[PPC] Properly update register save area offsets

The variables MinGPR/MinG8R were not updated properly when resetting the
offsets, which in the included testcase lead to saving the CR register
in the same location as R30.

This fixes another issue reported in PR26519.

Differential Revision: https://reviews.llvm.org/D33017

llvm-svn: 303257

1 files changed, 14 insertions, 9 deletions

diff --git a/llvm/lib/Target/PowerPC/PPCFrameLowering.cpp b/llvm/lib/Target/PowerPC/PPCFrameLowering.cpp
index 40bfe3a449f..57a1d373c88 100644
--- a/llvm/lib/Target/PowerPC/PPCFrameLowering.cpp
+++ b/llvm/lib/Target/PowerPC/PPCFrameLowering.cpp
@@ -1765,31 +1765,36 @@ void PPCFrameLowering::processFunctionBeforeFrameFinalized(MachineFunction &MF,
   // Check whether the frame pointer register is allocated. If so, make sure it
   // is spilled to the correct offset.
   if (needsFP(MF)) {
-    HasGPSaveArea = true;
-
     int FI = PFI->getFramePointerSaveIndex();
     assert(FI && "No Frame Pointer Save Slot!");
-
     MFI.setObjectOffset(FI, LowerBound + MFI.getObjectOffset(FI));
+    // FP is R31/X31, so no need to update MinGPR/MinG8R.
+    HasGPSaveArea = true;
   }
 
   if (PFI->usesPICBase()) {
-    HasGPSaveArea = true;
-
     int FI = PFI->getPICBasePointerSaveIndex();
     assert(FI && "No PIC Base Pointer Save Slot!");
-
     MFI.setObjectOffset(FI, LowerBound + MFI.getObjectOffset(FI));
+
+    MinGPR = std::min<unsigned>(MinGPR, PPC::R30);
+    HasGPSaveArea = true;
   }
 
   const PPCRegisterInfo *RegInfo = Subtarget.getRegisterInfo();
   if (RegInfo->hasBasePointer(MF)) {
-    HasGPSaveArea = true;
-
     int FI = PFI->getBasePointerSaveIndex();
     assert(FI && "No Base Pointer Save Slot!");
-
     MFI.setObjectOffset(FI, LowerBound + MFI.getObjectOffset(FI));
+
+    unsigned BP = RegInfo->getBaseRegister(MF);
+    if (PPC::G8RCRegClass.contains(BP)) {
+      MinG8R = std::min<unsigned>(MinG8R, BP);
+      HasG8SaveArea = true;
+    } else if (PPC::GPRCRegClass.contains(BP)) {
+      MinGPR = std::min<unsigned>(MinGPR, BP);
+      HasGPSaveArea = true;
+    }
   }
 
   // General register save area starts right below the Floating-point