ARM: consolidate frame pointer register knowledge

[oota-llvm.git] / lib / Target / MSP430 / MSP430FrameLowering.cpp

diff --git a/lib/Target/MSP430/MSP430FrameLowering.cpp b/lib/Target/MSP430/MSP430FrameLowering.cpp
index 2e170f17bf9db730e0f2f4b0cb89c48b64a1e48a..82c8b298c51f4be46a1ae8ef5b4353834bd1afac 100644 (file)
--- a/lib/Target/MSP430/MSP430FrameLowering.cpp
+++ b/lib/Target/MSP430/MSP430FrameLowering.cpp
@@ -14,15 +14,15 @@
 #include "MSP430FrameLowering.h"
 #include "MSP430InstrInfo.h"
 #include "MSP430MachineFunctionInfo.h"
-#include "llvm/Function.h"
 #include "llvm/CodeGen/MachineFrameInfo.h"
 #include "llvm/CodeGen/MachineFunction.h"
 #include "llvm/CodeGen/MachineInstrBuilder.h"
 #include "llvm/CodeGen/MachineModuleInfo.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
-#include "llvm/DataLayout.h"
-#include "llvm/Target/TargetOptions.h"
+#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/Function.h"
 #include "llvm/Support/CommandLine.h"
+#include "llvm/Target/TargetOptions.h"
 
 using namespace llvm;
 
@@ -71,7 +71,7 @@ void MSP430FrameLowering::emitPrologue(MachineFunction &MF) const {
       .addReg(MSP430::SPW);
 
     // Mark the FramePtr as live-in in every block except the entry.
-    for (MachineFunction::iterator I = llvm::next(MF.begin()), E = MF.end();
+    for (MachineFunction::iterator I = std::next(MF.begin()), E = MF.end();
          I != E; ++I)
       I->addLiveIn(MSP430::FPW);
 
@@ -138,7 +138,7 @@ void MSP430FrameLowering::emitEpilogue(MachineFunction &MF,
 
   // Skip the callee-saved pop instructions.
   while (MBBI != MBB.begin()) {
-    MachineBasicBlock::iterator PI = prior(MBBI);
+    MachineBasicBlock::iterator PI = std::prev(MBBI);
     unsigned Opc = PI->getOpcode();
     if (Opc != MSP430::POP16r && !PI->isTerminator())
       break;
@@ -222,13 +222,73 @@ MSP430FrameLowering::restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
   return true;
 }
 
-void
-MSP430FrameLowering::processFunctionBeforeFrameFinalized(MachineFunction &MF)
-                                                                         const {
-  const TargetFrameLowering *TFI = MF.getTarget().getFrameLowering();
+void MSP430FrameLowering::
+eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
+                              MachineBasicBlock::iterator I) const {
+  const MSP430InstrInfo &TII =
+    *static_cast<const MSP430InstrInfo*>(MF.getTarget().getInstrInfo());
+  unsigned StackAlign = getStackAlignment();
+
+  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 = nullptr;
+      if (Old->getOpcode() == TII.getCallFrameSetupOpcode()) {
+        New = BuildMI(MF, Old->getDebugLoc(),
+                      TII.get(MSP430::SUB16ri), MSP430::SPW)
+          .addReg(MSP430::SPW).addImm(Amount);
+      } else {
+        assert(Old->getOpcode() == TII.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() == TII.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
+MSP430FrameLowering::processFunctionBeforeFrameFinalized(MachineFunction &MF,
+                                                         RegScavenger *) const {
   // Create a frame entry for the FPW register that must be saved.
-  if (TFI->hasFP(MF)) {
+  if (hasFP(MF)) {
     int FrameIdx = MF.getFrameInfo()->CreateFixedObject(2, -4, true);
     (void)FrameIdx;
     assert(FrameIdx == MF.getFrameInfo()->getObjectIndexBegin() &&