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digitalmars.D.bugs - [Issue 2350] New: Contracts with a naked body are indecent

reply d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=2350

           Summary: Contracts with a naked body are indecent
           Product: D
           Version: 1.034
          Platform: PC
        OS/Version: Windows
            Status: NEW
          Keywords: wrong-code
          Severity: normal
          Priority: P4
         Component: DMD
        AssignedTo: bugzilla digitalmars.com
        ReportedBy: clugdbug yahoo.com.au


It seems that in/out contracts assume that a stack frame has been set up. This
is not true for naked functions, so bad code is generated. Ideally, if the body
contains the keyword 'naked', in/out contracts should create and destroy a
stack frame.

----
void rude(int a)
in {
        assert(a==1);
}
body {
        asm { naked; }
}

void main() {
        rude(1);
}


--
Sep 09 2008
next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=2350


Stewart Gordon <smjg iname.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |smjg iname.com



In which case, what would "naked" do?  If nothing, the compiler ought to
disallow it.

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Sep 04 2011
prev sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=2350






 In which case, what would "naked" do?  If nothing, the compiler ought to
 disallow it.


For non-naked functions, the contracts don't set up a stack frame, because the
function already does it. The generated code is:
 push EBP;
 mov EBP, ESP;
 <run in contract>
 <run function body>
 <run out contract>
 pop EBP;

If no contracts are present, or with -release, the generated code is currently:
 <run naked body>
which is correct.

But if contracts are present, and not in a release build, the code is:
 <run in contract>
 <run naked body>
 <run out contract>
which causes a crash. Correct behaviour would be:

 push EBP;
 mov EBP, ESP;
 <run in contract>
 pop EBP;
 <run naked body>
 push EBP;
 mov EBP, ESP;
 <run out contract>
 pop EBP;

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Sep 05 2011