Fix ARM hasFP() semantics. It should return true whenever FP register is

reserved, not available for general allocation. This eliminates all the
extra checks for Darwin.

This change also fixes the use of FP to access frame indices in leaf
functions and cleaned up some confusing code in epilogue emission.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@110655 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 5 insertions, 6 deletions

diff --git a/lib/Target/ARM/Thumb1RegisterInfo.cpp b/lib/Target/ARM/Thumb1RegisterInfo.cpp
index 9ae3145..50328e3 100644
--- a/lib/Target/ARM/Thumb1RegisterInfo.cpp
+++ b/lib/Target/ARM/Thumb1RegisterInfo.cpp
@@ -742,11 +742,11 @@ void Thumb1RegisterInfo::emitPrologue(MachineFunction &MF) const {
       dl = MBBI->getDebugLoc();
   }
 
-  // Darwin ABI requires FP to point to the stack slot that contains the
-  // previous FP.
-  if (STI.isTargetDarwin() || hasFP(MF)) {
+  // Adjust FP so it point to the stack slot that contains the previous FP.
+  if (hasFP(MF)) {
     BuildMI(MBB, MBBI, dl, TII.get(ARM::tADDrSPi), FramePtr)
       .addFrameIndex(FramePtrSpillFI).addImm(0);
+    AFI->setShouldRestoreSPFromFP(true);
   }
 
   // Determine starting offsets of spill areas.
@@ -764,10 +764,9 @@ void Thumb1RegisterInfo::emitPrologue(MachineFunction &MF) const {
     emitSPUpdate(MBB, MBBI, TII, dl, *this, -NumBytes);
   }
 
-  if (STI.isTargetELF() && hasFP(MF)) {
+  if (STI.isTargetELF() && hasFP(MF))
     MFI->setOffsetAdjustment(MFI->getOffsetAdjustment() -
                              AFI->getFramePtrSpillOffset());
-  }
 
   AFI->setGPRCalleeSavedArea1Size(GPRCS1Size);
   AFI->setGPRCalleeSavedArea2Size(GPRCS2Size);
@@ -828,7 +827,7 @@ void Thumb1RegisterInfo::emitEpilogue(MachineFunction &MF,
                  AFI->getGPRCalleeSavedArea2Size() +
                  AFI->getDPRCalleeSavedAreaSize());
 
-    if (hasFP(MF)) {
+    if (AFI->shouldRestoreSPFromFP()) {
       NumBytes = AFI->getFramePtrSpillOffset() - NumBytes;
       // Reset SP based on frame pointer only if the stack frame extends beyond
       // frame pointer stack slot or target is ELF and the function has FP.