How to overload member function pointer and a regualr member function

[Ali Çehreli via Digitalmars-d-learn]

On 04/25/2017 11:28 AM, ParticlePeter wrote:
 > On Tuesday, 25 April 2017 at 16:27:43 UTC, Basile B. wrote:

 >> with pragma(inline, true), the function body should be injected at the
 >> call sites.
 >
 > This would not help I fear, the body of the function pointer is unknown
 > in an external lib. I rather hoped that the compiler "sees" the
 > parameter forwarding to the fp and is able to directly call it. Best
 > thing would be for both overloads, but I would not know how to verify 
this.

pragma(inline, true) works because all you need inlined in this case is 
the body of bar(int, float). The compiler does call the function pointer 
directly.

import std.stdio;

struct Foo1
{
     private void function(int,float) _bar;
     void bar(float f) {
         pragma(inline, true);
         writefln("Called with %s", f);
     }
     void bar(int i, float f) {
         pragma(inline, true);
         _bar(i,f);
     }
}

void func(int i, float f) {
     writefln("Called with %s and %s", i, f);
}

void main() {
     auto f = Foo1(&func);
     f.bar(1.5);
     f.bar(42, 2.5);
}

Compile with -inline (and perhaps with -O):

   dmd -inline deneme.d

Generate the disassembly with obj2asm that comes with dmd (or with any 
other disassembly tool):

   obj2asm deneme.o > deneme.asm

You can open deneme.asm in an editor and search for function "_Dmain:" 
in it. Here is what my dmd 2.074 produced:

_Dmain:
		push	RBP
		mov	RBP,RSP
		sub	RSP,010h
		mov	RAX,_D6deneme4funcFifZv at GOTPCREL[RIP]
		mov	-010h[RBP],RAX
		movss	XMM0,FLAT:.rodata[00h][RIP]
		movss	-8[RBP],XMM0
		lea	RDX,_TMP0 at PC32[RIP]
		mov	EDI,0Eh
		mov	RSI,RDX
		movss	XMM0,-8[RBP]
		call	  _D3std5stdio17__T8writeflnTaTfZ8writeflnFNfxAafZv at PLT32
		mov	EAX,02Ah
		movss	XMM1,FLAT:.rodata[00h][RIP]
		movss	-4[RBP],XMM1
		mov	RDI,RAX
		movss	XMM0,-4[RBP]
		call	qword ptr -010h[RBP]
		xor	EAX,EAX
		leave
		ret
		add	[RAX],AL
.text._Dmain	ends

The call to jumbled writefln() is a direct call inside func():

		call	  _D3std5stdio17__T8writeflnTaTfZ8writeflnFNfxAafZv at PLT32

So, you're good... :)

Ali