Merge commit '9c3d4f344685' from llvm.org/release/19.x into stable/20240723

Author: git apple-llvm automerger

llvm/lib/Target/PowerPC/PPCFrameLowering.cpp

@@ -1007,7 +1007,7 @@ void PPCFrameLowering::emitPrologue(MachineFunction &MF,
         // R0 cannot be used as a base register, but it can be used as an
         // index in a store-indexed.
         int LastOffset = 0;
-        if (HasFP)  {
+        if (HasFP) {
           // R0 += (FPOffset-LastOffset).
           // Need addic, since addi treats R0 as 0.
           BuildMI(MBB, MBBI, dl, TII.get(PPC::ADDIC), ScratchReg)
@@ -2025,8 +2025,18 @@ void PPCFrameLowering::determineCalleeSaves(MachineFunction &MF,
   // code. Same goes for the base pointer and the PIC base register.
   if (needsFP(MF))
     SavedRegs.reset(isPPC64 ? PPC::X31 : PPC::R31);
-  if (RegInfo->hasBasePointer(MF))
+  if (RegInfo->hasBasePointer(MF)) {
     SavedRegs.reset(RegInfo->getBaseRegister(MF));
+    // On AIX, when BaseRegister(R30) is used, need to spill r31 too to match
+    // AIX trackback table requirement.
+    if (!needsFP(MF) && !SavedRegs.test(isPPC64 ? PPC::X31 : PPC::R31) &&
+        Subtarget.isAIXABI()) {
+      assert(
+          (RegInfo->getBaseRegister(MF) == (isPPC64 ? PPC::X30 : PPC::R30)) &&
+          "Invalid base register on AIX!");
+      SavedRegs.set(isPPC64 ? PPC::X31 : PPC::R31);
+    }
+  }
   if (FI->usesPICBase())
     SavedRegs.reset(PPC::R30);
 

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

@@ -6,6 +6,7 @@
 
 ; Use an overaligned buffer to force base-pointer usage. Test verifies:
 ; - base pointer register (r30) is saved/defined/restored.
+; - frame pointer register (r31) is saved/defined/restored.
 ; - stack frame is allocated with correct alignment.
 ; - Address of %AlignedBuffer is calculated based off offset from the stack
 ;   pointer.
@@ -25,7 +26,9 @@ declare void @callee(ptr)
 ; 32BIT:         subfic 0, 0, -224
 ; 32BIT:         stwux 1, 1, 0
 ; 32BIT:         addi 3, 1, 64
+; 32BIT:         stw 31, -12(30)
 ; 32BIT:         bl .callee
+; 32BIT:         lwz 31, -12(30)
 ; 32BIT:         mr 1, 30
 ; 32BIT:         lwz 30, -16(1)
 
@@ -36,6 +39,8 @@ declare void @callee(ptr)
 ; 64BIT:         subfic 0, 0, -288
 ; 64BIT:         stdux 1, 1, 0
 ; 64BIT:         addi 3, 1, 128
+; 64BIT:         std 31, -16(30)
 ; 64BIT:         bl .callee
+; 64BIT:         ld 31, -16(30)
 ; 64BIT:         mr 1, 30
 ; 64BIT:         ld 30, -24(1)