[PATCH] D138208: [AArch64][SME] Always allocate a lazy-save buffer if a function has ZA state.

[Sander de Smalen via Phabricator via llvm-commits]

This revision was landed with ongoing or failed builds.
This revision was automatically updated to reflect the committed changes.
Closed by commit rG3f9d64a2adc5: [AArch64][SME] Always allocate a lazy-save buffer if a function has ZA state. (authored by sdesmalen).

Changed prior to commit:
  https://reviews.llvm.org/D138208?vs=476116&id=476921#toc

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D138208/new/

https://reviews.llvm.org/D138208

Files:
  llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
  llvm/test/CodeGen/AArch64/sme-disable-gisel-fisel.ll
  llvm/test/CodeGen/AArch64/sme-shared-za-interface.ll


Index: llvm/test/CodeGen/AArch64/sme-shared-za-interface.ll
===================================================================
--- llvm/test/CodeGen/AArch64/sme-shared-za-interface.ll
+++ llvm/test/CodeGen/AArch64/sme-shared-za-interface.ll
@@ -48,12 +48,12 @@
 ; CHECK-NEXT:    sub x9, x9, x8
 ; CHECK-NEXT:    mov sp, x9
 ; CHECK-NEXT:    sub x10, x29, #16
-; CHECK-NEXT:    sturh w8, [x29, #-8]
 ; CHECK-NEXT:    stur x9, [x29, #-16]
+; CHECK-NEXT:    sturh w8, [x29, #-8]
 ; CHECK-NEXT:    msr TPIDR2_EL0, x10
 ; CHECK-NEXT:    bl __addtf3
 ; CHECK-NEXT:    smstart za
-; CHECK-NEXT:    add x0, x29, #0
+; CHECK-NEXT:    sub x0, x29, #16
 ; CHECK-NEXT:    mrs x8, TPIDR2_EL0
 ; CHECK-NEXT:    cbnz x8, .LBB1_2
 ; CHECK-NEXT:  // %bb.1:
Index: llvm/test/CodeGen/AArch64/sme-disable-gisel-fisel.ll
===================================================================
--- llvm/test/CodeGen/AArch64/sme-disable-gisel-fisel.ll
+++ llvm/test/CodeGen/AArch64/sme-disable-gisel-fisel.ll
@@ -310,12 +310,12 @@
 ; CHECK-COMMON-NEXT:    sub x9, x9, x8
 ; CHECK-COMMON-NEXT:    mov sp, x9
 ; CHECK-COMMON-NEXT:    sub x10, x29, #16
-; CHECK-COMMON-NEXT:    sturh w8, [x29, #-8]
 ; CHECK-COMMON-NEXT:    stur x9, [x29, #-16]
+; CHECK-COMMON-NEXT:    sturh w8, [x29, #-8]
 ; CHECK-COMMON-NEXT:    msr TPIDR2_EL0, x10
 ; CHECK-COMMON-NEXT:    bl __addtf3
 ; CHECK-COMMON-NEXT:    smstart za
-; CHECK-COMMON-NEXT:    add x0, x29, #0
+; CHECK-COMMON-NEXT:    sub x0, x29, #16
 ; CHECK-COMMON-NEXT:    mrs x8, TPIDR2_EL0
 ; CHECK-COMMON-NEXT:    cbnz x8, .LBB8_2
 ; CHECK-COMMON-NEXT:  // %bb.1:
Index: llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
===================================================================
--- llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
+++ llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
@@ -6013,21 +6013,6 @@
 }
 
 
-/// Returns true if the Function has ZA state and contains at least one call to
-/// a function that requires setting up a lazy-save buffer.
-static bool requiresBufferForLazySave(const Function &F) {
-  SMEAttrs CallerAttrs(F);
-  if (!CallerAttrs.hasZAState())
-    return false;
-
-  for (const BasicBlock &BB : F)
-    for (const Instruction &I : BB)
-      if (const CallInst *Call = dyn_cast<CallInst>(&I))
-        if (CallerAttrs.requiresLazySave(SMEAttrs(*Call)))
-          return true;
-  return false;
-}
-
 unsigned
 AArch64TargetLowering::allocateLazySaveBuffer(SDValue &Chain, const SDLoc &DL,
                                               SelectionDAG &DAG) const {
@@ -6443,8 +6428,8 @@
   if (Subtarget->hasCustomCallingConv())
     Subtarget->getRegisterInfo()->UpdateCustomCalleeSavedRegs(MF);
 
-  if (requiresBufferForLazySave(MF.getFunction())) {
-    // Set up a buffer once and store the buffer in the MachineFunctionInfo.
+  // Conservatively assume the function requires the lazy-save mechanism.
+  if (SMEAttrs(MF.getFunction()).hasZAState()) {
     unsigned TPIDR2Obj = allocateLazySaveBuffer(Chain, DL, DAG);
     FuncInfo->setLazySaveTPIDR2Obj(TPIDR2Obj);
   }
@@ -7041,9 +7026,6 @@
     SDValue NN = DAG.getNode(ISD::MUL, DL, MVT::i64, N, N);
     unsigned TPIDR2Obj = FuncInfo->getLazySaveTPIDR2Obj();
 
-    if (!TPIDR2Obj)
-      TPIDR2Obj = allocateLazySaveBuffer(Chain, DL, DAG);
-
     MachinePointerInfo MPI = MachinePointerInfo::getStack(MF, TPIDR2Obj);
     SDValue TPIDR2ObjAddr = DAG.getFrameIndex(TPIDR2Obj,
         DAG.getTargetLoweringInfo().getFrameIndexTy(DAG.getDataLayout()));


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