PPC: Add base-pointer support to builtin setjmp/longjmp

First, this changes the base-pointer implementation to remove an unnecessary
complication (and one that is incompatible with how builtin SjLj is
implemented): instead of using r31 as the base pointer when it is not needed as
a frame pointer, now the base pointer will always be r30 when needed.

Second, we introduce another pseudo register, BP, which is used just like the FP
pseudo register to refer to the base register before we know for certain what
register it will be.

Third, we now save BP into the jmp_buf, and restore r30 from that slot in
longjmp.  If the function that called setjmp did not use a base pointer, then
r30 will be overwritten by the setjmp-calling-function's restore code. FP
restoration (which is restored into r31) works the same way.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186545 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 23 insertions, 15 deletions

diff --git a/lib/Target/PowerPC/PPCFrameLowering.cpp b/lib/Target/PowerPC/PPCFrameLowering.cpp
index 3b57390611..d846365112 100644
--- a/lib/Target/PowerPC/PPCFrameLowering.cpp
+++ b/lib/Target/PowerPC/PPCFrameLowering.cpp
@@ -297,6 +297,12 @@ void PPCFrameLowering::replaceFPWithRealFP(MachineFunction &MF) const {
   unsigned FPReg  = is31 ? PPC::R31 : PPC::R1;
   unsigned FP8Reg = is31 ? PPC::X31 : PPC::X1;
 
+  const PPCRegisterInfo *RegInfo =
+    static_cast<const PPCRegisterInfo*>(MF.getTarget().getRegisterInfo());
+  bool HasBP = RegInfo->hasBasePointer(MF);
+  unsigned BPReg  = HasBP ? (unsigned) PPC::R30 : FPReg;
+  unsigned BP8Reg = HasBP ? (unsigned) PPC::X30 : FPReg;
+
   for (MachineFunction::iterator BI = MF.begin(), BE = MF.end();
        BI != BE; ++BI)
     for (MachineBasicBlock::iterator MBBI = BI->end(); MBBI != BI->begin(); ) {
@@ -313,6 +319,13 @@ void PPCFrameLowering::replaceFPWithRealFP(MachineFunction &MF) const {
         case PPC::FP8:
           MO.setReg(FP8Reg);
           break;
+        case PPC::BP:
+          MO.setReg(BPReg);
+          break;
+        case PPC::BP8:
+          MO.setReg(BP8Reg);
+          break;
+
         }
       }
     }
@@ -393,8 +406,7 @@ void PPCFrameLowering::emitPrologue(MachineFunction &MF) const {
       BPOffset = FFI->getObjectOffset(BPIndex);
     } else {
       BPOffset =
-        PPCFrameLowering::getBasePointerSaveOffset(isPPC64, isDarwinABI,
-                                                   HasFP);
+        PPCFrameLowering::getBasePointerSaveOffset(isPPC64, isDarwinABI);
     }
   }
 
@@ -417,7 +429,7 @@ void PPCFrameLowering::emitPrologue(MachineFunction &MF) const {
 
     if (HasBP)
       BuildMI(MBB, MBBI, dl, TII.get(PPC::STD))
-        .addReg(HasFP ? PPC::X30 : PPC::X31)
+        .addReg(PPC::X30)
         .addImm(BPOffset)
         .addReg(PPC::X1);
 
@@ -448,7 +460,7 @@ void PPCFrameLowering::emitPrologue(MachineFunction &MF) const {
       // FIXME: On PPC32 SVR4, FPOffset is negative and access to negative
       // offsets of R1 is not allowed.
       BuildMI(MBB, MBBI, dl, TII.get(PPC::STW))
-        .addReg(HasFP ? PPC::R30 : PPC::R31)
+        .addReg(PPC::R30)
         .addImm(BPOffset)
         .addReg(PPC::R1);
 
@@ -475,8 +487,7 @@ void PPCFrameLowering::emitPrologue(MachineFunction &MF) const {
 
     if (HasBP) {
       // Save a copy of r1 as the base pointer.
-      BuildMI(MBB, MBBI, dl, TII.get(PPC::OR),
-              HasFP ? PPC::R30 : PPC::R31)
+      BuildMI(MBB, MBBI, dl, TII.get(PPC::OR), PPC::R30)
         .addReg(PPC::R1)
         .addReg(PPC::R1);
     }
@@ -527,8 +538,7 @@ void PPCFrameLowering::emitPrologue(MachineFunction &MF) const {
   } else {    // PPC64.
     if (HasBP) {
       // Save a copy of r1 as the base pointer.
-      BuildMI(MBB, MBBI, dl, TII.get(PPC::OR8),
-              HasFP ? PPC::X30 : PPC::X31)
+      BuildMI(MBB, MBBI, dl, TII.get(PPC::OR8), PPC::X30)
         .addReg(PPC::X1)
         .addReg(PPC::X1);
     }
@@ -597,8 +607,7 @@ void PPCFrameLowering::emitPrologue(MachineFunction &MF) const {
     }
 
     if (HasBP) {
-      unsigned Reg = isPPC64 ? (HasFP ? PPC::X30 : PPC::X31) :
-                               (HasFP ? PPC::R30 : PPC::R31);
+      unsigned Reg = isPPC64 ? PPC::X30 : PPC::R30;
       Reg = MRI->getDwarfRegNum(Reg, true);
       MMI.addFrameInst(
           MCCFIInstruction::createOffset(FrameLabel, Reg, BPOffset));
@@ -739,8 +748,7 @@ void PPCFrameLowering::emitEpilogue(MachineFunction &MF,
       BPOffset = FFI->getObjectOffset(BPIndex);
     } else {
       BPOffset =
-        PPCFrameLowering::getBasePointerSaveOffset(isPPC64, isDarwinABI,
-                                                   HasFP);
+        PPCFrameLowering::getBasePointerSaveOffset(isPPC64, isDarwinABI);
     }
   }
 
@@ -836,7 +844,7 @@ void PPCFrameLowering::emitEpilogue(MachineFunction &MF,
         .addImm(FPOffset).addReg(PPC::X1);
 
     if (HasBP)
-      BuildMI(MBB, MBBI, dl, TII.get(PPC::LD), HasFP ? PPC::X30 : PPC::X31)
+      BuildMI(MBB, MBBI, dl, TII.get(PPC::LD), PPC::X30)
         .addImm(BPOffset).addReg(PPC::X1);
 
     if (!MustSaveCRs.empty())
@@ -859,7 +867,7 @@ void PPCFrameLowering::emitEpilogue(MachineFunction &MF,
           .addImm(FPOffset).addReg(PPC::R1);
 
     if (HasBP)
-      BuildMI(MBB, MBBI, dl, TII.get(PPC::LWZ), HasFP ? PPC::R30 : PPC::R31)
+      BuildMI(MBB, MBBI, dl, TII.get(PPC::LWZ), PPC::R30)
           .addImm(FPOffset).addReg(PPC::R1);
 
     if (MustSaveLR)
@@ -968,7 +976,7 @@ PPCFrameLowering::processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
 
   int BPSI = FI->getBasePointerSaveIndex();
   if (!BPSI && RegInfo->hasBasePointer(MF)) {
-    int BPOffset = getBasePointerSaveOffset(isPPC64, isDarwinABI, needsFP(MF));
+    int BPOffset = getBasePointerSaveOffset(isPPC64, isDarwinABI);
     // Allocate the frame index for the base pointer save area.
     BPSI = MFI->CreateFixedObject(isPPC64? 8 : 4, BPOffset, true);
     // Save the result.