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.POPFRAME

Generates a WOD_PUSH_CANONICAL_FRAME Windows unwind data (WOD) unwind code entry in the epilogue.

Syntax

.POPFRAME ⟦CODE | value⟧

Parameters

value
An optional numeric modifier in the range 0–255.
Mutually exclusive with CODE. If you specify the optional CODE keyword, the unwind code entry receives a modifier of 1.
If you specify an optional numeric value instead, it receives the specified value.
If you don't pass an argument, the value is 0.

Remarks

Important

This directive is experimental and is subject to change. Enable Unwind Version 3 with ml64.exe /unwindv3.

The .POPFRAME directive lets ml64.exe users specify how a frame function unwinds in an epilog. You can only use it within an epilog region, between .BEGINEPILOG and .ENDEPILOG.

  • .POPFRAME is only valid in Unwind Version 3. It's the epilog counterpart of .PUSHFRAME. The operand value should match the corresponding .PUSHFRAME in the prologue.
  • In Unwind Version 3, .POPFRAME must appear before the instruction that implements the action to be unwound. To ensure agreement, wrap both the unwind directives and the code they're meant to unwind in a macro.
  • In Unwind Version 3, epilogue directives are mandatory for epilogue unwind code generation. No epilogue unwind codes are emitted without a .BEGINEPILOG/.ENDEPILOG pair.
  • These directives generate unwind metadata (.xdata and .pdata sections) but don't produce executable code.

Note

In Unwind Version 1, directives appear after the corresponding instruction. In Unwind Version 3, directives appear before the instruction.

Example for unwindv3

The following example shows how to use .POPFRAME in an epilogue to indicate an interrupt handler that pushes and pops a canonical machine frame.

; ml64 /unwindv3 ex1.asm /link /entry:Example1 /SUBSYSTEM:CONSOLE
_text SEGMENT
Example1 PROC FRAME
   .pushframe
   .pushreg rbx
   push rbx
   .allocstack 32
   sub rsp, 32
.endprolog
   ; interrupt handler body ...
   .beginepilog
   .freestack 32
   add rsp, 32
   .popreg rbx
   pop rbx
   .popframe
   .endepilog
   iretq
Example1 ENDP
_text ENDS
END

See also

x64 Unwind Version 3 (experimental)
.PUSHFRAME
.BEGINEPILOG
.ENDEPILOG
MASM BNF Grammar

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