[ARM] Handle debug instrs in ARM Low Overhead Loop pass

[vhscampos]

Summary

In function ConvertVPTBlocks(), it is assumed that every instruction
within a vector-predicated block is predicated. This is false for debug
instructions, used by LLVM.

Because of this, an assertion failure is reached when an input contains
debug instructions inside VPT blocks. In non-assert builds, an out of
bounds memory access took place.

The present patch properly covers the case of debug instructions.

[dmgreen]

llvm/lib/Target/ARM/ARMLowOverheadLoops.cpp

1469–1475

This looks like it should be an assert.

1520–1526

I think this might have to handle debug better. Can we try and make sure that DivergentNext is not a debug instruction.

[vhscampos]

Add assertion in RemovePredicate lambda.
SKip debug instructions inside VPT blocks with predicate divergence.

[dmgreen]

llvm/lib/Target/ARM/ARMLowOverheadLoops.cpp

1524

I'm not sure if DivergentNext can be end(), can it? I think the block will always contain a terminator.
(If it can be end(), we would still need to remove the predicates and replace the instruction)

[vhscampos]

Remove predicate of instructions after the divergent one even if there's no non-debug instruction after it.

[dmgreen]

Thanks for the fix. LGTM.

llvm/lib/Target/ARM/ARMLowOverheadLoops.cpp

1469–1475

It doesn't need both the assert and the unreachable - you can remove the if.

[vhscampos]

Remove if statement inside RemovePredicate as it's already covered by an assertion.

llvm/lib/Target/ARM/ARMLowOverheadLoops.cpp

MachineInstr* ARMLowOverheadLoops::ExpandLoopStart(LowOverheadLoop &LoLoop) {
   }
 
   LoLoop.ToRemove.insert(Start);
   return NewStart;
 }
 
 void ARMLowOverheadLoops::ConvertVPTBlocks(LowOverheadLoop &LoLoop) {
   auto RemovePredicate = [](MachineInstr *MI) {
+    if (MI->isDebugInstr())
+      return;
     LLVM_DEBUG(dbgs() << "ARM Loops: Removing predicate from: " << *MI);
-    if (int PIdx = llvm::findFirstVPTPredOperandIdx(*MI)) {
-      assert(MI->getOperand(PIdx).getImm() == ARMVCC::Then &&
-             "Expected Then predicate!");
-      MI->getOperand(PIdx).setImm(ARMVCC::None);
-      MI->getOperand(PIdx+1).setReg(0);
-    } else
-      llvm_unreachable("trying to unpredicate a non-predicated instruction");
+    int PIdx = llvm::findFirstVPTPredOperandIdx(*MI);
+    assert(PIdx >= 1 && "Trying to unpredicate a non-predicated instruction");
+    if (PIdx < 1) {
+      llvm_unreachable("trying to unpredicate a non-predicated instruction");
+      return;
+    }
+    MI->getOperand(PIdx + 1).setReg(0);
   };
 
   for (auto &Block : LoLoop.getVPTBlocks()) {
     SmallVectorImpl<MachineInstr *> &Insts = Block.getInsts();
 
     auto ReplaceVCMPWithVPT = [&](MachineInstr *&TheVCMP, MachineInstr *At) {
       assert(TheVCMP && "Replacing a removed or non-existent VCMP");
       // Replace the VCMP with a VPT
if (VPTState::isEntryPredicatedOnVCTP(Block, /*exclusive*/ true)) {
         // The VPT block has a non-uniform predicate but it uses a vpst and its
         // entry is guarded only by a vctp, which means we:
         // - Need to remove the original vpst.
         // - Then need to unpredicate any following instructions, until
         //   we come across the divergent vpr def.
         // - Insert a new vpst to predicate the instruction(s) that following
         //   the divergent vpr def.
         MachineInstr *Divergent = VPTState::getDivergent(Block);
+        MachineBasicBlock *MBB = Divergent->getParent();
         auto DivergentNext = ++MachineBasicBlock::iterator(Divergent);
+        while (DivergentNext != MBB->end() && DivergentNext->isDebugInstr())
+          ++DivergentNext;
+
+        if (DivergentNext == MBB->end())
+          continue;
+
         bool DivergentNextIsPredicated =
             getVPTInstrPredicate(*DivergentNext) != ARMVCC::None;
 
         for (auto I = ++MachineBasicBlock::iterator(VPST), E = DivergentNext;
              I != E; ++I)
           RemovePredicate(&*I);
 
         // Check if the instruction defining vpr is a vcmp so it can be combined

llvm/test/CodeGen/Thumb2/LowOverheadLoops/skip-vpt-debug.mir

+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc -mtriple=thumbv8.1m.main -mattr=+mve -run-pass=arm-low-overhead-loops %s -o - --verify-machineinstrs | FileCheck %s
+--- |
+  ; ModuleID = 'skip-vpt-debug.ll'
+  source_filename = "skip-vpt-debug.c"
+  target datalayout = "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64"
+  target triple = "thumbv8.1m.main-arm-none-eabihf"
+
+  ; Function Attrs: nofree norecurse nounwind optsize
+  define hidden void @arm_max_no_idx_f32(float* nocapture readonly %pSrc, i32 %blockSize, float* nocapture %pResult) local_unnamed_addr #0 !dbg !13 {
+  entry:
+    call void @llvm.dbg.value(metadata float* %pSrc, metadata !24, metadata !DIExpression()), !dbg !29
+    call void @llvm.dbg.value(metadata i32 %blockSize, metadata !25, metadata !DIExpression()), !dbg !29
+    call void @llvm.dbg.value(metadata float* %pResult, metadata !26, metadata !DIExpression()), !dbg !29
+    call void @llvm.dbg.value(metadata float 0x3810000000000000, metadata !27, metadata !DIExpression()), !dbg !29
+    %cmp.not7 = icmp eq i32 %blockSize, 0, !dbg !30
+    br i1 %cmp.not7, label %while.end, label %vector.ph, !dbg !31
+
+  vector.ph:                                        ; preds = %entry
+    %n.rnd.up = add i32 %blockSize, 3, !dbg !31
+    %n.vec = and i32 %n.rnd.up, -4, !dbg !31
+    %0 = add i32 %n.vec, -4, !dbg !31
+    %1 = lshr i32 %0, 2, !dbg !31
+    %2 = add nuw nsw i32 %1, 1, !dbg !31
+    %3 = call i32 @llvm.start.loop.iterations.i32(i32 %2), !dbg !31
+    br label %vector.body, !dbg !31
+
+  vector.body:                                      ; preds = %vector.body, %vector.ph
+    %lsr.iv1 = phi float* [ %scevgep, %vector.body ], [ %pSrc, %vector.ph ]
+    %vec.phi = phi <4 x float> [ <float 0x3810000000000000, float 0x3810000000000000, float 0x3810000000000000, float 0x3810000000000000>, %vector.ph ], [ %10, %vector.body ]
+    %4 = phi i32 [ %3, %vector.ph ], [ %11, %vector.body ]
+    %5 = phi i32 [ %blockSize, %vector.ph ], [ %7, %vector.body ]
+    %lsr.iv12 = bitcast float* %lsr.iv1 to <4 x float>*
+    %6 = call <4 x i1> @llvm.arm.mve.vctp32(i32 %5)
+    %7 = sub i32 %5, 4
+    %wide.masked.load = call <4 x float> @llvm.masked.load.v4f32.p0v4f32(<4 x float>* %lsr.iv12, i32 4, <4 x i1> %6, <4 x float> poison), !dbg !32, !tbaa !34
+    %8 = fcmp nnan ninf nsz olt <4 x float> %vec.phi, %wide.masked.load, !dbg !38
+    %9 = and <4 x i1> %6, %8, !dbg !40
+    %10 = select <4 x i1> %9, <4 x float> %wide.masked.load, <4 x float> %vec.phi, !dbg !40
+    %scevgep = getelementptr float, float* %lsr.iv1, i32 4
+    %11 = call i32 @llvm.loop.decrement.reg.i32(i32 %4, i32 1)
+    %12 = icmp ne i32 %11, 0
+    br i1 %12, label %vector.body, label %middle.block, !llvm.loop !41
+
+  middle.block:                                     ; preds = %vector.body
+    %13 = call nnan ninf nsz float @llvm.vector.reduce.fmax.v4f32(<4 x float> %10), !dbg !31
+    br label %while.end, !dbg !45
+
+  while.end:                                        ; preds = %middle.block, %entry
+    %maxValue.0.lcssa = phi float [ 0x3810000000000000, %entry ], [ %13, %middle.block ], !dbg !29
+    store float %maxValue.0.lcssa, float* %pResult, align 4, !dbg !45, !tbaa !34
+    ret void, !dbg !46
+  }
+
+  ; Function Attrs: nofree nosync nounwind readnone speculatable willreturn
+  declare void @llvm.dbg.value(metadata, metadata, metadata) #1
+
+  ; Function Attrs: nofree nosync nounwind readnone willreturn
+  declare <4 x i1> @llvm.get.active.lane.mask.v4i1.i32(i32, i32) #2
+
+  ; Function Attrs: argmemonly nofree nosync nounwind readonly willreturn
+  declare <4 x float> @llvm.masked.load.v4f32.p0v4f32(<4 x float>*, i32 immarg, <4 x i1>, <4 x float>) #3
+
+  ; Function Attrs: nofree nosync nounwind readnone willreturn
+  declare float @llvm.vector.reduce.fmax.v4f32(<4 x float>) #2
+
+  ; Function Attrs: noduplicate nofree nosync nounwind willreturn
+  declare i32 @llvm.start.loop.iterations.i32(i32) #4
+
+  ; Function Attrs: noduplicate nofree nosync nounwind willreturn
+  declare i32 @llvm.loop.decrement.reg.i32(i32, i32) #4
+
+  ; Function Attrs: nounwind readnone
+  declare <4 x i1> @llvm.arm.mve.vctp32(i32) #5
+
+  attributes #0 = { nofree norecurse nounwind optsize "denormal-fp-math"="preserve-sign,preserve-sign" "denormal-fp-math-f32"="ieee,ieee" "frame-pointer"="none" "no-infs-fp-math"="true" "no-nans-fp-math"="true" "no-signed-zeros-fp-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="cortex-m55" "target-features"="+armv8.1-m.main,+dsp,+fp-armv8d16,+fp-armv8d16sp,+fp16,+fp64,+fullfp16,+hwdiv,+lob,+mve,+mve.fp,+ras,+thumb-mode,+vfp2,+vfp2sp,+vfp3d16,+vfp3d16sp,+vfp4d16,+vfp4d16sp,-aes,-bf16,-cdecp0,-cdecp1,-cdecp2,-cdecp3,-cdecp4,-cdecp5,-cdecp6,-cdecp7,-crc,-crypto,-dotprod,-fp16fml,-hwdiv-arm,-i8mm,-sb,-sha2" }
+  attributes #1 = { nofree nosync nounwind readnone speculatable willreturn }
+  attributes #2 = { nofree nosync nounwind readnone willreturn }
+  attributes #3 = { argmemonly nofree nosync nounwind readonly willreturn }
+  attributes #4 = { noduplicate nofree nosync nounwind willreturn }
+  attributes #5 = { nounwind readnone }
+
+  !llvm.dbg.cu = !{!0}
+  !llvm.module.flags = !{!3, !4, !5, !6, !7, !8, !9, !10, !11}
+  !llvm.ident = !{!12}
+
+  !0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "Component: ARM Compiler 6.17.0.0 (permissive) Tool: armclang [00000000]", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, splitDebugInlining: false, nameTableKind: None)
+  !1 = !DIFile(filename: "skip-vpt-debug.c", directory: "/home/vicspe01")
+  !2 = !{}
+  !3 = !{i32 7, !"Dwarf Version", i32 4}
+  !4 = !{i32 2, !"Debug Info Version", i32 3}
+  !5 = !{i32 1, !"wchar_size", i32 4}
+  !6 = !{i32 1, !"static_rwdata", i32 1}
+  !7 = !{i32 1, !"enumsize_buildattr", i32 2}
+  !8 = !{i32 1, !"armlib_unavailable", i32 0}
+  !9 = !{i32 1, !"branch-target-enforcement", i32 0}
+  !10 = !{i32 1, !"sign-return-address", i32 0}
+  !11 = !{i32 1, !"sign-return-address-all", i32 0}
+  !12 = !{!"Component: ARM Compiler 6.17.0.0 (permissive) Tool: armclang [00000000]"}
+  !13 = distinct !DISubprogram(name: "arm_max_no_idx_f32", scope: !1, file: !1, line: 5, type: !14, scopeLine: 6, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !23)
+  !14 = !DISubroutineType(types: !15)
+  !15 = !{null, !16, !20, !22}
+  !16 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !17, size: 32)
+  !17 = !DIDerivedType(tag: DW_TAG_const_type, baseType: !18)
+  !18 = !DIDerivedType(tag: DW_TAG_typedef, name: "float32_t", file: !1, line: 1, baseType: !19)
+  !19 = !DIBasicType(name: "float", size: 32, encoding: DW_ATE_float)
+  !20 = !DIDerivedType(tag: DW_TAG_typedef, name: "uint32_t", file: !1, line: 2, baseType: !21)
+  !21 = !DIBasicType(name: "unsigned int", size: 32, encoding: DW_ATE_unsigned)
+  !22 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !18, size: 32)
+  !23 = !{!24, !25, !26, !27, !28}
+  !24 = !DILocalVariable(name: "pSrc", arg: 1, scope: !13, file: !1, line: 5, type: !16)
+  !25 = !DILocalVariable(name: "blockSize", arg: 2, scope: !13, file: !1, line: 5, type: !20)
+  !26 = !DILocalVariable(name: "pResult", arg: 3, scope: !13, file: !1, line: 6, type: !22)
+  !27 = !DILocalVariable(name: "maxValue", scope: !13, file: !1, line: 7, type: !18)
+  !28 = !DILocalVariable(name: "newVal", scope: !13, file: !1, line: 8, type: !18)
+  !29 = !DILocation(line: 0, scope: !13)
+  !30 = !DILocation(line: 10, column: 20, scope: !13)
+  !31 = !DILocation(line: 10, column: 3, scope: !13)
+  !32 = !DILocation(line: 11, column: 14, scope: !33)
+  !33 = distinct !DILexicalBlock(scope: !13, file: !1, line: 10, column: 26)
+  !34 = !{!35, !35, i64 0}
+  !35 = !{!"float", !36, i64 0}
+  !36 = !{!"omnipotent char", !37, i64 0}
+  !37 = !{!"Simple C/C++ TBAA"}
+  !38 = !DILocation(line: 12, column: 18, scope: !39)
+  !39 = distinct !DILexicalBlock(scope: !33, file: !1, line: 12, column: 9)
+  !40 = !DILocation(line: 12, column: 9, scope: !33)
+  !41 = distinct !{!41, !31, !42, !43, !44}
+  !42 = !DILocation(line: 15, column: 3, scope: !13)
+  !43 = !{!"llvm.loop.mustprogress"}
+  !44 = !{!"llvm.loop.isvectorized", i32 1}
+  !45 = !DILocation(line: 16, column: 12, scope: !13)
+  !46 = !DILocation(line: 17, column: 1, scope: !13)
+
+...
+---
+name:            arm_max_no_idx_f32
+alignment:       4
+exposesReturnsTwice: false
+legalized:       false
+regBankSelected: false
+selected:        false
+failedISel:      false
+tracksRegLiveness: true
+hasWinCFI:       false
+registers:       []
+liveins:
+  - { reg: '$r0', virtual-reg: '' }
+  - { reg: '$r1', virtual-reg: '' }
+  - { reg: '$r2', virtual-reg: '' }
+frameInfo:
+  isFrameAddressTaken: false
+  isReturnAddressTaken: false
+  hasStackMap:     false
+  hasPatchPoint:   false
+  stackSize:       8
+  offsetAdjustment: 0
+  maxAlignment:    4
+  adjustsStack:    false
+  hasCalls:        false
+  stackProtector:  ''
+  maxCallFrameSize: 0
+  cvBytesOfCalleeSavedRegisters: 0
+  hasOpaqueSPAdjustment: false
+  hasVAStart:      false
+  hasMustTailInVarArgFunc: false
+  localFrameSize:  0
+  savePoint:       ''
+  restorePoint:    ''
+fixedStack:      []
+stack:
+  - { id: 0, name: '', type: spill-slot, offset: -4, size: 4, alignment: 4,
+      stack-id: default, callee-saved-register: '$lr', callee-saved-restored: false,
+      debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
+  - { id: 1, name: '', type: spill-slot, offset: -8, size: 4, alignment: 4,
+      stack-id: default, callee-saved-register: '$r7', callee-saved-restored: true,
+      debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
+callSites:       []
+debugValueSubstitutions: []
+constants:
+  - id:              0
+    value:           float 0x3810000000000000
+    alignment:       4
+    isTargetSpecific: false
+machineFunctionInfo: {}
+body:             |
+  ; CHECK-LABEL: name: arm_max_no_idx_f32
+  ; CHECK: bb.0.entry:
+  ; CHECK:   successors: %bb.4(0x30000000), %bb.1(0x50000000)
+  ; CHECK:   liveins: $lr, $r0, $r1, $r2, $r7
+  ; CHECK:   DBG_VALUE $r0, $noreg, !24, !DIExpression(), debug-location !29
+  ; CHECK:   DBG_VALUE $r1, $noreg, !25, !DIExpression(), debug-location !29
+  ; CHECK:   DBG_VALUE $r1, $noreg, !25, !DIExpression(), debug-location !29
+  ; CHECK:   DBG_VALUE $r2, $noreg, !26, !DIExpression(), debug-location !29
+  ; CHECK:   DBG_VALUE $r2, $noreg, !26, !DIExpression(), debug-location !29
+  ; CHECK:   frame-setup tPUSH 14 /* CC::al */, $noreg, killed $r7, killed $lr, implicit-def $sp, implicit $sp
+  ; CHECK:   frame-setup CFI_INSTRUCTION def_cfa_offset 8
+  ; CHECK:   frame-setup CFI_INSTRUCTION offset $lr, -4
+  ; CHECK:   frame-setup CFI_INSTRUCTION offset $r7, -8
+  ; CHECK:   DBG_VALUE float 0x3810000000000000, $noreg, !27, !DIExpression(), debug-location !29
+  ; CHECK:   DBG_VALUE $r0, $noreg, !24, !DIExpression(), debug-location !29
+  ; CHECK:   tCBZ renamable $r1, %bb.4, debug-location !31
+  ; CHECK: bb.1.vector.ph:
+  ; CHECK:   successors: %bb.2(0x80000000)
+  ; CHECK:   liveins: $r0, $r1, $r2
+  ; CHECK:   DBG_VALUE float 0x3810000000000000, $noreg, !27, !DIExpression(), debug-location !29
+  ; CHECK:   DBG_VALUE $r2, $noreg, !26, !DIExpression(), debug-location !29
+  ; CHECK:   DBG_VALUE $r1, $noreg, !25, !DIExpression(), debug-location !29
+  ; CHECK:   DBG_VALUE $r0, $noreg, !24, !DIExpression(), debug-location !29
+  ; CHECK:   renamable $q0 = MVE_VMOVimmi32 1152, 0, $noreg, undef renamable $q0
+  ; CHECK:   $lr = MVE_DLSTP_32 killed renamable $r1, debug-location !31
+  ; CHECK: bb.2.vector.body (align 4):
+  ; CHECK:   successors: %bb.2(0x7c000000), %bb.3(0x04000000)
+  ; CHECK:   liveins: $lr, $q0, $r0, $r2
+  ; CHECK:   DBG_VALUE float 0x3810000000000000, $noreg, !27, !DIExpression(), debug-location !29
+  ; CHECK:   DBG_VALUE $r2, $noreg, !26, !DIExpression(), debug-location !29
+  ; CHECK:   renamable $r0, renamable $q1 = MVE_VLDRWU32_post killed renamable $r0, 16, 0, $noreg, debug-location !32 :: (load 16 from %ir.lsr.iv12, align 4, !tbaa !34)
+  ; CHECK:   DBG_VALUE $r0, $noreg, !24, !DIExpression(DW_OP_LLVM_entry_value, 1), debug-location !29
+  ; CHECK:   MVE_VPTv4f32 8, renamable $q1, renamable $q0, 12, implicit-def $vpr, debug-location !40
+  ; CHECK:   renamable $q0 = MVE_VORR killed renamable $q1, killed renamable $q1, 1, killed renamable $vpr, killed renamable $q0, debug-location !40
+  ; CHECK:   DBG_VALUE $r1, $noreg, !25, !DIExpression(DW_OP_LLVM_entry_value, 1), debug-location !29
+  ; CHECK:   $lr = MVE_LETP killed renamable $lr, %bb.2
+  ; CHECK: bb.3.middle.block:
+  ; CHECK:   successors: %bb.5(0x80000000)
+  ; CHECK:   liveins: $q0, $r2
+  ; CHECK:   DBG_VALUE float 0x3810000000000000, $noreg, !27, !DIExpression(), debug-location !29
+  ; CHECK:   DBG_VALUE $r2, $noreg, !26, !DIExpression(), debug-location !29
+  ; CHECK:   renamable $s4 = nnan ninf nsz VFP_VMAXNMS renamable $s2, renamable $s3, debug-location !31
+  ; CHECK:   renamable $s0 = nnan ninf nsz VFP_VMAXNMS killed renamable $s0, killed renamable $s1, implicit killed $q0, debug-location !31
+  ; CHECK:   renamable $s0 = nnan ninf nsz VFP_VMAXNMS killed renamable $s0, killed renamable $s4, debug-location !31
+  ; CHECK:   tB %bb.5, 14 /* CC::al */, $noreg
+  ; CHECK: bb.4:
+  ; CHECK:   successors: %bb.5(0x80000000)
+  ; CHECK:   liveins: $r2
+  ; CHECK:   DBG_VALUE float 0x3810000000000000, $noreg, !27, !DIExpression(), debug-location !29
+  ; CHECK:   DBG_VALUE $r2, $noreg, !26, !DIExpression(), debug-location !29
+  ; CHECK:   DBG_VALUE $r1, $noreg, !25, !DIExpression(), debug-location !29
+  ; CHECK:   DBG_VALUE $r0, $noreg, !24, !DIExpression(), debug-location !29
+  ; CHECK:   renamable $s0 = VLDRS %const.0, 0, 14 /* CC::al */, $noreg :: (load 4 from constant-pool)
+  ; CHECK: bb.5.while.end:
+  ; CHECK:   liveins: $r2, $s0
+  ; CHECK:   DBG_VALUE float 0x3810000000000000, $noreg, !27, !DIExpression(), debug-location !29
+  ; CHECK:   DBG_VALUE $r2, $noreg, !26, !DIExpression(), debug-location !29
+  ; CHECK:   VSTRS killed renamable $s0, killed renamable $r2, 0, 14 /* CC::al */, $noreg, debug-location !45 :: (store 4 into %ir.pResult, !tbaa !34)
+  ; CHECK:   frame-destroy tPOP_RET 14 /* CC::al */, $noreg, def $r7, def $pc, debug-location !46
+  ; CHECK: bb.6 (align 4):
+  ; CHECK:   CONSTPOOL_ENTRY 0, %const.0, 4
+  bb.0.entry:
+    successors: %bb.4(0x30000000), %bb.1(0x50000000)
+    liveins: $r0, $r1, $r2, $r7, $lr
+
+    DBG_VALUE $r0, $noreg, !24, !DIExpression(), debug-location !29
+    DBG_VALUE $r1, $noreg, !25, !DIExpression(), debug-location !29
+    DBG_VALUE $r1, $noreg, !25, !DIExpression(), debug-location !29
+    DBG_VALUE $r2, $noreg, !26, !DIExpression(), debug-location !29
+    DBG_VALUE $r2, $noreg, !26, !DIExpression(), debug-location !29
+    frame-setup tPUSH 14 /* CC::al */, $noreg, killed $r7, killed $lr, implicit-def $sp, implicit $sp
+    frame-setup CFI_INSTRUCTION def_cfa_offset 8
+    frame-setup CFI_INSTRUCTION offset $lr, -4
+    frame-setup CFI_INSTRUCTION offset $r7, -8
+    DBG_VALUE float 0x3810000000000000, $noreg, !27, !DIExpression(), debug-location !29
+    DBG_VALUE $r0, $noreg, !24, !DIExpression(), debug-location !29
+    tCBZ renamable $r1, %bb.4, debug-location !31
+
+  bb.1.vector.ph:
+    successors: %bb.2(0x80000000)
+    liveins: $r0, $r1, $r2
+
+    DBG_VALUE float 0x3810000000000000, $noreg, !27, !DIExpression(), debug-location !29
+    DBG_VALUE $r2, $noreg, !26, !DIExpression(), debug-location !29
+    DBG_VALUE $r1, $noreg, !25, !DIExpression(), debug-location !29
+    DBG_VALUE $r0, $noreg, !24, !DIExpression(), debug-location !29
+    renamable $r3, dead $cpsr = tADDi3 renamable $r1, 3, 14 /* CC::al */, $noreg, debug-location !31
+    renamable $r3 = t2BICri killed renamable $r3, 3, 14 /* CC::al */, $noreg, $noreg, debug-location !31
+    renamable $r12 = t2SUBri killed renamable $r3, 4, 14 /* CC::al */, $noreg, $noreg, debug-location !31
+    renamable $r3, dead $cpsr = tMOVi8 1, 14 /* CC::al */, $noreg
+    renamable $r3 = nuw nsw t2ADDrs killed renamable $r3, killed renamable $r12, 19, 14 /* CC::al */, $noreg, $noreg, debug-location !31
+    renamable $q0 = MVE_VMOVimmi32 1152, 0, $noreg, undef renamable $q0
+    renamable $lr = t2DoLoopStartTP killed renamable $r3, renamable $r1, debug-location !31
+
+  bb.2.vector.body (align 4):
+    successors: %bb.2(0x7c000000), %bb.3(0x04000000)
+    liveins: $lr, $q0, $r0, $r1, $r2
+
+    DBG_VALUE float 0x3810000000000000, $noreg, !27, !DIExpression(), debug-location !29
+    DBG_VALUE $r2, $noreg, !26, !DIExpression(), debug-location !29
+    renamable $vpr = MVE_VCTP32 renamable $r1, 0, $noreg
+    MVE_VPST 2, implicit $vpr, debug-location !32
+    renamable $r0, renamable $q1 = MVE_VLDRWU32_post killed renamable $r0, 16, 1, renamable $vpr, debug-location !32 :: (load 16 from %ir.lsr.iv12, align 4, !tbaa !34)
+    DBG_VALUE $r0, $noreg, !24, !DIExpression(DW_OP_LLVM_entry_value, 1), debug-location !29
+    renamable $vpr = MVE_VCMPf32 renamable $q1, renamable $q0, 12, 1, killed renamable $vpr, debug-location !40
+    renamable $q0 = MVE_VORR killed renamable $q1, renamable $q1, 1, killed renamable $vpr, killed renamable $q0, debug-location !40
+    renamable $r1, dead $cpsr = tSUBi8 killed renamable $r1, 4, 14 /* CC::al */, $noreg
+    DBG_VALUE $r1, $noreg, !25, !DIExpression(DW_OP_LLVM_entry_value, 1), debug-location !29
+    renamable $lr = t2LoopEndDec killed renamable $lr, %bb.2, implicit-def dead $cpsr
+    tB %bb.3, 14 /* CC::al */, $noreg
+
+  bb.3.middle.block:
+    successors: %bb.5(0x80000000)
+    liveins: $q0, $r2
+
+    DBG_VALUE float 0x3810000000000000, $noreg, !27, !DIExpression(), debug-location !29
+    DBG_VALUE $r2, $noreg, !26, !DIExpression(), debug-location !29
+    renamable $s4 = nnan ninf nsz VFP_VMAXNMS renamable $s2, renamable $s3, debug-location !31
+    renamable $s0 = nnan ninf nsz VFP_VMAXNMS killed renamable $s0, killed renamable $s1, implicit $q0, debug-location !31
+    renamable $s0 = nnan ninf nsz VFP_VMAXNMS killed renamable $s0, killed renamable $s4, debug-location !31
+    tB %bb.5, 14 /* CC::al */, $noreg
+
+  bb.4:
+    successors: %bb.5(0x80000000)
+    liveins: $r2
+
+    DBG_VALUE float 0x3810000000000000, $noreg, !27, !DIExpression(), debug-location !29
+    DBG_VALUE $r2, $noreg, !26, !DIExpression(), debug-location !29
+    DBG_VALUE $r1, $noreg, !25, !DIExpression(), debug-location !29
+    DBG_VALUE $r0, $noreg, !24, !DIExpression(), debug-location !29
+    renamable $s0 = VLDRS %const.0, 0, 14 /* CC::al */, $noreg :: (load 4 from constant-pool)
+
+  bb.5.while.end:
+    liveins: $r2, $s0
+
+    DBG_VALUE float 0x3810000000000000, $noreg, !27, !DIExpression(), debug-location !29
+    DBG_VALUE $r2, $noreg, !26, !DIExpression(), debug-location !29
+    VSTRS killed renamable $s0, killed renamable $r2, 0, 14 /* CC::al */, $noreg, debug-location !45 :: (store 4 into %ir.pResult, !tbaa !34)
+    frame-destroy tPOP_RET 14 /* CC::al */, $noreg, def $r7, def $pc, debug-location !46
+
+  bb.6 (align 4):
+    CONSTPOOL_ENTRY 0, %const.0, 4
+
+...