This patch corrects logic in PPCFrameLowering for save and restore of

nonvolatile condition register fields across calls under the SVR4 ABIs.                                            
                                                                                                                   
 * With the 64-bit ABI, the save location is at a fixed offset of 8 from                                           
the stack pointer.  The frame pointer cannot be used to access this                                                
portion of the stack frame since the distance from the frame pointer may                                           
change with alloca calls.                                                                                          
                                                                                                                   
 * With the 32-bit ABI, the save location is just below the general
register save area, and is accessed via the frame pointer like the rest
of the save areas.  This is an optional slot, so it must only be created                                           
if any of CR2, CR3, and CR4 were modified.                                                                      
                                                                                                                   
 * For both ABIs, save/restore logic is generated only if one of the     
nonvolatile CR fields were modified.                                   

I also took this opportunity to clean up an extra FIXME in
PPCFrameLowering.h.  Save area offsets for 32-bit GPRs are meaningless
for the 64-bit ABI, so I removed them for correctness and efficiency.


Fixes PR13708 and partially also PR13623. It lets us enable exception handling
on PPC64.

Patch by William J. Schmidt!


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@163713 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 15 insertions, 56 deletions

diff --git a/lib/Target/PowerPC/PPCFrameLowering.h b/lib/Target/PowerPC/PPCFrameLowering.h
index d708541c66..4d957b91c7 100644
--- a/lib/Target/PowerPC/PPCFrameLowering.h
+++ b/lib/Target/PowerPC/PPCFrameLowering.h
@@ -45,6 +45,16 @@ public:
                                             RegScavenger *RS = NULL) const;
   void processFunctionBeforeFrameFinalized(MachineFunction &MF) const;
 
+  bool spillCalleeSavedRegisters(MachineBasicBlock &MBB,
+                                 MachineBasicBlock::iterator MI,
+                                 const std::vector<CalleeSavedInfo> &CSI,
+                                 const TargetRegisterInfo *TRI) const;
+
+  bool restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
+                                   MachineBasicBlock::iterator MI,
+                                   const std::vector<CalleeSavedInfo> &CSI,
+                                   const TargetRegisterInfo *TRI) const;
+
   /// targetHandlesStackFrameRounding - Returns true if the target is
   /// responsible for rounding up the stack frame (probably at emitPrologue
   /// time).
@@ -170,23 +180,11 @@ public:
       {PPC::R15, -68},
       {PPC::R14, -72},
 
-      // CR save area offset.
-      // FIXME SVR4: Disable CR save area for now.
-//      {PPC::CR2, -4},
-//      {PPC::CR3, -4},
-//      {PPC::CR4, -4},
-//      {PPC::CR2LT, -4},
-//      {PPC::CR2GT, -4},
-//      {PPC::CR2EQ, -4},
-//      {PPC::CR2UN, -4},
-//      {PPC::CR3LT, -4},
-//      {PPC::CR3GT, -4},
-//      {PPC::CR3EQ, -4},
-//      {PPC::CR3UN, -4},
-//      {PPC::CR4LT, -4},
-//      {PPC::CR4GT, -4},
-//      {PPC::CR4EQ, -4},
-//      {PPC::CR4UN, -4},
+      // CR save area offset.  We map each of the nonvolatile CR fields
+      // to the slot for CR2, which is the first of the nonvolatile CR
+      // fields to be assigned, so that we only allocate one save slot.
+      // See PPCRegisterInfo::hasReservedSpillSlot() for more information.
+      {PPC::CR2, -4},
 
       // VRSAVE save area offset.
       {PPC::VRSAVE, -4},
@@ -228,27 +226,6 @@ public:
       {PPC::F14, -144},
 
       // General register save area offsets.
-      // FIXME 64-bit SVR4: Are 32-bit registers actually allocated in 64-bit
-      //                    mode?
-      {PPC::R31, -4},
-      {PPC::R30, -12},
-      {PPC::R29, -20},
-      {PPC::R28, -28},
-      {PPC::R27, -36},
-      {PPC::R26, -44},
-      {PPC::R25, -52},
-      {PPC::R24, -60},
-      {PPC::R23, -68},
-      {PPC::R22, -76},
-      {PPC::R21, -84},
-      {PPC::R20, -92},
-      {PPC::R19, -100},
-      {PPC::R18, -108},
-      {PPC::R17, -116},
-      {PPC::R16, -124},
-      {PPC::R15, -132},
-      {PPC::R14, -140},
-
       {PPC::X31, -8},
       {PPC::X30, -16},
       {PPC::X29, -24},
@@ -268,24 +245,6 @@ public:
       {PPC::X15, -136},
       {PPC::X14, -144},
 
-      // CR save area offset.
-      // FIXME SVR4: Disable CR save area for now.
-//      {PPC::CR2, -4},
-//      {PPC::CR3, -4},
-//      {PPC::CR4, -4},
-//      {PPC::CR2LT, -4},
-//      {PPC::CR2GT, -4},
-//      {PPC::CR2EQ, -4},
-//      {PPC::CR2UN, -4},
-//      {PPC::CR3LT, -4},
-//      {PPC::CR3GT, -4},
-//      {PPC::CR3EQ, -4},
-//      {PPC::CR3UN, -4},
-//      {PPC::CR4LT, -4},
-//      {PPC::CR4GT, -4},
-//      {PPC::CR4EQ, -4},
-//      {PPC::CR4UN, -4},
-
       // VRSAVE save area offset.
       {PPC::VRSAVE, -4},