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From:	"Dave Korn" <dave DOT korn AT artimi DOT com>
To:	<cygwin AT cygwin DOT com>
References:	<20070121143731 DOT GC25379 AT ns1 DOT anodized DOT com> <009401c73d79$4cf91d40$a501a8c0 AT CAM DOT ARTIMI DOT COM> <loom DOT 20070122T085309-902 AT post DOT gmane DOT org>
Subject:	RE: cygwin source question
Date:	Mon, 22 Jan 2007 10:42:19 -0000
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On 22 January 2007 08:19, Yitzchak Scott-Thoennes wrote:

> 
> Some people prefer (expr) ? 1 : 0, which looks a lot worse to me than
> !!(expr). 
> 

  Compiles to the exact same thing at -O0 and at -O2, as it happens...

/tmp $ gcc -x c -S -o - -

int foo (int argc)
{
  return (argc == 23) ? 1 : 0;
}

int bar (int argc)
{
  return !!(argc == 23);
}

        .file   ""
        .text
.globl _foo
        .def    _foo;   .scl    2;      .type   32;     .endef
_foo:
        pushl   %ebp
        movl    %esp, %ebp
        cmpl    $23, 8(%ebp)
        sete    %al
        movzbl  %al, %eax
        popl    %ebp
        ret
.globl _bar
        .def    _bar;   .scl    2;      .type   32;     .endef
_bar:
        pushl   %ebp
        movl    %esp, %ebp
        cmpl    $23, 8(%ebp)
        sete    %al
        movzbl  %al, %eax
        popl    %ebp
        ret
@_______. .
(       /"\
 ||--||(___)
 '"  '"'---'
/tmp $ gcc -O0 -x c -S -o - -

int foo (int argc)
{
  return (argc == 23) ? 1 : 0;
}

int bar (int argc)
{
  return !!(argc == 23);
}

        .file   ""
        .text
.globl _foo
        .def    _foo;   .scl    2;      .type   32;     .endef
_foo:
        pushl   %ebp
        movl    %esp, %ebp
        cmpl    $23, 8(%ebp)
        sete    %al
        movzbl  %al, %eax
        popl    %ebp
        ret
.globl _bar
        .def    _bar;   .scl    2;      .type   32;     .endef
_bar:
        pushl   %ebp
        movl    %esp, %ebp
        cmpl    $23, 8(%ebp)
        sete    %al
        movzbl  %al, %eax
        popl    %ebp
        ret
@_______. .
(       /"\
 ||--||(___)
 '"  '"'---'
/tmp $ gcc -O2 -x c -S -o - -

int foo (int argc)
{
  return (argc == 23) ? 1 : 0;
}

int bar (int argc)
{
  return !!(argc == 23);
}

        .file   ""
        .text
        .p2align 4,,15
.globl _foo
        .def    _foo;   .scl    2;      .type   32;     .endef
_foo:
        pushl   %ebp
        xorl    %eax, %eax
        movl    %esp, %ebp
        cmpl    $23, 8(%ebp)
        popl    %ebp
        sete    %al
        ret
        .p2align 4,,15
.globl _bar
        .def    _bar;   .scl    2;      .type   32;     .endef
_bar:
        pushl   %ebp
        xorl    %eax, %eax
        movl    %esp, %ebp
        cmpl    $23, 8(%ebp)
        popl    %ebp
        sete    %al
        ret
@_______. .
(       /"\
 ||--||(___)
 '"  '"'---'
/tmp $


  ... so no reason not to choose whichever you like the best.

    cheers,
      DaveK
-- 
Can't think of a witty .sigline today....


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