Don't reserve R2 on Darwin/PPC

Now that only the register-scavenger version of the CR spilling code remains,
we no longer need the Darwin R2 hack. Darwin can use R0 as a spare register in
any case where the System V ABI uses it (R0 is special architecturally, and so
is reserved under all common ABIs).

A few test cases needed to be updated to reflect the register-allocation changes.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@176868 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 2 insertions, 16 deletions

diff --git a/lib/Target/PowerPC/PPCRegisterInfo.cpp b/lib/Target/PowerPC/PPCRegisterInfo.cpp
index fd79de1387..3e5ee752a9 100644
--- a/lib/Target/PowerPC/PPCRegisterInfo.cpp
+++ b/lib/Target/PowerPC/PPCRegisterInfo.cpp
@@ -121,12 +121,6 @@ BitVector PPCRegisterInfo::getReservedRegs(const MachineFunction &MF) const {
     Reserved.set(PPC::R2);  // System-reserved register
     Reserved.set(PPC::R13); // Small Data Area pointer register
   }
-  // Reserve R2 on Darwin to hack around the problem of save/restore of CR
-  // when the stack frame is too big to address directly; we need two regs.
-  // This is a hack.
-  if (Subtarget.isDarwinABI()) {
-    Reserved.set(PPC::R2);
-  }
   
   // On PPC64, r13 is the thread pointer. Never allocate this register.
   // Note that this is over conservative, as it also prevents allocation of R31
@@ -144,12 +138,6 @@ BitVector PPCRegisterInfo::getReservedRegs(const MachineFunction &MF) const {
     if (Subtarget.isSVR4ABI()) {
       Reserved.set(PPC::X2);
     }
-    // Reserve X2 on Darwin to hack around the problem of save/restore of CR
-    // when the stack frame is too big to address directly; we need two regs.
-    // This is a hack.
-    if (Subtarget.isDarwinABI()) {
-      Reserved.set(PPC::X2);
-    }
   }
 
   if (PPCFI->needsFP(MF))
@@ -334,8 +322,7 @@ void PPCRegisterInfo::lowerCRSpilling(MachineBasicBlock::iterator II,
   (void) RS;
 
   bool LP64 = Subtarget.isPPC64();
-  unsigned Reg = Subtarget.isDarwinABI() ?  (LP64 ? PPC::X2 : PPC::R2) :
-                                            (LP64 ? PPC::X0 : PPC::R0);
+  unsigned Reg = LP64 ? PPC::X0 : PPC::R0;
   unsigned SrcReg = MI.getOperand(0).getReg();
 
   // We need to store the CR in the low 4-bits of the saved value. First, issue
@@ -377,8 +364,7 @@ void PPCRegisterInfo::lowerCRRestore(MachineBasicBlock::iterator II,
   (void) RS;
 
   bool LP64 = Subtarget.isPPC64();
-  unsigned Reg = Subtarget.isDarwinABI() ?  (LP64 ? PPC::X2 : PPC::R2) :
-                                            (LP64 ? PPC::X0 : PPC::R0);
+  unsigned Reg = LP64 ? PPC::X0 : PPC::R0;
   unsigned DestReg = MI.getOperand(0).getReg();
   assert(MI.definesRegister(DestReg) &&
     "RESTORE_CR does not define its destination");