[llvm] r308562 - Revert "[PEI] Separate saving and restoring CSRs into different functions. NFC"

[Francis Visoiu Mistrih via llvm-commits]

Author: thegameg
Date: Wed Jul 19 17:08:02 2017
New Revision: 308562

URL: http://llvm.org/viewvc/llvm-project?rev=308562&view=rev
Log:
Revert "[PEI] Separate saving and restoring CSRs into different functions. NFC"

This reverts commit a84d1fa6847e70ebf63594d41a00b473c941bd72.

Modified:
    llvm/trunk/lib/CodeGen/PrologEpilogInserter.cpp

Modified: llvm/trunk/lib/CodeGen/PrologEpilogInserter.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/PrologEpilogInserter.cpp?rev=308562&r1=308561&r2=308562&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/PrologEpilogInserter.cpp (original)
+++ llvm/trunk/lib/CodeGen/PrologEpilogInserter.cpp Wed Jul 19 17:08:02 2017
@@ -455,47 +455,76 @@ static void updateLiveness(MachineFuncti
   }
 }
 
-/// Insert restore code for the callee-saved registers used in the function.
-static void insertCSRSaves(MachineBasicBlock &SaveBlock,
-                           ArrayRef<CalleeSavedInfo> CSI) {
-  MachineFunction &Fn = *SaveBlock.getParent();
+/// insertCSRSpillsAndRestores - Insert spill and restore code for
+/// callee saved registers used in the function.
+///
+static void insertCSRSpillsAndRestores(MachineFunction &Fn,
+                                       const MBBVector &SaveBlocks,
+                                       const MBBVector &RestoreBlocks) {
+  // Get callee saved register information.
+  MachineFrameInfo &MFI = Fn.getFrameInfo();
+  const std::vector<CalleeSavedInfo> &CSI = MFI.getCalleeSavedInfo();
+
+  MFI.setCalleeSavedInfoValid(true);
+
+  // Early exit if no callee saved registers are modified!
+  if (CSI.empty())
+    return;
+
   const TargetInstrInfo &TII = *Fn.getSubtarget().getInstrInfo();
   const TargetFrameLowering *TFI = Fn.getSubtarget().getFrameLowering();
   const TargetRegisterInfo *TRI = Fn.getSubtarget().getRegisterInfo();
+  MachineBasicBlock::iterator I;
 
-  MachineBasicBlock::iterator I = SaveBlock.begin();
-  if (!TFI->spillCalleeSavedRegisters(SaveBlock, I, CSI, TRI)) {
-    for (const CalleeSavedInfo &CS : CSI) {
-      // Insert the spill to the stack frame.
-      unsigned Reg = CS.getReg();
-      const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
-      TII.storeRegToStackSlot(SaveBlock, I, Reg, true, CS.getFrameIdx(), RC,
-                              TRI);
+  // Spill using target interface.
+  for (MachineBasicBlock *SaveBlock : SaveBlocks) {
+    I = SaveBlock->begin();
+    if (!TFI->spillCalleeSavedRegisters(*SaveBlock, I, CSI, TRI)) {
+      for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
+        // Insert the spill to the stack frame.
+        unsigned Reg = CSI[i].getReg();
+        const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
+        TII.storeRegToStackSlot(*SaveBlock, I, Reg, true, CSI[i].getFrameIdx(),
+                                RC, TRI);
+      }
     }
+    // Update the live-in information of all the blocks up to the save point.
+    updateLiveness(Fn);
   }
-}
-
-/// Insert restore code for the callee-saved registers used in the function.
-static void insertCSRRestores(MachineBasicBlock &RestoreBlock,
-                              ArrayRef<CalleeSavedInfo> CSI) {
-  MachineFunction &Fn = *RestoreBlock.getParent();
-  const TargetInstrInfo &TII = *Fn.getSubtarget().getInstrInfo();
-  const TargetFrameLowering *TFI = Fn.getSubtarget().getFrameLowering();
-  const TargetRegisterInfo *TRI = Fn.getSubtarget().getRegisterInfo();
 
-  // Restore all registers immediately before the return and any
-  // terminators that precede it.
-  MachineBasicBlock::iterator I = RestoreBlock.getFirstTerminator();
-
-  if (!TFI->restoreCalleeSavedRegisters(RestoreBlock, I, CSI, TRI)) {
-    for (const CalleeSavedInfo &CI : reverse(CSI)) {
-      unsigned Reg = CI.getReg();
-      const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
-      TII.loadRegFromStackSlot(RestoreBlock, I, Reg, CI.getFrameIdx(), RC, TRI);
-      assert(I != RestoreBlock.begin() &&
-             "loadRegFromStackSlot didn't insert any code!");
-      // Insert in reverse order.  loadRegFromStackSlot can insert
-      // multiple instructions.
+  // Restore using target interface.
+  for (MachineBasicBlock *MBB : RestoreBlocks) {
+    I = MBB->end();
+
+    // Skip over all terminator instructions, which are part of the return
+    // sequence.
+    MachineBasicBlock::iterator I2 = I;
+    while (I2 != MBB->begin() && (--I2)->isTerminator())
+      I = I2;
+
+    bool AtStart = I == MBB->begin();
+    MachineBasicBlock::iterator BeforeI = I;
+    if (!AtStart)
+      --BeforeI;
+
+    // Restore all registers immediately before the return and any
+    // terminators that precede it.
+    if (!TFI->restoreCalleeSavedRegisters(*MBB, I, CSI, TRI)) {
+      for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
+        unsigned Reg = CSI[i].getReg();
+        const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
+        TII.loadRegFromStackSlot(*MBB, I, Reg, CSI[i].getFrameIdx(), RC, TRI);
+        assert(I != MBB->begin() &&
+               "loadRegFromStackSlot didn't insert any code!");
+        // Insert in reverse order.  loadRegFromStackSlot can insert
+        // multiple instructions.
+        if (AtStart)
+          I = MBB->begin();
+        else {
+          I = BeforeI;
+          ++I;
+        }
+      }
     }
   }
 }
@@ -503,8 +532,6 @@ static void insertCSRRestores(MachineBas
 void PEI::doSpillCalleeSavedRegs(MachineFunction &Fn) {
   const Function *F = Fn.getFunction();
   const TargetFrameLowering *TFI = Fn.getSubtarget().getFrameLowering();
-  MachineFrameInfo &MFI = Fn.getFrameInfo();
-  ArrayRef<CalleeSavedInfo> CSI = MFI.getCalleeSavedInfo();
   MinCSFrameIndex = std::numeric_limits<unsigned>::max();
   MaxCSFrameIndex = 0;
 
@@ -516,20 +543,8 @@ void PEI::doSpillCalleeSavedRegs(Machine
   assignCalleeSavedSpillSlots(Fn, SavedRegs, MinCSFrameIndex, MaxCSFrameIndex);
 
   // Add the code to save and restore the callee saved registers.
-  if (!F->hasFnAttribute(Attribute::Naked)) {
-    MFI.setCalleeSavedInfoValid(true);
-
-    if (!CSI.empty()) {
-      for (MachineBasicBlock *SaveBlock : SaveBlocks) {
-        insertCSRSaves(*SaveBlock, CSI);
-        // Update the live-in information of all the blocks up to the save
-        // point.
-        updateLiveness(Fn);
-      }
-      for (MachineBasicBlock *RestoreBlock : RestoreBlocks)
-        insertCSRRestores(*RestoreBlock, CSI);
-    }
-  }
+  if (!F->hasFnAttribute(Attribute::Naked))
+    insertCSRSpillsAndRestores(Fn, SaveBlocks, RestoreBlocks);
 }
 
 /// AdjustStackOffset - Helper function used to adjust the stack frame offset.