Avoid broadcast/extract when implementing memset

llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp

@@ -8556,19 +8556,12 @@ LegalizerHelper::lowerMemset(MachineInstr &MI, Register Dst, Register Val,
                              bool IsVolatile) {
   auto &MF = *MI.getParent()->getParent();
   const auto &TLI = *MF.getSubtarget().getTargetLowering();
-  auto &DL = MF.getDataLayout();
-  LLVMContext &C = MF.getFunction().getContext();
 
   assert(KnownLen != 0 && "Have a zero length memset length!");
 
-  bool DstAlignCanChange = false;
-  MachineFrameInfo &MFI = MF.getFrameInfo();
+  const bool DstAlignCanChange = false;
   bool OptSize = shouldLowerMemFuncForSize(MF);
 
-  MachineInstr *FIDef = getOpcodeDef(TargetOpcode::G_FRAME_INDEX, Dst, MRI);
-  if (FIDef && !MFI.isFixedObjectIndex(FIDef->getOperand(1).getIndex()))
-    DstAlignCanChange = true;
-
   unsigned Limit = TLI.getMaxStoresPerMemset(OptSize);
   std::vector<LLT> MemOps;
 
@@ -8587,19 +8580,6 @@ LegalizerHelper::lowerMemset(MachineInstr &MI, Register Dst, Register Val,
                                      MF.getFunction().getAttributes(), TLI))
     return UnableToLegalize;
 
-  if (DstAlignCanChange) {
-    // Get an estimate of the type from the LLT.
-    Type *IRTy = getTypeForLLT(MemOps[0], C);
-    Align NewAlign = DL.getABITypeAlign(IRTy);
-    if (NewAlign > Alignment) {
-      Alignment = NewAlign;
-      unsigned FI = FIDef->getOperand(1).getIndex();
-      // Give the stack frame object a larger alignment if needed.
-      if (MFI.getObjectAlign(FI) < Alignment)
-        MFI.setObjectAlignment(FI, Alignment);
-    }
-  }
-
   MachineIRBuilder MIB(MI);
   // Find the largest store and generate the bit pattern for it.
   LLT LargestTy = MemOps[0];

llvm/test/CodeGen/AIE/aie2p/GlobalIsel/legalize-memset.mir

@@ -0,0 +1,138 @@
+# NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 4
+# This file is licensed under the Apache License v2.0 with LLVM Exceptions.
+# See https://llvm.org/LICENSE.txt for license information.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+#
+# (c) Copyright 2025 Advanced Micro Devices, Inc. or its affiliates
+
+# RUN: llc --start-after=irtranslator %s -o - | FileCheck %s
+
+--- |
+  target datalayout = "e-m:e-p:20:32-i1:8:32-i8:8:32-i16:16:32-i32:32:32-f32:32:32-i64:32-f64:32-a:0:32-n32"
+  target triple = "aie2p"
+
+  %struct.S = type { [14 x i32] }
+
+  define dso_local void @f() local_unnamed_addr #0 {
+  ; CHECK-LABEL: f:
+  ; CHECK:         .p2align 4
+  ; CHECK-NEXT:  // %bb.0: // %entry
+  ; CHECK-NEXT:    mova m0, #-60; nopb ; nops ; paddxm [sp], #64; nopv
+  ; CHECK-NEXT:    nopx ; mov p1, sp
+  ; CHECK-NEXT:    mova m0, #4; paddb [p1], m0; movx r0, #0; st lr, [sp, #-64] // 4-byte Folded Spill
+  ; CHECK-NEXT:    padda [p1], m0; st r0, [p1, #0]; mov p0, p1
+  ; CHECK-NEXT:    st r0, [p1], #4
+  ; CHECK-NEXT:    st r0, [p1], #4
+  ; CHECK-NEXT:    st r0, [p1], #4; jl #g
+  ; CHECK-NEXT:    st r0, [p1], #4 // Delay Slot 5
+  ; CHECK-NEXT:    st r0, [p1], #4 // Delay Slot 4
+  ; CHECK-NEXT:    st r0, [p1], #4 // Delay Slot 3
+  ; CHECK-NEXT:    st r0, [p1, #0] // Delay Slot 2
+  ; CHECK-NEXT:    nop // Delay Slot 1
+  ; CHECK-NEXT:    lda lr, [sp, #-64]; nopb ; nops ; nopxm ; nopv // 4-byte Folded Reload
+  ; CHECK-NEXT:    nopx
+  ; CHECK-NEXT:    nop
+  ; CHECK-NEXT:    nop
+  ; CHECK-NEXT:    nop
+  ; CHECK-NEXT:    nop
+  ; CHECK-NEXT:    nop
+  ; CHECK-NEXT:    ret lr
+  ; CHECK-NEXT:    nop // Delay Slot 5
+  ; CHECK-NEXT:    nop // Delay Slot 4
+  ; CHECK-NEXT:    nop // Delay Slot 3
+  ; CHECK-NEXT:    paddxm [sp], #-64 // Delay Slot 2
+  ; CHECK-NEXT:    nop // Delay Slot 1
+  entry:
+    %s = alloca %struct.S, align 4
+    call void @llvm.lifetime.start.p0(i64 56, ptr nonnull %s) #4
+    call void @llvm.memset.p0.i64(ptr noundef nonnull align 4 dereferenceable(56) %s, i8 0, i64 56, i1 false)
+    call void @g(ptr nonnull %s) #4
+    call void @llvm.lifetime.end.p0(i64 56, ptr nonnull %s) #4
+    ret void
+  }
+
+  declare void @llvm.lifetime.start.p0(i64 immarg, ptr nocapture) #1
+  declare dso_local void @g(ptr) local_unnamed_addr #2
+  declare void @llvm.lifetime.end.p0(i64 immarg, ptr nocapture) #1
+  declare void @llvm.memset.p0.i64(ptr nocapture writeonly, i8, i64, i1 immarg) #3
+
+  attributes #0 = { nounwind "no-trapping-math"="true" "stack-protector-buffer-size"="8" }
+  attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
+  attributes #2 = { "no-trapping-math"="true" "stack-protector-buffer-size"="8" }
+  attributes #3 = { nocallback nofree nounwind willreturn memory(argmem: write) }
+  attributes #4 = { nounwind }
+
+...
+---
+name:            f
+alignment:       16
+exposesReturnsTwice: false
+legalized:       false
+regBankSelected: false
+selected:        false
+failedISel:      false
+tracksRegLiveness: true
+hasWinCFI:       false
+callsEHReturn:   false
+callsUnwindInit: false
+hasEHCatchret:   false
+hasEHScopes:     false
+hasEHFunclets:   false
+isOutlined:      false
+debugInstrRef:   false
+failsVerification: false
+tracksDebugUserValues: false
+registers:
+  - { id: 0, class: _, preferred-register: '' }
+  - { id: 1, class: _, preferred-register: '' }
+  - { id: 2, class: _, preferred-register: '' }
+  - { id: 3, class: _, preferred-register: '' }
+liveins:         []
+frameInfo:
+  isFrameAddressTaken: false
+  isReturnAddressTaken: false
+  hasStackMap:     false
+  hasPatchPoint:   false
+  stackSize:       0
+  offsetAdjustment: 0
+  maxAlignment:    4
+  adjustsStack:    false
+  hasCalls:        false
+  stackProtector:  ''
+  functionContext: ''
+  maxCallFrameSize: 4294967295
+  cvBytesOfCalleeSavedRegisters: 0
+  hasOpaqueSPAdjustment: false
+  hasVAStart:      false
+  hasMustTailInVarArgFunc: false
+  hasTailCall:     false
+  localFrameSize:  0
+  savePoint:       ''
+  restorePoint:    ''
+fixedStack:      []
+stack:
+  - { id: 0, name: s, type: default, offset: 0, size: 56, alignment: 4,
+      stack-id: default, callee-saved-register: '', callee-saved-restored: true,
+      debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
+entry_values:    []
+callSites:       []
+debugValueSubstitutions: []
+constants:       []
+machineFunctionInfo:
+  varArgsFrameIndex: 0
+body:             |
+  bb.1.entry:
+    %1:_(s8) = G_CONSTANT i8 0
+    %2:_(s64) = G_CONSTANT i64 32
+    %0:_(p0) = G_FRAME_INDEX %stack.0.s
+    LIFETIME_START %stack.0.s
+    %3:_(s20) = G_TRUNC %2(s64)
+    G_MEMSET %0(p0), %1(s8), %3(s20), 0 :: (store (s8) into %ir.s, align 4)
+    ADJCALLSTACKUP 0, 0, implicit-def $sp, implicit $sp
+    $p0 = COPY %0(p0)
+    PseudoJL @g, csr_aie2p, implicit-def $lr, implicit $p0
+    ADJCALLSTACKDOWN 0, 0, implicit-def $sp, implicit $sp
+    LIFETIME_END %stack.0.s
+    PseudoRET implicit $lr
+
+...