delphi - 如何在Delphi中检测AVX2？

如果CPU具有AVX1或AVX2，则以下代码返回True。有人知道如何修改此代码以准确检测AVX2指令支持吗？

function isAvxSupported: Boolean;
asm
{$IFDEF CPUX86}
    push ebx
{$ENDIF}
{$IFDEF CPUX64}
    mov r10, rbx
{$ENDIF}
    xor eax, eax
    cpuid
    cmp eax, 1
    jb @not_supported
    mov eax, 1
    cpuid
    and ecx, 018000000h
    cmp ecx, 018000000h
    jne @not_supported
    xor ecx, ecx
    db 0Fh, 01h, 0D0h //XGETBV
    and eax, 110b
    cmp eax, 110b
    jne @not_supported
    mov eax, 1
    jmp @done
@not_supported:
    xor eax, eax
@done:
{$IFDEF CPUX86}
    pop ebx
{$ENDIF}
{$IFDEF CPUX64}
    mov rbx, r10
{$ENDIF}
end;

最佳答案

本质上，在使用AVX2之前，您需要检查


如果通过检查CPUID支持AVX2指令集。（EAX = 07H，ECX = 0H）：EBX.AVX2 [bit 5] = 1
如果操作系统启用了YMM寄存器的使用


步骤1可以完成，例如使用此功能：

function IsAVX2supported: boolean;
asm
    // Save EBX
    {$IFDEF CPUx86}
      push ebx
    {$ELSE CPUx64}
      mov r10, rbx
    {$ENDIF}
    //Check CPUID.0
    xor eax, eax
    cpuid //modifies EAX,EBX,ECX,EDX
    cmp al, 7 // do we have a CPUID leaf 7 ?
    jge @Leaf7
      xor eax, eax
      jmp @Exit
    @Leaf7:
      //Check CPUID.7
      mov eax, 7h
      xor ecx, ecx
      cpuid
      bt ebx, 5 //AVX2: CPUID.(EAX=07H, ECX=0H):EBX.AVX2[bit 5]=1
      setc al
   @Exit:
   // Restore EBX
   {$IFDEF CPUx86}
     pop ebx
   {$ELSE CPUx64}
     mov rbx, r10
   {$ENDIF}
end;

步骤2可以完成，例如使用此功能：

function OSEnabledXmmYmm: boolean;
// necessary to check before using AVX, FMA or AES instructions!
asm
  {$IFDEF CPUx86}
  push ebx
  {$ELSE CPUx64}
  mov r10, rbx
  {$ENDIF}
  mov eax,1
  cpuid
  bt ecx, 27  // CPUID.1:ECX.OSXSAVE[bit 27] = 1 (XGETBV enabled for application use; implies XGETBV is an available instruction also)
  jnc @not_supported
    xor ecx,ecx //Specify control register XCR0 = XFEATURE_ENABLED_MASK register
    db 0Fh, 01h, 0D0h // xgetbv //Reads XCR (extended control register) -> EDX:EAX
    {lgdt eax = db 0Fh, 01h = privileged instruction, so don't go here unless xgetbv is allowed}
      //CHECK XFEATURE_ENABLED_MASK[2:1] = ‘11b’
      and eax, 06h //06h= 00000000000000000000000000000110b
      cmp eax, 06h//; check OS has enabled both XMM (bit 1) and YMM (bit 2) state management support
    jne @not_supported
      mov eax,1
      jmp @out
  @not_supported:
    xor eax,eax
  @out:
 {$IFDEF CPUx86}
  pop ebx
  {$ELSE CPUx64}
  mov rbx, r10
  {$ENDIF}
end;

当然，您也可以使用它来修改发布的函数，使其仅具有一个要调用的函数。

关于delphi - 如何在Delphi中检测AVX2？，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/41468871/