Allow a target to choose whether to prefer the scavenger emergency spill slot

be next to the frame pointer or the stack pointer.

llvm-svn: 126956

2 files changed, 13 insertions, 7 deletions

diff --git a/llvm/include/llvm/Target/TargetRegisterInfo.h b/llvm/include/llvm/Target/TargetRegisterInfo.h
index 121091c9b49..af10748ef4f 100644
--- a/llvm/include/llvm/Target/TargetRegisterInfo.h
+++ b/llvm/include/llvm/Target/TargetRegisterInfo.h
@@ -631,6 +631,13 @@ public:
     return false;
   }
 
+  /// useFPForScavengingIndex - returns true if the target wants to use
+  /// frame pointer based accesses to spill to the scavenger emergency spill
+  /// slot.
+  virtual bool useFPForScavengingIndex(const MachineFunction &MF) const {
+    return true;
+  }
+
   /// requiresFrameIndexScavenging - returns true if the target requires post
   /// PEI scavenging of registers for materializing frame index constants.
   virtual bool requiresFrameIndexScavenging(const MachineFunction &MF) const {
diff --git a/llvm/lib/CodeGen/PrologEpilogInserter.cpp b/llvm/lib/CodeGen/PrologEpilogInserter.cpp
index ad7b6e4aa97..92e25e150f5 100644
--- a/llvm/lib/CodeGen/PrologEpilogInserter.cpp
+++ b/llvm/lib/CodeGen/PrologEpilogInserter.cpp
@@ -559,7 +559,8 @@ void PEI::calculateFrameObjectOffsets(MachineFunction &Fn) {
   // Make sure the special register scavenging spill slot is closest to the
   // frame pointer if a frame pointer is required.
   const TargetRegisterInfo *RegInfo = Fn.getTarget().getRegisterInfo();
-  if (RS && TFI.hasFP(Fn) && !RegInfo->needsStackRealignment(Fn)) {
+  if (RS && TFI.hasFP(Fn) && RegInfo->useFPForScavengingIndex(Fn) &&
+      !RegInfo->needsStackRealignment(Fn)) {
     int SFI = RS->getScavengingFrameIndex();
     if (SFI >= 0)
       AdjustStackOffset(MFI, SFI, StackGrowsDown, Offset, MaxAlign);
@@ -641,7 +642,8 @@ void PEI::calculateFrameObjectOffsets(MachineFunction &Fn) {
 
   // Make sure the special register scavenging spill slot is closest to the
   // stack pointer.
-  if (RS && (!TFI.hasFP(Fn) || RegInfo->needsStackRealignment(Fn))) {
+  if (RS && (!TFI.hasFP(Fn) || RegInfo->needsStackRealignment(Fn) ||
+             !RegInfo->useFPForScavengingIndex(Fn))) {
     int SFI = RS->getScavengingFrameIndex();
     if (SFI >= 0)
       AdjustStackOffset(MFI, SFI, StackGrowsDown, Offset, MaxAlign);
@@ -811,7 +813,6 @@ void PEI::scavengeFrameVirtualRegs(MachineFunction &Fn) {
     // directly.
     for (MachineBasicBlock::iterator I = BB->begin(); I != BB->end(); ) {
       MachineInstr *MI = I;
-      bool DoIncr = true;
       for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
         if (MI->getOperand(i).isReg()) {
           MachineOperand &MO = MI->getOperand(i);
@@ -842,10 +843,8 @@ void PEI::scavengeFrameVirtualRegs(MachineFunction &Fn) {
 
         }
       }
-      if (DoIncr) {
-        RS->forward(I);
-        ++I;
-      }
+      RS->forward(I);
+      ++I;
     }
   }
 }