DfsTest

Clang.asm

; ModuleID = 'test2.cpp'
source_filename = "test2.cpp"
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-pc-linux-gnu"

@_ZL3cnt = internal unnamed_addr global i32 0, align 4
@.str = private unnamed_addr constant [16 x i8] c"%d\0ATime: %ldms\0A\00", align 1

; Function Attrs: nofree nounwind uwtable
define dso_local void @_Z3Dfsiiii(i32 %0, i32 %1, i32 %2, i32 %3) local_unnamed_addr #0 {
  %5 = or i32 %2, %1
  %6 = or i32 %5, %3
  %7 = and i32 %6, 32767
  %8 = xor i32 %7, 32767
  %9 = icmp eq i32 %8, 0
  br i1 %9, label %34, label %10

10:                                               ; preds = %4
  %11 = icmp eq i32 %0, 15
  %12 = add nsw i32 %0, 1
  br i1 %11, label %13, label %22

13:                                               ; preds = %10
  %14 = load i32, i32* @_ZL3cnt, align 4, !tbaa !2
  br label %15

15:                                               ; preds = %13, %15
  %16 = phi i32 [ %20, %15 ], [ %14, %13 ]
  %17 = phi i32 [ %19, %15 ], [ %8, %13 ]
  %18 = add i32 %17, -1
  %19 = and i32 %17, %18
  %20 = add nsw i32 %16, 1
  %21 = icmp eq i32 %19, 0
  br i1 %21, label %33, label %15

22:                                               ; preds = %10, %22
  %23 = phi i32 [ %26, %22 ], [ %8, %10 ]
  %24 = sub nsw i32 0, %23
  %25 = and i32 %23, %24
  %26 = xor i32 %25, %23
  %27 = or i32 %25, %1
  %28 = or i32 %25, %2
  %29 = ashr i32 %28, 1
  %30 = or i32 %25, %3
  %31 = shl i32 %30, 1
  tail call void @_Z3Dfsiiii(i32 %12, i32 %27, i32 %29, i32 %31)
  %32 = icmp eq i32 %26, 0
  br i1 %32, label %34, label %22

33:                                               ; preds = %15
  store i32 %20, i32* @_ZL3cnt, align 4, !tbaa !2
  br label %34

34:                                               ; preds = %22, %33, %4
  ret void
}

; Function Attrs: norecurse nounwind uwtable
define dso_local i32 @main() local_unnamed_addr #1 {
  tail call void @_Z3Dfsiiii(i32 1, i32 0, i32 0, i32 0)
  tail call void @_Z3Dfsiiii(i32 1, i32 0, i32 0, i32 0)
  tail call void @_Z3Dfsiiii(i32 1, i32 0, i32 0, i32 0)
  tail call void @_Z3Dfsiiii(i32 1, i32 0, i32 0, i32 0)
  tail call void @_Z3Dfsiiii(i32 1, i32 0, i32 0, i32 0)
  tail call void @_Z3Dfsiiii(i32 1, i32 0, i32 0, i32 0)
  tail call void @_Z3Dfsiiii(i32 1, i32 0, i32 0, i32 0)
  tail call void @_Z3Dfsiiii(i32 1, i32 0, i32 0, i32 0)
  tail call void @_Z3Dfsiiii(i32 1, i32 0, i32 0, i32 0)
  tail call void @_Z3Dfsiiii(i32 1, i32 0, i32 0, i32 0)
  store i32 0, i32* @_ZL3cnt, align 4, !tbaa !2
  %1 = tail call i64 @clock() #4
  store i32 0, i32* @_ZL3cnt, align 4, !tbaa !2
  tail call void @_Z3Dfsiiii(i32 1, i32 0, i32 0, i32 0)
  store i32 0, i32* @_ZL3cnt, align 4, !tbaa !2
  tail call void @_Z3Dfsiiii(i32 1, i32 0, i32 0, i32 0)
  store i32 0, i32* @_ZL3cnt, align 4, !tbaa !2
  tail call void @_Z3Dfsiiii(i32 1, i32 0, i32 0, i32 0)
  store i32 0, i32* @_ZL3cnt, align 4, !tbaa !2
  tail call void @_Z3Dfsiiii(i32 1, i32 0, i32 0, i32 0)
  store i32 0, i32* @_ZL3cnt, align 4, !tbaa !2
  tail call void @_Z3Dfsiiii(i32 1, i32 0, i32 0, i32 0)
  store i32 0, i32* @_ZL3cnt, align 4, !tbaa !2
  tail call void @_Z3Dfsiiii(i32 1, i32 0, i32 0, i32 0)
  store i32 0, i32* @_ZL3cnt, align 4, !tbaa !2
  tail call void @_Z3Dfsiiii(i32 1, i32 0, i32 0, i32 0)
  store i32 0, i32* @_ZL3cnt, align 4, !tbaa !2
  tail call void @_Z3Dfsiiii(i32 1, i32 0, i32 0, i32 0)
  store i32 0, i32* @_ZL3cnt, align 4, !tbaa !2
  tail call void @_Z3Dfsiiii(i32 1, i32 0, i32 0, i32 0)
  store i32 0, i32* @_ZL3cnt, align 4, !tbaa !2
  tail call void @_Z3Dfsiiii(i32 1, i32 0, i32 0, i32 0)
  %2 = tail call i64 @clock() #4
  %3 = load i32, i32* @_ZL3cnt, align 4, !tbaa !2
  %4 = sub nsw i64 %2, %1
  %5 = sdiv i64 %4, 10000
  %6 = tail call i32 (i8*, ...) @printf(i8* nonnull dereferenceable(1) getelementptr inbounds ([16 x i8], [16 x i8]* @.str, i64 0, i64 0), i32 %3, i64 %5)
  ret i32 0
}

; Function Attrs: nounwind
declare dso_local i64 @clock() local_unnamed_addr #2

; Function Attrs: nofree nounwind
declare dso_local i32 @printf(i8* nocapture readonly, ...) local_unnamed_addr #3

attributes #0 = { nofree nounwind uwtable "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "frame-pointer"="none" "less-precise-fpmad"="false" "min-legal-vector-width"="0" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
attributes #1 = { norecurse nounwind uwtable "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "frame-pointer"="none" "less-precise-fpmad"="false" "min-legal-vector-width"="0" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
attributes #2 = { nounwind "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "frame-pointer"="none" "less-precise-fpmad"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
attributes #3 = { nofree nounwind "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "frame-pointer"="none" "less-precise-fpmad"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
attributes #4 = { nounwind }

!llvm.module.flags = !{!0}
!llvm.ident = !{!1}

!0 = !{i32 1, !"wchar_size", i32 4}
!1 = !{!"Ubuntu clang version 11.0.0-2~ubuntu20.04.1"}
!2 = !{!3, !3, i64 0}
!3 = !{!"int", !4, i64 0}
!4 = !{!"omnipotent char", !5, i64 0}
!5 = !{!"Simple C++ TBAA"}

GCC.asm

	.file	"test2.cpp"
	.text
	.p2align 4
	.globl	_Z3Dfsiiii
	.type	_Z3Dfsiiii, @function
_Z3Dfsiiii:
.LFB30:
	.cfi_startproc
	endbr64
	pushq	%r15
	.cfi_def_cfa_offset 16
	.cfi_offset 15, -16
	pushq	%r14
	.cfi_def_cfa_offset 24
	.cfi_offset 14, -24
	pushq	%r13
	.cfi_def_cfa_offset 32
	.cfi_offset 13, -32
	pushq	%r12
	.cfi_def_cfa_offset 40
	.cfi_offset 12, -40
	pushq	%rbp
	.cfi_def_cfa_offset 48
	.cfi_offset 6, -48
	pushq	%rbx
	.cfi_def_cfa_offset 56
	.cfi_offset 3, -56
	movl	%edx, %ebx
	orl	%ecx, %ebx
	orl	%esi, %ebx
	notl	%ebx
	subq	$24, %rsp
	.cfi_def_cfa_offset 80
	andl	$32767, %ebx
	je	.L1
	cmpl	$15, %edi
	jne	.L13
	movl	_ZL3cnt(%rip), %eax
	leal	1(%rax), %edx
.L4:
	movl	%ebx, %eax
	movl	%ebx, %ecx
	movl	%edx, %esi
	addl	$1, %edx
	negl	%eax
	andl	%ebx, %eax
	xorl	%eax, %ebx
	cmpl	%ecx, %eax
	jne	.L4
	movl	%esi, _ZL3cnt(%rip)
.L1:
	addq	$24, %rsp
	.cfi_remember_state
	.cfi_def_cfa_offset 56
	popq	%rbx
	.cfi_def_cfa_offset 48
	popq	%rbp
	.cfi_def_cfa_offset 40
	popq	%r12
	.cfi_def_cfa_offset 32
	popq	%r13
	.cfi_def_cfa_offset 24
	popq	%r14
	.cfi_def_cfa_offset 16
	popq	%r15
	.cfi_def_cfa_offset 8
	ret
	.p2align 4,,10
	.p2align 3
.L13:
	.cfi_restore_state
	movl	%esi, %ebp
	movl	%edx, %r12d
	leal	1(%rdi), %r15d
	movl	%ecx, %r13d
.L3:
	movl	%ebx, %eax
	movl	%r13d, %ecx
	movl	%r12d, %edx
	movl	%ebp, %esi
	negl	%eax
	movl	%r15d, %edi
	movl	%ebx, %r14d
	andl	%ebx, %eax
	orl	%eax, %ecx
	orl	%eax, %edx
	orl	%eax, %esi
	movl	%eax, 12(%rsp)
	addl	%ecx, %ecx
	sarl	%edx
	xorl	%eax, %ebx
	call	_Z3Dfsiiii
	movl	12(%rsp), %eax
	cmpl	%eax, %r14d
	jne	.L3
	addq	$24, %rsp
	.cfi_def_cfa_offset 56
	popq	%rbx
	.cfi_def_cfa_offset 48
	popq	%rbp
	.cfi_def_cfa_offset 40
	popq	%r12
	.cfi_def_cfa_offset 32
	popq	%r13
	.cfi_def_cfa_offset 24
	popq	%r14
	.cfi_def_cfa_offset 16
	popq	%r15
	.cfi_def_cfa_offset 8
	ret
	.cfi_endproc
.LFE30:
	.size	_Z3Dfsiiii, .-_Z3Dfsiiii
	.section	.rodata.str1.1,"aMS",@progbits,1
.LC0:
	.string	"%d\nTime: %ldms\n"
	.section	.text.startup,"ax",@progbits
	.p2align 4
	.globl	main
	.type	main, @function
main:
.LFB31:
	.cfi_startproc
	endbr64
	pushq	%r15
	.cfi_def_cfa_offset 16
	.cfi_offset 15, -16
	pushq	%r14
	.cfi_def_cfa_offset 24
	.cfi_offset 14, -24
	pushq	%r13
	.cfi_def_cfa_offset 32
	.cfi_offset 13, -32
	pushq	%r12
	.cfi_def_cfa_offset 40
	.cfi_offset 12, -40
	pushq	%rbp
	.cfi_def_cfa_offset 48
	.cfi_offset 6, -48
	movl	$10, %ebp
	pushq	%rbx
	.cfi_def_cfa_offset 56
	.cfi_offset 3, -56
	subq	$8, %rsp
	.cfi_def_cfa_offset 64
	.p2align 4,,10
	.p2align 3
.L19:
	movl	$32767, %r11d
.L15:
	movl	%r11d, %r9d
	movl	%r11d, %r12d
	negl	%r9d
	andl	%r11d, %r9d
	leal	(%r9,%r9), %r13d
	movl	%r9d, %ebx
	xorl	%r9d, %r11d
	sarl	%ebx
	movl	%r13d, %r8d
	orl	%ebx, %r8d
	orl	%r9d, %r8d
	notl	%r8d
	andl	$32767, %r8d
	je	.L17
.L18:
	movl	%r8d, %r10d
	movl	%r13d, %ecx
	movl	%ebx, %edx
	movl	%r9d, %esi
	negl	%r10d
	movl	$3, %edi
	movl	%r8d, %r14d
	andl	%r8d, %r10d
	orl	%r10d, %ecx
	orl	%r10d, %edx
	orl	%r10d, %esi
	xorl	%r10d, %r8d
	addl	%ecx, %ecx
	sarl	%edx
	call	_Z3Dfsiiii
	cmpl	%r14d, %r10d
	jne	.L18
.L17:
	cmpl	%r9d, %r12d
	jne	.L15
	subl	$1, %ebp
	jne	.L19
	movl	$0, _ZL3cnt(%rip)
	movl	$10, %ebp
	call	clock@PLT
	movq	%rax, %rbx
	.p2align 4,,10
	.p2align 3
.L24:
	movl	$0, _ZL3cnt(%rip)
	movl	$32767, %r10d
.L20:
	movl	%r10d, %r9d
	movl	%r10d, %r12d
	negl	%r9d
	andl	%r10d, %r9d
	leal	(%r9,%r9), %r13d
	movl	%r9d, %r11d
	xorl	%r9d, %r10d
	sarl	%r11d
	movl	%r13d, %r8d
	orl	%r11d, %r8d
	orl	%r9d, %r8d
	notl	%r8d
	andl	$32767, %r8d
	je	.L22
.L23:
	movl	%r8d, %r14d
	movl	%r13d, %ecx
	movl	%r11d, %edx
	movl	%r9d, %esi
	negl	%r14d
	movl	%r8d, %r15d
	movl	$3, %edi
	andl	%r8d, %r14d
	orl	%r14d, %ecx
	orl	%r14d, %edx
	orl	%r14d, %esi
	xorl	%r14d, %r8d
	addl	%ecx, %ecx
	sarl	%edx
	call	_Z3Dfsiiii
	cmpl	%r15d, %r14d
	jne	.L23
.L22:
	cmpl	%r9d, %r12d
	jne	.L20
	subl	$1, %ebp
	jne	.L24
	call	clock@PLT
	leaq	.LC0(%rip), %rsi
	movl	$1, %edi
	movabsq	$3777893186295716171, %rdx
	subq	%rbx, %rax
	movq	%rax, %rcx
	imulq	%rdx
	xorl	%eax, %eax
	sarq	$63, %rcx
	sarq	$11, %rdx
	subq	%rcx, %rdx
	movq	%rdx, %rcx
	movl	_ZL3cnt(%rip), %edx
	call	__printf_chk@PLT
	addq	$8, %rsp
	.cfi_def_cfa_offset 56
	xorl	%eax, %eax
	popq	%rbx
	.cfi_def_cfa_offset 48
	popq	%rbp
	.cfi_def_cfa_offset 40
	popq	%r12
	.cfi_def_cfa_offset 32
	popq	%r13
	.cfi_def_cfa_offset 24
	popq	%r14
	.cfi_def_cfa_offset 16
	popq	%r15
	.cfi_def_cfa_offset 8
	ret
	.cfi_endproc
.LFE31:
	.size	main, .-main
	.local	_ZL3cnt
	.comm	_ZL3cnt,4,4
	.ident	"GCC: (Ubuntu 9.3.0-17ubuntu1~20.04) 9.3.0"
	.section	.note.GNU-stack,"",@progbits
	.section	.note.gnu.property,"a"
	.align 8
	.long	 1f - 0f
	.long	 4f - 1f
	.long	 5
0:
	.string	 "GNU"
1:
	.align 8
	.long	 0xc0000002
	.long	 3f - 2f
2:
	.long	 0x3
3:
	.align 8
4:

Java.asm

============================= C2-compiled nmethod ==============================
----------------------------------- Assembly -----------------------------------

Compiled method (c2)      71   60       4       DfsTest2::Dfs (76 bytes)
 total in heap  [0x00007f09771e4090,0x00007f09771e4540] = 1200
 relocation     [0x00007f09771e41e8,0x00007f09771e4208] = 32
 main code      [0x00007f09771e4220,0x00007f09771e4300] = 224
 stub code      [0x00007f09771e4300,0x00007f09771e4328] = 40
 oops           [0x00007f09771e4328,0x00007f09771e4330] = 8
 metadata       [0x00007f09771e4330,0x00007f09771e4338] = 8
 scopes data    [0x00007f09771e4338,0x00007f09771e43b0] = 120
 scopes pcs     [0x00007f09771e43b0,0x00007f09771e4520] = 368
 dependencies   [0x00007f09771e4520,0x00007f09771e4528] = 8
 handler table  [0x00007f09771e4528,0x00007f09771e4540] = 24

[Constant Pool (empty)]

[MachCode]
[Verified Entry Point]
  # {method} {0x00007f09490a0498} 'Dfs' '(IIII)V' in 'DfsTest2'
  # parm0:    rsi       = int
  # parm1:    rdx       = int
  # parm2:    rcx       = int
  # parm3:    r8        = int
  #           [sp+0x40]  (sp of caller)
  0x00007f09771e4220: 8984 2400 | c0fe ff55

  0x00007f09771e4228: ;*synchronization entry
                      ; - DfsTest2::Dfs@-1 (line 6)
  0x00007f09771e4228: 4883 ec30 | 4489 4424 | 0889 4c24 | 0489 1424 | 448b da44 | 0bd9 450b | d841 baff | 7f00 00c4
  0x00007f09771e4248: ;*iand {reexecute=0 rethrow=0 return_oop=0}
                      ; - DfsTest2::Dfs@10 (line 6)
  0x00007f09771e4248: c220 f2ea

  0x00007f09771e424c: ;*ifeq {reexecute=0 rethrow=0 return_oop=0}
                      ; - DfsTest2::Dfs@15 (line 7)
  0x00007f09771e424c: 85ed 7450 | 83fe 0f74 | 5b44 8bde

  0x00007f09771e4258: ;*iadd {reexecute=0 rethrow=0 return_oop=0}
                      ; - DfsTest2::Dfs@52 (line 13)
  0x00007f09771e4258: 41ff c389 | 7424 0c44 | 895c 2410 | 660f 1f44 | 0000 660f

  0x00007f09771e426c: ;*iload {reexecute=0 rethrow=0 return_oop=0}
                      ; - DfsTest2::Dfs@18 (line 8)
  0x00007f09771e426c: 1f44 0000 | c4e2 20f3

  0x00007f09771e4274: ;*iand {reexecute=0 rethrow=0 return_oop=0}
                      ; - DfsTest2::Dfs@23 (line 8)
  0x00007f09771e4274: dd44 8b44 | 2408 450b | c38b 4c24 | 0441 0bcb

  0x00007f09771e4284: ;*ixor {reexecute=0 rethrow=0 return_oop=0}
                      ; - DfsTest2::Dfs@30 (line 9)
  0x00007f09771e4284: 4133 eb8b | 1424 410b

  0x00007f09771e428c: ;*ior {reexecute=0 rethrow=0 return_oop=0}
                      ; - DfsTest2::Dfs@56 (line 13)
  0x00007f09771e428c: d341 d1e0

  0x00007f09771e4290: ;*ishr {reexecute=0 rethrow=0 return_oop=0}
                      ; - DfsTest2::Dfs@62 (line 13)
  0x00007f09771e4290: d1f9 8b74

  0x00007f09771e4294: ;   {static_call}
  0x00007f09771e4294: 2410 90e8

  0x00007f09771e4298: ; ImmutableOopMap {}
                      ;*invokestatic Dfs {reexecute=0 rethrow=0 return_oop=0}
                      ; - DfsTest2::Dfs@69 (line 13)
  0x00007f09771e4298: 84ff ffff

  0x00007f09771e429c: ;*ifeq {reexecute=0 rethrow=0 return_oop=0}
                      ; - DfsTest2::Dfs@15 (line 7)
  0x00007f09771e429c: 85ed 75d0 | 4883 c430 | 5d4d 8b97 | 1001 0000

  0x00007f09771e42ac: ;   {poll_return}
  0x00007f09771e42ac: 4185 02c3

  0x00007f09771e42b0: ;   {oop(a 'java/lang/Class'{0x000000044084ca48} = 'DfsTest2')}
  0x00007f09771e42b0: 49ba 48ca | 8440 0400 | 0000 458b

  0x00007f09771e42bc: ;*goto {reexecute=0 rethrow=0 return_oop=0}
                      ; - DfsTest2::Dfs@72 (line 14)
  0x00007f09771e42bc: 4274 6690 | 4d8b 9f10 | 0100 00c4 | e230 f3dd

  0x00007f09771e42cc: ;*ixor {reexecute=0 rethrow=0 return_oop=0}
                      ; - DfsTest2::Dfs@30 (line 9)
  0x00007f09771e42cc: 4133 e941

  0x00007f09771e42d0: ;*iadd {reexecute=0 rethrow=0 return_oop=0}
                      ; - DfsTest2::Dfs@43 (line 11)
  0x00007f09771e42d0: ffc0 4589

  0x00007f09771e42d4: ; ImmutableOopMap {r10=Oop }
                      ;*goto {reexecute=1 rethrow=0 return_oop=0}
                      ; - (reexecute) DfsTest2::Dfs@72 (line 14)
                      ;   {poll}
  0x00007f09771e42d4: 4274 4185

  0x00007f09771e42d8: ;*goto {reexecute=0 rethrow=0 return_oop=0}
                      ; - DfsTest2::Dfs@72 (line 14)
  0x00007f09771e42d8: 0385 ed75

  0x00007f09771e42dc: ;*ifeq {reexecute=0 rethrow=0 return_oop=0}
                      ; - DfsTest2::Dfs@15 (line 7)
  0x00007f09771e42dc: e3eb c148 | 8bf0 4883

  0x00007f09771e42e4: ;   {runtime_call _rethrow_Java}
  0x00007f09771e42e4: c430 5de9

  0x00007f09771e42e8: ;*iload {reexecute=0 rethrow=0 return_oop=0}
                      ; - DfsTest2::Dfs@18 (line 8)
  0x00007f09771e42e8: 140e 56f8 | f4f4 f4f4 | f4f4 f4f4 | f4f4 f4f4 | f4f4 f4f4 | f4f4 f4f4
[Stub Code]
  0x00007f09771e4300: ;   {no_reloc}
  0x00007f09771e4300: 48bb 0000 | 0000 0000

  0x00007f09771e4308: ;   {runtime_call}
  0x00007f09771e4308: 0000 e9fb

  0x00007f09771e430c: ;   {runtime_call ExceptionBlob}
  0x00007f09771e430c: ffff ffe9 | 6c2b 55f8
[Deopt Handler Code]
  0x00007f09771e4314: e800 0000 | 0048 832c

  0x00007f09771e431c: ;   {runtime_call DeoptimizationBlob}
  0x00007f09771e431c: 2405 e97d | 994a f8f4 | f4f4 f4f4
[/MachCode]

把JVM的asm清理了一下扔进反汇编是这样：

mov dword ptr [rsp - 0x14000], eax
push rbp
sub rsp, 0x30
mov dword ptr [rsp + 8], r8d
mov dword ptr [rsp + 4], ecx
mov dword ptr [rsp], edx
mov r11d, edx
or r11d, ecx
or r11d, r8d
mov r10d, 0x7fff
andn ebp, r11d, r10d
test ebp, ebp
je 0x7f09771e42a0
cmp esi, 0xf
je 0x7f09771e42b0
mov r11d, esi
inc r11d
mov dword ptr [rsp + 0xc], esi
mov dword ptr [rsp + 0x10], r11d
nop word ptr [rax + rax]
nop word ptr [rax + rax]
blsi r11d, ebp
mov r8d, dword ptr [rsp + 8]
or r8d, r11d
mov ecx, dword ptr [rsp + 4]
or ecx, r11d
xor ebp, r11d
mov edx, dword ptr [rsp]
or edx, r11d
shl r8d, 1
sar ecx, 1
mov esi, dword ptr [rsp + 0x10]
nop 
call 0x7f09771e4220
test ebp, ebp
jne 0x7f09771e4270
add rsp, 0x30
pop rbp
mov r10, qword ptr [r15 + 0x110]
test dword ptr [r10], eax
ret 
movabs r10, 0x44084ca48
mov r8d, dword ptr [r10 + 0x74]
nop 
mov r11, qword ptr [r15 + 0x110]
blsi r9d, ebp
xor ebp, r9d
inc r8d
mov dword ptr [r10 + 0x74], r8d
test dword ptr [r11], eax
test ebp, ebp
jne 0x7f09771e42c0
jmp 0x7f09771e42a0
mov rsi, rax
add rsp, 0x30
pop rbp
jmp 0x7f096f745100

然后单独Dfs拿gcc Ofast是这样：

static cnt
Dfs(int, int, int, int):
        push    r15
        push    r14
        push    r13
        push    r12
        push    rbp
        push    rbx
        mov     ebx, edx
        or      ebx, ecx
        or      ebx, esi
        not     ebx
        sub     rsp, 24
        and     ebx, 32767
        je      .L1
        cmp     edi, 15
        jne     .L13
        mov     edx, DWORD PTR cnt[rip]
.L4:
        mov     eax, ebx
        mov     ecx, ebx
        add     edx, 1
        neg     eax
        and     eax, ebx
        xor     ebx, eax
        cmp     eax, ecx
        jne     .L4
        mov     DWORD PTR cnt[rip], edx
.L1:
        add     rsp, 24
        pop     rbx
        pop     rbp
        pop     r12
        pop     r13
        pop     r14
        pop     r15
        ret
.L13:
        mov     ebp, esi
        mov     r12d, edx
        lea     r15d, [rdi+1]
        mov     r13d, ecx
.L3:
        mov     eax, ebx
        mov     ecx, r13d
        mov     edx, r12d
        mov     esi, ebp
        neg     eax
        mov     edi, r15d
        mov     r14d, ebx
        and     eax, ebx
        or      ecx, eax
        or      edx, eax
        or      esi, eax
        mov     DWORD PTR [rsp+12], eax
        add     ecx, ecx
        sar     edx
        xor     ebx, eax
        call    Dfs(int, int, int, int)
        mov     eax, DWORD PTR [rsp+12]
        cmp     r14d, eax
        jne     .L3
        add     rsp, 24
        pop     rbx
        pop     rbp
        pop     r12
        pop     r13
        pop     r14
        pop     r15
        ret

看起来大体结构是相似的，自只有些小区别：

• 一些指令的使用不同，比如gcc的not+and+je和jvm的mov+andn+test+je，还有jvm用了blsi。

• gcc第二个跳转是jne，jvm是je，分支的顺序调换了一下（可能是PGO的效果，觉得row==n几率比较小？）

• gcc pop比较多……

Sources:

dfs.c

#include <stdio.h>

static const int n = 15;
static int cnt;

static void Dfs (int row, int shu, int pie, int na) {
    int ave = ((1 << n) - 1) & ~(shu | pie | na);
    while (ave) {
        int p = ave & -ave;
        ave ^= p;
        if (row == n)
            ++cnt;
        else
            Dfs(row + 1, shu | p, (pie | p) >> 1, (na | p) << 1);
    }
}

int main () {
    Dfs(1, 0, 0, 0);
    printf("%d\n", cnt);
}

Dfs.java

public class Dfs {
    private static final int n = 15;
    private static int cnt = 0;

    private static void Dfs (int row, int shu, int pie, int na) {
        int ave = ((1 << n) - 1) & ~(shu | pie | na);
        while (ave != 0) {
            int p = ave & -ave;
            ave ^= p;
            if (row == n)
                ++cnt;
            else
                Dfs(row + 1, shu | p, (pie | p) >> 1, (na | p) << 1);
        }
    }


    public static void main(String[] args) {
        Dfs(1, 0, 0, 0);
        System.out.println(cnt);
    }
}

dfs.rs

const N: i32 = 15;

static mut CNT: i32 = 0;

fn dfs(row: i32, shu: i32, pie: i32, na: i32) {
    let mut ave = ((1 << N) - 1) & !(shu | pie | na);
    while ave != 0 {
        let p = ave & -ave;
        ave ^= p;
        if row == N {
            unsafe { CNT += 1 };
        } else {
            dfs(row + 1, shu | p, (pie | p) >> 1, (na | p) << 1);
        }
    }
}

fn main() {
    dfs(1, 0, 0, 0);
    println!("{}", unsafe { CNT });
}

Dfs.hs:

{-# LANGUAGE BangPatterns #-}
import Data.IORef
import Data.Bits
import GHC.IO

n = 15

{-# NOINLINE cnt #-}
cnt = unsafePerformIO $ newIORef 0

dfs :: Int -> Int -> Int -> Int -> IO ()
dfs !row !shu !pie !na = go (((1 `shiftL` n) - 1) .&. complement (shu .|. pie .|. na))
  where go 0    = pure ()
        go !ave = if row == n
                    then modifyIORef cnt (+1)
                    else do
                      dfs (row + 1) (shu .|. p) ((pie .|. p) `shiftR` 1) ((na .|. p) `shiftL` 1)
                      go $ ave `xor` p
          where !p = ave .&. (-ave)

    
main = do
    dfs 1 0 0 0
    cnt' <- readIORef cnt
    print cnt'