SSE2 MOVDUP不移动值
有人能解释一下为什么这个程序的输出是SSE2 MOVDUP不移动值,d,sse,sse2,D,Sse,Sse2,有人能解释一下为什么这个程序的输出是[nan，nan]？代码应该将d的值加载到XMM1寄存器的高64位和低64位，然后将XMM1的内容移动到a中。由于a未初始化为一组特定值，因此D将每个元素初始化为nan。如果movupd指令不在objdump中，我会理解结果，但指令在那里。想法 import std.stdio; void main() { enum double d = 1.0 / cast(double)2; double[] a = new double[2];
[nan，nan]daananmovupdimport std.stdio;
void main()
{
enum double d = 1.0 / cast(double)2;
double[] a = new double[2];
auto aptr = a.ptr;
asm
{
movddup XMM1, d;
movupd [aptr], XMM1;
}
writeln(a);
}
0000000000426b88 <_Dmain>:
426b88: 55 push %rbp
426b89: 48 8b ec mov %rsp,%rbp
426b8c: 48 83 ec 50 sub $0x50,%rsp
426b90: f2 48 0f 10 05 77 81 rex.W movsd 0x28177(%rip),%xmm0
426b97: 02 00
426b99: f2 48 0f 11 45 b0 rex.W movsd %xmm0,-0x50(%rbp)
426b9f: 48 be 02 00 00 00 00 movabs $0x2,%rsi
426ba6: 00 00 00
426ba9: f2 48 0f 10 05 66 81 rex.W movsd 0x28166(%rip),%xmm0
426bb0: 02 00
426bb2: 48 8d 7d c0 lea -0x40(%rbp),%rdi
426bb6: e8 65 d1 00 00 callq 433d20 <_memsetDouble>
426bbb: f2 48 0f 10 0d 4c 81 rex.W movsd 0x2814c(%rip),%xmm1
426bc2: 02 00
426bc4: f2 48 0f 11 4d c0 rex.W movsd %xmm1,-0x40(%rbp)
426bca: f2 48 0f 10 15 3d 81 rex.W movsd 0x2813d(%rip),%xmm2
426bd1: 02 00
426bd3: f2 48 0f 11 55 c8 rex.W movsd %xmm2,-0x38(%rbp)
426bd9: 48 8d 45 c0 lea -0x40(%rbp),%rax
426bdd: 48 89 45 d0 mov %rax,-0x30(%rbp)
426be1: 48 8d 55 e0 lea -0x20(%rbp),%rdx
426be5: 48 b8 02 00 00 00 00 movabs $0x2,%rax
426bec: 00 00 00
426bef: 48 89 c1 mov %rax,%rcx
426bf2: 49 89 d0 mov %rdx,%r8
426bf5: 51 push %rcx
426bf6: 41 50 push %r8
426bf8: 48 be 02 00 00 00 00 movabs $0x2,%rsi
426bff: 00 00 00
426c02: 48 bf c0 84 65 00 00 movabs $0x6584c0,%rdi
426c09: 00 00 00
426c0c: e8 87 ce 00 00 callq 433a98 <_d_arrayliteralTX>
426c11: 48 89 45 f0 mov %rax,-0x10(%rbp)
426c15: f2 48 0f 10 05 02 81 rex.W movsd 0x28102(%rip),%xmm0
426c1c: 02 00
426c1e: f2 48 0f 11 00 rex.W movsd %xmm0,(%rax)
426c23: f2 48 0f 10 0d f4 80 rex.W movsd 0x280f4(%rip),%xmm1
426c2a: 02 00
426c2c: 48 8b 45 f0 mov -0x10(%rbp),%rax
426c30: f2 48 0f 11 48 08 rex.W movsd %xmm1,0x8(%rax)
426c36: 48 8b 55 f0 mov -0x10(%rbp),%rdx
426c3a: 48 be 02 00 00 00 00 movabs $0x2,%rsi
426c41: 00 00 00
426c44: 41 58 pop %r8
426c46: 59 pop %rcx
426c47: 48 bf 08 00 00 00 00 movabs $0x8,%rdi
426c4e: 00 00 00
426c51: e8 8e 95 00 00 callq 4301e4 <_d_arraycopy>
426c56: f2 0f 12 4d b0 movddup -0x50(%rbp),%xmm1
426c5b: 66 0f 11 4d d0 movupd %xmm1,-0x30(%rbp)
426c60: ff 75 c8 pushq -0x38(%rbp)
426c63: ff 75 c0 pushq -0x40(%rbp)
426c66: e8 09 00 00 00 callq 426c74 <_D3std5stdio16__T7writelnTG2dZ7writelnFG2dZv>
426c6b: 48 83 c4 10 add $0x10,%rsp
426c6f: 31 c0 xor %eax,%eax
426c71: c9 leaveq
426c72: c3 retq
426c73: 90 nop
0000000000 426B88:
426b88:55%按需付费
426b89:488B ec mov%rsp，%rbp
426b8c:48 83 ec 50分$0x50，%rsp
426b90:F248 0f 10 05 77 81 rex.W movsd 0x28177（%rip），%xmm0
426b97:02 00
426b99:F248 0f 11 45 b0 rex.W movsd%xmm0，-0x50（%rbp）
426b9f:48 be 02 00 movabs$0x2，%rsi
426ba6:00
426ba9:F248 0f 10 05 66 81 rex.W movsd 0x28166（%rip），%xmm0
426bb0:02 00
426bb2:48 8d 7d c0 lea-0x40（%rbp），%rdi
426bb6:e8 65 d1 00 00呼叫433d20
426BB:F248 0f 10 0d 4c 81 rex.W movsd 0x2814c（%rip），%xmm1
426bc2:02 00
426bc4:F248 0f 11 4d c0 rex.W移动%xmm1，-0x40（%rbp）
426bca:F248 0f 10 15 3d 81 rex.W movsd 0x2813d（%rip），%xmm2
426bd1:02 00
426bd3:F248 0f 11 55 c8 rex.W movsd%xmm2，-0x38（%rbp）
426bd9:48 8d 45 c0 lea-0x40（%rbp），%rax
426bdd:48 89 45 d0 mov%rax，-0x30（%rbp）
426be1:48 8d 55 e0 lea-0x20（%rbp），%rdx
426be5:48 b8 02 00 movabs$0x2，%rax
426贝克：00
426bef:48 89 c1移动百分比rax，%rcx
426bf2:49 89 d0 mov%rdx，%r8
426bf5:51推力%rcx
426bf6:41 50%推力r8
426bf8:48 be 02 00 movabs$0x2，%rsi
426BF:00
426c02:48 bf c0 84 65 00 movabs$0x6584c0，%rdi
426c09:00
426c0c:e8 87 ce 00 00 callq 433a98
426c11:48 89 45 f0 mov%rax，-0x10（%rbp）
426c15:F248 0f 10 05 02 81 rex.W movsd 0x28102（%rip），%xmm0
426c1c:02 00
426c1e:F248 0f 11 00 rex.W移动%xmm0，（%rax）
426c23:F248 0f 10 0d f4 80 rex.W movsd 0x280f4（%rip），%xmm1
426c2a:02 00
426c2c:48 8b 45 f0 mov-0x10（%rbp），%rax
426c30:F248 0f 11 48 08 rex.W移动%xmm1,0x8（%rax）
426c36:48 8b 55 f0 mov-0x10（%rbp），%rdx
426c3a:48 be 02 00 movabs$0x2，%rsi
426c41:00
426c44:41 58%r8
426c46:59 pop%rcx
426c47:48 bf 08 00 movabs$0x8，%rdi
426c4e:00
426c51:e8 8e 95 00 00 callq 4301e4
426c56:F20F 12 4d b0 movddup-0x50（%rbp），%xmm1
426c5b:66 0f 11 4d d0 movupd%xmm1，-0x30（%rbp）
426c60:ff 75 c8推杆-0x38（%rbp）
426c63:ff 75 c0推力-0x40（%rbp）
426c66:e8 09 00 00呼叫426c74
426c6b:48 83 c4 10添加$0x10，%rsp
426c6f:31 c0异或%eax，%eax
426c71:c9-Q
426c72:c3 retq
426c73:90无
movupd[aptr]，XMM1movupd-aptr，XMM1aptrmov-aptr，RAX；movupd[RAX]，XMM1