
+  }
+
+  MBB.erase(I);
+}
+
 void
 MSP430RegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II,
                                         int SPAdj, RegScavenger *RS) const {