[ARM][LowOverheadLoops] Skip debug values

[samparker]

Summary

While iterating through the loop, don't inspect any dbg values.

[SjoerdMeijer]

LGTM

llvm/lib/Target/ARM/ARMLowOverheadLoops.cpp

bool ARMLowOverheadLoops::ProcessLoop(MachineLoop *ML) {
   else
     return false;
 
   // Find the low-overhead loop components and decide whether or not to fall
   // back to a normal loop. Also look for a vctp instructions and decide
   // whether we can convert that predicate using tail predication.
   for (auto *MBB : reverse(ML->getBlocks())) {
     for (auto &MI : *MBB) {
-      if (MI.getOpcode() == ARM::t2LoopDec)
+      if (MI.isDebugValue())
+        continue;
+      else if (MI.getOpcode() == ARM::t2LoopDec)
         LoLoop.Dec = &MI;
       else if (MI.getOpcode() == ARM::t2LoopEnd)
         LoLoop.End = &MI;
       else if (isLoopStart(MI))
         LoLoop.Start = &MI;
       else if (MI.getDesc().isCall()) {
         // TODO: Though the call will require LE to execute again, does this
         // mean we should revert? Always executing LE hopefully should be

llvm/test/CodeGen/Thumb2/LowOverheadLoops/skip-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
+--- |
+  define dso_local arm_aapcs_vfpcc void @skip_debug(i32* nocapture %a, i16* nocapture readonly %b, i32 %N) !dbg !8 {
+  entry:
+    call void @llvm.dbg.value(metadata i32* %a, metadata !17, metadata !DIExpression()), !dbg !23
+    call void @llvm.dbg.value(metadata i16* %b, metadata !18, metadata !DIExpression()), !dbg !23
+    call void @llvm.dbg.value(metadata i32 %N, metadata !19, metadata !DIExpression()), !dbg !23
+    %0 = load i32, i32* %a, align 4, !dbg !24
+    call void @llvm.dbg.value(metadata i32 %0, metadata !20, metadata !DIExpression()), !dbg !23
+    call void @llvm.dbg.value(metadata i32 0, metadata !21, metadata !DIExpression()), !dbg !29
+    %cmp7 = icmp eq i32 %N, 0, !dbg !30
+    %1 = add i32 %N, 3, !dbg !32
+    %2 = lshr i32 %1, 2, !dbg !32
+    %3 = shl nuw i32 %2, 2, !dbg !32
+    %4 = add i32 %3, -4, !dbg !32
+    %5 = lshr i32 %4, 2, !dbg !32
+    %6 = add nuw nsw i32 %5, 1, !dbg !32
+    br i1 %cmp7, label %for.cond.cleanup, label %vector.ph, !dbg !32
+
+  vector.ph:                                        ; preds = %entry
+    %7 = insertelement <4 x i32> <i32 undef, i32 0, i32 0, i32 0>, i32 %0, i32 0, !dbg !32
+    call void @llvm.set.loop.iterations.i32(i32 %6), !dbg !32
+    %8 = shl i32 %5, 2, !dbg !32
+    %9 = sub i32 %N, %8, !dbg !32
+    br label %vector.body, !dbg !32
+
+  vector.body:                                      ; preds = %vector.body, %vector.ph
+    %lsr.iv = phi i16* [ %scevgep, %vector.body ], [ %b, %vector.ph ], !dbg !33
+    %vec.phi = phi <4 x i32> [ %7, %vector.ph ], [ %15, %vector.body ]
+    %10 = phi i32 [ %6, %vector.ph ], [ %16, %vector.body ]
+    %11 = phi i32 [ %N, %vector.ph ], [ %13, %vector.body ]
+    %lsr.iv14 = bitcast i16* %lsr.iv to <4 x i16>*
+    %12 = call <4 x i1> @llvm.arm.mve.vctp32(i32 %11), !dbg !34
+    %13 = sub i32 %11, 4, !dbg !34
+    %wide.masked.load = call <4 x i16> @llvm.masked.load.v4i16.p0v4i16(<4 x i16>* %lsr.iv14, i32 2, <4 x i1> %12, <4 x i16> undef), !dbg !34
+    %14 = sext <4 x i16> %wide.masked.load to <4 x i32>, !dbg !34
+    %15 = sub <4 x i32> %vec.phi, %14, !dbg !38
+    %scevgep = getelementptr i16, i16* %lsr.iv, i32 4, !dbg !33
+    %16 = call i32 @llvm.loop.decrement.reg.i32.i32.i32(i32 %10, i32 1), !dbg !33
+    %17 = icmp ne i32 %16, 0, !dbg !33
+    br i1 %17, label %vector.body, label %middle.block, !dbg !33
+
+  middle.block:                                     ; preds = %vector.body
+    %vec.phi.lcssa = phi <4 x i32> [ %vec.phi, %vector.body ]
+    %.lcssa = phi <4 x i32> [ %15, %vector.body ], !dbg !38
+    %18 = call <4 x i1> @llvm.arm.mve.vctp32(i32 %9), !dbg !34
+    %19 = select <4 x i1> %18, <4 x i32> %.lcssa, <4 x i32> %vec.phi.lcssa, !dbg !38
+    %20 = call i32 @llvm.experimental.vector.reduce.add.v4i32(<4 x i32> %19), !dbg !32
+    br label %for.cond.cleanup, !dbg !42
+
+  for.cond.cleanup:                                 ; preds = %middle.block, %entry
+    %temp.0.lcssa = phi i32 [ %0, %entry ], [ %20, %middle.block ], !dbg !23
+    call void @llvm.dbg.value(metadata i32 %temp.0.lcssa, metadata !20, metadata !DIExpression()), !dbg !23
+    store i32 %temp.0.lcssa, i32* %a, align 4, !dbg !42
+    ret void, !dbg !43
+  }
+
+  declare void @llvm.dbg.value(metadata, metadata, metadata)
+  declare <4 x i16> @llvm.masked.load.v4i16.p0v4i16(<4 x i16>*, i32 immarg, <4 x i1>, <4 x i16>)
+  declare i32 @llvm.experimental.vector.reduce.add.v4i32(<4 x i32>)
+  declare void @llvm.set.loop.iterations.i32(i32)
+  declare i32 @llvm.loop.decrement.reg.i32.i32.i32(i32, i32)
+  declare <4 x i1> @llvm.arm.mve.vctp32(i32)
+
+  !llvm.dbg.cu = !{!0}
+  !llvm.module.flags = !{!3, !4, !5, !6}
+  !llvm.ident = !{!7}
+
+  !0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, splitDebugInlining: false, nameTableKind: None)
+  !1 = !DIFile(filename: "skip-debug", directory: "")
+  !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, !"min_enum_size", i32 4}
+  !7 = !{!""}
+  !8 = distinct !DISubprogram(name: "skip_debug", scope: !1, file: !1, line: 2, type: !9, scopeLine: 2, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !16)
+  !9 = !DISubroutineType(types: !10)
+  !10 = !{null, !11, !13, !15}
+  !11 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !12, size: 32)
+  !12 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+  !13 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !14, size: 32)
+  !14 = !DIBasicType(name: "short", size: 16, encoding: DW_ATE_signed)
+  !15 = !DIBasicType(name: "unsigned int", size: 32, encoding: DW_ATE_unsigned)
+  !16 = !{!17, !18, !19, !20, !21}
+  !17 = !DILocalVariable(name: "a", arg: 1, scope: !8, file: !1, line: 2, type: !11)
+  !18 = !DILocalVariable(name: "b", arg: 2, scope: !8, file: !1, line: 2, type: !13)
+  !19 = !DILocalVariable(name: "N", arg: 3, scope: !8, file: !1, line: 2, type: !15)
+  !20 = !DILocalVariable(name: "temp", scope: !8, file: !1, line: 3, type: !12)
+  !21 = !DILocalVariable(name: "i", scope: !22, file: !1, line: 4, type: !15)
+  !22 = distinct !DILexicalBlock(scope: !8, file: !1, line: 4, column: 3)
+  !23 = !DILocation(line: 0, scope: !8)
+  !24 = !DILocation(line: 3, column: 14, scope: !8)
+  !25 = !{!26, !26, i64 0}
+  !26 = !{!"int", !27, i64 0}
+  !27 = !{!"omnipotent char", !28, i64 0}
+  !28 = !{!"Simple C/C++ TBAA"}
+  !29 = !DILocation(line: 0, scope: !22)
+  !30 = !DILocation(line: 4, column: 26, scope: !31)
+  !31 = distinct !DILexicalBlock(scope: !22, file: !1, line: 4, column: 3)
+  !32 = !DILocation(line: 4, column: 3, scope: !22)
+  !33 = !DILocation(line: 4, column: 31, scope: !31)
+  !34 = !DILocation(line: 5, column: 13, scope: !35)
+  !35 = distinct !DILexicalBlock(scope: !31, file: !1, line: 4, column: 36)
+  !36 = !{!37, !37, i64 0}
+  !37 = !{!"short", !27, i64 0}
+  !38 = !DILocation(line: 5, column: 10, scope: !35)
+  !39 = distinct !{!39, !32, !40, !41}
+  !40 = !DILocation(line: 6, column: 3, scope: !22)
+  !41 = !{!"llvm.loop.isvectorized", i32 1}
+  !42 = !DILocation(line: 7, column: 6, scope: !8)
+  !43 = !DILocation(line: 8, column: 1, scope: !8)
+
+...
+---
+name:            skip_debug
+alignment:       2
+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: '$r2', virtual-reg: '' }
+frameInfo:
+  isFrameAddressTaken: false
+  isReturnAddressTaken: false
+  hasStackMap:     false
+  hasPatchPoint:   false
+  stackSize:       16
+  offsetAdjustment: -8
+  maxAlignment:    4
+  adjustsStack:    false
+  hasCalls:        false
+  stackProtector:  ''
+  maxCallFrameSize: 0
+  cvBytesOfCalleeSavedRegisters: 0
+  hasOpaqueSPAdjustment: false
+  hasVAStart:      false
+  hasMustTailInVarArgFunc: false
+  localFrameSize:  0
+  savePoint:       ''
+  restorePoint:    ''
+fixedStack:      []
+stack:
+  - { id: 0, name: '', type: spill-slot, offset: -4, size: 4, alignment: 4,
+      stack-id: default, callee-saved-register: '$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: '$r7', callee-saved-restored: true,
+      debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
+  - { id: 2, name: '', type: spill-slot, offset: -12, size: 4, alignment: 4,
+      stack-id: default, callee-saved-register: '$r6', callee-saved-restored: true,
+      debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
+  - { id: 3, name: '', type: spill-slot, offset: -16, size: 4, alignment: 4,
+      stack-id: default, callee-saved-register: '$r4', callee-saved-restored: true,
+      debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
+callSites:       []
+constants:       []
+machineFunctionInfo: {}
+body:             |
+  ; CHECK-LABEL: name: skip_debug
+  ; CHECK: bb.0.entry:
+  ; CHECK:   successors: %bb.4(0x30000000), %bb.1(0x50000000)
+  ; CHECK:   liveins: $lr, $r0, $r1, $r2, $r4, $r6
+  ; CHECK:   DBG_VALUE $r0, $noreg, !17, !DIExpression(), debug-location !23
+  ; CHECK:   DBG_VALUE $r0, $noreg, !17, !DIExpression(), debug-location !23
+  ; CHECK:   DBG_VALUE $r1, $noreg, !18, !DIExpression(), debug-location !23
+  ; CHECK:   DBG_VALUE $r1, $noreg, !18, !DIExpression(), debug-location !23
+  ; CHECK:   DBG_VALUE $r2, $noreg, !19, !DIExpression(), debug-location !23
+  ; CHECK:   DBG_VALUE $r2, $noreg, !19, !DIExpression(), debug-location !23
+  ; CHECK:   frame-setup tPUSH 14, $noreg, killed $r4, killed $r6, killed $lr, implicit-def $sp, implicit $sp
+  ; CHECK:   frame-setup CFI_INSTRUCTION def_cfa_offset 16
+  ; CHECK:   frame-setup CFI_INSTRUCTION offset $lr, -4
+  ; CHECK:   frame-setup CFI_INSTRUCTION offset $r7, -8
+  ; CHECK:   frame-setup CFI_INSTRUCTION offset $r6, -12
+  ; CHECK:   frame-setup CFI_INSTRUCTION offset $r4, -16
+  ; CHECK:   dead $r7 = frame-setup tADDrSPi $sp, 2, 14, $noreg
+  ; CHECK:   frame-setup CFI_INSTRUCTION def_cfa $r7, 8
+  ; CHECK:   renamable $r12 = t2LDRi12 renamable $r0, 0, 14, $noreg, debug-location !24 :: (load 4 from %ir.a)
+  ; CHECK:   DBG_VALUE 0, $noreg, !21, !DIExpression(), debug-location !25
+  ; CHECK:   DBG_VALUE $r12, $noreg, !20, !DIExpression(), debug-location !23
+  ; CHECK:   tCBZ $r2, %bb.4, debug-location !28
+  ; CHECK: bb.1.vector.ph:
+  ; CHECK:   successors: %bb.2(0x80000000)
+  ; CHECK:   liveins: $r0, $r1, $r2, $r12
+  ; CHECK:   renamable $r3, dead $cpsr = tADDi3 renamable $r2, 3, 14, $noreg, debug-location !28
+  ; CHECK:   renamable $lr = t2MOVi 1, 14, $noreg, $noreg
+  ; CHECK:   renamable $r3 = t2BICri killed renamable $r3, 3, 14, $noreg, $noreg, debug-location !28
+  ; CHECK:   renamable $r4, dead $cpsr = tMOVi8 0, 14, $noreg
+  ; CHECK:   renamable $r3, dead $cpsr = tSUBi8 killed renamable $r3, 4, 14, $noreg, debug-location !28
+  ; CHECK:   renamable $q0 = MVE_VDUP32 killed renamable $r4, 0, $noreg, undef renamable $q0, debug-location !28
+  ; CHECK:   renamable $q0 = MVE_VMOV_to_lane_32 killed renamable $q0, killed renamable $r12, 0, 14, $noreg, debug-location !28
+  ; CHECK:   renamable $lr = nuw nsw t2ADDrs killed renamable $lr, renamable $r3, 19, 14, $noreg, $noreg, debug-location !28
+  ; CHECK:   renamable $r3, dead $cpsr = tLSRri killed renamable $r3, 2, 14, $noreg, debug-location !28
+  ; CHECK:   renamable $r3 = t2SUBrs renamable $r2, killed renamable $r3, 18, 14, $noreg, $noreg, debug-location !28
+  ; CHECK:   $lr = t2DLS killed renamable $lr, debug-location !28
+  ; CHECK: bb.2.vector.body:
+  ; CHECK:   successors: %bb.2(0x7c000000), %bb.3(0x04000000)
+  ; CHECK:   liveins: $lr, $q0, $r0, $r1, $r2, $r3
+  ; CHECK:   renamable $vpr = MVE_VCTP32 renamable $r2, 0, $noreg, debug-location !30
+  ; CHECK:   DBG_VALUE $vpr, $noreg, !17, !DIExpression(), debug-location !30
+  ; CHECK:   $q1 = MVE_VORR killed $q0, killed $q0, 0, $noreg, undef $q1
+  ; CHECK:   MVE_VPST 8, implicit $vpr, debug-location !30
+  ; CHECK:   renamable $r1, renamable $q0 = MVE_VLDRHU32_post killed renamable $r1, 8, 1, killed renamable $vpr, debug-location !30 :: (load 8 from %ir.lsr.iv14, align 2)
+  ; CHECK:   renamable $r2, dead $cpsr = tSUBi8 killed renamable $r2, 4, 14, $noreg, debug-location !30
+  ; CHECK:   renamable $q0 = MVE_VMOVLs16bh killed renamable $q0, 0, $noreg, undef renamable $q0, debug-location !30
+  ; CHECK:   renamable $q0 = MVE_VSUBi32 renamable $q1, killed renamable $q0, 0, $noreg, undef renamable $q0, debug-location !32
+  ; CHECK:   $lr = t2LEUpdate killed renamable $lr, %bb.2, debug-location !29
+  ; CHECK: bb.3.middle.block:
+  ; CHECK:   successors: %bb.4(0x80000000)
+  ; CHECK:   liveins: $q0, $q1, $r0, $r3
+  ; CHECK:   renamable $vpr = MVE_VCTP32 killed renamable $r3, 0, $noreg, debug-location !30
+  ; CHECK:   renamable $q0 = MVE_VPSEL killed renamable $q0, killed renamable $q1, 0, killed renamable $vpr, debug-location !32
+  ; CHECK:   renamable $r12 = MVE_VADDVu32no_acc killed renamable $q0, 0, $noreg, debug-location !28
+  ; CHECK: bb.4.for.cond.cleanup:
+  ; CHECK:   liveins: $r0, $r12
+  ; CHECK:   DBG_VALUE $r12, $noreg, !20, !DIExpression(), debug-location !23
+  ; CHECK:   t2STRi12 killed renamable $r12, killed renamable $r0, 0, 14, $noreg, debug-location !33 :: (store 4 into %ir.a)
+  ; CHECK:   tPOP_RET 14, $noreg, def $r4, def $r6, def $r7, def $pc, debug-location !34
+  bb.0.entry:
+    successors: %bb.4(0x30000000), %bb.1(0x50000000)
+    liveins: $r0, $r1, $r2, $r4, $r6, $lr
+
+    DBG_VALUE $r0, $noreg, !17, !DIExpression(), debug-location !23
+    DBG_VALUE $r0, $noreg, !17, !DIExpression(), debug-location !23
+    DBG_VALUE $r1, $noreg, !18, !DIExpression(), debug-location !23
+    DBG_VALUE $r1, $noreg, !18, !DIExpression(), debug-location !23
+    DBG_VALUE $r2, $noreg, !19, !DIExpression(), debug-location !23
+    DBG_VALUE $r2, $noreg, !19, !DIExpression(), debug-location !23
+    frame-setup tPUSH 14, $noreg, killed $r4, killed $r6, killed $lr, implicit-def $sp, implicit $sp
+    frame-setup CFI_INSTRUCTION def_cfa_offset 16
+    frame-setup CFI_INSTRUCTION offset $lr, -4
+    frame-setup CFI_INSTRUCTION offset $r7, -8
+    frame-setup CFI_INSTRUCTION offset $r6, -12
+    frame-setup CFI_INSTRUCTION offset $r4, -16
+    $r7 = frame-setup tADDrSPi $sp, 2, 14, $noreg
+    frame-setup CFI_INSTRUCTION def_cfa $r7, 8
+    renamable $r12 = t2LDRi12 renamable $r0, 0, 14, $noreg, debug-location !24 :: (load 4 from %ir.a)
+    DBG_VALUE 0, $noreg, !21, !DIExpression(), debug-location !29
+    DBG_VALUE $r12, $noreg, !20, !DIExpression(), debug-location !23
+    tCBZ $r2, %bb.4, debug-location !32
+
+  bb.1.vector.ph:
+    successors: %bb.2(0x80000000)
+    liveins: $r0, $r1, $r2, $r12
+
+    renamable $r3, dead $cpsr = tADDi3 renamable $r2, 3, 14, $noreg, debug-location !32
+    renamable $lr = t2MOVi 1, 14, $noreg, $noreg
+    renamable $r3 = t2BICri killed renamable $r3, 3, 14, $noreg, $noreg, debug-location !32
+    renamable $r4, dead $cpsr = tMOVi8 0, 14, $noreg
+    renamable $r3, dead $cpsr = tSUBi8 killed renamable $r3, 4, 14, $noreg, debug-location !32
+    renamable $q0 = MVE_VDUP32 killed renamable $r4, 0, $noreg, undef renamable $q0, debug-location !32
+    renamable $q0 = MVE_VMOV_to_lane_32 killed renamable $q0, killed renamable $r12, 0, 14, $noreg, debug-location !32
+    renamable $lr = nuw nsw t2ADDrs killed renamable $lr, renamable $r3, 19, 14, $noreg, $noreg, debug-location !32
+    renamable $r3, dead $cpsr = tLSRri killed renamable $r3, 2, 14, $noreg, debug-location !32
+    renamable $r3 = t2SUBrs renamable $r2, killed renamable $r3, 18, 14, $noreg, $noreg, debug-location !32
+    t2DoLoopStart renamable $lr, debug-location !32
+
+  bb.2.vector.body:
+    successors: %bb.2(0x7c000000), %bb.3(0x04000000)
+    liveins: $lr, $q0, $r0, $r1, $r2, $r3
+
+    renamable $vpr = MVE_VCTP32 renamable $r2, 0, $noreg, debug-location !34
+    DBG_VALUE $vpr, $noreg, !17, !DIExpression(), debug-location !34
+    $q1 = MVE_VORR killed $q0, $q0, 0, $noreg, undef $q1
+    MVE_VPST 8, implicit $vpr, debug-location !34
+    renamable $r1, renamable $q0 = MVE_VLDRHU32_post killed renamable $r1, 8, 1, killed renamable $vpr, debug-location !34 :: (load 8 from %ir.lsr.iv14, align 2)
+    renamable $r2, dead $cpsr = tSUBi8 killed renamable $r2, 4, 14, $noreg, debug-location !34
+    renamable $q0 = MVE_VMOVLs16bh killed renamable $q0, 0, $noreg, undef renamable $q0, debug-location !34
+    renamable $lr = t2LoopDec killed renamable $lr, 1, debug-location !33
+    renamable $q0 = MVE_VSUBi32 renamable $q1, killed renamable $q0, 0, $noreg, undef renamable $q0, debug-location !38
+    t2LoopEnd renamable $lr, %bb.2, implicit-def dead $cpsr, debug-location !33
+    tB %bb.3, 14, $noreg, debug-location !33
+
+  bb.3.middle.block:
+    successors: %bb.4(0x80000000)
+    liveins: $q0, $q1, $r0, $r3
+
+    renamable $vpr = MVE_VCTP32 killed renamable $r3, 0, $noreg, debug-location !34
+    renamable $q0 = MVE_VPSEL killed renamable $q0, killed renamable $q1, 0, killed renamable $vpr, debug-location !38
+    renamable $r12 = MVE_VADDVu32no_acc killed renamable $q0, 0, $noreg, debug-location !32
+
+  bb.4.for.cond.cleanup:
+    liveins: $r0, $r12
+
+    DBG_VALUE $r12, $noreg, !20, !DIExpression(), debug-location !23
+    t2STRi12 killed renamable $r12, killed renamable $r0, 0, 14, $noreg, debug-location !42 :: (store 4 into %ir.a)
+    tPOP_RET 14, $noreg, def $r4, def $r6, def $r7, def $pc, debug-location !43
+
+...