[llvm-branch-commits] [llvm] [AArch64][SME] Support split ZPR and PPR area allocation (PR #142392)

[Benjamin Maxwell via llvm-branch-commits]

================
@@ -2324,73 +2340,96 @@ void AArch64FrameLowering::emitPrologue(MachineFunction &MF,
   StackOffset SVECalleeSavesSize = PPRCalleeSavesSize + ZPRCalleeSavesSize;
   StackOffset PPRLocalsSize = getPPRStackSize(MF) - PPRCalleeSavesSize;
   StackOffset ZPRLocalsSize = getZPRStackSize(MF) - ZPRCalleeSavesSize;
+  std::optional<MachineBasicBlock::iterator> ZPRCalleeSavesBegin,
+      ZPRCalleeSavesEnd, PPRCalleeSavesBegin, PPRCalleeSavesEnd;
 
   StackOffset CFAOffset =
       StackOffset::getFixed((int64_t)MFI.getStackSize() - NumBytes);
   if (!FPAfterSVECalleeSaves) {
-    MachineBasicBlock::iterator ZPRCalleeSavesBegin = MBBI,
-                                ZPRCalleeSavesEnd = MBBI;
-    MachineBasicBlock::iterator PPRCalleeSavesBegin = MBBI,
-                                PPRCalleeSavesEnd = MBBI;
-
-    // Process the SVE callee-saves to determine what space needs to be
-    // allocated.
-
+    // Process the SVE callee-saves to find the starts/ends of the ZPR and PPR
+    // areas.
+    PPRCalleeSavesBegin = MBBI;
     if (PPRCalleeSavesSize) {
       LLVM_DEBUG(dbgs() << "PPRCalleeSavedStackSize = "
                         << PPRCalleeSavesSize.getScalable() << "\n");
 
-      PPRCalleeSavesBegin = MBBI;
-      assert(isPartOfPPRCalleeSaves(PPRCalleeSavesBegin) &&
+      assert(isPartOfPPRCalleeSaves(*PPRCalleeSavesBegin) &&
              "Unexpected instruction");
       while (isPartOfPPRCalleeSaves(MBBI) && MBBI != MBB.getFirstTerminator())
         ++MBBI;
-      PPRCalleeSavesEnd = MBBI;
     }
-
+    PPRCalleeSavesEnd = ZPRCalleeSavesBegin = MBBI;
     if (ZPRCalleeSavesSize) {
       LLVM_DEBUG(dbgs() << "ZPRCalleeSavedStackSize = "
                         << ZPRCalleeSavesSize.getScalable() << "\n");
-      ZPRCalleeSavesBegin = MBBI;
-      assert(isPartOfZPRCalleeSaves(ZPRCalleeSavesBegin) &&
+      assert(isPartOfZPRCalleeSaves(*ZPRCalleeSavesBegin) &&
              "Unexpected instruction");
       while (isPartOfZPRCalleeSaves(MBBI) && MBBI != MBB.getFirstTerminator())
         ++MBBI;
-      ZPRCalleeSavesEnd = MBBI;
     }
-
-    // Allocate space for the callee saves (if any).
-    StackOffset LocalsSize =
-        PPRLocalsSize + ZPRLocalsSize + StackOffset::getFixed(NumBytes);
-    MachineBasicBlock::iterator CalleeSavesBegin =
-        AFI->getPPRCalleeSavedStackSize() ? PPRCalleeSavesBegin
-                                          : ZPRCalleeSavesBegin;
-    allocateStackSpace(MBB, CalleeSavesBegin, 0, SVECalleeSavesSize, false,
-                       nullptr, EmitAsyncCFI && !HasFP, CFAOffset,
-                       MFI.hasVarSizedObjects() || LocalsSize);
-
-    CalleeSavesEnd = AFI->getZPRCalleeSavedStackSize() ? ZPRCalleeSavesEnd
-                                                       : PPRCalleeSavesEnd;
+    ZPRCalleeSavesEnd = CalleeSavesEnd = MBBI;
   }
 
-  CFAOffset += SVECalleeSavesSize;
-
   if (EmitAsyncCFI)
     emitCalleeSavedSVELocations(MBB, CalleeSavesEnd);
 
-  // Allocate space for the rest of the frame including SVE locals. Align the
-  // stack as necessary.
-  assert(!(canUseRedZone(MF) && NeedsRealignment) &&
-         "Cannot use redzone with stack realignment");
-  if (!canUseRedZone(MF)) {
-    // FIXME: in the case of dynamic re-alignment, NumBytes doesn't have
-    // the correct value here, as NumBytes also includes padding bytes,
-    // which shouldn't be counted here.
-    StackOffset SVELocalsSize = PPRLocalsSize + ZPRLocalsSize;
-    allocateStackSpace(MBB, CalleeSavesEnd, RealignmentPadding,
-                       SVELocalsSize + StackOffset::getFixed(NumBytes),
-                       NeedsWinCFI, &HasWinCFI, EmitAsyncCFI && !HasFP,
-                       CFAOffset, MFI.hasVarSizedObjects());
+  if (AFI->hasSplitSVEObjects()) {
+    assert(!FPAfterSVECalleeSaves &&
----------------
MacDue wrote:

Done https://github.com/llvm/llvm-project/pull/161217 (and adjusted the PR stack).

https://github.com/llvm/llvm-project/pull/142392