Improve PPC VR (Altivec) register spilling

This change cleans up two issues with Altivec register spilling:

  1. The spilling code was inefficient (using two instructions, and add and a
     load, when just one would do)

  2. The code assumed that r0 would always be available (true for now, but this
     will change)

The new code handles VR spilling just like GPR spills but forced into r+r mode.
As a result, when any VR spills are present, we must now always allocate the
register-scavenger spill slot.

llvm-svn: 177231

1 files changed, 24 insertions, 3 deletions

diff --git a/llvm/lib/Target/PowerPC/PPCRegisterInfo.cpp b/llvm/lib/Target/PowerPC/PPCRegisterInfo.cpp
index 5ce284be71c..e2c7221be37 100644
--- a/llvm/lib/Target/PowerPC/PPCRegisterInfo.cpp
+++ b/llvm/lib/Target/PowerPC/PPCRegisterInfo.cpp
@@ -442,7 +442,25 @@ PPCRegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II,
     isIXAddr = true;
     break;
   }
-  
+
+  bool noImmForm = false;
+  switch (OpC) {
+  case PPC::LVEBX:
+  case PPC::LVEHX:
+  case PPC::LVEWX:
+  case PPC::LVX:
+  case PPC::LVXL:
+  case PPC::LVSL:
+  case PPC::LVSR:
+  case PPC::STVEBX:
+  case PPC::STVEHX:
+  case PPC::STVEWX:
+  case PPC::STVX:
+  case PPC::STVXL:
+    noImmForm = true;
+    break;
+  }
+
   // Now add the frame object offset to the offset from r1.
   int Offset = MFI->getObjectOffset(FrameIndex);
   if (!isIXAddr)
@@ -466,7 +484,8 @@ PPCRegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II,
   // only "std" to a stack slot that is at least 4-byte aligned, but it can
   // happen in invalid code.
   if (OpC == PPC::DBG_VALUE || // DBG_VALUE is always Reg+Imm
-      (isInt<16>(Offset) && (!isIXAddr || (Offset & 3) == 0))) {
+      (!noImmForm &&
+       isInt<16>(Offset) && (!isIXAddr || (Offset & 3) == 0))) {
     if (isIXAddr)
       Offset >>= 2;    // The actual encoded value has the low two bits zero.
     MI.getOperand(OffsetOperandNo).ChangeToImmediate(Offset);
@@ -493,7 +512,9 @@ PPCRegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II,
   //   addi 0:rA 1:rB, 2, imm ==> add 0:rA, 1:rB, 2:r0
   unsigned OperandBase;
 
-  if (OpC != TargetOpcode::INLINEASM) {
+  if (noImmForm)
+    OperandBase = 1;
+  else if (OpC != TargetOpcode::INLINEASM) {
     assert(ImmToIdxMap.count(OpC) &&
            "No indexed form of load or store available!");
     unsigned NewOpcode = ImmToIdxMap.find(OpC)->second;