[PowerPC][AIX] Update save/restore offset for frame and base pointers.

General purpose registers 30 and 31 are handled differently when they are
reserved as the base-pointer and frame-pointer respectively. This fixes the
offset of their fixed-stack objects when there are fpr calle-saved registers.

Differential Revision: https://reviews.llvm.org/D85850

Author: mandlebug

llvm/lib/Target/PowerPC/PPCFrameLowering.cpp

@@ -863,26 +863,18 @@ void PPCFrameLowering::emitPrologue(MachineFunction &MF,
 
   int FPOffset = 0;
   if (HasFP) {
-    if (isSVR4ABI) {
-      MachineFrameInfo &MFI = MF.getFrameInfo();
-      int FPIndex = FI->getFramePointerSaveIndex();
-      assert(FPIndex && "No Frame Pointer Save Slot!");
-      FPOffset = MFI.getObjectOffset(FPIndex);
-    } else {
-      FPOffset = getFramePointerSaveOffset();
-    }
+    MachineFrameInfo &MFI = MF.getFrameInfo();
+    int FPIndex = FI->getFramePointerSaveIndex();
+    assert(FPIndex && "No Frame Pointer Save Slot!");
+    FPOffset = MFI.getObjectOffset(FPIndex);
   }
 
   int BPOffset = 0;
   if (HasBP) {
-    if (isSVR4ABI) {
-      MachineFrameInfo &MFI = MF.getFrameInfo();
-      int BPIndex = FI->getBasePointerSaveIndex();
-      assert(BPIndex && "No Base Pointer Save Slot!");
-      BPOffset = MFI.getObjectOffset(BPIndex);
-    } else {
-      BPOffset = getBasePointerSaveOffset();
-    }
+    MachineFrameInfo &MFI = MF.getFrameInfo();
+    int BPIndex = FI->getBasePointerSaveIndex();
+    assert(BPIndex && "No Base Pointer Save Slot!");
+    BPOffset = MFI.getObjectOffset(BPIndex);
   }
 
   int PBPOffset = 0;
@@ -1551,8 +1543,6 @@ void PPCFrameLowering::emitEpilogue(MachineFunction &MF,
 
   // Get processor type.
   bool isPPC64 = Subtarget.isPPC64();
-  // Get the ABI.
-  bool isSVR4ABI = Subtarget.isSVR4ABI();
 
   // Check if the link register (LR) has been saved.
   PPCFunctionInfo *FI = MF.getInfo<PPCFunctionInfo>();
@@ -1600,24 +1590,16 @@ void PPCFrameLowering::emitEpilogue(MachineFunction &MF,
   SingleScratchReg = ScratchReg == TempReg;
 
   if (HasFP) {
-    if (isSVR4ABI) {
-      int FPIndex = FI->getFramePointerSaveIndex();
-      assert(FPIndex && "No Frame Pointer Save Slot!");
-      FPOffset = MFI.getObjectOffset(FPIndex);
-    } else {
-      FPOffset = getFramePointerSaveOffset();
-    }
+    int FPIndex = FI->getFramePointerSaveIndex();
+    assert(FPIndex && "No Frame Pointer Save Slot!");
+    FPOffset = MFI.getObjectOffset(FPIndex);
   }
 
   int BPOffset = 0;
   if (HasBP) {
-    if (isSVR4ABI) {
       int BPIndex = FI->getBasePointerSaveIndex();
       assert(BPIndex && "No Base Pointer Save Slot!");
       BPOffset = MFI.getObjectOffset(BPIndex);
-    } else {
-      BPOffset = getBasePointerSaveOffset();
-    }
   }
 
   int PBPOffset = 0;

llvm/test/CodeGen/PowerPC/aix-base-pointer.ll

@@ -10,33 +10,33 @@
 ; - Address of %AlignedBuffer is calculated based off offset from the stack
 ;   pointer.
 
-define void @caller() {
+define float @caller(float %f) {
   %AlignedBuffer = alloca [32 x i32], align 32
   %Pointer = getelementptr inbounds [32 x i32], [32 x i32]* %AlignedBuffer, i64 0, i64 0
   call void @callee(i32* %Pointer)
-  ret void
+  ret float %f
 }
 
 declare void @callee(i32*)
 
 ; 32BIT-LABEL: .caller:
-; 32BIT:         stw 30, -8(1)
+; 32BIT:         stw 30, -16(1)
 ; 32BIT:         mr 30, 1
 ; 32BIT:         clrlwi  0, 1, 27
 ; 32BIT:         subfic 0, 0, -224
 ; 32BIT:         stwux 1, 1, 0
 ; 32BIT:         addi 3, 1, 64
 ; 32BIT:         bl .callee
 ; 32BIT:         lwz 1, 0(1)
-; 32BIT:         lwz 30, -8(1)
+; 32BIT:         lwz 30, -16(1)
 
 ; 64BIT-LABEL: .caller:
-; 64BIT:         std 30, -16(1)
+; 64BIT:         std 30, -24(1)
 ; 64BIT:         mr 30, 1
 ; 64BIT:         clrldi  0, 1, 59
 ; 64BIT:         subfic 0, 0, -288
 ; 64BIT:         stdux 1, 1, 0
 ; 64BIT:         addi 3, 1, 128
 ; 64BIT:         bl .callee
 ; 64BIT:         ld 1, 0(1)
-; 64BIT:         ld 30, -16(1)
+; 64BIT:         ld 30, -24(1)

llvm/test/CodeGen/PowerPC/aix-framepointer-save-restore.ll

@@ -0,0 +1,27 @@
+; RUN: llc -verify-machineinstrs < %s -mcpu=pwr4 -mattr=-altivec \
+; RUN:     -mtriple=powerpc-ibm-aix-xcoff | \
+; RUN:   FileCheck %s -check-prefix=AIX32
+
+; RUN: llc -verify-machineinstrs < %s -mcpu=pwr4 -mattr=-altivec \
+; RUN:     -mtriple=powerpc64-ibm-aix-xcoff | \
+; RUN:   FileCheck %s -check-prefixes=AIX64
+
+declare void @clobber(i32*)
+
+define dso_local float @frameptr_only(i32 %n, float %f) {
+entry:
+  %0 = alloca i32, i32 %n
+  call void @clobber(i32* %0)
+  ret float %f
+}
+
+; AIX32: stw 31, -12(1)
+; AIX32: stwu 1, -80(1)
+; AIX32: lwz 1, 0(1)
+; AIX32: lwz 31, -12(1)
+
+; AIX64: std 31, -16(1)
+; AIX64: stdu 1, -144(1)
+; AIX64: ld 1, 0(1)
+; AIX64: ld 31, -16(1)
+