Remove real type

[bearophile]

Walter Bright:
> I agree. The only reason to use float or double is to save on storage.

A little D1 program, that I compile with LDC:

import tango.stdc.stdio: printf;
import tango.stdc.stdlib: atof;
alias real FP;
void main() {
    FP x = atof("1.5");
    FP y = atof("2.5");    
    FP xy = x * y;
    printf("%lf\n", xy);
}


ldc -O3 -release -inline -output-s temp.d

FP = double:

_Dmain:
	subl	$36, %esp
	movl	$.str, (%esp)
	call	atof
	movl	$.str1, (%esp)
	fstpl	24(%esp)
	call	atof
	fstpl	16(%esp)
	movsd	24(%esp), %xmm0
	mulsd	16(%esp), %xmm0
	movsd	%xmm0, 4(%esp)
	movl	$.str2, (%esp)
	call	printf
	xorl	%eax, %eax
	addl	$36, %esp
	ret	$8

-------------------------

FP = real:

_Dmain:
	subl	$28, %esp
	movl	$.str, (%esp)
	call	atof
	fstpt	16(%esp)
	movl	$.str1, (%esp)
	call	atof
	fldt	16(%esp)
	fmulp	%st(1)
	fstpt	4(%esp)
	movl	$.str2, (%esp)
	call	printf
	xorl	%eax, %eax
	addl	$28, %esp
	ret	$8


If you use the real type you are forced to use X86 FPU, that is very inefficient if used by LDC.

Bye,
bearophile