Re: vax/ddb(4): clean up machine dependent code and improve usability

Rhialto <[email protected]> Tue, 11 Mar 2025 18:08:07 +0100
Newsgroups	gmane.os.netbsd.ports.vax
Message-ID	<[email protected]>
On Mon 10 Mar 2025 at 13:08:09 +0100, Hans Rosenfeld wrote:
> Since this is a rather large change, I'd like to give anyone interested
> a chance to do a proper code review before I commit this. I've been

It's not a change you made, but it occurs in the diff a lot:

In functions that take a printf-like function pointer pr:
void (*pr)(const char *, ...), the function is called as

	(*pr)("hallo");

Due to the vagaries of the C type system (a value of type "function"
decays to the function's address), *pr is effectively the same thing as
pr. In fact, also if you write a call like  foo(arg)   this same
mechanism takes effect. So you could equally well write

	(*******pr)("hallo");

but more practical would be simply

	pr("hallo");

And yes, this means you really can use "C++-like syntax" like
ptr->member(arg1, arg2) if you have a struct with function pointers in
it.

For an example of generated code, see https://godbolt.org/z/v8cbvss1r
a.k.a.
https://godbolt.org/#g:!((g:!((g:!((h:codeEditor,i:(filename:'1',fontScale:14,fontUsePx:'0',j:1,lang:c%2B%2B,selection:(endColumn:15,endLineNumber:6,positionColumn:15,positionLineNumber:6,selectionStartColumn:15,selectionStartLineNumber:6,startColumn:15,startLineNumber:6),source:'static+void%0Adb_trace_process(struct+lwp+*l,+struct+proc+*p,+void+(*pr)(const+char+*,+...))%0A%7B%0A++++++++pr(%22hallo%22)%3B%0A++++++++(*pr)(%22hallo%22)%3B%0A++++++++(******pr)(%22hallo%22)%3B%0A%7D%0A'),l:'5',n:'0',o:'C%2B%2B+source+%231',t:'0')),k:50,l:'4',n:'0',o:'',s:0,t:'0'),(g:!((h:compiler,i:(compiler:vaxg1050,filters:(b:'0',binary:'1',binaryObject:'1',commentOnly:'0',debugCalls:'1',demangle:'0',directives:'0',execute:'1',intel:'0',libraryCode:'0',trim:'1',verboseDemangling:'0'),flagsViewOpen:'1',fontScale:14,fontUsePx:'0',j:1,lang:c%2B%2B,libs:!(),options:'',overrides:!(),selection:(endColumn:1,endLineNumber:1,positionColumn:1,positionLineNumber:1,selectionStartColumn:1,selectionStartLineNumber:1,startColumn:1,startLineNumber:1),source:1),l:'5',n:'0',o:'+VAX+gcc+NetBSDELF+10.5.0+(Nov+15+03:50:22+2023)+(Editor+%231)',t:'0')),k:50,l:'4',n:'0',o:'',s:0,t:'0')),l:'2',n:'0',o:'',t:'0')),version:4

-Olaf.
-- 
___ Olaf 'Rhialto' Seibert                            <rhialto/at/falu.nl>
\X/ There is no AI. There is just someone else's work.           --I. Rose
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