; LLVM IR from upupming/algorithm :: acwing/算法基础课/第四讲 数学知识/高斯消元/883. 高斯消元解线性方程组 (main)

; Unoptimized IR (clang -disable-llvm-passes):
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"

%"class.std::basic_istream" = type { ptr, i64, %"class.std::basic_ios" }
%"class.std::basic_ios" = type { %"class.std::ios_base", ptr, i8, i8, ptr, ptr, ptr, ptr }
%"class.std::ios_base" = type { ptr, i64, i64, i32, i32, i32, ptr, %"struct.std::ios_base::_Words", [8 x %"struct.std::ios_base::_Words"], i32, ptr, %"class.std::locale" }
%"struct.std::ios_base::_Words" = type { ptr, i64 }
%"class.std::locale" = type { ptr }

@n = external dso_local global i32, align 4
@a = external dso_local global [110 x [110 x double]], align 16
@_ZSt3cin = external global %"class.std::basic_istream", align 8
@.str = external hidden unnamed_addr constant [7 x i8], align 1
@.str.1 = external hidden unnamed_addr constant [25 x i8], align 1
@.str.2 = external hidden unnamed_addr constant [12 x i8], align 1

; Function Attrs: mustprogress uwtable
declare dso_local noundef i32 @_Z5gaussv() #0

; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
declare void @llvm.lifetime.start.p0(i64 immarg, ptr nocapture) #1

; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
declare void @llvm.lifetime.end.p0(i64 immarg, ptr nocapture) #1

; Function Attrs: mustprogress norecurse uwtable
define dso_local noundef i32 @main() #2 {
  %1 = alloca i32, align 4
  %2 = alloca i32, align 4
  %3 = alloca i32, align 4
  %4 = alloca i32, align 4
  %5 = alloca i32, align 4
  %6 = alloca i32, align 4
  store i32 0, ptr %1, align 4
  %7 = call noundef nonnull align 8 dereferenceable(16) ptr @_ZNSirsERi(ptr noundef nonnull align 8 dereferenceable(16) @_ZSt3cin, ptr noundef nonnull align 4 dereferenceable(4) @n)
  call void @llvm.lifetime.start.p0(i64 4, ptr %2) #4
  store i32 0, ptr %2, align 4, !tbaa !5
  br label %8

8:                                                ; preds = %32, %0
  %9 = load i32, ptr %2, align 4, !tbaa !5
  %10 = load i32, ptr @n, align 4, !tbaa !5
  %11 = icmp slt i32 %9, %10
  br i1 %11, label %13, label %12

12:                                               ; preds = %8
  store i32 2, ptr %3, align 4
  call void @llvm.lifetime.end.p0(i64 4, ptr %2) #4
  br label %35

13:                                               ; preds = %8
  call void @llvm.lifetime.start.p0(i64 4, ptr %4) #4
  store i32 0, ptr %4, align 4, !tbaa !5
  br label %14

14:                                               ; preds = %28, %13
  %15 = load i32, ptr %4, align 4, !tbaa !5
  %16 = load i32, ptr @n, align 4, !tbaa !5
  %17 = add nsw i32 %16, 1
  %18 = icmp slt i32 %15, %17
  br i1 %18, label %20, label %19

19:                                               ; preds = %14
  store i32 5, ptr %3, align 4
  call void @llvm.lifetime.end.p0(i64 4, ptr %4) #4
  br label %31

20:                                               ; preds = %14
  %21 = load i32, ptr %2, align 4, !tbaa !5
  %22 = sext i32 %21 to i64
  %23 = getelementptr inbounds [110 x [110 x double]], ptr @a, i64 0, i64 %22
  %24 = load i32, ptr %4, align 4, !tbaa !5
  %25 = sext i32 %24 to i64
  %26 = getelementptr inbounds [110 x double], ptr %23, i64 0, i64 %25
  %27 = call noundef nonnull align 8 dereferenceable(16) ptr @_ZNSirsERd(ptr noundef nonnull align 8 dereferenceable(16) @_ZSt3cin, ptr noundef nonnull align 8 dereferenceable(8) %26)
  br label %28

28:                                               ; preds = %20
  %29 = load i32, ptr %4, align 4, !tbaa !5
  %30 = add nsw i32 %29, 1
  store i32 %30, ptr %4, align 4, !tbaa !5
  br label %14, !llvm.loop !9

31:                                               ; preds = %19
  br label %32

32:                                               ; preds = %31
  %33 = load i32, ptr %2, align 4, !tbaa !5
  %34 = add nsw i32 %33, 1
  store i32 %34, ptr %2, align 4, !tbaa !5
  br label %8, !llvm.loop !11

35:                                               ; preds = %12
  call void @llvm.lifetime.start.p0(i64 4, ptr %5) #4
  %36 = call noundef i32 @_Z5gaussv()
  store i32 %36, ptr %5, align 4, !tbaa !5
  %37 = load i32, ptr %5, align 4, !tbaa !5
  %38 = icmp eq i32 %37, 0
  br i1 %38, label %39, label %58

39:                                               ; preds = %35
  call void @llvm.lifetime.start.p0(i64 4, ptr %6) #4
  store i32 0, ptr %6, align 4, !tbaa !5
  br label %40

40:                                               ; preds = %54, %39
  %41 = load i32, ptr %6, align 4, !tbaa !5
  %42 = load i32, ptr @n, align 4, !tbaa !5
  %43 = icmp slt i32 %41, %42
  br i1 %43, label %45, label %44

44:                                               ; preds = %40
  store i32 8, ptr %3, align 4
  call void @llvm.lifetime.end.p0(i64 4, ptr %6) #4
  br label %57

45:                                               ; preds = %40
  %46 = load i32, ptr %6, align 4, !tbaa !5
  %47 = sext i32 %46 to i64
  %48 = getelementptr inbounds [110 x [110 x double]], ptr @a, i64 0, i64 %47
  %49 = load i32, ptr @n, align 4, !tbaa !5
  %50 = sext i32 %49 to i64
  %51 = getelementptr inbounds [110 x double], ptr %48, i64 0, i64 %50
  %52 = load double, ptr %51, align 8, !tbaa !12
  %53 = call i32 (ptr, ...) @printf(ptr noundef @.str, double noundef %52)
  br label %54

54:                                               ; preds = %45
  %55 = load i32, ptr %6, align 4, !tbaa !5
  %56 = add nsw i32 %55, 1
  store i32 %56, ptr %6, align 4, !tbaa !5
  br label %40, !llvm.loop !14

57:                                               ; preds = %44
  br label %66

58:                                               ; preds = %35
  %59 = load i32, ptr %5, align 4, !tbaa !5
  %60 = icmp eq i32 %59, 1
  br i1 %60, label %61, label %63

61:                                               ; preds = %58
  %62 = call i32 @puts(ptr noundef @.str.1)
  br label %65

63:                                               ; preds = %58
  %64 = call i32 @puts(ptr noundef @.str.2)
  br label %65

65:                                               ; preds = %63, %61
  br label %66

66:                                               ; preds = %65, %57
  store i32 0, ptr %1, align 4
  store i32 1, ptr %3, align 4
  call void @llvm.lifetime.end.p0(i64 4, ptr %5) #4
  %67 = load i32, ptr %1, align 4
  ret i32 %67
}

declare noundef nonnull align 8 dereferenceable(16) ptr @_ZNSirsERi(ptr noundef nonnull align 8 dereferenceable(16), ptr noundef nonnull align 4 dereferenceable(4)) #3

; Function Attrs: mustprogress uwtable
declare noundef nonnull align 8 dereferenceable(16) ptr @_ZNSirsERd(ptr noundef nonnull align 8 dereferenceable(16), ptr noundef nonnull align 8 dereferenceable(8)) #0 align 2

declare i32 @printf(ptr noundef, ...) #3

declare i32 @puts(ptr noundef) #3

attributes #0 = { mustprogress uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
attributes #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
attributes #2 = { mustprogress norecurse uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
attributes #3 = { "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
attributes #4 = { nounwind }

!llvm.module.flags = !{!0, !1, !2, !3}
!llvm.ident = !{!4}

!0 = !{i32 1, !"wchar_size", i32 4}
!1 = !{i32 8, !"PIC Level", i32 2}
!2 = !{i32 7, !"PIE Level", i32 2}
!3 = !{i32 7, !"uwtable", i32 2}
!4 = !{!"clang version 19.1.0 (git@github.com:llvm/llvm-project.git a4bf6cd7cfb1a1421ba92bca9d017b49936c55e4)"}
!5 = !{!6, !6, i64 0}
!6 = !{!"int", !7, i64 0}
!7 = !{!"omnipotent char", !8, i64 0}
!8 = !{!"Simple C++ TBAA"}
!9 = distinct !{!9, !10}
!10 = !{!"llvm.loop.mustprogress"}
!11 = distinct !{!11, !10}
!12 = !{!13, !13, i64 0}
!13 = !{!"double", !7, i64 0}
!14 = distinct !{!14, !10}


; Optimized IR (opt -passes='default<O3>'):
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"

%"class.std::basic_istream" = type { ptr, i64, %"class.std::basic_ios" }
%"class.std::basic_ios" = type { %"class.std::ios_base", ptr, i8, i8, ptr, ptr, ptr, ptr }
%"class.std::ios_base" = type { ptr, i64, i64, i32, i32, i32, ptr, %"struct.std::ios_base::_Words", [8 x %"struct.std::ios_base::_Words"], i32, ptr, %"class.std::locale" }
%"struct.std::ios_base::_Words" = type { ptr, i64 }
%"class.std::locale" = type { ptr }

@n = external dso_local global i32, align 4
@a = external dso_local global [110 x [110 x double]], align 16
@_ZSt3cin = external global %"class.std::basic_istream", align 8
@.str = external hidden unnamed_addr constant [7 x i8], align 1
@.str.1 = external hidden unnamed_addr constant [25 x i8], align 1
@.str.2 = external hidden unnamed_addr constant [12 x i8], align 1

; Function Attrs: mustprogress uwtable
declare dso_local noundef i32 @_Z5gaussv() local_unnamed_addr #0

; Function Attrs: mustprogress norecurse uwtable
define dso_local noundef i32 @main() local_unnamed_addr #1 {
  %1 = tail call noundef nonnull align 8 dereferenceable(16) ptr @_ZNSirsERi(ptr noundef nonnull align 8 dereferenceable(16) @_ZSt3cin, ptr noundef nonnull align 4 dereferenceable(4) @n)
  %2 = load i32, ptr @n, align 4, !tbaa !5
  %3 = icmp sgt i32 %2, 0
  br i1 %3, label %.preheader16, label %._crit_edge20

.preheader16:                                     ; preds = %0, %._crit_edge
  %4 = phi i32 [ %8, %._crit_edge ], [ %2, %0 ]
  %indvars.iv25 = phi i64 [ %indvars.iv.next26, %._crit_edge ], [ 0, %0 ]
  %.not17 = icmp slt i32 %4, 0
  br i1 %.not17, label %.preheader16.._crit_edge_crit_edge, label %.lr.ph

.preheader16.._crit_edge_crit_edge:               ; preds = %.preheader16
  %.pre = sext i32 %4 to i64
  br label %._crit_edge

._crit_edge20:                                    ; preds = %._crit_edge, %0
  %5 = tail call noundef i32 @_Z5gaussv()
  switch i32 %5, label %22 [
    i32 0, label %.preheader
    i32 1, label %.loopexit.sink.split
  ]

.preheader:                                       ; preds = %._crit_edge20
  %6 = load i32, ptr @n, align 4, !tbaa !5
  %7 = icmp sgt i32 %6, 0
  br i1 %7, label %.lr.ph22, label %.loopexit

._crit_edge:                                      ; preds = %.lr.ph, %.preheader16.._crit_edge_crit_edge
  %.pre-phi = phi i64 [ %.pre, %.preheader16.._crit_edge_crit_edge ], [ %13, %.lr.ph ]
  %8 = phi i32 [ %4, %.preheader16.._crit_edge_crit_edge ], [ %12, %.lr.ph ]
  %indvars.iv.next26 = add nuw nsw i64 %indvars.iv25, 1
  %9 = icmp slt i64 %indvars.iv.next26, %.pre-phi
  br i1 %9, label %.preheader16, label %._crit_edge20, !llvm.loop !9

.lr.ph:                                           ; preds = %.preheader16, %.lr.ph
  %indvars.iv = phi i64 [ %indvars.iv.next, %.lr.ph ], [ 0, %.preheader16 ]
  %10 = getelementptr inbounds [110 x [110 x double]], ptr @a, i64 0, i64 %indvars.iv25, i64 %indvars.iv
  %11 = tail call noundef nonnull align 8 dereferenceable(16) ptr @_ZNSirsERd(ptr noundef nonnull align 8 dereferenceable(16) @_ZSt3cin, ptr noundef nonnull align 8 dereferenceable(8) %10)
  %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
  %12 = load i32, ptr @n, align 4, !tbaa !5
  %13 = sext i32 %12 to i64
  %.not.not = icmp slt i64 %indvars.iv, %13
  br i1 %.not.not, label %.lr.ph, label %._crit_edge, !llvm.loop !12

.lr.ph22:                                         ; preds = %.preheader, %.lr.ph22
  %indvars.iv28 = phi i64 [ %indvars.iv.next29, %.lr.ph22 ], [ 0, %.preheader ]
  %14 = phi i32 [ %19, %.lr.ph22 ], [ %6, %.preheader ]
  %15 = sext i32 %14 to i64
  %16 = getelementptr inbounds [110 x [110 x double]], ptr @a, i64 0, i64 %indvars.iv28, i64 %15
  %17 = load double, ptr %16, align 8, !tbaa !13
  %18 = tail call i32 (ptr, ...) @printf(ptr noundef nonnull dereferenceable(1) @.str, double noundef %17)
  %indvars.iv.next29 = add nuw nsw i64 %indvars.iv28, 1
  %19 = load i32, ptr @n, align 4, !tbaa !5
  %20 = sext i32 %19 to i64
  %21 = icmp slt i64 %indvars.iv.next29, %20
  br i1 %21, label %.lr.ph22, label %.loopexit, !llvm.loop !15

22:                                               ; preds = %._crit_edge20
  br label %.loopexit.sink.split

.loopexit.sink.split:                             ; preds = %._crit_edge20, %22
  %.str.1.sink = phi ptr [ @.str.2, %22 ], [ @.str.1, %._crit_edge20 ]
  %23 = tail call i32 @puts(ptr noundef nonnull dereferenceable(1) %.str.1.sink)
  br label %.loopexit

.loopexit:                                        ; preds = %.lr.ph22, %.loopexit.sink.split, %.preheader
  ret i32 0
}

declare noundef nonnull align 8 dereferenceable(16) ptr @_ZNSirsERi(ptr noundef nonnull align 8 dereferenceable(16), ptr noundef nonnull align 4 dereferenceable(4)) local_unnamed_addr #2

; Function Attrs: mustprogress uwtable
declare noundef nonnull align 8 dereferenceable(16) ptr @_ZNSirsERd(ptr noundef nonnull align 8 dereferenceable(16), ptr noundef nonnull align 8 dereferenceable(8)) local_unnamed_addr #0 align 2

; Function Attrs: nofree nounwind
declare noundef i32 @printf(ptr nocapture noundef readonly, ...) local_unnamed_addr #3

; Function Attrs: nofree nounwind
declare noundef i32 @puts(ptr nocapture noundef readonly) local_unnamed_addr #3

attributes #0 = { mustprogress uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
attributes #1 = { mustprogress norecurse uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
attributes #2 = { "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
attributes #3 = { nofree nounwind "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }

!llvm.module.flags = !{!0, !1, !2, !3}
!llvm.ident = !{!4}

!0 = !{i32 1, !"wchar_size", i32 4}
!1 = !{i32 8, !"PIC Level", i32 2}
!2 = !{i32 7, !"PIE Level", i32 2}
!3 = !{i32 7, !"uwtable", i32 2}
!4 = !{!"clang version 19.1.0 (git@github.com:llvm/llvm-project.git a4bf6cd7cfb1a1421ba92bca9d017b49936c55e4)"}
!5 = !{!6, !6, i64 0}
!6 = !{!"int", !7, i64 0}
!7 = !{!"omnipotent char", !8, i64 0}
!8 = !{!"Simple C++ TBAA"}
!9 = distinct !{!9, !10, !11}
!10 = !{!"llvm.loop.mustprogress"}
!11 = !{!"llvm.loop.unswitch.partial.disable"}
!12 = distinct !{!12, !10}
!13 = !{!14, !14, i64 0}
!14 = !{!"double", !7, i64 0}
!15 = distinct !{!15, !10}


; Effective O3 passes: EarlyCSEPass,GVNPass,GlobalOptPass,IndVarSimplifyPass,InferFunctionAttrsPass,InstCombinePass,InstSimplifyPass,JumpThreadingPass,LCSSAPass,LICMPass,LoopRotatePass,LoopSimplifyCFGPass,LoopSimplifyPass,LoopUnrollPass,SCCPPass,SROAPass,SimpleLoopUnswitchPass,SimplifyCFGPass,TailCallElimPass