Reworking the stack layout generated by the MBlaze backend.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121355 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 35 insertions, 7 deletions

diff --git a/lib/Target/MBlaze/MBlazeRegisterInfo.cpp b/lib/Target/MBlaze/MBlazeRegisterInfo.cpp
index f8f77f1487..58aa151cd5 100644
--- a/lib/Target/MBlaze/MBlazeRegisterInfo.cpp
+++ b/lib/Target/MBlaze/MBlazeRegisterInfo.cpp
@@ -164,11 +164,40 @@ getReservedRegs(const MachineFunction &MF) const {
   return Reserved;
 }
 
-// This function eliminate ADJCALLSTACKDOWN,
-// ADJCALLSTACKUP pseudo instructions
+// This function eliminate ADJCALLSTACKDOWN/ADJCALLSTACKUP pseudo instructions
 void MBlazeRegisterInfo::
 eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
                               MachineBasicBlock::iterator I) const {
+  const TargetFrameInfo *TFI = MF.getTarget().getFrameInfo();
+
+  if (!TFI->hasReservedCallFrame(MF)) {
+    // If we have a frame pointer, turn the adjcallstackup instruction into a
+    // 'addi r1, r1, -<amt>' and the adjcallstackdown instruction into
+    // 'addi r1, r1, <amt>'
+    MachineInstr *Old = I;
+    int Amount = Old->getOperand(0).getImm() + 4;
+    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.
+      unsigned Align = MF.getTarget().getFrameInfo()->getStackAlignment();
+      Amount = (Amount+Align-1)/Align*Align;
+
+      MachineInstr *New;
+      if (Old->getOpcode() == MBlaze::ADJCALLSTACKDOWN) {
+        New = BuildMI(MF, Old->getDebugLoc(), TII.get(MBlaze::ADDI), MBlaze::R1)
+                .addReg(MBlaze::R1).addImm(-Amount);
+      } else {
+        assert(Old->getOpcode() == MBlaze::ADJCALLSTACKUP);
+        New = BuildMI(MF, Old->getDebugLoc(), TII.get(MBlaze::ADDI), MBlaze::R1)
+                .addReg(MBlaze::R1).addImm(Amount);
+      }
+
+      // Replace the pseudo instruction with a new instruction...
+      MBB.insert(I, New);
+    }
+  }
+
   // Simply discard ADJCALLSTACKDOWN, ADJCALLSTACKUP instructions.
   MBB.erase(I);
 }
@@ -204,12 +233,11 @@ eliminateFrameIndex(MachineBasicBlock::iterator II, int SPAdj,
 
   // as explained on LowerFormalArguments, detect negative offsets
   // and adjust SPOffsets considering the final stack size.
-  int Offset = (spOffset < 0) ? (stackSize - spOffset) : (spOffset + 4);
-  Offset    += MI.getOperand(oi).getImm();
-
-  DEBUG(errs() << "Offset     : " << Offset << "\n" << "<--------->\n");
+  spOffset = (spOffset < 0) ? (stackSize - spOffset) : spOffset;
+  spOffset += MI.getOperand(oi).getImm();
+  DEBUG(errs() << "Offset     : " << spOffset << "\n" << "<--------->\n");
 
-  MI.getOperand(oi).ChangeToImmediate(Offset);
+  MI.getOperand(oi).ChangeToImmediate(spOffset);
   MI.getOperand(i).ChangeToRegister(getFrameRegister(MF), false);
 }